Halothane solubility in blood during cardiopulmonary bypass: the effect of haemodilution and hypothermia.

The influence of haemodilution and cooling on the solubility of halothane in blood during cardiopulmonary bypass was studied in six normothermic and six hypothermic patients undergoing open-heart operations. The solubility of halothane in blood was 2.17 at 30 degrees C and 1.34 at 37 degrees C. There was also an increase in the blood/gas partition coefficient of about 8.7 per cent for each degree celsius of temperature fall. These changes in haemodiluted blood explain the different anaesthetic requirements observed in patients undergoing cardiopulmonary bypass, either at normal temperature or at moderate hypothermia.