Plasma exchange for treatment of thrombotic thrombocytopenic purpura in critically ill patients.

Objective: Description of diagnostic procedures, treatment modalities and intensive care management of patients with thrombotic thrombocytopenic purpura (TTP).
Design: Descriptive study.
Setting: Internal medicine Intensive Care Unit (University Hospital of Vienna).
Patients: Six patients (two after allogeneic bone marrow transplantation), treated for 12 episodes of TTP.
Interventions: Treatment with plasma exchange (fresh frozen plasma, 50-80 ml/kg per day), prednisone (0.75 mg/kg b.i.d.) and, in some cases, vincristine. Supportive therapy as needed.
Measurements and Results: Patients were admitted to the ICU because of neurological symptoms with acute onset (42% mild, 58% severe), hemolysis and thrombocytopenia. Additional symptoms were fever (50%), bleeding tendency (50%), acute renal failure (42%) and metabolic derangement (8%). Initial laboratory values showed thrombocytopenia (median 17 G/l), hemolysis (median hemoglobin 10.0 g/dl, lactate dehydrogenase 635 U/l, reticulocyte count 175 G/l) with red cell fragmentation. Coagulation tests were normal. Respiratory assist was needed in six episodes (severe seizures, cardiopulmonary resuscitation). In patients without preexisting hematological abnormality the platelet counts exceeded 100 G/l after 3-8 cycles of plasma exchange. In patients after bone marrow transplantation, the platelet counts never exceeded 40 G/l, but the lactate dehydrogenase levels dropped significantly. The neurological symptoms disappeared in all patients and renal function normalized. One patient died before the initiation of therapy. Three patients relapsed 1-3 times between 2 weeks and 5 months after the last episode. The relapses were associated with symptoms similar to the first episode and responded promptly to plasma therapy.
Conclusions: TTP is a rare, but life-threatening disorder. It needs immediate diagnosis and has a good prognosis after adequate treatment with plasma exchange.