Ocular Venous Air Embolism (OVAE): A Review

Abstract

Purpose: The purpose of this article is to review and analyze reported cases of ocular venous air embolism (OVAE) to develop a reliable clinical definition of OVAE and effective prevention strategies. Methods: We reviewed all reports of suspected air embolism during vitrectomy published in PubMed since the introduction of pars plana vitrectomy, and 5 cases found elsewhere and separately reported concurrent with this review. Results: OVAE is a precipitous drop in end-tidal CO2, a choroidal detachment, or a choroidal wound, followed by signs of impending or actual cardiovascular collapse, during vitrectomy air infusion. In each case meeting the above clinical definition, entrained air was found whenever it was sought (8/8, 100%), either by antemortem imaging or postmortem forensic investigations. Most OVAE cases were fatal (9/13, 69%), with 8 of 9 deaths (89%) occurring the day of surgery. Conclusions: OVEA is a rare but usually fatal complication of air infusion into the eye during vitrectomy. Although received with skepticism when first reported (2005), OVAE may be the most lethal type of surgical air embolization because of its high entrainment pressure and proximity to the heart. Because the effective response time to avoid a fatal OVAE outcome can be less than 1 minute, use of preventive measures is critical—most notably a “time out” before air infusion to confirm infusion cannula positioning, and immediate cessation of air infusion if choroidal detachment is detected.