Air Embolism – Definition, Pathophysiology, and Acute Management

Definition & Pathophysiology

Air embolism is the entrainment of air or gas into the venous or arterial circulation, producing obstruction of the right‑ventricular outflow tract or pulmonary arterioles and leading to cardiovascular dysfunction and failure. 1
Morbidity and mortality increase proportionally with the volume of air entrained and the rate at which it accumulates. 2
In adults, a lethal volume is approximately 200–300 mL (3–5 mL kg⁻¹) when delivered at a rate of about 100 mL s⁻¹. 2
Air bubbles obstruct the right‑ventricular outflow tract or pulmonary arterioles as a mixture of air and fibrin clots formed within the heart. 3

Place the patient in the left lateral decubitus (Trendelenburg) position and administer 100 % oxygen immediately. 2
The left lateral decubitus position traps air in the apex of the right ventricle, preventing migration into the pulmonary artery. 5
Trendelenburg (head‑down) positioning raises central venous pressure, reducing further air entry. 5
100 % normobaric oxygen reduces bubble size and improves tissue oxygenation. 5

Immediately stop any pressurized infusion or arthroscopic pump that could be delivering air. 5

When a central venous or pulmonary artery catheter is in place, attempt rapid aspiration of air from the right atrium or right ventricle. 2
Aspiration can produce immediate clinical improvement by decreasing the intravascular air burden. 5
Intra‑operative aspiration is occasionally performed to relieve large air bubbles. 2

Initiate aggressive fluid resuscitation and vasopressor therapy to maintain coronary perfusion pressure. 5
Fluids are given to increase central venous pressure and limit further air entrainment. 5
Norepinephrine or vasopressin should be used if hypotension persists. 5
Dobutamine is recommended for inotropic support to improve right‑ventricular contractility. 6
Milrinone may be considered as an alternative inotrope with pulmonary vasodilatory effects. 6
Excessive fluid administration must be avoided because it can worsen right‑ventricular distention and impair left‑ventricular filling. 5

Continuously monitor heart rate, blood pressure, oxygen saturation, and end‑tidal CO₂. 5
Perform bedside echocardiography to assess right‑ventricular function and confirm the presence of intravascular air. 5
A gradual decline in end‑tidal CO₂ is an early warning sign preceding cardiovascular collapse. 5

Hyperbaric oxygen therapy (HBOT) should be considered for severe presentations, especially when neurological symptoms or paradoxical arterial embolism (right‑to‑left shunt) are suspected. 5

Inhaled nitric oxide or sildenafil may be employed to provide selective pulmonary vasodilation without aggravating systemic hypotension. 5

Failure to recognize early signs such as a gradual drop in end‑tidal CO₂ can delay life‑saving interventions. 5
Delaying positional change and oxygen administration while pursuing other measures worsens outcomes. 5
Continuing to pump fluid or air after an embolism is suspected must be stopped immediately. 5

Outcomes are largely dependent on rapid recognition and prompt implementation of the above interventions. 2