Inspired Gas Composition Influences Recovery from Experimental Venous Air Embolism

Venous air embolism (VAE) is a potentially fatal occurrence frequently encountered in neurosurgical procedures performed in the sitting position. The morbidity of this event has been reduced primarily by efforts at early detection and prevention. Clinically, VAE is accompanied by hypoxia, hypercarbia, and an increase in dead space, manifested initially by a precipitous fall in end tidal carbon dioxide (ETC02). Treatment consists of identifying and controlling the source, and hyperventilation on 100% oxygen. Hemodynamic support is given as required. A canine model of VAE was used to evaluate the effect of different inspired gas mixtures on the recovery from continuous venous air infusion. Sulfur hexafluoride (SF6), a non-hyperoxic, nitrogen free inspired gas was tested to determine if it would be a preferable alternative to recovery on 100% oxygen. Residual air effect was identified after the recovery period by a nitrous oxide challenge. In this study, recovery from VAE on 100% oxygen, as determined by response to nitrous oxide, was demonstrated to be significantly superior to either room air or SF6. ETC02, pulmonary artery diastolic pressure (PAD) and arterial oxygen tension (PaO2) all demonstrated a greater ability to tolerate the nitrous oxide challenge in subjects recovered with 100% oxygen. Embolism, Air, Nitrous oxide, End tidal C02, Hyperoxia.