[Osmotic activity of plasma in plasmapheresis in patients with multiple myeloma]

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.

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.

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.

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 them 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.