Clinical oxygen transfer comparison of the Terumo Capiox SX18 and SX25 membrane oxygenators

The purpose of this current study was to compare the Terumo Capiox SX18 (1.8 m2) with the recently released Capiox SX25 (2.5 m2). Specifically, their oxygen transfer slopes, degree of blood shunting, extrapolated maximum oxygen transfer, blood side pressure drop and oxygen transfer consistency were compared. The lower intercept value (0.209 vs 0.236) coupled with the flatter slope (0.00171 vs 0.00225) of the oxygen transfer line for the SX25 is consistent with improved oxygen transfer performance. A lower FiO2 value would be predicted for the SX25, to achieve a specific PaO2 value, when the oxygen transfer requirement is equal for both devices. Extrapolated maximum oxygen transfer for the SX25 (462.6 ml O2/min) was 36.2% higher than that for the SX18 (339.6 ml O2/min). When indexed to membrane surface area, the SX18 (188.7 ml O2/m2/min performed 2.0% better than the SX25 (185.0 ml O2/m2/min). Both the slope (3.110 vs 3.744) and the intercept (4.595 vs 6.223) of the shunt fraction line were lower for the SX25, indicating that a lower shunt fraction would be predicted for all clinical blood flow rates. The slope (23.934 vs 22.443) and intercept values (-28.388 vs -22.650) of the pressure drop lines for the two devices indicate that the blood side pressure drop, over the range of clinical blood flows, were within 2% of each other. Oxygen transfer consistency, when expressed as the standard deviation of the oxygenator performance index and the percentage of predicted shunt, was not statistically different for the two devices.