Fat and solid filtration in clinical perfusions

The purpose of this study was to define the fat filtration characteristics of a packed polyester wool filter when used alone in the cardiotomy suction (12 cases) and the arterial lines (10 cases) during clinical hemodilution, extracorporeal circulation. The pressure gradient-flow relationship and the efficiency of removal of fibrin microparticles were first ascertained in vitro. Total fat was extracted from the polyester wool with a Soxhlet device. Whole blood and plasma lipids were measured before and after bypass. The results showed a 23 mm. Hg pressure drop across a wool filter with a water flow rate of 5 L. per minute and a 40 to 52 percent efficiency for fibrin microparticles 15 to 250 mu. The total lipid extracted from the cardiotomy filters averaged 376 plus or minus 72 mg. compared with 512 plus or minus 95 mg. in the arterial line filters, although there was no statistically significant difference. Additionally 245 plus or minus 101 mg. of nonlipid material were extracted from the arterial line filters. The postperfusion whole blood contained a higher concentration of lipid than the preperfusion blood when corrected for dilution. It was concluded that significant quantities of solids, two thirds of which were fat, were removed by packed polyester wool filters during total body perfusions. Most of the fat was derived from the cardiotomy suction system. The amount of filtered fat and solids increased with perfusion time. These findings endorse the concept of cardiotomy filtration during extracorporeal circulation.