Desflurane and sevoflurane concentrations in blood passing through the oxygenator during cardiopulmonary bypass: a randomized prospective pilot study.

PURPOSE: Volatile anesthetics (VAs) protect myocardial cells in cardiovascular surgery. A recent clinical trial of cardiopulmonary bypass (CPB) surgery reported no significant difference in mortality rates between the use of VAs and total intravenous anesthetics at 1 year postoperatively. However, oxygenator function may affect the VA pharmacokinetics. Thus, we measured the VA blood concentrations during CPB in patients managed with four different microporous polypropylene hollow fiber membrane oxygenators.

METHODS: Twenty-four patients scheduled for elective CPB were randomly allocated to one of the two VA groups (desflurane and sevoflurane groups) and, then, randomly divided into one of four oxygenator groups: Terumo, LivaNova, Medtronic, and Senko (n = 3). Additionally, in each VA group, three patients were randomly selected and redundantly allocated to the human lung group (for control blood VA concentration without oxygenator). Blood samples collected 20 min after starting 6.0 vol% desflurane or 1.7 vol% sevoflurane were analyzed using gas chromatography. Oxygenator-related complications and structural changes in the membrane surface of each oxygenator after surgery were evaluated.

RESULTS: The mean (standard deviation) concentrations of desflurane and sevoflurane in the human lung were 182.4 (23.2) and 54.0 (9.6) μg/ml, respectively; not significantly different from those in the four oxygenator groups. No oxygenator-related complications occurred. Structural changes in membrane fibers did not occur after clinical use, except for difficulty in image acquisition with Senko products.

CONCLUSION: Our results demonstrated that the blood concentrations of desflurane and sevoflurane passing through oxygenators used during CPB were similar to those in the human lung control.