Osmotic activity of plasma in patients with multiple myeloma undergoing plasmapheresis

Aim. To control safety and efficiency of therapeutic plasmapheresis (PA) by osmolality, colloido-osmotic pressure (COP), total protein concentration before and after the procedure in patients with paraproteinemic hemoblastosis. Material and methods. 20 patients with multiple myeloma have undergone 42 PA procedures conducted by two techniques: continuous flow centrifugation on blood fractioners or intermittent centrifugation of blood in plastic containers. The removed plasma volume averaged 1/3 (group 1) or 2/3 of the plasma volume (group 2). The removed protein reached 62-197 g. Isotonic sodium chloride solution and/or reopolyglucin (20-60 g) replaced the removed plasm. Total protein concentration was measured colorimetrically in biuretic reaction, plasma osmolality - cryoscopically and COP - on Knauer osmometer. Results. PA leads to a short decline in osmolality (97.0-99.1%), of total protein concentration (82.8-78.6%) and of COD (79.2% in replacement with saline and 90.2% in replacement with dextran). During recovery after the procedure plasma osmotic activity and protein concentration return to the baseline. Conclusion. In elimination of 1/3 of plasma volume and crystalloid infusion, hemodilution promotes release of abnormal proteins from the tissues into the circulation and thereafter removal then: from the organism. In removal of 1/2 and more of plasma volume, COP demans correction made by administration of colloids, e.g. solution of low molecular dextran. There is a potential danger of COD lowering several hours after PA due to different speed of dextran elimination and mobilization of protein reserve.