Delivery of Vapors on Cardiopulmonary Bypass using Different Oxygenator Membranes

Florentin M. Wilfart, Ainsley McFadgen, Blaine Kent, Kenneth Gardiner, and Michael K. Schmidt


Reliability and Failure, Oxygenator, Cardiopulmonary Bypass (CPB), Sevoflurane


Objectives: World wide about 1,000,000 patients undergo cardiopulmonary bypass (CPB) related procedures every year. Anaesthetic vapors, such as Sevoflurane and Isoflurane, have shown neuro- and cardio-protective effects and are used widely during CPB. Modern oxygenators are using different types of hollow-fibers and the question arises, if vapor molecules effectively travel through these membranes to be delivered to the patient blood during CPB. Methods: An artificial CPB circuit study (human blood, hematocrit 30, 30°C) is presented. An oxygen-mixture with 2% vapor at 1l/min is delivered to the oxygenator. The vapor concentration in the reservoir is recorded over time until a stabile concentration is obtained, then the gas stream is switched to vapor free room air. Results: The Quadrox D, Maquet (dense polymethylpentene membrane) as compared to the Synthesis, Sorin (micro-porous polypropylene membrane) shows relative limited performance in delivery of vapors (Sevoflurane < Isoflurane). Conclusions: An artificial CPB circuit is used to test physico-chemical properties of different membranes. The oxygenator model using a plasma-tight (as compared to porous) membrane shows relative limited performance in delivery of vapors through the membrane, suggesting a limited use of plasma-tight membranes for clinically relevant and cost-effective delivery of vapors during CPB to achieve neuro- and cardio-protection.

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