Figure 8-21 Proposed mechanism of carbon monoxide formation from difluoromethyl-ethyl ether anesthetics. The backbone structures for isoflurane (X = CI) and desflurane (X = F) are shown, along with a putative mechanism for the concomitant formation of trifluoromethane. Water in line 3 may also react as OH^- (Adapted from Baxter PJ, Garton K, Kharasch ED: Mechanistic aspects of carbon monoxide formation from volatile anesthetics. Anesthesiology 89:929–941, 1998.)