Increase in anesthetic uptake, excretion, and blood solubility in man after eating

Abstract

Blood-gas partition coefficients of N2O, enflurane, halothane, methoxyflurane, and isoflurane were measured on blood samples from 12 healthy male volunteers before and after eating. The solubility values determined while volunteers fasted substantiate previously reported blood-gas partition coefficients for enflurane, isoflurane, and halothane. Solubility values for methoxyflurane and N2O were slightly greater and smaller, respectively, than accepted values. The uptake and excretion of N2O, enflurane, halothane, and methoxyflurane also were measured in 6 of these subjects in the fasted and postprandial states. Subjects breathed a constant, inspired mixture containing trace concentrations of all 4 gases. Eating increased blood solubility by 17 to 24 percent for all agents except N2O. Accordingly, the rates of rise of the end-tidal enflurane, halothane, and methoxyflurane concentrations were 7 to 8 percent below control, and the rates of anesthetic uptake increased 20 to 23 percent. Simulation studies showed that the increased ventilation induced by eating opposed and, therfore, minimized the impact of increased blood solubility and cardiac output on the rate of end-tidal anesthetic rise. Changes in blood solubility did not correlate with levels of plasma triglycerides and cholesterol.