Complications of plasma exchange in patients treated for clinically suspected thrombotic thrombocytopenic purpura‐hemolytic uremic syndrome

Because the frequency of plasma exchange (PE) treatment for thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS) has increased, complications caused by PE are an increasingly important consideration in management decisions. Because the diagnosis of TTP-HUS is often uncertain, the balance between the potential benefits and risks of PE is a critical issue in deciding appropriate treatment. Our previous two reports on 149 consecutive patients treated with PE for clinically suspected TTP-HUS from 1996 to 2002 have documented major complications in 42 (28%) patients, including three deaths attributed to PE treatment. This report describes our continuing experience during the subsequent 3 years, 2002 to 2005, and confirms the substantial risks associated with PE treatment for TTP-HUS. From June 25, 2002, to June 25, 2005, a total of 60 consecutive patients were referred to Oklahoma Blood Institute (OBI) for PE treatment of their first episode of clinically suspected TTP-HUS. The OBI is the sole provider for PE procedures in central and western Oklahoma; therefore, all patients for whom PE was ordered for a clinical suspicion of TTP-HUS are included in this case series. Three patients were excluded because they died before a central venous catheter for PE was inserted. Twelve (21%) of the 57 patients included in this analysis subsequently had an alternative diagnosis that explained their acute disorder. Patients were treated in 11 different hospitals; therefore, a variety of catheter types (principally Quinton, Mahukar, and Arrow) were used. Analysis of complications related to catheter type was not done. Catheters in these hospitals are increasingly placed by interventional radiology physicians, although some catheters in this case series were placed by surgeons or intensive-care physicians. PE was routinely performed with cryoprecipitatepoor plasma with ACD-A anticoagulant with an AC ratio of 12:1; no heparin was used except to pack the catheter between procedures, and calcium was not routinely infused. Details of our definitions for major complications have been described previously. Examples of major complications were systemic infection, prevention of the PE procedure because of catheter obstruction, requirement for an invasive procedure such as replacement of the central venous catheter, requirement for or prolongation of hospitalization or transfer to an intensive-care unit, and requirement for systemic medications other than diphenhydramine, hydrocortisone, and CaCl2. Fifteen of 57 patients (26%) had 19 major complications, similar to our previously reported complication rate; 2 patients died (Table 1). One patient died as a result of sepsis from Staphylococcus epidermidis 15 days after insertion of a left internal jugular catheter. One patient died from acute hemorrhage immediately after percutaneous insertion of a right subclavian central venous catheter. In both patients, the diagnosis of TTPHUS was supported by the demonstration of a severe deficiency of ADAMTS13 activity (<3%) and the presence of a strong ADAMTS13 inhibitor (assays performed by Drs J. Kremer Hovinga and B. Lämmle, Berne, Switzerland). Both women were obese (Table 1), typical for TTP, and obesity may have contributed to catheter-related complications. The death from hemorrhage in Patient 2 occurred in spite of a platelet (PLT) count of 67 × 10 per L; Staphy-