Influence of the Concentration Effect on the Uptake of Anesthetic Mixtures

Abstract

The uptake of halo-thane given in constant concentration (1%) was more rapid in a mixture with 70% N2O than one with 10% N2O. This demonstrates that the uptake of a gas is influenced by the constituents of the mixture of which it is a component. Changes in the concentration of other components which are sufficient to produce a significant concentration effect will produce alterations of uptake rate of companion gases given in constant concentration ("second gas effect"). This acceleration of uptake was interpreted to be a result of additional inspirator/ inflow secondary to the absorption of N2O at a higher concentration. This absorption produces the concentration effect on the rate of uptake of the N2O itself, also observed in this study. Second gas effects presumably occur as well for the other gases in the inspiratory mixture, including the usual respiratory gases.