Study of three patients with thrombotic thrombocytopenic purpura exchangedwith solvent/detergent-treated plasma: Is its decreased protein S activityclinically related to their development of deep venous thromboses?

Solvent/detergent treated plasma (S/DP) has reduced protein S activity (abo ut 0.5 units/mL) as compared with fresh frozen plasma (FFP). When used as r eplacement fluid for repetitive therapeutic plasma exchange (PEX), e.g., in patients with thrombotic thrombocytopenic purpura (TTP), S/DP could lead t o lowered protein S levels and, possibly, risk of hypercoagulable complicat ions. We describe three patients with TTP who had low functional protein S (FPS) levels during PEX for TTP. Each developed one or more deep vein throm boses (DVTs) while receiving 100% S/DP or 50% S/DP and 50% cryosupernatant plasma (CSP) as replacement fluid. FPS levels rose when 100% CSP was substi tuted for SIDP. Our observations suggest that use of S/DP alone or in 50% c ombination with CSP as replacement fluid in PEX for TTP may lead to difficu lty in maintaining safe FPS levels. Determination of risk of resulting clin ically significant thrombotic events requires further study. J. Clin. Apher esis, 15:169-172, 2000. (C) 2000 Wiley-Liss,Inc.