Prebypass filtration of cardiopulmonary bypass circuits: an outdated technique?

Filtration of cardiopulmonary bypass (CPB) priming fluid before connection of the circuit to the patient was first accomplished by arterial line filtration. When dedicated prebypass filters (PBFs) with smaller pore sizes became available, a large number of particles could be found on the filter surface. In recent years, modern manufacturing methods for CPB circuit components were believed to be associated with a reduced number of particles found in components of extracorporeal circuits, making separate filtration of CPB priming solution unnecessary. Microemboli generated during the preparation and priming procedure of the CPB circuit may consist of either solid particles or gaseous emboli and may contribute to patient morbidity. Endotoxins found in infusion solutions and CPB priming solutions may trigger inflammatory responses when administered into the circulatory system. Filtration of crystalloid CPB priming solutions with a PBF consisting of a filter membrane with a pore size of 0.2 microm was found to effectively reduce the number of microemboli. Infusion filters with a filter pore size of 0.2 microm were found to reduce the endotoxin contamination in infusion solutions. Prebypass filtration with filters containing pores of 0.2 pm should be a necessity for contemporary perfusion practice.