Pneumothorax In The Adult Patient

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.

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

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:

• Breast tissue expander placement
• Central venous catheterization
• Chest acupuncture
• Colonoscopy
• Mechanical ventilation
• Pacemaker insertion
• Percutaneous or transbronchial biopsy of the lung or mediastinum
• Shoulder arthroscopy
• Thoracentesis
• Thoracic or esophageal procedures or surgery
• Tracheostomy

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:

• Anorexia nervosa:
  • Patients with anorexia nervosa may develop SSP.²
  • It is thought that the pulmonary parenchymal consequences of malnutrition (e.g., emphysema) contribute to the development of pneumothorax in these patients, but other unknown processes may be at play.
• Exercise, illicit drug use, immunosuppressant drugs:
  • Rare case reports and anecdotes suggest a possible relationship between pneumothorax and exercise, drug abuse (e.g., cocaine or heroin), or chemotherapeutic drugs.²
  • It has been postulated that exercise and illicit drug use may cause pneumothorax by leading to deeper inhalation and Valsalva maneuvers.
  • Some injection drug users may also develop traumatic pneumothorax from attempting to inject into the neck veins.
• Air travel and scuba diving:
  • Pneumothorax may be associated with air travel and diving, although an underlying lung disorder may increase this risk further.²

The classic presentation of patients with pneumothorax include the following:

Hemodynamically unstable patients and patients with severe respiratory distress are typically those patients with:

• A large or tension pneumothorax
• Extensive trauma
• Significant underlying lung disease

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:

• Patients are undergoing a chest CT for another indication (e.g., stable trauma patients undergoing total body CT for additional injuries, or patients with suspected PE undergoing CT pulmonary angiography). In such patients, the CT will readily detect a pneumothorax.
• Patients in whom a pneumothorax has been excluded by pleural ultrasonography.
  • In cases where pleural ultrasonography has been used for a procedure (e.g., thoracentesis or central venous catheterization), it can be used to exclude a pneumothorax.
  • However, if the diagnosis of a pneumothorax remains in doubt following pleural ultrasonography, a CXR should be performed.
  • Some experts advocate for CXR even in pleural ultrasonography-identified pneumothorax, since size can only be assessed on a CXR. Size, in turn, dictates management.
• Pleural ultrasonography is being increasingly used in critically-ill patients on mechanical ventilation but CXR and chest CT are also frequently used depending upon the severity of presentation.

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

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.

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:

• Lung disorder known to be associated with pneumothorax (e.g., COPD, CF, malignancy, LAM, PCP)
• Procedural-related pneumothorax (e.g., following central venous catheterization, thoracentesis etc.)
• Trauma–related pneumothorax

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:

• CP or hemoptysis premenstrually in a young woman with or without a history of endometriosis might suggest catamenial pneumothorax.
• A family history of pneumothorax may suggest inheritable disorders such as alpha-1 antitrypsin deficiency or BHD syndrome, and rarely Marfan or Ehlers Danlos syndrome. A personal or family history of renal cancer may also support BHD syndrome.
• A history of travel (e.g., to regions where TB is endemic) or reason to suspect underlying human immune deficiency disorder may be sought in those with a possible infectious reason for a pneumothorax.
• A joint and skin examination may reveal dry eye and joint disease suggestive of Sjögren syndrome (which can be complicated by lung cysts), joint hypermobility, or hyperextensible skin consistent with Ehlers Danlos syndrome, or pectus carinatum and disproportionate tall stature to suggest Marfan syndrome.
• A detailed drug history or track marks may suggest illicit drug use or identify immunosuppressant drugs not previously suspected as an etiology of a pneumothorax.
• A history of weight loss or sweats may suggest occult malignancy.
• A detailed social history may identify recent air travel or scuba diving as a hobby.
• Any lucencies or nodules on CXR in a young smoking male or nonsmoking female should prompt a chest CT to look for evidence of Langerhans cell histiocytosis (LCH), subpleural blebs, or LAM.
• Cysts identified on CT should prompt a diagnostic evaluation for cystic lung disorders.

Though thoracotomy and thoracostomy sound almost the same, the terms describe two very different procedures:

• Thoracotomy is a surgery that makes an incision to access the chest. It is often done to remove part or all of a lung in patients with lung cancer.
• Thoracostomy is a procedure that places a tube in the space between the lungs and chest wall (pleural space). It is done to drain fluid, blood, or air from the area around the lungs.

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

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

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.

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
• Air leak meter
• Observation using timing during the respiratory cycle
• Localizing the air leak (sequential balloon occlusion)

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.

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.

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.

Options for treating PSP include:

• Supplemental oxygen and observation
• Chest tube or catheter thoracostomy
• Simple aspiration

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:

• Clinically stable patients with a PSP who fail observation or aspiration
• Patients who are unstable due to a pneumothorax
• Patients with recurrent PSP

Thoracostomy is also appropriate for the following:

• Complex loculated pneumothorax (unusual in PSP)
• Concurrent hemothorax or pleural effusion necessitating drainage
• In centers without expertise for air aspiration
• In patients with bilateral or very large pneumothoraces (e.g., complete collapse)
• Severe symptoms

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:

• Radiologic evaluation:
  • CXR is obtained to ensure the continued full expansion of the lung.
  • Chest CT is generally not required unless the pneumothorax was loculated or complex, or a previously unidentified underlying lung disorder is suspected.
• Clinical evaluation:
  • Patients should be assessed for CP or dyspnea that would suggest recurrence or post pleurodesis pain.
  • Patients with SSP that is due to underlying lung disease should be evaluated for control of their underlying lung disease.
  • Patients with PSP should be re-assessed for any potential diagnoses missed during the initial evaluation.
    • If a previously unidentified underlying lung process is discovered, then patients should be treated as if they have SSP and electively undergo a definitive procedure, should they consent.
• Smoking:
  • Patients should be advised to stop smoking cigarettes, as well as other tobacco products, marijuana, and illicit drugs.
  • Although poorly studied, the strong association between smoking and pneumothorax suggests that smoking cessation may help prevent recurrent pneumothoraces.⁹
  • In addition, smoking, in one retrospective study, has been shown to predict a higher recurrence rate in those who undergo pleurodesis.⁹
• Air travel:
  • An acute pneumothorax is an absolute contraindication for air travel.
  • After therapy, the optimal time for avoiding air travel is unknown, but patients are typically advised not to travel by air for about two weeks, although that may be over-conservative. However, it likely depends upon the type of treatment the patient received (e.g., simple aspiration, tube thoracostomy, chemical or mechanical pleurodesis) and the estimated risk of recurrence.
• Deep-sea diving:
  • Patients should be advised to avoid scuba diving.
  • Experts suggest that diving be permanently avoided unless the patient has undergone bilateral surgical pleurectomy and has normal lung function and CT scan.
• Exercise:
  • Exercise can be gradually re-introduced two weeks after treatment, but the introduction of contact sports, heavy weight lifting, or extreme forms of exercise may warrant longer periods of avoidance.

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:

• Desire to avoid recurrence
• High burden of cysts
• High-risk occupation or hobby (e.g., airline pilot, deep-sea diver)
• Large, bilateral, or life-threatening PSP in whom tube thoracostomy was required for management
• PAL (typically defined as an air leak >5 days)
• Undergoing thoracoscopy for another indication (e.g., hemothorax, lung biopsy).

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

• Rates of recurrence for males:
  • 4% (<7 days)
  • 8% (<30 days)
  • 10% (<3 months)
  • 13% (<1 year)
  • 20% (<5 years)
• Rates of recurrence for females:
  • 5% (<7 days)
  • 9% (<30 days)
  • 11% (<3 months)
  • 15% (<1 year)
  • 22% (<5 years)

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

• Blebs or bullae on chest CT scan
• Failure to stop smoking or presence of respiratory bronchiolitis
• Female gender
• Large initial pneumothorax size
• Low body weight
• Previous events
• Tall stature in men

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.

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.

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:

• Are asymptomatic or minimally symptomatic
• Have a first episode of SSP that is small (<2 cm from the pleural line to the chest wall at the level of the apex)
• Have limited options

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.

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:

• Sealed air leak
  • Patients with SSP in whom the air leak has sealed should proceed directly to having a preventive measure. If patients, however, choose to decline immediate intervention, they can be discharged with an ambulatory valve (e.g., Heimlich valve), provided there is no concurrent fluid that continues to drain, and then return for a definitive procedure as soon as possible at a later date. As a lesser option, patients can have their chest tube/pigtail catheter removed in the same way as patients with PSP, understanding the risk of recurrence is highest in the first 30 days after pneumothorax.
• PAL
  • Compared with those who have PSP, PALs due to ruptured subpleural bullae or cysts (e.g., COPD, PCP) are more common and tend to persist longer in patients with SSP.¹⁰ These patients require definitive measures to seal the defect and prevent future recurrence.
• In most patients, VATS is preferred, although nonsurgical pleurodesis (with chemicals or blood) or prolonged thoracostomy drainage are options in patients who are not good candidates for or are unwilling to undergo surgery. Rarely, intrabronchial/endobronchial valves are an option (e.g., severe emphysema).

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:

• Efficacy of pleurodesis in this population
• Likelihood of a life-threatening event
• Recurrence rate of SSP (generally >50%)

Individual exceptions may apply to patients:

• With very small loculated pneumothoraces (e.g., patients with CF)¹⁰
• Who declines pleurodesis

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:

• Stop smoking cigarettes, as well as other tobacco products, marijuana, and illicit drugs
• Avoid air travel, scuba diving, and exercise for a limited period of time

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:

• 7% (<7 days)
• 14% (<30 days)
• 20% (<3 months)
• 27% (<1 year)
• 33% (<5 years)

Rates of recurrence for females were:

• 6% (<7 days)
• 13% (<30 days)
• 19% (<3 months)
• 25% (<1 year)
• 31% (<5 years)

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:

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:

• Cellulose mesh with fibrin glue⁷
• Intrapleural insufflation of talc or a tetracycline derivative (i.e., chemical pleurodesis)⁷
• Laser abrasion of the parietal pleura⁷
• Parietal or full pleurectomy (usually unilateral, occasionally bilateral)⁷
• Pleural abrasion to visceral pleura with dry gauze⁷
• Combinations of the above (e.g., abrasion with partial pleurectomy or chemical pleurodesis)

Choosing among these options is often at the discretion of the surgeon but also dependent upon factors including the following:

• Number of previous recurrences of pneumothorax
• Potential future need for lung transplantation
• Preferences and values of the patient
• Presenting manifestations of the patient (e.g., severe, life-threatening symptoms versus asymptomatic)
• Previous pleurodesis
• Risk associated with VATS
• Severity of underlying lung disease or burden of cysts

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.

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:

• Air travel
• Anorexia
• Exercise
• Illicit drug use
• Immunosuppressant drugs
• Scuba diving

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