Monitoring lung compliance and end-tidal oxygen content for the detection of venous air embolism

Abstract

Venous air embolism (VAE) is a recognized complication of surgery performed with the patient in the sitting position, but it occurs also during other operations. We report two cases of VAE, associated with a notable decrease in dynamic lung compliance, detected by side-stream spirometry. Based on these cases, an experiment with 10 pigs was designed to evaluate the usefulness of side-stream spirometry in the diagnosis of VAE. Three doses of air (0.5, 1.0 and 2.0 ml kg-1 were injected via the proximal part of a 5- French gauge pulmonary artery catheter. Only the largest dose was followed by haemodynamic deterioration. Significant increases in end-tidal oxygen content and decreases in dynamic lung compliance were detected with all doses of air together with conventional signs of VAE, that is increases in pulmonary artery pressures and arterial carbon dioxide tensions, and decreases in end-tidal concentration of carbon dioxide. We conclude that continuous monitoring of end-tidal oxygen concentration and side-stream spirometry offers valuable supplements to other monitoring techniques in the detection of VAE.