Seeing is Believing: Chasing Sevoflurane Vapor Trails.

PURPOSE:Sevoflurane is an inhalational general anesthetic that has been used recently to treat chronic, painful lesions, reportedly supporting analgesia and wound healing. The potential for repeated exposure to off-gassed sevoflurane vapor, especially outside the air-conditioned operating theatre environment, is of some concern. DESIGN:This paper explores the qualitative and quantitative pathing of off-gassed sevoflurane from a topically applied liquid source. METHODS:Using a small, unventilated test-box (total volume 0.5 m3) with infra-red imaging and gas-analysing, we investigated the spatial distribution of sevoflurane vapor following complete vaporization of a 20 mL liquid sample. Utilizing the infra-red absorption of sevoflurane, it was possible to visualize (as an apparent reduction in temperature) the streaming path of the sevoflurane vapor. Sevoflurane levels (%) in the test-box were measured using an infra-red gas analyzer. FINDINGS:In keeping with its higher density than air, sevoflurane vapor was seen to "waterfall" from the liquid source and accumulate in the bottom of the test-box. Sevoflurane vapor concentration was minimal above the liquid source. When extrapolated to a larger (unventilated) room, we estimate that the sevoflurane concentration would be less than 10 ppm one centimetre above the liquid pool. With vacuum extraction, these levels would be even lower. CONCLUSIONS:Due to sevoflurane's tendency to accumulate on the floor, it is concluded that topical application of liquid sevoflurane posses virtually no risk to off-gas exposure in unventilated spaces.