Normalization of experimental results with respect to inlet conditions in membrane oxygenator testing

This study looked at the problem of the excessive variability in oxygenator testing results, induced by variation of inlet parameters, particularly of inlet oxyhaemoglobin saturation. The investigation was carried out in the laboratory. An in vitro circuit was used to perfuse a small oxygenating cell. Blood flow rate (BFR) and film thickness (BFT) were varied to obtain different oxygenation conditions, while the inspired oxygen fraction (FiO2) and ventilation ratio were kept at constant values. With each test condition, inlet saturation was varied in the range 60-70% and a number of veno-arterial blood samples (at least 20) were withdrawn and analysed for numerical computing and statistical analysis. The generic law relating oxygenation increment to inlet saturation was found. This allowed a useful normalization procedure to be applied to oxygenator testing results and render them comparable, even if obtained at different inlet conditions.