INFLUENCE OF TYPE OF EXCHANGE FLUID ON SURVIVAL IN THERAPEUTIC APHERESIS FOR THROMBOTIC THROMBOCYTOPENIC PURPURA

Thrombotic thrombocytopenic purpura (TTP) is a potentially lethal dise ase that may respond favorably to plasma infusion or therapeutic plasm a exchange (TPE) with frozen plasma (FP) as the exchange fluid. Frozen plasma from which the cryo-precipitated fraction has been removed (cr yopoor plasma, CP) has reportedly been useful in refractory cases in w hich a response to FP is not being observed. We report a retrospective analysis of all cases of TTP treated by TPE with either FP (1985-1989 ) or CP (1989-1993) as exchange fluid at a large tertiary care hospita l between the years 1985 and 1993. A severity score index was compiled for each patient using the platelet count, mental status, hematocrit, and renal function at the time of diagnosis. Nineteen patients were t reated with FP (group 1) and 18 patients with CP (group 2). Groups did not differ in age, gender, race, hematologic parameters, or severity scores. Patients treated with CP, however, had more plasma exchanges ( 14 +/- 10 vs. 12 +/- 8, respectively) and more fluid exchanged than th ese treated with FP (50 L +/- 36 vs. 37 L +/- 40, respectively). Survi val was 72% in the CP group and 47% in the FP group. Although a surviv al advantage for the use of CP as exchange fluid in the treatment of T TP is suggested by our observations, the retrospective nature of the s tudy, lack of randomization, and sequential rather than concurrent use of FP and CP indicates caution in interpretation. The data do indicat e, however, that use of CP is acceptable as the initial exchange fluid in TTP. (C) 1995 Wiley-Liss, Inc.