The effect of serial therapeutic plasmapheresis on platelet count, coagulation factors, plasma immunoglobulin, and complement levels.

One hundred therapeutic plasmaphereses were carried out at biweekly intervals in seven patients, without morbidity or mortality, using the IBM 2997 blood fraction separator. In standardised procedures, 1.5 times the calculated plasma volume was replaced with an electrolyte solution containing 4% salt-free human albumin. Anticoagulation was achieved using a whole venous blood to acid-citrate dextrose ratio of 11 to 1. Median flow rates, plasma collection, and procedure times were respectively 40 ml/minute, 20 ml/minute, and 3 hours. Haemoglobin and total white cell counts were not significantly affected by the procedures. In contrast, platelet count, fibrinogen, immunoglobulin levels, total haemolytic complement, as well as C3 and C4 fractions fell, and the prothrombin and partial thromboplastin times were lengthened by the exchanges. All these measurements had returned to normal within 24 hours, apart from the fibrinogen, which took between 48 and 72 hours, and the immunoglobulin level, which required 35 days to return to baseline. In a further patient, more detailed studies (n = 13) were carried out to characterise the behaviour of antithrombin III and factor VIII. Both levels were markedly reduced immediately following the procedure and, like fibrinogen, had returned to normal within 48 hours. These data indicate that in an isovolemic plasmapheresis there was a transient but rapidly reversible effect on all the factors studied, with fibrinogen level, antithrombin III, and factor VIII returning more slowly to normal than the others, and immunoglobulin levels responding the slowest. None of these changes was associated with clinically significant haemostatic abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)