Effects of anaesthesia and surgery on the solubility of volatile anaesthetics in blood.

To determine the effects of anaesthesia and surgery on the solubility of volatile anaesthetics in blood, we measured the blood/gas partition coefficients of enflurane, halothane, isoflurane, and methoxyflurane in vitro in blood obtained from six healthy unpremedicated adults at three different times during isoflurane anaesthesia: awake; 20 minutes after induction of anaesthesia, but before surgical incision; and, 90 minutes after surgical incision. The blood/gas partition coefficients of the four volatile anaesthetics decreased significantly after induction of anaesthesia and after surgical incision (p less than 0.05). Values for haematocrit and the serum concentrations of albumin, globulin, and cholesterol decreased parallel to the decrease in blood/gas partition coefficients.