Gas in the pleural space is termed a pneumothorax. A primary spontaneous pneumothorax (PSP) is a pneumothorax that occurs in the absence of clinical lung disease. A secondary spontaneous pneumothorax (SSP) is a pneumothorax which presents as a complication of underlying lung disease. Other etiologies of pneumothorax include traumatic and miscellaneous (anorexia nervosa, exercise, illicit drug use, immunosuppressant drugs, air travel and scuba diving). Determining the etiology of a pneumothorax dictates immediate and definitive management. As such, the clinician needs to be familiar with the wide array of etiologies when faced with pneumothorax so that appropriate therapy can be administered promptly to prevent deterioration and recurrence.
The roles of the respiratory tract are to cushion the lungs and reduce any friction which may develop between the lungs, rib cage, and chest cavity. The pleura consists of a two-layered membrane that covers each lung. The layers are separated by a small amount of viscous lubricant known as pleural fluid.1
There are a number of medical conditions that can affect the pleura, including pleural effusions, pneumothoraces, a collapsed lung, and cancer. When excess fluid accumulates between the pleural membranes, various procedures may be used to either drain the fluid or eliminate the space between the membranes. The plural form of pleura is pleurae.
There are two pleurae, one for each lung, and each pleura is a single membrane that folds back on itself to form two layers. The space between the membranes (i.e., the pleural cavity) is filled with a thin, lubricating liquid (i.e., the pleural fluid). The pleura is comprised of two distinct layers. 1 (Picture 1)
The visceral pleura is the thin, slippery membrane that covers the surface of the lungs and dips into the areas separating the different lobes of the lungs (i.e., the hilum). The parietal pleura is the outer membrane that lines the inner chest wall and diaphragm (the muscle separating the chest and abdominal cavities).
The visceral and parietal pleura join at the hilum, which also serves as the point of entry for the bronchus, blood vessels, and nerves.
The pleural cavity, also known as the intrapleural space, contains pleural fluid secreted by the mesothelial cells. The fluid allows the layers to glide over each other as the lungs inflate and deflate during respiration.
The structure of the pleura is essential to respiration, providing the lungs with the lubrication and cushioning needed to inhale and exhale. The intrapleural space contains roughly 4 cubic centimeters (ccs) to 5 ccs of pleural fluid, which reduces friction whenever the lungs expand or contract.1
The pleura fluid itself has a slightly adhesive quality that helps draw the lungs outward during inhalation rather than slipping round in the chest cavity. Pleural fluid also creates surface tension that helps maintain the position of the lungs against the chest wall.
The pleurae also serve as a division between other organs in the body, preventing them from interfering with lung function and vice versa. Because the pleura is self-contained, it can help prevent the spread of infection to and from the lungs.
A PSP is traditionally defined as a pneumothorax that presents without a precipitating external event in the absence of clinical lung disease. Although PSP is not associated with known clinical lung disease (e.g., chronic obstructive pulmonary disease [COPD]), most affected patients have unrecognized lung abnormalities (mostly subpleural blebs) that likely predispose to pneumothorax.2
However, following investigation, some patients with apparent PSP may have other more serious underlying lung diseases (e.g., Birt-Hogg-Dubé [BHD] syndrome, thoracic endometriosis, lymphangioleiomyomatosis [LAM]), thereby re-categorizing them as having SSP. Thus, many experts believe that the distinction between pneumothorax in patients “without” lung disease (i.e., pneumothorax with subpleural blebs, also known as PSP) and pneumothorax in patients with lung diseases (i.e., SSP) is somewhat artificial and that PSP and SSP may exist on either end of a continuum.2
PSP is more common in men than women (roughly three to six times higher). The incidence of PSP in men ranges from 7.4 per 100,000 population/year in the United States to 37 per 100,000 population/year in the United Kingdom. The incidence in women ranges from 1.2 per 100,000 population/year in the United States to 15.4 per 100,000 population/year in the United Kingdom.2 The reason for these geographic differences is unknown.
Another hospital database study of emergency department (ED) visits from January 2008 to December 2014 reported that 79% of pneumothoraces were in males and 21% in females.2 The prevalence of asymptomatic PSP is unknown, but one retrospective study of Japanese students suggested that the rate may be as high as 0.042% and higher in men than women.2 Mild collapse (i.e., <10% collapse) was present in approximately half of the individuals, most of whom underwent intervention.
PSP is thought to be due to small apical subpleural blebs or bullae (i.e., air sacs between the lung tissue and pleura) that rupture into the pleural cavity. The mechanism of bleb/bulla formation is unknown. However, since PSP classically occurs in tall, thin males between the ages of 10 and 30 years2, the development of subpleural blebs is thought to be due to either increasing negative pressure or greater mechanical alveolar stretch at the apex of the lungs during growth or a congenital phenomenon in which lung tissue at the apex grows more quickly than the vasculature, thereby outstripping its blood supply.
Pathologic assessment of resected specimens suggests that there are disrupted areas of mesothelial cells, inflammation, and pores of 10 to 20 microns in diameter rather than a breach in the visceral pleural membrane.2 Leakage of fluorescein seen on autofluorescence thoracoscopy also supports this theory.2
Cigarette smoking (current or past) is a significant risk factor for PSP, probably due to airway inflammation and respiratory bronchiolitis. For example, in an analysis of four studies that included 505 patients with PSP, 91% were smokers.2 Furthermore, the risk of PSP was directly related to the amount of cigarette smoking. Compared with nonsmokers, the relative risk of PSP in men was seven times higher in light smokers (1 to 12 cigarettes/day), 21 times higher in moderate smokers (13 to 22 cigarettes/day), and 102 times higher in heavy smokers (>22 cigarettes/day).2
For women, the relative risk was 4, 14, and 68 times higher in light, moderate, and heavy smokers, respectively. Similarly, patients with PSP who smoke cigarettes have more respiratory bronchiolitis and higher recurrence rates than those who do not smoke.2
Regularly smoking cannabis appears to increase the risk of PSP similarly to smoking cigarettes.2
Reports have been published describing the clustering of PSP in certain families.2 Autosomal dominant, autosomal recessive, polygenic, and X-linked recessive inheritance mechanisms have all been proposed.2 Genetic variants associated with PSP include2:
The autosomal dominant BHD syndrome due to mutations in the folliculin [FLCN] gene), hyperhomocysteinemia, alpha-1 antitrypsin and Marfan syndrome are also inherited conditions associated with pneumothorax that may masquerade as PSP when the diagnosis is not known. For example, one study reported that 5% to 10% of patients with PSP turned out to have BHD syndrome following investigation.2
Several reports suggest that drops in atmospheric pressure may be associated with an increase in the incidence of pneumothorax.2
SSP is defined as a pneumothorax that presents as a complication of underlying lung disease.2
SSP has a male preponderance, but in contrast with PSP, SSP presents in older patients (>55 years).2 One large hospital database of admissions reported that the rate of admissions for spontaneous pneumothorax, 61% of which were due to COPD, has increased by 9% over a 48-year period from 1968 through 2016.2 Rates were higher in males than females (73% versus 27%).
Nearly every lung disease can be complicated by SSP, although the most commonly associated diseases are COPD and, in endemic areas, tuberculosis (TB). Other common causes include cystic fibrosis (CF), primary or metastatic lung malignancy, and necrotizing pneumonia.2
Pneumothorax typically presents as a complication of these common diseases and is rarely an initial manifestation. In contrast, pneumothorax may be the presenting feature of uncommon causes of SSP, and the diagnosis may not be known upon presentation (e.g., LAM, BHD syndrome). In one study of hospital admissions, up to 80% of SSP cases were due to emphysema/COPD, interstitial lung disease, and malignancy while TB, sarcoidosis, and CF were responsible for <2% of cases.2
COPD is the most common cause of SSP, with 50 to 70% of SSP cases attributed to COPD in small case series.2 Rupture of apical blebs or bullae is the usual cause. Patients with COPD may also be at higher risk for iatrogenic pneumothorax (e.g., venous catheterization, mechanical ventilation), particularly when there is a significant amount of underlying emphysema or air trapping.
The severity of COPD correlates with the likelihood of developing SSP. For example, more than 30% of patients with SSP due to COPD have a forced expiratory volume in one second (FEV1) less than one liter and an FEV1 to forced vital capacity (FEV1/FVC) ratio less than 40%.2
Approximately 3 to 4% of patients with CF will have an episode of SSP during their lifetime. However, in those who survive to age 18, the incidence is 16% to 20%.2 CF-related SSP is usually due to the rupture of apical subpleural cysts. The risk of pneumothorax in CF increases with the severity of lung function abnormalities.
In one report, nearly half of all patients with CF who had an FEV1 less than 20% of predicted experienced at least one SSP.2 Other than cysts and fibrosis, other factors that may predispose to the development of pneumothorax in CF which may reflect disease severity rather than being independent risk factors include2:
Both primary and metastatic lung malignancies have been associated with SSP. Among 168 patients with SSP, malignancy was the underlying cause of 16%. The underlying malignancy was more commonly a lung primary than metastatic disease.2 Potential mechanisms include tumor necrosis, endobronchial obstruction with air trapping, development of necrotizing cysts or pneumonia, and coexisting COPD/emphysema.
Less commonly, malignancies that metastasize to the lung are associated with the development of necrotic cysts, which can result in SSP. Examples include:
SSP can complicate the course of necrotizing pneumonia due to Pneumocystis jirovecii (i.e., pneumocystis pneumonitis [PCP]), TB, bacteria, and less often fungi or other microorganisms.2 The relative frequency of these etiologies depends upon the frequency of these diseases in the population studied.
The presumed common mechanism underlying pneumothorax in patients with lung infection is direct invasion and necrosis of lung tissue, including the pleura by the microorganism itself.
Unilateral and bilateral SSP can be seen in patients with PCP, most often in patients with human immune deficiency virus (HIV).2 In the era of antiretroviral therapy (ART), the frequency of pneumothorax complicating PCP is approximately 5% to 10%.2 However, another study reported lower rates, with pneumothorax complicating only 1.2% of all hospital admissions in a cohort of 599 HIV-infected patients. However, over half had non-pulmonary reasons for admission.2
In patients with HIV-related PCP, it has been hypothesized that the administration of aerosolized pentamidine may increase the likelihood for PCP to grow and cause cavitation in the peripheral parts of the upper lobe, thereby increasing the risk for pneumothorax.2 This phenomenon may relate to the preferential delivery of the aerosolized agent to the proximal parenchyma of the lower lobes rather than upper lobes. Unlike bacterial pneumonia, pneumothorax associated with PCP is more likely to be bilateral than unilateral.2
SSP occurs in 1% to 3% of patients hospitalized with pulmonary TB.2 Rates are higher in endemic areas.2 The pneumothorax is usually due to the rupture of a tuberculous cavity into the pleural space.
SSP has been associated with bacterial pneumonias caused by Staphylococcus, Klebsiella, Pseudomonas, Streptococcus pneumoniae, and anaerobic organisms. Among 168 patients with SSP, bacterial pneumonia was the etiology in 11% of cases.2 SSP in the setting of bacterial pneumonia is more likely to be unilateral than bilateral and can be associated with extension of the bacterial infection into the pleura and development of empyema, giving the appearance of a hydropneumothorax.
Several other pulmonary infections have been associated with pneumothorax including fungal, viral, and mycobacterial infections other than TB.2
Pneumothorax is common in lung conditions associated with cysts. However, since many of these conditions are rare, pneumothorax in this setting may masquerade as PSP when the underlying diagnosis is unknown. Disorders associated with cysts include:
Catamenial pneumothorax refers to a pneumothorax occurring in association with menses due to thoracic endometriosis. In this condition pneumothorax is thought to relate to the development and involution of pleural implants comprised of endometrial tissue. Subsequently, some experts consider this a PSP since parenchymal lung disease is typically absent.
Pneumothorax is seen in HIV due to several etiologies, particularly infections including PCP pneumonia, bacterial pneumonia, and pulmonary TB, as well as, toxoplasmosis, and fungal, viral, and mycobacterial infections.2 Patients with HIV can also be at risk for iatrogenic pneumothorax, as well as, pneumothorax due to the presence of pneumatoceles (typically from old Staphylococcal or PCP infection), Kaposi sarcoma, intravenous drug abuse, and cigarette smoking.2 One report suggested that the degree of immunosuppression in HIV may affect the etiology of pneumothorax. In patients with CD4 positive lymphocyte counts >200 cells/mL, pneumothorax was more likely due to bacterial pneumonia whereas in those with counts <200 cells/mL, pneumothorax was more often associated with Pneumocystis jirovecii.2
Pneumothorax may occur in conditions where the integrity of the pleural membrane and parenchyma is abnormal, the diagnosis of which may or may not be known at the time of presentation. These include2:
In Marfan and Ehlers-Danlos syndrome, it is thought that abnormal elastin or collagen content of the pleural membrane and parenchyma may predispose patients to pneumothorax. Patients with Marfan syndrome may also develop parenchymal cysts that may increase the risk of developing a pneumothorax.
Why patients with homocystinuria develop pneumothorax is less clear, but homocysteine plays a role in vascular homeostasis and the regulation of smooth muscle and collagen production in the lung.2
Less common causes of SSP include2:
Pneumothorax is traumatic when due to blunt or, more commonly, penetrating thoracic trauma. Trauma is probably the most common cause of pneumothorax. Traumatic pneumothorax can be categorized as iatrogenic or non-iatrogenic.
Pneumothorax is iatrogenic when it is induced by a medical procedure, typically procedures that have the potential to introduce air into the pleural space via the chest, neck, gut, or abdomen.2 Most commonly, iatrogenic pneumothorax is induced by2:
The prevalence of iatrogenic pneumothorax is poorly studied but likely varies with the prevalence of procedures performed, presence of risk factors such as underlying lung disease, and operator experience.2 In one study of over 12,000 procedures, the prevalence of pneumothorax was 1.4%, among which 57% were due to emergency procedures.2
The most frequent procedures associated with pneumothorax were central venous catheterization (44%), thoracentesis (20%), and barotrauma due to mechanical ventilation (9%). Another study reported a higher incidence of iatrogenic pneumothorax in teaching compared with non-teaching hospitals.2
Non-iatrogenic pneumothorax due to external trauma may be minor or severe. It is also termed “open pneumothorax” when a penetrating traumatic chest wall defect is present, through which atmospheric air enters the pleural space during inspiration (i.e., a "sucking wound") and exits during expiration, resulting in a mediastinal swing away from the affected side during inspiration and toward the affected side during expiration (“mediastinal flutter”).
Several rare case reports have described pneumothorax in association with the following:
Pneumothorax should be suspected in patients who present with acute dyspnea and chest pain (CP) (classically pleuritic), particularly in those with an underlying risk factor. The major competing diagnoses include:
The classic presentation of patients with pneumothorax include the following:
Pneumothorax most often presents with sudden onset of dyspnea and pleuritic CP. Since pneumothorax is usually unilateral, the pain is usually felt on the ipsilateral, i.e., on the same side of the body. However, it may be central or bilateral in rare cases where pneumothorax is bilateral. The intensity of dyspnea can range from mild to severe. The severity of the symptoms primarily relates to the volume of air in the pleural space and the degree of pulmonary reserve, with dyspnea being more prominent if the pneumothorax is large and/or underlying disease is present.
Pneumothorax can present at all ages. Patients with PSP, i.e., that associated with subpleural blebs in the absence of an underlying disorder,3 are typically in their early 20s. PSP is rare after age 40 and classically occurs in young, tall, thin, smoking males.
In contrast, since most cases of SSP, i.e., that associated with underlying lung disease, is due to emphysema, these patients tend to be older. This finding, however, is not absolute. For example, pneumothorax in patients with LAM or thoracic endometriosis presents in young, non-smoking females of reproductive age. Symptoms usually develop when the patient is at rest, although occasionally, pneumothorax develops during exercise, air travel, scuba diving, or illicit drug use.
Alternatively, symptoms may occur during or following an invasive procedure or trauma to the chest, neck, gut, or abdomen. A history of a risk factor or a disorder that can be complicated by pneumothorax may be present.
In patients with a small pneumothorax, physical examination findings may not be evident or may be limited to signs of the underlying lung disease, if present. However, characteristic physical findings when a large pneumothorax is present include:
Evidence of labored breathing, or accessory muscle usage suggests a sizeable pneumothorax or a pneumothorax in a patient with significant underlying lung disease. Tracheal deviation away from the affected side is a late sign but is not always indicative of a tension pneumothorax. Hemodynamic compromise (e.g., tachycardia, hypotension) is an ominous sign and suggests a tension pneumothorax and/or impending cardiopulmonary collapse.
Some patients with mild or chronic pneumothorax may be asymptomatic and discovered incidentally. For example, among women with LAM who underwent chest imaging for research purposes after traveling to the National Institutes of Health (NIH), pneumothorax was discovered in 6% of women, among which 57% were chronic and not associated with new symptoms.3 Patients with pneumothorax on mechanical ventilation (i.e., barotrauma) are more likely to present with acute respiratory distress and elevated pressures.
Laboratory findings of pneumothorax are nonspecific but may reveal a mild leukocytosis without left shift. Most patients who present with pneumothorax have routine laboratories performed, including D-dimer level and troponin levels to investigate the cause of dyspnea and CP. As such, these laboratory tests are useful for the detection or exclusion of competing etiologies such as myocardial ischemia or PE or for the diagnosis of possible etiologies that underlie the pneumothorax such as infection.
In patients with pneumothorax, peripheral oxygen saturation (SpO2) may be normal in those without underlying lung disease in whom the pneumothorax is small. However, in patients with sizeable pneumothorax or lung disease, oxygen desaturation is usually evident. ABGs are typically obtained when a patient demonstrates:
Hypoxemia is common but may be within normal limits if the pneumothorax is small and underlying lung disease is absent. Pneumothorax typically causes an acute respiratory alkalosis, particularly when pain, anxiety, and/or hypoxemia are substantial. However, acute hypercapnic respiratory acidosis is unusual because adequate alveolar ventilation can usually be maintained by the contralateral lung unless underlying disease such as COPD or cardiovascular compromise is present.3 In one study of patients with SSP, the arterial oxygen tension (PaO2) was below 55 mmHg in 17% of patients and below 45 mmHg in 4%, while the arterial tension of carbon dioxide (PaCO2) exceeded 50 mmHg in 16% and exceeded 60 mmHg in 4%.3
ECG findings are also nonspecific and may reveal a sinus tachycardia. A more serious rhythm disturbance (e.g., bradycardia) may be associated with severe hypoxemia or indicate tension pneumothorax and impending cardiovascular collapse.
The diagnosis of pneumothorax is a radiologic one. The choice of imaging modality is dependent upon the stability of presentation, the availability of bedside pleural ultrasonography, and the degree of suspicion for competing diagnoses.
In general, while those who are unstable should have rapid bedside imaging with pleural ultrasonography, those with a stable presentation can wait for confirmation by plain chest x-ray (CXR). Occasionally, chest computed tomography (chest CT) is required for those:
Hemodynamically unstable patients and patients with severe respiratory distress are typically those patients with:
Such patients are resuscitated with the emphasis on stabilization of the airway, breathing, and circulation. Unstable patients should also concomitantly undergo rapid bedside imaging, usually with pleural ultrasonography, to confirm the diagnosis before undergoing emergent needle or chest tube thoracostomy. In the event that pleural ultrasonography is unavailable or unhelpful, then an empiric decision to place a chest tube without confirmatory imaging should be made on clinical assessment alone.
Most patients suspected of having a pneumothorax who are hemodynamically stable and/or not in severe respiratory distress should undergo a routine bedside CXR in the upright position. Inspiratory and expiratory films have equal sensitivity in detecting pneumothoraces. As such, a standard inspiratory CXR is sufficient in most cases.3
CXR may not be needed when:
Chest CT is reserved for patients in whom the diagnosis is uncertain following CXR (e.g., patients with suspected loculated pneumothorax, complicated bullae, or a complex pleural space).
CXR (typically performed in the upright position) is the most common diagnostic imaging modality used for stable patients with suspected pneumothorax. When a pneumothorax is clinically suspected, a CXR should be performed on both inspiration (as per usual) AND expiration. On an expiratory film, a pneumothorax will appear relatively larger, taking up a larger percentage of the thoracic cavity. The pleura is pushed further away from the chest wall, and the pneumothorax is usually a lot more evident than on the inspiratory radiograph.
Picture 3: A chest x-ray film of a patient with spontaneous pneumothorax, a visceral pleura is seen separated from the parietal pleura
The presence of a pneumothorax is established by demonstrating a white visceral pleural line on the CXR. The visceral pleural line defines the interface between the lung and pleural air. Bronchovascular markings are not typically visible beyond the visceral pleural edge unless it is loculated. The ipsilateral hemithorax size may be increased. Most pneumothoraces are simple pneumothoraces, whereas, although uncommon, true tension pneumothorax is a life-threatening emergency.
A simple pneumothorax is one without a mediastinal shift to the contralateral side. Patients are clinically and hemodynamically stable.
A tension pneumothorax arises when the air in the pleural space builds up enough pressure to interfere with venous return, leading to hypotension, tachycardia and severe dyspnea. Tension pneumothorax may be seen in approximately 1% to 2% of patients,3 likely higher in patients with trauma and patients receiving mechanical ventilation. In the mechanical ventilation group, patients who develop initial signs of a pneumothorax are more likely to rapidly progress to cardiovascular collapse than those who are not on mechanical ventilation.3
Chest x-ray showing tension pneumothorax on the left side of the lung. The pathology causes pressure effect and midline shift of the heart and trachea. The patient needs emergent chest tube drainage.
Traditional teaching suggested that contralateral (i.e., on the opposite side of the body) shift of the trachea and mediastinum, splaying of the ribs, and flattening of the ipsilateral diaphragm represent radiographic tension. However, these findings can be due to the elevated pleural pressure and do not necessarily indicate tension.
Clinical evidence of tachycardia, hypotension, and severe dyspnea is more indicative of tension because these signs can be seen in patients without clinical evidence of tension. Conversely, patients may have clinical evidence of tension in the absence of typical CXR findings of tension. A one-way valve mechanism is responsible for tension pneumothorax allowing gas to enter the pleural space during inspiration but not exit fully during expiration. As gas accumulates, pressure increases within the ipsilateral pleural space resulting in hypotension from reduced venous return, low cardiac output, and respiratory failure due to compression of the contralateral lung. Patients with these findings need immediate attention with needle or chest tube insertion.
Several other types of pneumothorax can be appreciated on CXR.
Hydropneumothorax in patients who have evidence of both fluid and air in the pleural space (e.g., trauma patients who have both hemo- and pneumothorax). A hydropneumothorax can be appreciated by the presence of a liquid-gas level when the patient is upright and a hazy opacity in a supine patient, that may obscure the pneumothorax.3
Pneumothorax ex vacuo is seen following pleural fluid removal when the lung is trapped by a thick fibrous pleural rind and cannot fully expand. Instead of lung re-expansion, gas replaces the effusion and is termed pneumothorax ex vacuo.
Most pneumothoraces are unilateral but can be bilateral (also known as simultaneous bilateral spontaneous pneumothoraces [SBSP]). Bilateral pneumothoraces may be seen in patients who have a single pleural space. This phenomenon is rare but can be congenital ("buffalo chest"; buffalo only have one thoracic cavity)3 or iatrogenic in nature following thoracic surgery that disrupts the anterior junction line complex between the right and left thoracic cavity (e.g., heart-transplant recipients, in patients following esophagectomy).3
Bilateral pneumothoraces can also present in patients with severe underlying lung disease who have two normal intact pleural spaces that do not communicate with each other (e.g., COPD or alpha-1 antitrypsin deficiency, PCP, barotrauma from mechanical ventilation, CF, some drugs, metastatic malignancy).3 Case reports, however, have described bilateral pneumothoraces in patients without significant lung disease.3 For example, in one study of 616 cases of PSP, 1.6% were bilateral. All patients were male with a low body mass index and higher height to body weight ratio compared with patients who had unilateral PSP.3
Air moves to the least dependent portion of the lung, and therefore, the CXR appearance of a pneumothorax depends upon the patient’s position. In most cases, CXR is performed in an upright position, and the pneumothorax can be appreciated in the apical or apicolateral position. It is estimated that only 50 mL of air in the pleural space is needed for the detection of pneumothorax in the upright position.3 The first rib and clavicle can sometimes interfere with the detection of a small pneumothorax in the upright position.
When the patient is in the supine position (e.g., patients who are mechanically ventilated), pleural gas accumulates anteriorly and in a subpulmonic location. This may result in the "deep sulcus" sign (i.e., where gas outlines the costophrenic sulcus). Rarely, pneumothorax can be appreciated in the phrenicovertebral location. In supine patients with pneumomediastinum, a “continuous diaphragm” sign may be evident (i.e., where both leaflets of the diaphragm appear as one). It is estimated that approximately 500 mL of air in the pleural space is needed for the detection of pneumothorax in the supine position.3 For patients in the lateral decubitus position, air rises to the non-dependent lateral location. Only 5 mL of pleural air may be needed to detect pneumothorax in this position.3 However, imaging in this position may be technically difficult and has largely been supplanted by CT.
Several conditions can mimic a pneumothorax on plain CXR. When in doubt, a chest CT scan may be needed to distinguish these entities.
Subpleural bullae can mimic a loculated pneumothorax. The distinction is clinically important because the insertion of a chest tube into a bulla results in an iatrogenic pneumothorax and increases the risk for the development of a bronchopleural fistula. Similar to a pneumothorax, bullae have a lateral wall that is convex to the chest wall, but unlike pneumothorax, the medial border of a bulla may be appreciated as concave to the chest wall.3
Skin folds (e.g., due to obesity or distortion of the skin by the imaging cassette) may mimic pneumothorax. However, skin folds frequently demonstrate a line (mistakenly interpreted as the visceral pleural line) that, when followed, extends beyond or ends just before the rib cage. Other findings include an increase in opacification, which ceases at the distal edge of the skin fold and the presence of visible bronchovascular markings beyond the skinfold line. Classically, the edge of the skinfold appears as a black “Mach band” instead of a thin pleural line typical of pneumothorax.
Herniation of the stomach into the chest (e.g., due to diaphragmatic rupture) can mimic the appearance of a left-sided pneumothorax and, if a chest tube is inserted, can result in viscus perforation. Intrathoracic stomach air can be hard to distinguish from pneumothorax but the presence of loops of bowel in the left hemithorax is supportive of gastric herniation.
Several methods are available to assess the size of a pneumothorax, none of which are highly accurate or superior, and many tend to underestimate or overestimate the size.3 Such inaccuracy may result when the assessment of size uses a one-dimensional measurement that does not accurately reflect the three-dimensional nature of the pleural space. Additionally, such measurements also assume that the lung collapses uniformly, which is not always the case.
Despite available methods, considerable variation in practice exists, and many clinicians use gestalt assessment of size in conjunction with symptoms to make management decisions. Available methods for size assessment include the following:
Most of these assessments are made on CXRs. Chest CT, however, is likely the most accurate modality to assess size. Newer CT-based measurements of the ratio of lung volume to hemithorax volume may hold promise.3 Pleural ultrasonography is not typically used to assess pneumothorax size.
Ultrasound of the pleura is best utilized when bedside rapid imaging is needed to make the diagnosis of pneumothorax (e.g., unstable patients with trauma, or patients with suspected tension) because ultrasound has been shown to be sensitive diagnostically3 and ultrasonography is more readily available with shorter wait times than for bedside CXR.3 Pleural ultrasonography is also typically used for suspected pneumothorax that follows ultrasound-guided procedures (e.g., thoracentesis or central venous catheterization) and is being increasingly used in critically ill patients.
The presence of a lung point on pleural ultrasonography is diagnostic of pneumothorax. In the partially deflated lung, the lung point is the intermittent and respirophasic observation of lung sliding at the boundary between the pneumothorax (where there is no apposition of the pleura, so no lung sliding is seen) and the partially inflated lung (where there is still apposition of the two pleural surfaces, so lung sliding is seen). A pneumothorax is also suggested if lung sliding and/or lung pulse is absent. A lung point, however, may not always be present (e.g., complete deflation of the lung), and the absence of lung sliding or lung pulse is not specific since it can be seen in other conditions. Thus, if a pneumothorax is not confirmed by ultrasonography, it should be investigated by additional chest imaging, if clinically feasible.
Importantly, pleural ultrasonography is not used to estimate the size of a pneumothorax. Several studies indicate that ultrasonography may be superior to standard CXR for the detection of pneumothorax.3 Two meta-analyses of mostly observational studies reported sensitivities of ultrasound that were superior to CXR (79% to 91% versus 40% to 50%).3 However, there was significant heterogeneity among different populations studied. Additionally, the sensitivity of CXR may have been underestimated due to the high frequency of supine CXRs in many of the studies.
Chest CT is the best modality for determining the presence, size, and location of intrapleural gas.3 Small amounts of air in the pleural space and pleural pathology, including pleural effusions and adhesions, as well as, locations can be better appreciated by chest CT compared with a plain CXR. Based upon its superior resolution and observational studies, chest CT is considered more accurate than either CXR3 or pleural ultrasonography3 for the diagnosis of pneumothorax. Chest CT can readily distinguish gas from other structures, including the lung parenchyma, the pleural membranes, and the mediastinum, making it the modality of choice when diagnostic doubt exists.
Following initial diagnosis and management, additional steps need to be taken to identify a potential etiology(s) for pneumothorax. For many patients with pneumothorax, an underlying cause (e.g., trauma or iatrogenic) may be evident or an underlying lung disorder (e.g., COPD, interstitial lung disease, lung cancer, infection) may be known at the time of presentation. In others, pneumothorax may be the first manifestation of an unknown disorder (e.g., catamenial pneumothorax, LAM, BHD syndrome). The following approach is suggested since there are no guidelines or data to help guide the clinician in this matter.
In many cases, the etiology is evident from the history, physical examination, and CXR or chest CT findings. For example, patients in this category would include those patients with:
In such cases, no additional testing is typically required unless a second disorder is suspected.
In some cases, the pneumothorax may not have an apparent cause, and clinicians need to decide how much testing should be performed to identify a cause. After initial therapy, these patients should be re-evaluated with another detailed history and physical examination and with a re-examination of chest imaging to identify abnormalities that may have been missed during the initial assessment. In many instances, this re-evaluation is performed after the initial therapy and discharge and may prompt noncontrast high-resolution chest CT (HRCT), if not already performed, as well as pulmonary function testing. Additional testing may be subsequently targeted at specific suspected etiologies.
Clinical re-evaluation should consider but not be limited to the following:
In the majority of cases, the diagnosis of pneumothorax is made on CXR.
If not already performed, a proportion of patients additionally need a chest CT when a specific etiology is suspected or the underlying etiology remains unknown. A chest CT is typically performed in the following situations. Patients with abnormalities on their CXR (e.g., lucencies that suggest cysts, bullae that suggest COPD), or on clinical evaluation (e.g., clubbing, hemoptysis, systemic symptoms, or basal crackles) that suggest an underlying lung disorder. Patients with a suspected etiology for pneumothorax which may be more readily identified on chest CT.
A chest CT should be performed in:
Pulmonary function tests (PFTs) are not routinely performed and are not valuable at the time of diagnosis or during treatment. However, PFTs may be performed after recovery (e.g., weeks) when an underlying lung disease (e.g., asthma, COPD, LCH, LAM) is suspected. PFTs should be performed in stable patients and are not helpful in those in whom a chest tube is in place or in whom pleurodesis has been recently performed (typically within three months).
Additional tests are performed when specific etiologies are being considered based upon clinical and radiologic re-evaluation. These might include genetic testing for suspected inheritable syndromes (e.g., alpha-1 antitrypsin deficiency, BHD syndrome, Ehlers Danlos syndrome, Marfan syndrome), vascular endothelial growth factor for suspected LAM, and serologic testing for suspected Sjögren's syndrome.
Lung biopsy is rarely performed for suspected interstitial lung disease or malignancy. However, when pleurodesis is being considered for pneumothorax, many surgeons also take tissue for occult conditions that are not easily detected clinically.
When infection is suspected, microbiologic, serologic testing, and/or bronchoscopy with bronchoalveolar lavage may also be required.
Though thoracotomy and thoracostomy sound almost the same, the terms describe two very different procedures:
A thoracostomy is a small incision in the chest wall (usually 2 to 3 cm in adults), with maintenance of the opening for drainage. It is most commonly used for the treatment of a pneumothorax. This is performed by physicians, emergency response nurses, and paramedics, usually via needle thoracostomy or with a thoracostomy tube, i.e, chest tube.
Chest tubes can be inserted directly into the chest cavity through an incision or by using the Seldinger technique, which places the chest tube over a guidewire. Commercially available kits are available for specialty tubes and pigtail catheters in which the tube is placed using the Seldinger technique (over a guidewire).
Placing a chest tube can be associated with severe complications, including damage to the lungs or other organs (chest, abdomen). The use of pleural ultrasound can minimize complications, and ultrasound also accurately identifies the location of pneumothorax by an absence of lung sliding on 2-D and M-mode imaging.4
The free end of the chest tube is usually attached to an underwater seal, below the level of the chest. This allows the air or fluid to escape from the pleural space and prevents anything from returning to the chest.
Three functional chambers are generally a part of most chest tube collection devices. From right to left, the first chamber (i.e., collection chamber, depicted with three subsections) accepts air and fluid from the patient via the chest tube. The fluid accumulates in this chamber. The air rises and enters the second chamber (i.e., water seal chamber), which contains water at the bottom. Air from the patient enters this chamber below the water level, bubbling through the water seal and preventing the return of air to the patient. The air enters the third chamber (i.e., suction chamber) connected to wall suction and is discharged through the hospital collection system. The height of water in the suction chamber indicates the amount of suction applied. Suction pressures are typically between -10 and -40 mmHg. An atmospheric vent prevents the application of excessive suction. Manual venting through a pressure relief valve rapidly equilibrates the collection chamber with atmospheric pressure. Modern devices vary in appearance, method of suction regulation, and volume of the fluid collection chambers.
The hemodynamically unstable patient with a suspected tension pneumothorax needs immediate decompression with the quickest method available. This can be either with a standard chest tube, pigtail catheter, or angiocatheter. Simply inserting the introducer needle will release the pressure from tension physiologically stabilizing the patient. This is usually performed on the affected side in the midclavicular line through the second intercostal space or at the fifth intercostal space midaxillary line with one of any readily available kits, a long angiocatheter (adult, pediatric), or the introducer needle for a pigtail catheter.
The angiocatheter from the kit is placed first, which allows for immediate decompression. Because these angiocatheters are small-bore thin-walled catheters, they are prone to kinking and may not completely relieve a tension pneumothorax. They can also be dislodged, leading to reaccumulation of air and recurrent tension pneumothorax. Thus, immediately following needle decompression, a thoracostomy tube should be placed, the size of which depends upon the expected pathology. For example, for spontaneous pneumothorax, an appropriately sized (e.g., 8.3 Fr, 14 Fr) pigtail catheter can be placed immediately over a wire into the pleural space using a modified Seldinger technique. As an alternative, a standard chest tube can be placed.
Following needle thoracostomy, the needle/catheter is attached to a syringe (5 or 10 mL in adults). It is inserted along the superior margin of the third rib in the midclavicular line or over the fifth rib in the midaxillary line. For adults, a standard-length 14 to 16 gauge angiocatheter is nearly always successful. Obese patients, however, usually will need a longer catheter for adequate penetration of the chest.
Once the catheter has been placed, the needle is withdrawn and the angiocatheter is initially left open to the air. An immediate rush of air out of the chest indicates the presence of a tension pneumothorax, which has now been converted to a large but simple pneumothorax. Tubing can be attached to the angiocatheter and the open end placed into a bottle of sterile water, which should be placed below the insertion site to avoid fluid being pulled into the pleural space. Bubbles indicate the flow of air. This is a temporizing measure to emergently address an air leak that may be acutely problematic or is anticipated to reaccumulate rapidly. A definitive tube for continued drainage can then be placed in a less emergent fashion. Catheter length should be chosen based upon the body habitus of the patient.4
Video-assisted thoracoscopic surgery (VATS) is a set of minimally invasive thoracic surgical (MITS) procedures used to diagnose or treat conditions of the chest (pulmonary, mediastinal, chest wall). MITS eliminates the need for a thoracotomy that requires the spreading of the ribs or sternotomy incisions.
Most major procedures traditionally performed with open thoracotomy can be performed using smaller incisions with video assistance. With VATS, the surgeon’s hands remain outside of the chest cavity to manipulate and work the end of the instruments, which are located inside the chest. MITS uses a thoracoscope attached to a video camera to see into the chest. The lens and the instruments necessary to perform the surgery are inserted between the ribs and into the chest cavity through one or multiple small incisions.
The prevalence of VATS for more complex procedures has been steadily increasing, primarily because of reduced complication and mortality rates, particularly among frail patients.5
VATS uses an access (or utility) incision that ranges from 2.5 to 8 cm in length and allows manipulation of multiple traditional or thoracoscopic instruments through the same incision at the same time. VATS can be performed with one (uniportal) or up to four chest incisions. The position of the incisions varies depending upon surgeon preference or procedure being performed.
Hand-assisted thoracoscopy uses a small thoracotomy that allows passage of the surgeon's hand in conjunction with imaging provided with a thoracoscope. During surgery, carbon dioxide insufflation facilitates soft tissue dissection and increases the domain of the chest by depressing the diaphragm.5
Drainage of hemothorax, pneumothorax, empyema, or malignant pleural effusion and mechanical or chemical pleurodesis are some of the more basic problems that can be approached using thoracoscopy. Pleurodesis or pleurectomy (i.e., decortication) can be indicated for recurrent pneumothorax or malignant pleural effusion.
Resection of pulmonary blebs and bullae may be indicated to prevent spontaneous pneumothorax from rupture or for ongoing air leak following thoracostomy tube placement.5 A bleb is smaller than 1 cm in diameter and typically subpleural and located more cephalad. Blebs may occur from an alveolar disruption in patients with otherwise relatively normal parenchyma.
Bullae, which are thinned areas of lung parenchyma, are typically >1 cm in diameter with wall thickness <1 mm and typically occur from parenchymal destruction such as that caused by emphysema. Large bullae can occupy up to one-half of the volume of the pleural cavity, leading to contralateral lung compression.
When intervention is indicated, the margins of resection should be performed in the more normal (less emphysematous) lung parenchyma, which is more likely to heal faster.
Like with open surgery, a prolonged/persistent air leak (PAL) can occur related to poor sealing of thin lung parenchyma at the staple line margin or from lung lacerations that may occur from taking down adhesions.
LVRS involves removing the apical portions of one or both lungs to improve overall respiratory function in patients with significant upper lobar emphysema. LVRS, which can be performed via sternotomy or bilateral thoracostomy, can also be performed by bilateral VATS. Because VATS is less invasive, there is a faster recovery time, decreased cost, decreased length of stay, and decreased rate of complications.5 There is no difference in functional results or mortality when comparing VATS with open methods of LVRS.
In general, complications related to MITS procedures are similar to those of the open surgical approach. Some complications, however, can be more significant. These include the potential for bleeding and complications related to the technical aspects of the surgery. Bleeding may obscure the view from soiling of the scope, and bleeding from major vessels (e.g., bleeding from a pulmonary artery, aorta) is of great concern and may require conversion to an open procedure for rapid hemostasis. Bleeding rates in VATS series range from 0.4 to 2%.5
Pleurodesis is a procedure that obliterates the pleural space to prevent recurrent pleural effusion or recurrent pneumothorax or to treat a persistent pneumothorax. Pleurodesis is commonly accomplished by draining the pleural fluid, when present, followed by either a mechanical procedure (i.e., abrasion, or (partial) pleurectomy) or installation of a chemical irritant into the pleural space, which causes inflammation and fibrosis.
The use of a chemical irritant is known as chemical pleurodesis. Alternatives to chemical pleurodesis include mechanical abrasion (also termed dry abrasion) of the parietal pleura during thoracoscopy or thoracotomy or placement of a tunneled pleural catheter, which drains pleural fluid and may induce pleurodesis without instillation of a sclerosing agent. Chemical pleurodesis has been used to manage pneumothorax, as well as other conditions.
Thoracoscopic pleurodesis and bedside methods of chemical pleurodesis (i.e., non-thoracoscopic methods) successfully prevent the recurrence of PSP and SSP.6 However, thoracoscopy with mechanical pleurodesis has benefits over chemical pleurodesis without thoracoscopy because thoracoscopy allows for simultaneous inspection and resection of subpleural blebs and bullae. In addition, thoracoscopic mechanical pleurodesis, although requiring more extended hospital stays, does not expose the patient to possible risks related to talc. Comparatively, evidence suggests a similar reduction in recurrence from thoracoscopy as compared with chemical pleurodesis.6 Thus, chemical pleurodesis is a reasonable option for those who prefer to avoid thoracoscopic surgery. Patients can undergo thoracoscopy with talc poudrage with reported recurrence rates for PSP and SSP of 1.7 to 9.5% and 25% respectively.6
Pleurodesis will fail if the lung cannot fully expand to the chest wall (e.g., trapped lung, interstitial pulmonary fibrosis, endobronchial obstruction) because successful pleurodesis requires contact of the visceral and parietal pleura. Chemical pleurodesis should, therefore, not be attempted when the lung does not fully expand after therapeutic thoracentesis. Patients whose lungs cannot fully expand usually have radiographic evidence of a pneumothorax after thoracentesis or experience chest discomfort during thoracentesis before all pleural fluid is drained.6
The most common chemical irritants used to induce pleurodesis in PSP and SSP include6:
Talc, a trilayered, magnesium sheet silicate, is the most effective and most commonly used agent. Talc installation (by insufflation or slurry) causes an intense intrapleural inflammatory response characterized by the production of cytokines, adhesion molecules, and other mediators of inflammation, such as interleukin-8 (IL-8), vascular endothelial growth factor (VEGF), and transforming growth factor-beta (TGF-beta).6 Among other effects, IL-8 induces neutrophil influx involved in the acute inflammatory response. VEGF causes increased capillary permeability and angio- and lymphogenesis. TGF-beta contributes profibrotic and immunomodulatory properties.
Minocycline and doxycycline are used for pleurodesis. Success rates with these agents in most reports are lower than those with talc, with recurrence rates of 13 to 35%.6 However, some clinicians prefer tetracycline derivatives for chemical pleurodesis in patients being treated for pneumothorax.
Silver nitrate and iodopovidone have also been used for chemical pleurodesis. However, larger studies of these agents are necessary before their use can be recommended. The efficacy of iodopovidone for pleurodesis was examined in two separate case series. Iodopovidone induced successful pleurodesis in 86 to 96% of patients.6
Each patient's medications should be reviewed prior to performing pleurodesis. Concomitant use of glucocorticoids may decrease the success of chemical pleurodesis, because pleurodesis requires pleural inflammation and glucocorticoids are potent antiinflammatory agents.6 A patient's glucocorticoids should be reduced or held 24 to 48 hours prior to pleurodesis if possible. Systemic anticoagulation is generally reversed for the placement of a chest tube. It is not necessary to hold anticoagulation for chemical pleurodesis once the chest tube is in place.
When pleurodesis is performed for pneumothorax, pleural air is drained until the lung is fully re-expanded. Chemical pleurodesis is often painful. Patients are usually pretreated with parenteral doses of an opiate (e.g., morphine) and an anxiolytic/amnestic agent (e.g., midazolam). Postprocedure analgesia should be provided as necessary to maintain comfort.
Chemical pleurodesis is typically performed using talc because of its demonstrated efficacy. As noted above, chemical pleurodesis can be performed using any of a number of different chemical agents, the most common of which are talc and the tetracycline derivative, doxycycline.
Chemical pleurodesis with talc can be accomplished with similar efficacy using insufflation (also called poudrage) during a thoracoscopy procedure or with slurry via tube thoracostomy.6 Generally, the dose of talc administered intrapleurally is 4 g for insufflation and 5 g for slurry. Size-calibrated talc that contains less than 10% of small particles (e.g., 5 to 10 microns in diameter) should always be used. Commercially available United States talc has a median diameter of 26.57 microns with a range of particle sizes from 0.399 microns to 100.237 microns.6
The typical dose of doxycycline used for intrapleural instillation is 500 mg dissolved in a total volume of 50 mL of normal saline.6 Doxycycline pleurodesis is often painful, although not more painful than other pleural sclerosants.6 Some practitioners add a local analgesic agent (e.g., lidocaine, 25 mL [250 mg] of a 1% solution, or mepivacaine, 20 mL [400 mg] of 2% solution) to the doxycycline solution, although data supporting this are lacking.6
Systemic absorption of the local anesthetic may be significant. In addition to local analgesia, systemic administration of an analgesic agent is usually necessary. At least one case of acute hypoxic/hypercapnic respiratory failure has been reported after pleurodesis with doxycycline (300 mg).6 CXR showed no pulmonary opacities and the presence of high peak ventilator pressures suggested acute bronchospasm due to an anaphylactic reaction. The patient improved in a few hours with ventilatory support and bronchodilator therapy.
Chemical pleurodesis may be performed at the time of thoracoscopy, at the bedside in the hospital, or in an outpatient clinic. When chemical pleurodesis is performed at the bedside via tube thoracostomy or a tunneled pleural catheter (e.g., installation of talc slurry or doxycycline), the usual protocol is as follows.
Pleural fluid drainage through the chest catheter should be discontinued for one to two hours following the installation of the chemical irritant. Talc slurry distributes poorly, so some clinicians rotate the patient. However, there is no evidence that such rotation improves the probability of successful pleurodesis.6 Studies with tetracycline also show no need to rotate the patient.6 After the catheter has been reopened, the results of passive drainage are observed. Some clinicians apply chest catheter suction (-20 cm H2O) for at least 24 hours if drainage is sluggish and the lung is slow to re-expand to the chest wall. The traditional approach is to leave the chest tube in place until the drainage is less than approximately 150 mL per 24 hours, although there are no scientific data to support this approach. The rationale is that ongoing pleural drainage helps to maintain apposition of the pleural surfaces and the chest tube is in place should repeat pleurodesis be needed. For example, if drainage is greater than 150 mL over 24 hours, repeat pleurodesis may be considered after 48 to 72 hours. Alternatively, some clinicians remove the chest tube within 24 hours after the installation of talc or doxycycline, based on two small randomized trials showing no difference between the two approaches.6
The most common adverse sequelae of chemical pleurodesis are6:
Pain can be treated with opioids with the addition, if necessary, of nonsteroidal anti-inflammatory agents, which do not decrease the rate of success of pleurodesis.6
Far less commonly, patients may experience:
The complication of acute respiratory failure, although rare, is more commonly seen after talc pleurodesis compared with other sclerosant agents. It is unlikely that the method of administration (insufflation versus slurry) plays a major role in the development of respiratory failure. However, the dose and mean particle size of talc may be important, because smaller particles can present an increased risk.
Cardiovascular complications, such as arrhythmias, cardiac arrest, CP, MI, and hypotension, have been reported following pleurodesis.6 It is unclear whether these complications are a result of the surgical procedure, co-morbid conditions, or the chemical irritant.
A mild systemic inflammatory reaction is common following chemical pleurodesis.6 As an example, in a retrospective study of 35 patients, patients who received talc insufflation via thoracoscopy had an increased temperature, white blood cell count, and C-reactive protein level compared to patients that underwent thoracoscopy alone.6
Bacterial empyema has been reported following pleurodesis using talc slurry (0 to 11%), talc insufflation (0 to 3%), or rarely tetracycline.6 Local site infection is uncommon.
Dissemination of the chemical agent talc into BAL fluid and multiple organs has been noted.6 The dissemination of talc into extrapulmonary organs appears to be dose-related.6
A link between talc and cancer has been reported in individuals who mine and process talc.6 This association has been attributed to asbestos within the talc. As a result, there is a theoretical concern that talc pleurodesis could place the patient at increased risk for mesothelioma or lung cancer.6 However, the incidence of malignancy is not increased in patients who undergo talc pleurodesis and talc used for medical purposes is asbestos-free.6
Despite the intrapleural administration of anesthetic (e.g., lidocaine) pre-procedurally, moderate to severe pain is a common complication after pleurodesis that may last for two weeks, sometimes longer.7 It is likely due to the inflammation induced by the procedure which is required to achieve effective symphysis of pleural membranes. It generally dissipates slowly (weeks to months). Post-thoracotomy pain from injuring the intercostal nerves is rare. Importantly, the severity of the pain is often underestimated by physicians. Accordingly, postoperative pain should be addressed in institutional protocols. Frequently, narcotic medication is needed in the short-term.
Nonsteroidal agents were avoided in the immediate postoperative period since it was thought that nonsteroidal anti-inflammatory drugs (NSAIDs) might interfere with the inflammation that is required to ensure effective pleural membrane symphysis. However, a study comparing opioids with NSAIDs for pain reported no difference in the efficacy of pleurodesis in patients with malignant pleural effusion.7
Following a definitive procedure, the chest tube remains in place, and patients are assessed daily for pain and the closure of the air leak. Frequent CXRs or ultrasonograms are performed to check for lung reexpansion.
Once the air leak has been sealed, the chest tube can be removed, and the patient can be discharged and followed up in an outpatient clinic.
If an air leak persists or pneumothorax recurs despite pleurodesis, management may be complex due to loculations from the previous attempt at pleurodesis. In such cases, a multidisciplinary approach is advised where discussion of several options should be undertaken, including catheter-directed pleurodesis, thoracoscopic revision, or conservative management. A rare patient is left with residual chronic pneumothorax.
An alveolopleural fistula (APF) is a pathological communication between the pulmonary parenchyma distal to a segmental bronchus (alveoli) and the pleural space. It presents as a pneumothorax, and if it persists beyond five days is labeled as a PAL. PAL is associated with significant morbidity and prolonged hospitalization.
APF and PALs are most commonly seen in patients following LVRS (up to 46%) and pulmonary resection or biopsy (3%) following wedge resection) but can also be seen following spontaneous pneumothorax.8 Less common causes include pulmonary infections (e.g., necrotizing pneumonia), malignancies (e.g., pulmonary metastasis), pleural drainage procedures, barotrauma due to mechanical ventilation, chest trauma and iatrogenic etiologies that can occur after thoracentesis or chest tube insertion (i.e., pleural drainage procedures).
In the setting of lung resection surgery, several risk factors for APF with PAL have been reported8:
Although likely, it is unknown whether similar risk factors promote APF with PAL in nonsurgical populations.
An APF should be suspected in a patient with risk factors who has a PAL seen on a chest tube drainage system for greater than five days. There are no specific signs or symptoms associated with PAL, but some patients have a persistent pneumothorax on chest imaging. Although APFs can theoretically cause hypercapnia due to loss of alveolar ventilation through the air leak, this is rare in clinical practice. This is probably because the leaked gas participates in gas exchange rather than being lost or wasted.8 Intractable respiratory acidosis and other serious complications are more likely due to the lung disease than the APF.
Continued flow through the fistula to the pleural space delays healing and prevents lung expansion. The longer air flows through the fistula, the more likely it is to remain patent. Thus, prompt reduction in the flow of air is critical for effective management. APF-associated PALs are not fatal but are associated with prolonged hospital stays, higher rates of intensive care unit (ICU) admission, and high morbidity (e.g., pneumonia, venous thromboembolism).8
Most patients with PAL respond to conservative therapy (up to 80%). Continued chest tube thoracostomy with low wall suction to promote lung expansion and pleural apposition. In some cases with large fistulas (e.g., SSP in patients with COPD secondary to rupture of large bullae), the addition of high suction and even insertion of a second chest tube may be warranted.
In contrast, in patients with non-expandable lung (trapped or entrapped lung), suction should be avoided. Patients should also receive adequate nutrition, and appropriate antibiotic therapy (if indicated), and therapy for comorbidities should be optimized. For patients who are mechanically ventilated, lowering the level of positive pressure and selective intubation of the healthy lung is appropriate.
It is controversial whether or not suction should be applied. On one hand, some experts apply low wall suction to increase adherence of the visceral and parietal membranes, thereby promoting healing and closure of the fistula.
In contrast, other experts avoid suction believing that suction promotes continued patency. This practice is supported by studies of patients in whom routine suction is applied immediately postoperatively that have suggested a reduced incidence of APF with PAL in patients whose chest tubes were placed on water seal compared with suction.8 However, none of these studies have been performed in patients with PAL from other etiologies. In addition, arguing against the practice of avoiding suction is that healing of the visceral pleural membrane is considerably less likely to occur if not apposed with the parietal membrane. Thus, suction is applied but minimized when possible, especially in patients with non-expandable lungs (trapped or entrapped lung) with PALs.
There is no optimal follow-up time for patients who undergo conservative therapy. Nonetheless, in general, smaller PALs that are improving with time (at minimum five days and occasionally up to two weeks) are more likely to spontaneously undergo closure with conservative management than larger air leaks that have been present for a prolonged period of time and are not improving despite conservative therapy. The latter is unlikely to resolve spontaneously and require intervention.
Although the exact proportion is unknown, about 20% of patients will fail conservative therapy and require some form of intervention. The presence of a severe air leak, incomplete lung expansion on chest CT and/or underlying lung disease (such as emphysema, interstitial lung disease, cancer) can probably predict the need for additional intervention for fistula closure.
Options for fistula closure in patients who fail conservative therapy include ambulatory non-endoscopic devices, bronchoscopic methods, pleural procedures or surgery. Choosing among these depends upon the available expertise and individual preferences.
With the exception of patients with spontaneous pneumothorax, who in general should undergo VATS blebectomy and mechanical pleurodesis, a systematic approach that measures the size, location, and integrity of the interlobar fissure of the affected lobe with the APF is preferred. This preference is based upon the rationale that it identifies those suitable for bronchoscopic closure, thereby allowing optimal selection of therapeutic options.
For example, leaks associated with minimal collateral ventilation between the target lobe and adjacent lobes are better suited to bronchoscopic therapy, while large leaks associated with significant collateral ventilation might be suited for surgical repair or pleural procedures, depending on the clinical status of the patient.
The quantification of air leak is important to assess whether the leak will spontaneously resolve with additional supportive care or need more aggressive intervention. In general, small air leaks resolve spontaneously, whereas larger leaks require intervention, although what constitutes small versus large is not clearly defined. Air leaks can be quantified using several methods. Digital drainage system devices usually are preferred since they may be more accurate with less interobserver variability and are easy to use. Methods include:
Digital chest drainage system devices can display the flow (mL/min) of air into the pleural space along with the pleural pressure difference in real-time.8 These devices are not always available but are being increasingly used by thoracic surgeons and interventional pulmonologists instead of standard commercially available drainage systems. The digital system works by maintaining the intrapleural pressure at a steady level within 0.1 cm H2O.
The regulated suction adjusts according to the condition or needs in the pleural cavity. The device will apply suction to keep the pleural cavity at the present level. If the patient does have an air leak with suction, the device will intermittently apply suction to restabilize the pleural space according to the degree of the air leak. The chest tube can be removed when there is no flow or air leak flow is less than 20 mL/min without large variation for at least six hours as measured by digital chest drainage system.
The air leak meter on commercially available chest drainage systems can measure leak on a scale from 1 to 7 with the number representing the columns through which bubbling occurs (the higher the number, the greater the leak).8 Some experts grade air leak from mild to severe when the leak occurs during forced expiration (grade 1), passive expiration only (grade 2), inspiration only (grade 3), or inspiration and expiration (grade 4), with grade 1 being the least and grade 4 being the worst leak.8
Sequential balloon occlusion through flexible bronchoscopy is a useful method to locate the bronchial segment or subsegment that is supplying the APF.8 A balloon, (e.g., a Fogarty balloon of appropriate size, typically 5-French), is placed endobronchially through the working channel and inflated to first occlude the main stem bronchus for up to two minutes. A significant reduction in air leak observed through the chest tube drainage system indicates that the bronchus selected leads to the defect. The operator subsequently repeats this step, moving distally through lobar, segmental, and subsegmental bronchi until the target lobe with the fistula is reached.
While some lobes in the lung are fissurally-contained, others communicate with adjacent lobes (also known as incomplete fissure or collateral ventilation), a phenomenon that is more common in patients with emphysema. The degree of collateral ventilation should be evaluated to determine whether bronchoscopic methods will be effective.
Sequential balloon testing not only localizes the air leak but once the target lobe is identified, it can also be used to assess collateral ventilation as an indicator of fissure completeness. On sequential balloon testing, a reduction in airflow of ≥50% (either estimated as bubbles per minute or measured with a digital chest drainage system), indicates that the APF may be responsive to bronchoscopic management.8 If a reduction in airflow of <50% is observed, then significant collateral ventilation (i.e., incomplete lung fissure) between the target and ipsilateral lobes is likely and bronchoscopic treatment will not be effective.8
Fissure completeness between target and ipsilateral lobes can also be evaluated by direct visual assessment of high-resolution chest CT images of the lobar fissures and/or quantified by chest CT image analysis software.8 Fissure integrity >90% suggests minimal collateral ventilation and indicates that the APF may be responsive to bronchoscopic management.8 If fissure integrity ≤90% is observed, then significant collateral ventilation (i.e., incomplete lung fissure) between the target and ipsilateral lobes is likely and bronchoscopic treatment will likely not be effective.
Air leaks with minimal collateral ventilation (e.g., >90% complete) that also demonstrate ≥50 reduction in airflow with bronchial occlusion are suitable for bronchoscopic methods of fistula closure.
Unidirectional airway devices are available in different sizes (5, 6, 7, and 9 mm) that can be placed in lobar, segmental, or subsegmental bronchi using a flexible therapeutic bronchoscope. Some commercial devices come with balloon kits to determine the optimal size. These airway valves limit airflow to portions of the lung distal to their placement while permitting mucous and air movement in the proximal direction, thereby reducing airflow through the fistula and allowing the defect to heal. Based upon studies, typically, two to three valves are needed to control the air leak. Currently, intrabronchial valves (IBVs) have been approved by the US Food and Drug Administration (FDA) to treat APFs through a humanitarian device exemption.
Case reports and case series consistently show a complete or near-complete resolution of air leak in the majority of patients with valve placement.8 In the largest trial of 75 patients with APF and PAL who underwent valve implantation, air leak resolution occurred in 70% of patients with a median time to resolution of 16 days.8 Additional subsequent procedures were needed by 20% (e.g., Heimlich valve, chemical pleurodesis). Two patients experienced complications, including empyema and contralateral pneumothorax.
Anecdotal reports of successful fistula closure using fibrin glue and other sealants including gelatin sponge and oxidized regenerated cellulose have been reported.8
Although infrequently used, stents can be placed to occlude the affected lobar bronchus, thus diverting flow away from a target lobe. For example, if the left upper lobe is the target lobe, a fully covered self-expanding metallic stent can be placed in the left main stem bronchus to the left lower lobe, thereby bypassing the left upper lobe.
During the immediate follow-up period, the clinician should assess for the degree of residual air leak, as well as for symptoms of complications of the procedure. Complete success is considered one where the air leak resolves, allowing removal of the chest tube (usually over days) while a partial response is one where the air leak no longer requires suction and is controlled with a water seal.
In cases of a partial response, an additional procedure, often the placement of an ambulatory drainage device such as Heimlich valve, chest drain valve, mobile dry seal drain, or digital chest tube, is performed in order to achieve successful closure. For those who undergo valve placement, follow-up depends on air leak cessation.
If the leak resolves, then the chest tube is removed. However, if the leak persists, patients are discharged on ambulatory drainage devices and reassessed in two weeks. All patients are re-evaluated at six weeks post air leak cessation, and valves are removed per the manufacturer’s recommendations.
Additionally, the clinician should look for symptoms of complications (e.g., fever, pneumonia, displacement, and expectoration) during the period when valves are present. For those who fail bronchoscopic occlusion of APF (generally 6 to 8 weeks), non-bronchoscopic methods or surgery are options.
Large APF with PAL associated with significant collateral ventilation with other lobes (e.g., ≤90% complete) or <50 reduction in airflow with balloon occlusion are not suitable for bronchoscopic valve treatment of fistula closure alone. Surgical repair and/or additional pleural intervention are typically necessary, depending upon the patient's candidacy for surgery.
Surgical intervention is usually considered for patients with spontaneous pneumothorax, those in whom bronchoscopic methods are not suitable or those refractory to bronchoscopic or other nonsurgical procedures. VATS may be used to achieve pleural adhesion with the application of sclerosing agents under vision, pleural abrasion, or pleurectomy. Other surgical interventions include over stapling of parenchymal lesions and application of sealants, thoracotomy with muscle or omental flap reinforcement at the site of the leak, pleural tenting, and buttressing of staple lines to obliterate the fistula.8
For patients who fail or are not candidates for bronchoscopic or surgical approaches, ambulatory drainage devices and nonsurgical pleural procedures are options. They are also considered additive when surgical or bronchoscopic methods achieve a partial response only. Choosing among them should be individualized and depends upon fistula characteristics, local expertise, and patient preference.
Chest drain valve, Heimlich valve, mobile dry seal drain, and digital chest tube drains are one-way, small valves that are applied to a chest tube, allowing patients to ambulate and even facilitate earlier hospital discharge. Chest drain valves, Heimlich valves, and mobile dry seal drains can only be placed once the patient demonstrates no pneumothorax on water seal while digital chest tube drains can be placed even when the patient requires continuous suction, since the system has the capability to provide ambulatory suction. A chest drain valve (pneumostat) allows the unidirectional flow of air away from the leak. Patients can be discharged home with these devices as long as they are asymptomatic without subcutaneous emphysema or enlarging pneumothorax size (Table 1).
|Heimlich valve||Air leak|
|Chest drain valve||Air leak with low volume pleural effusion|
|Mobile dry seal drain||Air leak with high volume pleural effusion|
|Digital chest drain||Pneumothorax that requires continuous suction and pleural effusion|
Chemical pleurodesis (via medical thoracoscopy or chest tube) using sclerosants such as talc or doxycycline induces an inflammatory response that leads to a scar obliterating the pleural space and allowing for the pleural defect to seal.8 Retrospective studies report success rates between 60 and 90%.8 Successful pleurodesis requires direct apposition of the visceral and parietal pleura and thus, should only be done if there is a small or no residual pneumothorax when the chest tube is on water seal.
Chemical pleurodesis performed with a large pneumothorax may result in failure of the lung to re-expand.
ABPP is an alternative technique that has been used in patients with APF and PAL with or without complete lung expansion. Studies have shown that ABPP is safe and well tolerated by most patients.8 A review of 10 retrospective studies reported a success rate of 92%.8
A sample of the patients own blood (usually 100 mL) is directed to the pleural space via the chest tube followed by 20 mL of saline. The chest tube is then hung over an intravenous pole (for one to two hours) to avoid drainage of blood and blockage to the tube with thrombus which could potentially induce a tension pneumothorax, particularly in those who require suction for pleural apposition. The proposed mechanism of action is likely due to direct sealing of the air leak, as well as, the induction of pleural inflammation and eventual pleurodesis.
The optimum blood required to achieve successful pleurodesis is unknown and ranges from 50 to 120 mL. However, studies have shown that patients who received 100 to 120 mL of blood achieved complete resolution of PAL faster and more successfully compared to lower blood volumes (50 to 60 mL).8 Thus, use of higher volumes of blood for this procedure is advocated. Complications occur in <10% of cases and include pleuritis, empyema, and chest tube obstruction.8
Patients with PSP, particularly those with failed lung re-expansion who have PAL are generally treated with VATS surgical pleurodesis.8 Patients with SSP also typically undergo surgical pleurodesis, although valves may be an option in those not fit for surgery.8
A PSP is considered one that presents in the absence of an external factor. The management strategies of PSP, i.e., that which presents in the absence of clinical lung disease and SSP, i.e., that which presents as a complication of underlying lung disease differ in their threshold to perform a chest tube thoracostomy and a definitive procedure to prevent a recurrence. Thus, following the radiographic identification of pneumothorax, clinicians should quickly estimate the size, assess the degree of symptomatology, and attempt to classify the pneumothorax as primary, secondary, or other (trauma, iatrogenic) so that appropriate therapy can be initiated.
The approach to managing PSP, as well as SSP, varies widely among institutions and across continents. The following approach expands upon that outlined in published clinical consensus statements and guidelines from The American College of Chest Physicians (ACCP; 2001), British Thoracic Society (BTS; 2010), European Respiratory Society (2015), and the Japanese Association for Chest Surgery (2014).9 While some experts use a symptom-driven approach and others prefer a size-driven approach, the following approaches are ones that primarily incorporates size and symptoms.
Stability defined for both PSP and SSP, as suggested by the ACCP,9 comprises patients with all of the following:
All other patients are considered unstable.
All patients with PSP should receive resuscitation with a focus on airway stabilization (if indicated), as well as, supplemental oxygen which treats hypoxemia (if present) and facilitates absorption of air from the pleural space. Subsequent management is directed at deciding whether air needs to be removed from the pleural space and, if so, by what means. Options include:
Size assessment for PSP in the United States typically uses a cutoff of 3 cm between the pleural line and the chest wall at the level of the apex on a CXR.9 Estimation of size is usually only performed on CXR and less commonly on chest CT. Pleural ultrasonography cannot reliably quantify pneumothorax size. After the pleural ultrasound is used to identify a pneumothorax, CXR should be done to estimate the size, although practice may vary considerably and no guidelines are available to facilitate this decision.
Initial management of stable patients who present with PSP depends upon the size of the pneumothorax, associated symptoms, and whether the event is a first or a recurrent event. Additional factors include the presence of bilateral pneumothorax, concurrent pleural effusion that may need to be drained, and presence of complex loculations.
Clinically stable patients with a first episode of PSP in whom the pneumothorax is small should be treated with supplemental oxygen and observation and be discharged, if feasible. The rationale for this approach is based upon the fact that many patients in this category improve with this strategy without an invasive procedure for the removal of gas and animal data that support the increased absorption of air from the pleural space by high flow oxygen.
Occasionally, patients with significant symptoms despite the small pneumothorax size should have aspiration or chest tube thoracostomy since these patients are more likely to fail or have a recurrence despite oxygen and observation. However, a presentation that is disproportionate with the small size is unusual in PSP (because underlying lung disease is absent) and should prompt consideration of an unidentified underlying lung disorder. This should not, however, delay the implementation of therapy.
Most patients who are clinically stable with a first PSP in whom the pneumothorax is large should undergo needle or catheter aspiration, provided expertise is available. If the pneumothorax does not recur after aspiration, the patient need not be admitted.9 While the BTS9 supports observation in rare cases of patients with a large pneumothorax who are minimally symptomatic, needle aspiration is preferred while awaiting further study on this issue. The rationale for this approach is based upon meta-analyses of small randomized trials that report similar efficacy at one year with needle aspiration compared with chest tube or catheter thoracostomy and shorter hospital stays.
Although some guidelines encourage needle or catheter aspiration,9 they have not been widely followed,9 which may be due to the ease and wide availability with which small-bore intrapleural catheters can be placed for pleural drainage. Although aspiration is preferred for all patients with a large pneumothorax, some experts perform chest tube or catheter thoracostomy.
In reality, choosing between needle aspiration and catheter or chest tube thoracostomy is often dependent upon the availability of local expertise, severity of the presentation, and patient preference. For example, needle aspiration is less painful than catheter or tube insertion. However, the initial failure rate is higher with needle aspiration (on average one-third of patients), thereby necessitating a second procedure. Thus, some clinicians choose chest tube or catheter thoracostomy when expertise in needle aspiration is not available or in patients with recurrent PSP, bilateral, or very large pneumothoraces (e.g., complete collapse, mediastinal shift), severe symptoms, concurrent hemothorax or pleural effusion necessitating drainage, or complex loculated pneumothorax (unusual in PSP).
Patients with PSP who are unstable or have tension should undergo immediate chest tube thoracostomy. If chest tube thoracostomy is delayed, needle decompression of the pleural space is recommended. Remember that tension pneumothorax is rare in patients with PSP (due to the absence of underlying lung disease or precipitating cause such as central line insertion or mechanical ventilation).9
Options for treating PSP include:
Supplemental oxygen and observation is generally the strategy used in clinically stable patients with a first episode of PSP that is small and without severe symptoms. The rationale for supplemental oxygen in this population is based upon experience and data from animal models which report that the rate of resorption of air from the pleural space is increased up to six-fold if humidified 100% oxygen is administered.9
Since patients with PSP have no underlying lung disease, when the pneumothorax is small, oxygenation is generally within normal limits or low normal. Thus, oxygen is administered to promote the resorption of air (mostly nitrogen) from the pleural space. However, the optimal target fraction of inspired oxygen (FiO2) or peripheral oxygen saturation (SpO2) is unclear. Many experts will deliver high FiO2 (e.g., 100% oxygen via a nonrebreather mask) targeting a SpO2 of 100% while others administer lower FiO2 (e.g., 6 to 10 L via nasal cannulae) to target an SpO2 >96%. A FiO2 >6 L is generally administered to target a SpO2 >96%.
High flow oxygen via nasal cannulae (HFNC) should not be used since a small amount of positive pressure is delivered to the upper airway and could theoretically worsen the pneumothorax. For similar reasons, noninvasive positive pressure should also be avoided.
Observation while on supplemental oxygen should last about six hours, after which a CXR should be performed. If the CXR demonstrates no progression or an improvement in pneumothorax size, reliable patients with ready access to emergency medical services can be discharged home off oxygen with instructions to return if symptoms worsen. For patients requiring admission, oxygen should be continued as long as the patient is in the hospital and has a pneumothorax. Regardless of the patient’s disposition, a repeat CXR is typically performed 12 to 48 hours later.
If the pneumothorax is resolved, patients should be followed up in an outpatient setting within two to four weeks with a repeat CXR and be given instructions to be evaluated in an acute care setting should symptoms recur. If the pneumothorax fails to improve or worsens, then the pleural air should be removed via catheter or chest tube thoracostomy, although some clinicians repeat the aspiration. Choosing among these is at the discretion of the clinician. If the CXR demonstrates the worsening of the pneumothorax, the patient should have a chest tube thoracostomy placed and be admitted.
Aspiration is generally performed in clinically stable patients with a large PSP in facilities with expertise. Catheter aspiration is preferred rather than needle aspiration using equipment available in most commercial thoracentesis kits since needle aspiration alone may increase the risk of perforating the visceral pleural membrane and perpetuating the pneumothorax.
Catheter aspiration is typically performed blindly, although ultrasound guidance may be used. Similar to the procedure described for thoracentesis, an 18-gauge needle with an 8 to 9 French (Fr) catheter, which is attached to a three-way stopcock, is inserted into the pleural space generally in the second intercostal space at the mid-clavicular line.
Once the clinician observes that air can be aspirated (i.e., demonstrates access to the pleural space), the catheter is threaded deeper into the pleural space, and then the needle is withdrawn. Once the catheter is in place, air is manually aspirated using a syringe (typically 60 cc syringe) attached to the stopcock. Aspiration should continue until resistance is met or 4 L of air has been removed. While BTS guidelines suggest that no more than 2.5 liters should be withdrawn, experience suggests that up to 4 L may be withdrawn. Volumes >4 L suggest that a prolonged or persistent air leak (PAL) is present and that further expansion of the lung is unlikely. Once resistance is felt during aspiration and no more air can be aspirated, this usually indicates lung re-expansion. In this situation, two equally acceptable approaches exist, which are at the discretion of the clinician.9
The stopcock should be closed, and the indwelling catheter secured to the chest wall. A CXR should be obtained four hours later. If the lung is fully expanded and symptoms have improved, the catheter can be removed. Following an additional two hours of observation, another CXR should be performed. If the lung remains expanded on this CXR, the patient can be discharged with appropriate clinical and radiographic follow up within 24 to 48 hours.9 If the lung has not expanded fully or the CXR demonstrates worsening of the pneumothorax, a chest tube thoracostomy should be placed.
The catheter can be left in place and attached to a Heimlich (i.e., one-way) valve. The patient can then be discharged with clinical and CXR follow-up within one to two days.9 If follow-up imaging demonstrates recurrence, then a chest tube or catheter thoracostomy should be placed.
A Heimlich valve allows the unidirectional flow of air away from the leak. The rubber flap in between both ends functions as the one-way valve. If there is no resistance after 4 L of air has been aspirated and/or the lung has not adequately expanded on imaging, it is assumed that there is a PAL, and a chest tube or catheter thoracostomy should be placed. Consideration should be given to a preventive measure as soon as feasible.
The preference for aspiration in patients with a first PSP rather than tube or catheter thoracostomy (small- or large-bore) is based upon evidence from observational studies, small randomized trials and meta-analyses that report efficacy rates ranging from 30% to 80% and shorter hospital stays with aspiration.9
For example, one meta-analysis of six studies (435 patients) reported that compared with tube thoracostomy, simple aspiration was associated with shorter hospital stays and a lower adverse event rate. However, aspiration was associated with lower rates of immediate success, although the success rates at one year were the same in both interventions.9 This meta-analysis is limited, however, since most of the included trials were small.
Another 2018 network meta-analysis of 29 randomized trials (4,262 patients) similarly reported that in patients with a first episode of PSP there was no difference in the recurrence rate when tube thoracostomy or aspiration was used, but aspiration was associated with fewer hospital days.9
A chest tube or catheter thoracostomy should be placed in the following subgroups of patients based upon the assumed high risk of recurrence:
Thoracostomy is also appropriate for the following:
Chest tube thoracostomy refers to the insertion of a standard chest tube, while catheter thoracostomy refers to the insertion of a catheter (e.g., pigtail catheter). Choosing among them is often at the discretion of the clinician and available expertise. However, small-bore pigtail catheters are being increasingly used since they are easy to place, less painful, and as effective for the drainage of air as tube thoracostomy.
While both can be placed blindly, pleural ultrasound or other imaging modalities (e.g., fluoroscopy, CT) are frequently used to guide chest catheter placement, particularly, when the pneumothorax is loculated. However, if the patient has an impending respiratory failure or hemodynamic instability due to pneumothorax, tube thoracostomy without image guidance should be performed immediately.
In most patients with PSP, a small-bore chest tube (≤22 Fr) or small-bore pigtail catheter (≤14 Fr) is placed.9 In most cases, a small caliber tube or catheter is sufficient for the drainage of air in patients with PSP. It is unusual in this population that an indication for a large-bore chest tube (e.g., 22 to 28 Fr) is present unless the patient is unstable with a tension pneumothorax. There is concomitant drainage of viscous pleural fluid (e.g., empyema) or blood is needed, or small-bore catheter drainage is insufficient.
One systematic review that compared small-bore pigtail catheters with large-bore chest tubes in patients with both PSP and SSP reported that the success rate was similar in both groups (80% versus 83%), but pigtail catheters had a lower complication rate and shorter drainage duration and hospital stay.9
For the majority of patients, suction is not initially applied, and the tube or catheter is connected to a water seal device only.9 If the lung fails to re-expand within the subsequent 24 to 48 hours, worsens despite chest tube drainage, or develops a PAL, low wall suction can be applied, and, in some cases, a second drainage device may be needed. If suction is applied, low rates of -10 cm H2O are generally started and increased to -20 cmH2O using a high pressure-low volume system. Other forms of suction using high pressure-high volume or low pressure-high volume systems should be avoided.9
Few data exist to support this strategy. However, lung re-expansion is achieved in 70% of patients within 72 hours without suction in most cases.9 Theoretically, avoiding suction may also help reduce the risk of re-expansion pulmonary edema. Additionally, prolonged use of suction may lead to a delay in definitive management by prolonging airflow through the PAL, thereby slowing down the natural healing of a ruptured bleb.
For patients with a first PSP in whom a catheter or chest tube has been placed, follow-up over the subsequent one to five days usually involves daily bedside assessments for:
Daily imaging with CXR is not always necessary, although frequent imaging is typically performed to assess the degree of lung re-expansion. Imaging should also be obtained when symptoms worsen to evaluate for worsening pneumothorax on the ipsilateral side or development of a new pneumothorax on the contralateral side, as well as for tube thoracostomy position.
While some data suggest that measuring the leak size with digital manometry to identify those with large leaks predicts treatment failure and a longer hospital stay, this is not routine at most centers.9 Further imaging and management strategies depend upon whether the air leak has sealed or is persistent. For patients with a recurrent PSP, the chest tube/catheter generally remains in place, while provisions are being made for the patients to undergo a definitive procedure to prevent a recurrence.
Most pneumothoraces in patients with a first episode of PSP resolve with the initial management strategies outlined above. Once the air leak has resolved, a CXR should be performed to confirm that the lung has fully re-expanded.
Once the air leak has sealed, and the lung is fully re-expanded, the chest tube/catheter should be clamped for an additional 4 to 12 hours. The following precautions should be adhered to following the clamping of a chest tube.
Keep the clamp outside the bedclothes and visible, instructing the bedside nurse about releasing it if the patient becomes hemodynamically unstable or otherwise symptomatic, Obtaining and examining the CXR after a set period (4 to 12 hours). Clamping the chest tube/catheter prevents invisible drainage of small amounts of air through the water seal and thus allows recognition of small leaks that would otherwise be missed. Some experts prefer not to clamp the chest tube because this might lead to the development of a tension pneumothorax. However, tension pneumothorax is rare in PSP.
The chest tube can be removed if the pneumothorax has not recurred and the patient can be discharged unless an indication for a definitive procedure is present. If the pneumothorax recurs, then the chest tube should be unclamped, and the process repeated. At this point, options include the following.
Continue with tube or catheter drainage to water seal for another 24 to 48 hours. Some experts prefer to avoid suction for a few more days, under the premise that suction encourages the flow of air through the defect and prevents closure. Data to support the latter strategy are largely derived from postsurgical patients.
The application of suction may be applied to increase pleural apposition and facilitate closure of the air leak. Occasionally, a second chest tube is required for patients in whom the lung does not fully expand or those with loculations, although this is rarely needed for patients with PSP.
If there is no air leak and the lung has not fully expanded, blockage of the chest tube or chest tube malposition should be considered. Under these circumstances, the chest tube/catheter should be flushed, and if patent, chest CT may be obtained to examine tube position. Rarely this phenomenon is due to pneumothorax ex vacuo.
A small proportion of patients with a first episode of PSP develop a PAL. An air leak is considered prolonged if it continues for five days or longer, although varying definitions exist in the literature ranging from three to seven days. Remember to check that the air leak is not coming from the:
Checking for air leaks is classically done by clamping the tube at different locations to isolate the site of the leak. These patients require a more aggressive approach for defect closure since the longer an air leak persists, the less likely it becomes that the air leak will close spontaneously and the more likely that a definitive intervention (e.g., blebectomy and pleurodesis) will be required.9
The approach varies among experts and depends upon factors including the degree of lung expansion, local expertise, and patient values and preferences. A multidisciplinary approach that also includes a pulmonary specialist and a thoracic surgeon is recommended.
The following approach is suggested:
For patients with a PAL, whose lung is at least 90% re-expanded, ambulatory drainage devices or continued chest tube drainage is preferred especially in those not suitable for an ambulatory device. Other options include non-surgical pleurodesis (e.g., blood patch), or VATS repair of the defect with pleurodesis. Choosing among these is at the discretion of the clinician, as well as local expertise and patient preference since there are no data to support one as superior to the other.
Continue chest tube drainage with an ambulatory drainage device. Many experts prefer ambulatory drainage devices based upon the rationale that the air leak is small and likely to seal spontaneously without intervention. In addition, experience indicates that continued time with conservative therapy often ensures successful closure and allows rapid discharge of the patient with subsequent outpatient management.
Ambulatory drainage should continue for about four or five days but longer, if necessary (e.g., up to one week). For those not suited to an ambulatory device (e.g., poor follow-up care), continued inpatient therapy with chest tube/catheter drainage is appropriate. Resolution of the air leak has been described with conservative management after as long as 14 days.9
Pleurodesis is an alternative for patients who prefer to achieve a more rapid and definitive resolution or for those who fail conservative therapy with ambulatory devices or continued chest tube thoracostomy. In general, surgical pleurodesis (typically VATS) may be preferred for patients who desire procedures with high success rates. Non-surgical techniques for pleurodesis, including an autologous blood patch, are reserved for patients who are not candidates for surgery or favor less invasive techniques.
For patients who have a PAL and whose lung is less than 90% re-expanded, the preferred procedure is VATS pleurodesis with the repair of the defect. Nonsurgical pleurodesis or conservative management with ambulatory devices, or chest tube drainage is an option for those who are not candidates for or are unwilling to undergo surgery.
Video-assisted thoracostomy surgery (VATS) use as primary therapy for PSP is unclear. A randomized trial compared recurrence rates in those who received a chest thoracostomy tube with VATS with bleb resection and mechanical pleurodesis.9
VATS was more effective at reducing recurrence rates when bullae ≥1 cm were noticed on chest CT. In contrast, a network meta-analysis reported that in patients with a first episode of PSP there was no difference in the recurrence rate when VATS, tube thoracostomy, or aspiration was used.9 Further study is required before VATS can become routine in patients with PSP.
Unlike those with SSP, most patients after a first episode of PSP, do not need to undergo a definitive procedure since the likelihood of a recurrence is considered low and PALs are unusual. Following the initial treatment of a first episode of PSP, a decision to treat with a definitive procedure (e.g., pleurodesis with blebectomy) to prevent recurrence needs to be made. Although practice varies widely, there is a general consensus among experts that a small population of patients with a first episode of PSP should be selected to undergo a definitive procedure including patients with a:
Other less well-established indications include patients:
The rationale for a definitive procedure in these patients is based upon the assumption that, among patients with PSP, the risk of recurrence is greatest in these subgroups, approaching that of patients with SSP. Data to support these indications, however, are few. In one small study of 214 patients with PSP (>2 cm from the pleural line to the chest wall), at one year, chemical pleurodesis with minocycline was more effective at preventing recurrence than no pleurodesis (29% versus 50%).9 Future studies should focus on defining which patients with PSP are at the highest risk of recurrence so that a targeted preventative intervention may be performed selectively.
Some experts also choose to perform a definitive procedure in patients with a first episode of PSP who have another indication for thoracoscopy. For example, such patients could include those with PSP who require a diagnostic lung biopsy (e.g., if catamenial pneumothorax is suspected) or those with hemopneumothorax where frank blood needs to be removed. In these circumstances, some surgeons choose to perform a definitive procedure (e.g., abrasion and/or blebectomy) at the time of surgery since the additional risk is considered relatively low.
Following the resolution of a pneumothorax, whether spontaneously, with a thoracostomy or with an ambulatory device, or after a definitive procedure, patients should be re-evaluated in two to four weeks in an outpatient setting for clinical and radiologic evaluation. In the intervening period, they are instructed to return to an acute care facility if they develop symptoms of CP or dyspnea since recurrence is greatest during the first month after presentation.
During the follow-up evaluation, the following is suggested:
For patients with a previous PSP who recur with either ipsilateral or contralateral pneumothorax, chest tube thoracostomy is suggested followed by a definitive procedure to prevent a further pneumothorax during the same hospital admission. Although some patients could potentially be managed with less aggressive options (e.g., oxygen and observation, aspiration), the risk of recurrence is considered high enough to justify an approach that is similar to that performed in patients with a SSP.
Since the risk of recurrence is considered low in patients with PSP, i.e., pneumothorax without underlying lung disorder, most patients with a first episode of PSP do not typically undergo definitive treatment until it recurs. However, a small percentage of patients need a preventive intervention, including patients with:
The estimated recurrence rate after the first PSP is broad, ranging from 0% to 60%. Newer studies suggest average occurrence rates between 10% and 30% at one to five year follow-up period, with the highest risk occurring in the first 30 days through the first year.7 One of the largest epidemiologic studies found that the rates of recurrent PSP are:7
These rates, however, may have been underestimated since they were calculated from inpatient admissions and did not include patients treated as outpatients. In contrast, in another systematic review that included 29 randomized trials and observational series, the pooled one-year recurrence rate for patients with PSP was 29%.7
Risk factors reported to be associated with an increased risk of recurrence of PSP include:7
For example, one study of 176 patients with PSP reported that the risk of ipsilateral recurrence for patients with blebs and bullae on chest CT was 68% compared with 6% in patients without blebs and bullae, with the highest risk in those with multiple and bilateral lesions (75%).7
The risk of contralateral pneumothorax was also higher in patients with blebs and bullae on CT (19% versus 0%). The broad range and high incidence of recurrence in subpopulations of patients with PSP, in particular those found to have blebs or bullae on imaging, has led some experts to propose that the classification of pneumothorax is not necessarily binary (primary versus secondary) but rather a continuum with risk of recurrence ranging from low to high.
At a minimum, a subpopulation of patients with suspected PSP may actually have undiagnosed lung disease, and this subpopulation may warrant reclassification as SSP so that appropriate preventions can be put in place. Future studies should focus on defining cutoffs for recurrence risk to distinguish those with high recurrence in whom pleurodesis is indicated after a first event, from those with a low recurrence in whom pleurodesis is not justified until pneumothorax recurs.
Most patients with SSP are treated with supplemental oxygen and removal of air from the pleural space, typically by chest tube thoracostomy. Patients also typically undergo a definitive procedure to prevent recurrence during the same hospitalization.
There is no consensus statement regarding size to guide clinicians when managing patients with SSP. Estimation of size is usually only performed on CXR and less commonly on chest CT. Pleural ultrasonography cannot reliably quantify pneumothorax size and is generally imperfect. For pneumothorax identified using pleural ultrasound, CXR should be done to estimate the size, although practice may vary considerably, and no guidelines are available to facilitate this decision. The suggested cut off from the pleural line to the apex of <2 cm (small pneumothorax) and ≥2 cm (large pneumothorax) is based upon experience and used as a general guideline only.
Most clinically stable patients with an SSP should be treated with catheter or chest tube thoracostomy based upon the rationale that compared with PSP, patients with SSP have underlying lung disease that increases the likelihood of failure of aspiration, a PAL, and the development of tension.10
In patients with a small SSP (<2 cm from the pleural line to the chest wall at the apex) who have significant symptoms, a catheter or tube thoracostomy is preferred, and the patient should be hospitalized.
Exceptions may exist. For example, for patients with a small SSP or patients who are asymptomatic or have minimal symptoms, treating with supplemental oxygen and observation or aspiration (in centers with expertise) is appropriate, and the threshold to admit the patients should be low. Progression of symptoms or an enlarging pneumothorax is an indication of pleural drainage.
For patients with a large SSP (≥2 cm from the pleural line to the chest wall at the apex), prompt drainage by tube or catheter thoracostomy and subsequent hospitalization are indicated because of the risk of respiratory impairment and need for definitive intervention.10
Instability due to pneumothorax (including tension pneumothorax) is more common in patients with SSP than PSP. Patients who are unstable due to SSP should undergo chest tube thoracostomy or alternatively, needle decompression of the pleural space, if chest tube decompression is delayed.
Patients with SSP are treated with supplemental oxygen, and the underlying reason for pneumothorax is treated. Patients are generally admitted. Supplemental oxygen and observation.
Unlike patients with PSP, hypoxemia is common in patients with SSP. Supplemental oxygen (for a minimum of six hours) and observation is an option for clinically stable patients who:
Supplemental oxygen is administered to virtually all patients with SSP to treat hypoxemia and facilitate the absorption of air from the pleural space.10 The protocol is similar to that described for patients with PSP except for the threshold for admission and placement of a thoracostomy tube is lower.
However, in contrast with patients who have PSP in whom high flow oxygen can be administered liberally, the fraction of FiO2 should be increased cautiously in patients with SSP who have or are at risk for oxygen-induced hypercapnia (e.g., moderate to severe COPD).10 Similar to patients with PSP, HFNC should be avoided, when feasible, since HFNC delivers a small amount of positive pressure to the airway that could potentially worsen the pneumothorax and perpetuate the air leak.
This strategy is not generally suitable for those with a recurrent episode but can be rarely considered in those with severe underlying lung disease and a small loculated pneumothorax in whom other options are limited.
Aspiration of air is an option in stable patients with a small SSP (<2 cm from the pleural line to the chest wall at the level of the apex) who have mild or no symptoms or for those in whom options are limited. This option is usually limited to centers with expertise. The procedure for aspirating air is similar to that described in patients with PSP except for the threshold for admission following aspiration should be lower since the likelihood of failing aspiration is higher.10
Patients with SSP may have a pneumothorax as a complication of their underlying lung disease, which may need to be treated together with the pneumothorax. As an example, pneumothorax: May precipitate or be a complication of a COPD exacerbation or asthma attack, necessitating therapy with nebulized bronchodilators and intravenous glucocorticoids.
Patients with SSP are more likely than those with PSP to need concomitant therapies. However, some may worsen the pneumothorax and should be avoided.
In general, NIV should be avoided when feasible (e.g., mild to moderate non-life-threatening obstructive sleep apnea) since it is plausible the application of positive pressure increases the risk of a PAL and progression to tension. In addition, a few anecdotal cases exist to support the development of pneumothorax in those receiving NIV, although no reports have been published demonstrating progression in those with an established pneumothorax. Despite this risk, caution is warranted in select circumstances (e.g., in patients with respiratory failure who prefer to avoid mechanical ventilation which have a thoracostomy tube in place).
For similar reasons, High-flow nasal oxygen via nasal cannulae (HFNC) is also avoided due to the small amount of positive pressure that is delivered to the airway with this mode of oxygen delivery.
Based upon experience individualizing airway clearance measures in patients with a pneumothorax is suggested based upon the risk of progression. For example, on the one hand, the risk of progression may be higher in those on positive expiratory pressure (PEP)/oscillating PEP and manual chest percussion while, on the other hand, the risk of mucus plugging from withholding therapy may also contribute to the progression.
Factors to take into consideration which are typically most pertinent to those with CF include the:
Nebulized therapy does not need to be held while pneumothorax is being treated.
Almost all patients with SSP should be hospitalized because the underlying lung disease increases the risk for an adverse outcome (e.g., respiratory failure, cardiovascular collapse, recurrent event).10 Exceptions are rare but might include stable patients with minimal symptoms and a small SSP (<2 cm), who may be observed in the outpatient setting if follow-up and access to healthcare are good.10
The majority of patients with SSP undergo tube or catheter thoracostomy placement. Less commonly, for minimally symptomatic small pneumothoraces, needle aspiration or oxygen and observation may be appropriate.
Chest tube or catheter (e.g., pigtail catheter) thoracostomy is generally preferred over simple aspiration for drainage of air in patients with SSP because it is more likely to be successful.10 Chest tube thoracostomy refers to the insertion of a standard chest tube, while catheter thoracostomy refers to the insertion of a catheter, which is usually small, more pliable, and therefore less painful (e.g., pigtail catheter). In one trial, 28 patients with SSP were randomly assigned to receive chest tube thoracostomy and 33 patients to simple aspiration.10
The chest tube thoracostomy group was more likely to have their pleural air completely evacuated than the needle aspiration group (93% versus 67%). The lower success rate of pleural aspiration in SSP than in PSP may be due to a higher rate of large PALs.10
For most clinically stable patients with SSP, small-bore pigtail catheters (≤14 French [Fr]) or small-bore chest tubes (≤22 Fr) should be used rather than large-bore chest tubes based upon ease of insertion, patient comfort, and evidence that supports equal efficacy.10 However, some patients may only benefit from the insertion of large-bore chest tubes (24 to 28 Fr).
Patients with large PALs may need a large-bore chest tube to provide enough drainage capacity. Alternatively, they may benefit from a second small-bore catheter.
Patients with concomitant empyema or hemothorax are thought to benefit from large-bore tubes for drainage since small-bore catheters are at increased risk of blockage from clot or debris. In the case of hemothorax, the purpose of a chest tube is also to monitor the rate of blood loss, making a large-bore tube desirable.
Patients who are unstable with tension pneumothorax a large-bore tube is often placed based upon the likelihood of a large or persistent PAL.
Patients with barotrauma from mechanical ventilation.
Many experts prefer large-bore chest tubes in patients with barotrauma since the air leak is likely to be large and may lead to a tension pneumothorax, although the risk is unquantified. Practice varies greatly, however, and is dependent upon the availability of expertise and institutional practices.
A retrospective study of 62 mechanically ventilated patients reported lower success rates with small-bore chest tubes when the pneumothorax was thought to be due to barotrauma than when the pneumothorax was due to iatrogenic causes (43% versus 88%).10
The general principles of immediate follow-up of patients with SSP who have chest tube or catheter thoracostomy, including the indications for the application of suction (most patients are initially placed on water seal), are similar to that of patients with PSP. However, the prevalence of a PAL is more common. Thus, most patients remain hospitalized with the chest tube in place until a definitive procedure is performed to prevent a recurrence.
After a thoracostomy is placed the following is suggested:
In contrast with patients who have PSP, most patients with a first episode of SSP should undergo a definitive intervention during the same hospitalization (e.g., within three to five days) to prevent a recurrence. This approach is suggested due to the high:
Individual exceptions may apply to patients:
In most cases, VATS or medical thoracoscopy with blebectomy and a procedure to induce pleurodesis (e.g., surgical abrasion or chemical pleurodesis) is the first choice procedure based upon its high efficacy.
For those unable or unwilling to undergo VATS, medical chemical pleurodesis at the bedside is preferred. For patients with emphysema who meet inclusion and exclusion criteria for LVRS, it may be appropriate to perform LVRS at the time of surgical pleurodesis.
After therapy, outpatient follow-up is similar to that described for patients with PSP. Patients should be evaluated clinically and radiologically in about two to four weeks after discharge. During this time, they are instructed to return to the hospital with symptoms of CP or dyspnea since recurrence is greatest during the first month after presentation.
Patients should be assessed for control of their underlying lung disease. Patients should be advised to:
While patients with SSP should have a definitive intervention after their first event to prevent a recurrence, some patients are ineligible or unwilling to undergo a definitive procedure. Should SSP recur, a chest tube or catheter thoracostomy should be placed to manage recurrence, and the option of a definitive procedure should be revisited.
Data to support high recurrence rates in this population are largely derived from patients with COPD. For example, one study reported a 50% likelihood of recurrent SSP over three years among patients with a pneumothorax due to COPD who did not have an intervention to prevent recurrence.7
Similar high recurrence rates have been described in other populations of patients with acute and chronic lung disease, including women with LAM and individuals with nontuberculous mycobacteria and BHD syndrome.7 One of the largest epidemiologic studies of SSP suggested that the rates of recurrent SSP may be lower than originally thought.7
Rates of recurrence for males were:
Rates of recurrence for females were:
However, these rates may have been underestimated since they were calculated from inpatient admissions over a 46-year period, and adjustments for interventions were not clear.
Risk factors for recurrence may be similar to those in patients with PSP (e.g., smoking) but are less well studied since most patients with SSP proceed with a definitive measure to prevent recurrence after their initial event.7
Once patients have undergone initial management for a pneumothorax, clinicians should assess the risk of recurrence to evaluate whether definitive management (usually pleurodesis) is indicated. Several indications for the prevention of recurrence exist:
Since the recurrence rate is considered high (e.g., >50%), most patients with a first episode of SSP should undergo a definitive intervention to prevent recurrence. Individual exceptions may be applied to patients with very small loculated pneumothoraces (e.g., patients with CF)7 or patients who decline definitive treatment.
Any pneumothorax that presents with a PAL beyond five days should be assessed for a definitive procedure based upon the rationale that the underlying defect is large and unlikely to heal rapidly on its own. In such cases a definitive procedure is both a therapeutic (to seal the leak) and a preventative measure. PALs are more commonly encountered in patients with SSP than PSP.
The risk of recurrence is considered high in patients with certain professions or hobbies (e.g., airline pilot, scuba diver) in whom there is also the potential for devastating consequences such that a definitive procedure is justified.
Any patient with recurrent pneumothorax should undergo a definitive procedure since the likelihood of future events, particularly life-threatening ones, is high.
Patients with a hemothorax or a need for lung biopsy may be considered for pleurodesis at the time of surgery.
The risk of recurrence should be individualized in other patient populations (e.g., trauma, iatrogenic). Among these causes, iatrogenic and traumatic pneumothorax are the most common, and a definitive procedure is not typically necessary unless a PAL develops. In contrast, patients with a structural abnormality that is irreversible, such as Marfan's syndrome, may potentially benefit from definitive treatment to prevent a recurrence.
Factors that should be taken into consideration that need discussion with the patient include:
The potential for lung transplantation is much higher in patients with SSP than PSP.
Although pleurodesis can increase the morbidity associated with subsequent lung transplantation (e.g., bleeding, requirement for transfusion, length of surgery), it should not affect the decision to proceed with the definitive intervention itself when indicated. However, it may affect the type of definitive procedure chosen.
Options for preventing recurrence include surgical and nonsurgical approaches.
VATS pleurodesis is preferred in most cases based upon its high efficacy when compared with nonsurgical approaches. The chosen method of pleurodesis (e.g., chemical, abrasion, pleurectomy) and the inclusion of a procedure to treat blebs (e.g., stapling, ligation) is usually at the discretion of the surgeon. However, it is acknowledged that significant variability exists among institutions and countries.
Pleurodesis performed via medical thoracoscopy should also produce similar results to VATS. For those unable or unwilling to undergo VATS (or medical thoracoscopy), chemical pleurodesis via chest tube is preferred.
In those with PSP or SSP with an indication for a definitive procedure, VATS or medical thoracoscopy is suggested based upon the high efficacy and lower adverse effect profile when compared with open thoracotomy.7 Choosing among VATS or medical thoracoscopy is often institution-dependent, with medical thoracoscopy being more frequently performed in Europe, and VATS more commonly performed in the USA.
Although pleurodesis via open thoracotomy has higher success rates, VATS has largely supplanted open thoracotomy for the management of spontaneous pneumothorax in most centers.7
Thoracotomy is recommended only if VATS is unavailable or has failed. This recommendation is based upon meta-analyses comparing open thoracotomy with VATS that have consistently shown lower recurrence rates with open procedures (approximately 1% with open versus 5% with VATS), but with greater blood loss, more postoperative pain, and longer hospital stays.7
The two most common procedures that are performed during surgical thoracoscopy are pleurodesis and blebectomy/bullectomy. Many surgeons choose to perform both at the time of surgery since some data suggest that the recurrence rate is lower when both procedures are performed simultaneously.
However, some surgeons perform pleurodesis without blebectomy/bullectomy or vice versa based upon data that suggest combining both procedures worsens the adverse effects. Combining blebectomy/bullectomy with pleurodesis makes biologic sense that recurrence is lower when both procedures are used.
Mechanical pleurodesis using pleural abrasion with dry gauze is preferred as the initial procedure since it is both simple and effective. However, talc, which is associated with the highest success rates, may be preferred in those considered at highest risk of recurrence or those with recalcitrant pneumothorax in whom avoidance of recurrence is critical.
In patients considered at high risk of recurrence, some surgeons also choose to combine an apical pleurectomy (i.e., partial pleurectomy to the region of lung most affected by blebs) with abrasion to the visceral pleura over the rest of the lung. In addition, some experts avoid talc in those with significant intraparenchymal disease burden, who may not have a significant reserve to tolerate an episode of acute lung injury.
Several surgical techniques have been reported to induce pleural symphysis (i.e., pleurodesis) with significant variation in practice among surgeons, institutions, and countries. These include:
Choosing among these options is often at the discretion of the surgeon but also dependent upon factors including the following:
There is also considerable variability among countries, with mesh and fibrin glue being popular in Japan, while mechanical abrasion or chemical pleurodesis is popular in the United States. Similarly, talc is often the preferred sclerosant used in Europe, while a tetracycline derivative is preferred by some United States institutions. Performing lung transplants in patients who have undergone pleurodesis is technically challenging and associated with increased blood loss due to dissection of the scarred pleural membrane.
Although a previous pleurodesis is not a contraindication for lung transplantation, a targeted/partial approach to pleurodesis in transplant candidates is preferred using VATS-directed mechanical abrasion of the apical pleural surface to achieve apical pleurodesis. This approach, in theory, provides enough pleurodesis to prevent large pneumothoraces while avoiding the formation of dense thick pleural symphysis, typical of chemical pleurodesis, which can be difficult to dissect.
When feasible, full pleurodesis with chemicals is avoided, unless the frequency and degree of recurrence indicates the need for more aggressive measures (e.g., bilateral life-threatening recurrence, recalcitrant pneumothorax).7
Resection of pulmonary blebs and bullae may be indicated to prevent spontaneous pneumothorax from rupture or for ongoing air leak following thoracostomy tube placement.9 A bleb is smaller than 1 cm in diameter and typically subpleural and located more cephalad. Blebs may occur from an alveolar disruption in patients with otherwise relatively normal parenchyma.
Bullae, which are thinned areas of the lung parenchyma, are typically >1 cm in diameter with wall thickness <1 mm and typically occur from parenchymal destruction such as that caused by emphysema. Large bullae can occupy up to one-half of the volume of the pleural cavity, leading to contralateral lung compression.
Consistent with the practice of many surgeons, VATS apical blebectomy/bullectomy simultaneously with pleurodesis is suggested based upon retrospective data that report recurrence rates <5% using this combined approach.7 However, data are conflicting, and some surgeons perform pleurodesis alone based upon data that report lower recurrence rates in patients with VATS-directed insufflation of talc compared with bullectomy alone (0.3% versus 3.8%)7 while others perform blebectomy/bullectomy alone based upon data that report recurrence rates <9% with bullectomy alone.7
The rationale for blebectomy/bullectomy is that patients with SSP and, less often, patients with PSP, have underlying subpleural blebs or bullae (cysts ≥1 cm) that are considered the most likely cause of SSP.
Blebs/bullae are typically apical in location. While some defects (with or without PALs) are visible to the naked eye (or on imaging), others are not apparent. Thus, many surgeons choose to resect the apex of the lung based upon the observation that even in the absence of obvious blebs/bullae, patients with a pneumothorax have subclinical blebs noted on pathologic analysis of resected tissue. In support, many high-grade blebs have been detected by fluorescein-enhanced autofluorescence thoracoscopy (FEAT) in areas that appear normal during white light thoracoscopy.7
When blebs or bullae are so numerous that resection of all blebs is not feasible, the surgeon may choose to resect only those that are large and leave smaller ones intact before proceeding with pleurodesis. The optimal surgical technique to treat underlying blebs/bullae is uncertain, and, in most cases, the decision is typically left to the discretion and experience of the surgeon. Most surgeons resect blebs/bullae using a stapling technique since data support low recurrence rates with stapling,7 and both pneumostasis and hemostasis can be achieved with this method.
Other techniques include suturing, staple reinforcement at the suture line, ligation, or coagulation of visible lesions.
Lung volume reduction surgery (LVRS) involves removing the apical portions of one or both lungs to improve overall respiratory function in patients with significant upper lobar emphysema. LVRS, which can be performed via sternotomy or bilateral thoracostomy, can also be performed by bilateral VATS.
Because VATS is less invasive, there is a faster recovery time, decreased cost, decreased length of stay, and decreased rate of complications.9 There is no difference in functional results or mortality when comparing VATS with open methods of LVRS.
For patients with COPD who meet inclusion and exclusion criteria for LVRS, it may be appropriate to perform LVRS at the time of surgical pleurodesis.
The optimal management of pneumothorax associated with other etiologies is unstudied and is generally based upon biologic plausibility and experience.
Patients with iatrogenic pneumothorax are generally treated as if they had PSP, and few require pleurodesis unless they have a PAL that is not responsive to conservative therapy.
The optimal treatment of patients with pneumothorax associated with structural abnormalities of the lung, including Marfan’s or Ehlers-Danlos syndrome, is unknown. However, in general, they are treated in a similar fashion to those with SSP based upon the assumption that recurrence is likely to be high.
Miscellaneous causes of pneumothorax include:
Treatment of pneumothorax should be individualized based upon the symptoms and assessed risk of recurrence. Some experts recommend bilateral pleurectomy for deep-sea divers who wish to resume diving.10
|Pneumothorax Type||Specific Diagnostic or Management Strategies to be Considered|
|Cystic lung disorders|
|Architectural abnormalities (e.g., Marfan syndrome, Ehlers-Danlos syndrome, Homocystinuria)|
|Illicit drug use|
*VATS: video-assisted thoracoscopic surgery
**PAL: prolonged (persistent) air leak
***VEGF-D: vascular endothelial growth factor-D.
**** Rapamycin, as an immunosuppressant, is a useful therapy for some patients with LAM but should not be started until the pneumothorax has healed for about six weeks.
Case reviews support the occurrence of PSP and SSP during pregnancy. However, the exact incidence of either entity is unknown.10 Older studies suggest that recurrence is greater during pregnancy, although it is plausible that recurrence is due to the progression of underlying lung disease that was undetected or unsuspected following the first event.
From a management perspective during pregnancy, general principles are as follows. Guidelines and experts support conservative measures including aspiration and oxygen in most stable women who develop PSP during pregnancy (provided there is no evidence of fetal distress).10 Chest tube or catheter thoracostomy is appropriate for pregnant patients in whom:
Because the risk of recurrence during future pregnancies is presumed to be high, pleurodesis should be offered to women after delivery, although case reports and anecdotal evidence report successful pregnancies without recurrence in patients in whom a definitive intervention has not been performed.10
Similarly, experts delay investigative testing to uncover possible underlying lung disease (e.g., suspicion for LAM in a pregnant woman with pneumothorax should be high) such as chest CT and lung function testing, until after delivery.
For pregnant women with or without a previous episode of a pneumothorax who are at risk of developing a pneumothorax during labor and delivery, close consultation with thoracic surgery, pulmonary, and obstetrics and gynecology consultant is advised. Most experts advise elective, assisted delivery at or near-term, with regional anesthesia to reduce maternal effort.10 Regional anesthesia is also preferable in those in whom a cesarean section is indicated.
Mr. Brown is a 19-year-old Caucasian male transported to the Emergency Room via EMS on August 5, 2019, at 2100. He states he was visiting his sister at her house when his sister got angry with him because he stated that he does not like her boyfriend. She grabbed a kitchen knife and stabbed him in his chest in an upward motion (at approximately 2030). He pointed to his left lower thorax. He called 911 after he realized she had stabbed him. He denies SHOB or chest pain. He c/o a “little pain” under his left-sided bandage. Otherwise, he no longer sees a reason to be in the Emergency Department and wants to go home.
Current Medical History:
Past Medical/Surgical History:
Discussion of Outcomes
Mr. Brown is being monitored in the Emergency Department awaiting laboratory, ABG, CXR and CT results. Tentative diagnoses: Potential left lower pneumothorax secondary to left lower thoracic stab wound; Potential splenic/abdominal bleeding
Strengths and Weaknesses
Mr. Brown will be monitored in the Emergency Department for the development of signs and symptoms of a pneumothorax and/or splenic/abdominal bleeding for a minimum of 4 hours. Mr. Brown’s health history and physical examination were performed quickly with appropriate orders written. Appropriate interventions initiated.
CEUFast, Inc. is committed to furthering diversity, equity, and inclusion (DEI). While reflecting on this course content, CEUFast, Inc. would like you to consider your individual perspective and question your own biases. Remember, implicit bias is a form of bias that impacts our practice as healthcare professionals. Implicit bias occurs when we have automatic prejudices, judgments, and/or a general attitude towards a person or a group of people based on associated stereotypes we have formed over time. These automatic thoughts occur without our conscious knowledge and without our intentional desire to discriminate. The concern with implicit bias is that this can impact our actions and decisions with our workplace leadership, colleagues, and even our patients. While it is our universal goal to treat everyone equally, our implicit biases can influence our interactions, assessments, communication, prioritization, and decision-making concerning patients, which can ultimately adversely impact health outcomes. It is important to keep this in mind in order to intentionally work to self-identify our own risk areas where our implicit biases might influence our behaviors. Together, we can cease perpetuating stereotypes and remind each other to remain mindful to help avoid reacting according to biases that are contrary to our conscious beliefs and values.