Effect of Nitrous Oxide Solubility on Vaporizer Aberrance

Abstract

Concentrations of halogenated anesthetics produced by contemporary vaporizers vary from vaporizer dial settings when carrier gas is not 100% oxygen. This effect is most marked when carrier gas changes from 100% O2 to 100% nitrous oxide (N2O). Vapor concentrations of halothane and enflurane from vaporizers with 6 L/min carrier gas flows were reduced to 3% from 4% until absorption of N20 by the liquid anesthetic ceased. Presaturation of liquid anesthetics with N2O eliminated the transient decrease of vapor output. Steady-state outputs of halothane and enflurane in 100% N2O were 10% below dial settings. The significance of these changes in administration of closed-circuit anesthesia with an out-of-circuit vaporizer is discussed.