2020 Volume 58 Issue 6 Pages 212-218
During the long-term use of oxygenator for extracorporeal membrane oxygenation (ECMO), reduced oxygenation capacity due to plasma leakage is very problematic. Currently, plasma leakage is detected by visually judging the color and viscosity of moisture discharged from the gas outlet of the oxygenator. Unfortunately, a better method has not yet been established. Therefore, we evaluated an indirect method for identifying plasma leakage by monitoring the gas inlet pressure using two different oxygenators: BIOCUBE 6000 with an asymmetrically structured membrane and ExcelungNHP with a composite structured membrane. Plasma leakage was simulated by using the surfactant sodium dodecyl sulfate (SDS) that reduces the surface tension. Three SDS solutions at different concentrations were prepared:0% (pure water), 0.1% SDS solution equivalent to the surface tension of plasma in healthy subjects, and 1% SDS solution with lower surface tension than 0.1% SDS solution. During 120 minutes of solution circulation, we evaluated the changes in both the gas inlet pressure and the volume of fluid leaking across the membrane into the gas flow path. In both oxygenators, the gas inlet pressure increased significantly when the 1% SDS solution was circulated. When the SDS concentration increased, the volume of water leaking through the oxygenator membrane increased. After 120 min of circulation, the gas inlet pressure was significantly higher when using BIOCUBE6000 than when using ExcelungNHP (p=0.0008), while the volume of fluid leaking across the membrane into the gas flow path was significantly greater when using ExcelungNHP (p=0.01). Since the gas inlet pressure increased markedly when circulating a 1% SDS solution, which has lower surface tension than that of human plasma, we concluded that monitoring gas inlet pressure changes is a simple method to identify plasma leakage accurately.
