Cardiac Output Directly Influences Intracardiac Air After Venous Air Embolism: An Echocardiographic Model Comparing Position Change on Intracardiac Air Bubble Clearance.

Abstract

Background and objectives: Venous air embolism (VAE) can cause significant morbidity and mortality. Prevention and management of VAE include cessation of air entrainment, positioning changes, and hemodynamic support. The degree to which position change and cardiac output (CO) moderate resolution of intracardiac air has not been rigorously studied using contemporary transesophageal echocardiography (TEE).

Methods: This observational cohort-type study aimed to identify the effect of supine vs sitting positioning on the movement and resolution of intracardiac air. In 20 patients undergoing seated neurosurgery, central venous air aspiration catheters were placed through the median basilic vein. TEE was used to estimate the time required for clearance of agitated microbubbles from the right atrium and ventricle in both the supine and sitting position. Estimates of CO were also obtained echocardiographically in each position.

Results: Average clearance time was faster in the sitting vs the supine position with no significant difference in CO. A negative correlation between CO and right atrial clearance time across all patients was demonstrated with a Pearson coefficient of -0.4 (95% CI -0.07, -0.65) with P = .02.

Conclusion: During VAE, both patient position and CO can significantly affect how bubbles move through intracardiac chambers. However, augmenting CO during VAE may be clinically more feasible, efficient, and productive than changing positioning-especially during crises unless the changing in position is intended to halt the entrainment of air. Further TEE studies of intravascular air movement affected by other position changes (lateral, reverse Trendelenburg) and vasopressors should be considered.