Development of a new hollow fiber silicone membrane oxygenator: In vitro study

An experimental silicone hollow fiber membrane oxygenator for long-term ext racorporeal membrane oxygenation (ECMO) was developed in our laboratory usi ng an ultrathin silicone hollow fiber. However, the marginal gas transfer p erformances and a high-pressure drop in some cases were demonstrated in the initial models. In order to improve performance the following features wer e incorporated in the most recent oxygenator model: increasing the fiber le ngth and total surface area, decreasing the packing density, and modifying the flow distributor. The aim of this study was to evaluate the gas transfe r performances and biocompatibility of this newly improved model with in vi tro experiments. According to the established method in our laboratory, in vitro studies were performed using fresh bovine blood. Gas transfer perform ance tests were performed at a blood flow rate of 0.5 to 6 L/min and a V/Q ratio (V = gas flow rate, Q = blood flow rate) of 2 and 3. Hemolysis tests were performed at a blood flow rate of 1 and 5 L/min. Blood pressure drop w as also measured. At a blood flow rate of 1 L/min and V/Q = 3, the O-2 and CO2 gas transfer rates were 72.45 +/- 1.24 and 39.87 +/- 2.92 ml/min, respe ctively. At a blood flow rate of 2 L/min and V/Q = 3, the O-2 and CO2 gas t ransfer rates were 128.83 +/- 1.09 and 47.49 +/- 5.11 ml/min. Clearly, thes e data were superior to those obtained with previous models. As for the pre ssure drop and hemolytic performance, remarkable improvements were also dem onstrated. These data indicate that this newly improved oxygenator is super ior to the previous model and may be clinically acceptable for long-term EC MO application.