Pregnancy And Solubility Of Volatile Anesthesia

Objective: Volatile anesthetics may be used for women during pregnancy , when maternal physiology and response to volatile anesthetics are altered profoundly. The minimum alveolar concentration (MAC) is decreased in pregnancy, but it is not known how pregnancy affects the blood/gas partition coefficient (B/G) of volatile anesthetics. The aim of this study was to determine the effect of pregnancy on B/G of volatile anesthetics and to evaluate the relation between B/G and blood component concentration.Methods: Blood sample were obtained from four groups of fasting wemen:8 nonpregnancies, 8 fist trimester pregnancies, 12 second trimester pregnancies, 12 diird trimester pregnancies. B/G of desflurane, isoflurane and halothane in each subject was measured by double equilibration tethnique. Red blood cell(RBC),Hemoglobin concentration(Hgb), hematocrit (Hct) and the serum concentration of cholesterol(Chol), triglyceride (Tg), albumen(Aib), globulin(g) were measured.Results: There is statistical difference in RBC, Hgb and Hct among the four groups. Pregnancy decreases RBC, Hgb and Hct to the lowest in second trimester pregnancy, and then increased slightly in third trimester pregnancy. Aib,A/G, Tg and Chol have significant difference among the groups. Aib was less in third trimester than that in nonpregnancy and first trimester pregnancy. A/G was the lowest and Tg, Chol were die highest in the third trimester pregnancy. Among the four groups, there was significant difference in B/G of isoflurane which is the lowest in second trimester and the highest in third trimester pregnancy. The trend direction of fluorane among four groups was similar to isoflurane, although it had no significant difference. There was no significant difference in B/G of desflurane among the four groups. There was correlation between serum Tg and B/G of flurane. The B/G of isoflurane correlated directly with Hgb and serum Tg.Conclusion: 1) pregnancy significantly alter blood components. Hgb was the lowest in second pregnancy . However in third pregnancy, Aib was the lowest and Tg,Chol were the highest.2) Pregnancy significantly affects the B/G of isoflurane and may affect that of fluorine.3) B/G of isoflurane is mostly influenced by Hgb and serum Tg. B/G of fluorane is mostly influenced by serum Tg.4) Desflurane may be the best choice for pregnancies because of its stable low Solubility. Understanding the alternation of maternal physiology and blood components is helpful for appropriate inhalation anesthesia for pregnancies .