MONITORING LUNG COMPLIANCE AND END-TIDAL OXYGEN-CONTENT FOR THE DETECTION OF VENOUS AIR-EMBOLISM

Venous air embolism (VAE) is a recognized complication of surgery perf ormed with the patient in the sitting position, but it occurs also dur ing other operations. We report two cases of VAE, associated with a no table decrease in dynamic lung compliance, detected by side-stream spi rometry. 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. Sign ificant increases in end-tidal oxygen content and decreases in dynamic lung compliance were detected with all doses of air together with con ventional signs of VAE, that is increases in pulmonary artery pressure s and arterial carbon dioxide tensions, and decreases in end-tidal con centration of carbon dioxide. We conclude that continuous monitoring o f end-tidal oxygen concentration and side-stream spirometry offers val uable supplements to other monitoring techniques in the detection of V AE.