Coagulation abnormalities produced by plasma exchange on the cell separator with special reference to fibrinogen and platelet levels.

Five patients with immunopathologic renal disease, 12 with malignant paraproteinaemia and one with myasthenia gravis underwent a total of 179 plasma exchanges on a continuous flow cell separator. Replacement fluids devoid of coagulation factors were used in 160 exchanges while 19 exchanges were replaced with Fresh Frozen Plasma. Coagulation screening was done immediately before and 30 min after each plasma exchange. Plasma fibrinogen concentrations fell to a mean of 25% of initial levels during individual exchanges. Sequential reduction to 10.7% was observed after five consecutive daily exchanges and in one patient fell to 1.2% after 10 daily exchanges. Low levels of fibrinogen could be maintained with daily or alternate daily exchanges. Platelet counts fell to a mean of 50% of pre-exchange levels during individual exchanges. Consecutive daily exchanges resulted in mean reductions to 20.7% after 5 d, but further reductions were not observed with longer periods of exchange. Platelet counts recovered to pre-exchange values during exchange intervals of 2 or more days. Mild clinical bleeding episodes, probably related to low platelet counts, occurred in one exchange in each of three patients. Haemostasis was rapidly achieved in these patients by infusions of platelet concentrates. Coagulation screening, including prothrombin ratio, thrombin time, reptilase time and partial thromboplastin time with kaolin showed progressively greater abnormalities as the intervals between exchanges shortened. The low incidence of clinical haemorrhagic episodes, three of 179 exchanges (2.2%), despite markedly abnormal coagulation parameters, emphasize the safety of the procedure even in moribund patients. We conclude that the use of FFP in intensive exchange programmes solely for the prevention of spontaneous haemorrhagic phenoma is unjustified.