Abstract
Ies. Although hyperbaric measurements suggested a MAC of 38.9 ± 6 atm (mean ± SD) for CF4, this pressure was nearly identical to the lethal pressure of 41.1 ± 5.8 atm. Hyperbaric studies of C2F6 caused death without causing anesthesia, the lethal pressure being 23.8 ± 2.6 atm. Results from studies of additivity with desflurane suggested that the MAC of CF4 was 66.5 ± 13.4 atm at an average CF4 test partial pressure of 17.7 ± 4.0 atm (i.e., 17.7 atm of CF4 decreased the MAC of desflurane by 26.6%). Studies of additivity with desflurane, isoflurane, or halothane did not reveal an anesthetic effect of C2F6 at a pressure of 7.2 ± 0.4 atm, or of larger perfluoroalkanes near to or at their saturated vapor pressures. We conclude that a cutoff in anesthetic potency for perfluoroalkanes exists between perfluoromethane and perfluoroethane. Address correspondence to Edmond I Eger, II, MD, Department of Anesthesia, Box 0464, University of California, San Francisco, CA 94143–0464. This work was supported in part by the Cheng Scholarship Program and by the Anesthesia Research Foundation. Accepted for publication February 10, 1994. © 1994 International Anesthesia Research Society...