In vitro uptake and elimination of isoflurane by different membrane oxygenators.
OBJECTIVE
This study was designed to investigate the effect of membrane oxygenator design and composition on the uptake and elimination of isoflurane.


METHODS
Prospective, in vitro laboratory study.


METHODS
Bioengineering laboratory.


METHODS
Three types of membrane oxygenator were tested: the SM-35 (polydimethylsiloxane in sheet form), the CML (polypropylene in sheet form), and the SAFE II (polypropylene in hollow-fiber form). The oxygenators were incorporated into a standard cardiopulmonary bypass circuit.


METHODS
Isoflurane was added to the oxygenator input gas and measured in exhaust gas and in (bovine) blood leaving the oxygenator at 1, 2, 3, 5, 7, 10, 15, and 20 minutes. The isoflurane vaporizer was then turned off, and samples were obtained at the same time intervals. The experiment was performed at 28 degrees C and 37 degrees C.


RESULTS
Uptake and elimination of isoflurane were slower via the SM-35 compared with the CML and the SAFE II (p < 0.01).


CONCLUSIONS
If isoflurane is administered during cardiopulmonary bypass, knowledge of the influence of oxygenator membrane composition on its pharmacokinetics is essential if patient awareness and unexpected cardiovascular depression are to be avoided.
Hickey
S
S
Department of Anaesthesia, Glasgow Royal Infirmary, United Kingdom.
Gaylor
J D
JD
Kenny
G N
GN
D000769:Anesthesia, Inhalation / Q000295:instrumentation; D018685:Anesthetics, Inhalation / Q000097:blood / Q000737:chemistry* / Q000493:pharmacokinetics; D000818:Animals; D002315:Cardiopulmonary Bypass / Q000295:instrumentation; D002417:Cattle; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D004867:Equipment Design; D007530:Isoflurane / Q000097:blood / Q000737:chemistry* / Q000493:pharmacokinetics; D008422:Materials Testing; D008567:Membranes, Artificial; D010107:Oxygenators, Membrane; D011126:Polypropylenes / Q000737:chemistry; D011446:Prospective Studies; D012828:Silicones / Q000737:chemistry; D013499:Surface Properties; D014835:Volatilization
D018685:Anesthetics, Inhalation; D004129:Dimethylpolysiloxanes; D008567:Membranes, Artificial; D011126:Polypropylenes; D012828:Silicones; C013830:baysilon; D007530:Isoflurane