IN-VITRO UPTAKE AND ELIMINATION OF ISOFLURANE BY DIFFERENT MEMBRANE OXYGENATORS

Objective: This study was designed to investigate the effect of membra ne oxygenator design and composition on the uptake and elimination of isoflurane. Design: Prospective, in vitro laboratory study. Setting: B ioengineering laboratory. Participants: Three types of membrane oxygen ator were tested: the SM-35 (polydimethylsiloxane in sheet form), the CML (polypropylene in sheet form), and the SAFE II (polypropylene in h ollow-fiber form). The oxygenators were incorporated into a standard c ardiopulmonary bypass circuit. Interventions: Isoflurane was added to the oxygenator input gas and measured in exhaust gas and in (bovine) b lood leaving the oxygenator at 1, 2, 3, 5, 7, 10, 15, and 20 minutes. The isoflurane vaporizer was then turned off, and samples were obtaine d at the same time intervals. The experiment was performed at 28 degre es C and 37 degrees C. Measurements and Main Results: Uptake and elimi nation of isoflurane were slower via the SM-35 compared with the CML a nd the SAFE II (p < 0.01). Conclusions: If isoflurane is administered during cardiopulmonary bypass, knowledge of the influence of oxygenato r membrane composition on its pharmacokinetics is essential if patient awareness and unexpected cardiovascular depression are to be avoided. Copyright (C) 1996 by W.B. Saunders Company.