The effect of temperature on solubility of volatile anesthetics in human tissues.
Hypothermia often occurs during surgery, a factor influencing anesthetic pharmacokinetics through its influence on solubility. Information on the tissue solubility of volatile anesthetics under hypothermia is limited. The present study supplies this information for the solubility of volatile anesthetics in human tissues. Tissue specimens of brain, heart, liver, muscle, and fat were obtained from 10 postmortem males (27 +/- 8 yr). Tissue/gas partition coefficients of desflurane, sevoflurane, enflurane, isoflurane and halothane were measured at 37 degrees C, 33 degrees C, 29 degrees C, 25 degrees C, 21 degrees C, and 17 degrees C. For each given tissue, the order of tissue/gas partition coefficient was halothane >enflurane >isoflurane >sevoflurane >desflurane. Tissue/gas partition coefficients at 37 degrees C differed significantly (P < 0.05) across drugs, except that liver/gas partition coefficients for isoflurane and enflurane did not differ. The logarithm of all tissue/gas partition coefficients increased linearly with decreasing temperature (P < 0.05). In conclusion, hypothermia increases tissue/gas partition coefficients of volatile anesthetics. The increases are proportional to those for blood/gas partition coefficients, and therefore tissue/blood partition coefficients will not change during hypothermic conditions.


CONCLUSIONS
Volatile anesthetics are often used during hypothermic conditions, and tissue solubility of volatile anesthetics is an important determinant for the wash-in and washout of the anesthetics in tissue. Tissue/gas partition coefficients during hypothermia have implications for understanding the pharmacokinetics of volatile anesthetics at hypothermic conditions.
Zhou
J X
JX
Department of Anesthesiology, First University Hospital, West China University of Medical Sciences, Chengdu, SiChuan, 610041, P. R. China. jianxinz@yeah.net
Liu
J
J
D000328:Adult; D000465:Algorithms; D018685:Anesthetics, Inhalation / Q000097:blood / Q000737:chemistry*; D002849:Chromatography, Gas; D006801:Humans; D066298:In Vitro Techniques; D012995:Solubility; D013696:Temperature
D018685:Anesthetics, Inhalation