title: Hematocrit and the solubility of volatile anesthetics in blood.
abstract: To clarify the effect of hematocrit on the solubility of volatile anesthetics in blood, we measured the blood-gas partition coefficients of isoflurane, enflurane, halothane, and methoxyflurane concurrently at 37 degrees C in blood from four adults. We measured the blood-gas partition coefficients in the plasma (hematocrit 0%) and packed red cell fractions (hematocrit 80%), and in four mixtures of these two fractions (hematocrits 10%, 25%, 40%, and 55%). The mixtures were prepared by recombining appropriate amounts of plasma and packed red cells from each adult. As hematocrit increased, the blood-gas partition coefficient of isoflurane decreased linearly (P less than 0.01), whereas that of enflurane increased linearly (P less than 0.05). The partition coefficient for isoflurane in plasma was 20% greater than that in packed red cells, whereas the partition coefficient for enflurane in plasma was 10% less than that in packed cells. The blood-gas partition coefficients of halothane and methoxyflurane did not change significantly between measurements in plasma and packed red cells. We conclude that hematocrit exerts a statistically significant effect on the blood-gas partition coefficient of isoflurane and enflurane.
mesh_terms: D000328:Adult; D000777:Anesthetics / Q000097:blood*; D004737:Enflurane / Q000097:blood; D004912:Erythrocytes / Q000378:metabolism; D006221:Halothane / Q000097:blood; D006400:Hematocrit; D006801:Humans; D007530:Isoflurane / Q000097:blood; D008297:Male; D008733:Methoxyflurane / Q000097:blood; D008875:Middle Aged; D009994:Osmolar Concentration; D012995:Solubility
chemical_list: D000777:Anesthetics; D008733:Methoxyflurane; D004737:Enflurane; D007530:Isoflurane; D006221:Halothane