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 b efore and after the procedure in patients with paraproteinemic hemoblastosi s. Material and methods. 20 patients with multiple myeloma have undergone 42 P A procedures conducted by two techniques: continuous flow centrifugation on blood fractioners or intermittent centrifugation of blood in plastic conta iners. The removed plasma volume averaged 1/3 (group 1) or 2/3 of the plasm a volume (group 2). The removed protein reached 62-197 g. Isotonic sodium c hloride solution and/or reopolyglucin (20-60 g) replaced the removed plasm. Total protein concentration was measured colorimetrically in biuretic reac tion, plasma osmolality - cryoscopically and COP - on Knauer osmometer. Results. PA leads to a short decline in osmolality (97.0-99.1%), of total p rotein concentration (82.8-78.6%) and of COD (79.2% in replacement with sal ine and 90.2% in replacement with dextran). During recovery after the proce dure plasma osmotic activity and protein concentration return to the baseli ne. 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 administrat ion of colloids, e.g. solution of low molecular dextran. There is a potenti al danger of COD lowering several hours after PA due to different speed of dextran elimination and mobilization of protein reserve.