Delivery of Vapors on Cardiopulmonary Bypass using Different Oxygenator Membranes



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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