Air Embolism: Risks, Prevention, and Critical Interventions

Types of Air Embolism

Air embolism can be classified into two broad types, depending on the location.

1. Venous embolism: This is also known as pulmonary embolism and is the most common type. It happens when the air enters the venous circulation, moves through the right side of the heart, and enters the lungs. In small amounts, the lungs can filter this air. However, the air can obstruct the pulmonary blood flow if in large quantities. A lethal form of venous embolism is when the embolism lodges just outside the right ventricle, blocking blood flow from the heart into the lungs. As a consequence, the patient develops cardiogenic shock due to decreased cardiac output and severe respiratory distress.

2. Arterial embolism: An arterial embolism occurs when the air gains entry into the venous circulation and then goes into arterial circulation through the heart. An arterial embolism can also occur in people who develop venous embolism and have a right-to-left shunt, which often happens in conditions like atrial or ventricular septal defects. The air bubble passes through the septum from the venous circulation into the arterial circulation. An arterial embolism can produce disastrous effects on the brain and heart. In the arterial circulation, even minimal amounts of air can cause death. According to scientists, as little as 0.5 mL of air in the pulmonary vein can cause death.

What Causes Air Embolism?

Iatrogenic or environmental causes can cause air embolism. Iatrogenic air embolism occurs during a treatment procedure. One frequent procedure predisposing a patient to an air embolism is the insertion, maintenance, or removal of a central line. The risk is the most significant during the insertion of a central line because the large-bore needle, which is in the vein, is at the hub while the catheter is threaded into the vein.

Venous embolisms are clinically recognized in 2% of patients. When it occurs, the mortality rate is 30%. In addition, air can be drawn into the circulation when the catheter is disconnected for a tubing change or when the catheter tubing system is accidentally disconnected or broken. Air can also enter the circulation when a central line is removed.

Other procedures that can predispose a patient to air embolism include:

• Cardiac catheterization
• Coronary arteriography
• Transcutaneous angioplasty
• Embolectomy
• Hemodialysis
• High-pressure mechanical ventilation
• Thoracocentesis

Surgical procedures like orthopedic, urological, gynecological, open heart, and brain surgeries can also increase the risk of an air embolism, especially if the patient is in an upright position.

An air embolism can also occur due to environmental factors, such as when a person is exposed to significantly different pressures than atmospheric pressure. This includes deep-sea diving (scuba diving) and flying at high altitudes. The high pressure forces unabsorbable nitrogen into the body, where it accumulates in the body tissues. From there, it can enter the bloodstream in the form of bubbles.

Assessment Of A Patient With Air Embolism

History

In the event of an iatrogenic air embolism, the patient is usually under the supervision of a healthcare team and admitted to the hospital. That can help the clinical team recognize this event as a complication of the ongoing treatment and suspect air embolism. As a nurse, you should always think of an air embolism if your patient becomes dyspneic, nauseous, anxious, confused, or complains of substernal chest pain upon the insertion, maintenance, or removal of a central line.

In cases of an environmental air embolism, the patient may recall a recent history of flying or scuba diving.

Physical Assessment

Upon inspection, your patient may seem anxious and distressed with cyanosis. The jugular vein may be distended. Some patients may even present with seizures or loss of consciousness.

On auscultation, there may be some findings in the chest and the heart. The heart sounds may be normal, or there may be a harsh systolic murmur. One late sign of air embolism is a mill-wheel murmur. It is produced by air bubbles in the right ventricle and is audible throughout the cardiac cycle. In the chest, you may hear wheezing due to bronchospasm.

Most patients have a rapid pulse and low blood pressure. Central venous pressure, pulmonary artery pressure, and systemic vascular resistance increase, and cardiac output falls.

Diagnosis

There are no definitive lab tests for an air embolism. However, some investigations, combined with a history and physical assessment, can help establish a diagnosis.

Arterial blood gases (ABGs) may reveal metabolic acidosis, hypoxemia, and hypercapnia. It is due to poor gas exchange in the lungs due to an air embolism.

Other tests that can help establish the diagnosis include an electrocardiogram, a chest X-ray, echocardiography, or precordial Doppler.

Management

When an air embolism is suspected, the initial efforts should be to prevent further air from entering into the circulation. If a central line is being inserted, the procedure should be stopped with the line clamped. It should not be removed unless the line can not be clamped.

Administer 100% oxygen to the patient. It helps in washing out the nitrogen from a bubble of atmospheric gas. Place the patient in the left lateral decubitus position. It shifts the air bubble towards the apex of the right ventricle, relieving the obstruction to the pulmonary blood flow. If the patient is in severe respiratory distress, perform endotracheal intubation and put the patient on mechanical ventilation.

If cardiopulmonary resuscitation (CPR) is required, it is recommended that the patient be placed in a supine head-down position. CPR also helps break large air bubbles into smaller ones that can flow with the blood, thus increasing cardiac output.

The Bottom Line

An air embolism is a very distressing event for the patient. It is life-threatening, and the patient may be very anxious. Your role as a nurse is crucial in managing this challenging situation by providing medical treatment and emotional support to the patient.

About the Author:

Dr. Zunaira Rizwan is a dedicated doctor with two years of professional writing experience. Her passion for writing, especially about medicine and related topics, allows her to combine her medical knowledge with her love for the craft, creating insightful and impactful content.

Zunaira is an independent contributor to CEUfast's Nursing Blog Program. Please note that the views, thoughts, and opinions expressed in this blog post are solely of the independent contributor and do not necessarily represent those of CEUfast. This blog post is not medical advice. Always consult with your personal healthcare provider for any health-related questions or concerns.

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