Makindo Medical Notes

An air embolism occurs when air bubbles enter the bloodstream and obstruct the flow of blood. Air can enter blood vessels during surgeries, medical procedures, or traumatic injuries, leading to blockages in arteries or veins, which can result in severe complications, depending on where the air is trapped. Position the patient: Head down, left side down to help keep air in the apex of the right ventricle where slow reabsorption occurs.

About Air Embolism

• Air is injected or sucked into the venous circulation and enters the RV and causes blockage.
• In the Bends with Divers air can block smaller arterial blood vessels
• Depending on the volume of air, this may result in vascular occlusion or sudden death.
• The severity also depends on the position of the patient.

Pathophysiology

• A venous entry point for air with a pressure gradient facilitates air entry.
• Occurs during operative procedures where the site is > 5 cm above the right atrium.

Causes

• Surgical procedures: Air can be introduced into the bloodstream during surgery, especially in procedures involving the chest, head, or neck.
• Trauma: Chest trauma, penetrating injuries, or fractures can allow air to enter the venous system.
• Intravascular catheters: Improper use or removal of central lines or catheters can introduce air into the veins.
• Diving accidents: In scuba diving, rapid ascent without proper decompression can cause nitrogen gas to form bubbles in the bloodstream, a condition known as decompression sickness, or the "bends."

Types of Air Embolism

• Venous Air Embolism (VAE): Occurs when air enters the veins and can travel to the lungs, causing a blockage in the pulmonary arteries. This can lead to respiratory distress and decreased oxygen levels in the blood.
• Arterial Air Embolism (AAE): Occurs when air enters the arterial system. If the air reaches vital organs like the brain or heart, it can cause strokes, heart attacks, or other life-threatening conditions.

Clinical Signs

• Difficulty breathing (dyspnea)
• Chest pain
• Dizziness or confusion
• Low blood pressure (hypotension)
• Seizures
• Unconsciousness

Investigations

• ABG: hypoxia, hypo/hypercarbia, metabolic acidosis
• ECG: tachycardia, ST/T changes of ischemia
• CXR: oligaemia

Differential Diagnosis

• Pulmonary embolism
• Stroke, myocardial infarction, tension pneumothorax
• Traumatic cardiac tamponade

Complications

• Cardiac arrest and death due to obstructive shock
• Myocardial infarction from air embolus entering the coronary artery
• Anoxic brain injury secondary to prolonged cerebral hypoperfusion

Prevention

• For surgeries and medical procedures needs careful handling of IV lines, catheters, and surgical instruments to avoid introducing air into the bloodstream
• For divers, gradual ascent and proper decompression are crucial to avoid nitrogen bubble formation.

Management

• Follow the ABC protocol, administer high flow oxygen (O₂).
• Position patient: head down and left side down to trap air in the right ventricle apex. Traditionally left lateral decubitus or Trendelenburg position to prevent air from traveling to the brain or heart
• Intubate and ventilate; administer fluids and pressors as needed.
• Administer 100% O₂ and perform IV fluid resuscitation with inotropes.

Additional management options

• If venous lines are in the right atrium (RA) or right ventricle (RV), aspirate the air from the RV.
• If the chest is open, aspirate the RV apex with a needle after positioning.
• If the chest is open, perform cardiac massage to relieve RV outflow obstruction.