Removal and Recovery of Cholesterol in Thermofiltration

Abstract

Thermofiltration, a system of membrane plasmapheresis for LDL apheresis, was applied to the treatment of hypercholesterolemic patients to assess its lipid lowering potential, clinical feasibility and post-treatment lipid recovery. Plasma separated by a membrane separator was warmed above physiologic temperature, filtered with a plasma filter and returned to the patient on-line without requiring supplemental plasma product infusion. One calculated plasma volume was treated. Treatment schedules were weekly, biweekly or monthly. Patients treated by thermofiltration in this study were diagnosed as type II hypercholesterolemia. Reductions and sievings of high density lipoprotein (HDL) cholesterol and low density lipoprotein (LDL) cholesterol were evaluated. In addition, post-treatment solute recovery was assessed. The reduction ratios of HDL cholesterol and LDL cholesterol were 0.31 +/- 0.08 and 0.58 +/- 0.08, respectively (mean +/- S.D. of 7 patients). Sieving coefficients of the plasma filter for HDL cholesterol and LDL cholesterol were 0.62 +/- 0.12 and 0.03 +/- 0.02, respectively (mean +/- S.D. of 32 treatments). Cholesterol reduction fitted well to a single pool model. HDL cholesterol recovered significantly faster than LDL cholesterol and LDL cholesterol recovery differed among individuals. For some patients total cholesterol and LDL cholesterol levels were lowered by the biweekly treatment while for others the weekly treatment was required. Significant removal of LDL cholesterol with sparing of HDL cholesterol was achieved without the requirement for plasma products.