Treatment of plasma refractory thrombotic thrombocytopenic purpura with protein A immunoabsorption

The objective of this study was to assess the effect of protein A immunoabsorption in terms of response rate and toxicities in patients with classical thrombotic thrombocytopenic purpura (TTP) refractory to therapeutic plasma exchange. The study included nine females and one male with a diagnosis of classical TTP treated at multiple university hospital centers with protein A immunoabsorption (PAI) after having failed plasma exchange. The 10 patients had an age range 17-62 years. Prior to PAI, the patients had failed to respond to a mean of 15 (range 6-39) therapeutic plasma exchanges. Three patients had previous episodes of TTP. Evaluation for response to PAI included serial measurements of serum creatinine, lactate dehydrogenase (LDH), hemoglobin, hematocrit, and platelet count before, during, and up to 18 months post-PAI treatment. Seven of 10 study patients had resolution of their TTP. Six of the patients required six or fewer therapeutic PAIs and one required 12 treatments. All responding patients had evidence of improvement by the third PAI treatment. Three patients demonstrated no response to PAI, with two patients expiring from complications of TTP and one patient demonstrating a complete response to a subsequent therapy. No significant toxicity was noted with the use of PAI in this setting. Protein A immunoabsorption in patients with classical TTP refractory to plasma exchange can produce durable complete remissions and warrants comparative studies.

Research and development in the blood bank: efforts of a hospital donor center to improve efficiency of in-line leukocyte reduction filters for automated plateletpheresis

In-line leukocyte reduction filters (LRF) are available for use with an automated plateletpheresis (PPH) system. Initially, 62% of PPH units produced with such a filter (LRF6, N = 29) had postfiltration (POF) white blood cell (WBC) counts < 5 x 10(6), with a mean POF WBC of 42 x 10(6). In an attempt to decrease POF WBCs, PPH were rested 30 to 60 minutes before filtration with LRF6. A new, larger-volume LRF (LRF10) was also assessed for its efficiency of leukodepletion. A total of 625 PPH, 490 filtered with LRF6 and 135 with LRF10, were evaluated using prefiltration (PRF) and POF samples. Mean prefiltration WBC loads averaged 80 x 10(6) (range, 60-88 x 10(6)) using seven combinations of filters, collection software, and PRF rest periods. Ninety-three percent of PPH units rested prior to filtration with LRF6 (N = 237) had < 5 x 10(6) WBC POF, with a mean of 5 x 10(6) WBC POF. All PPH units filtered with LRF10 (N = 135), whether rested or not, had < 5 x 10(6) WBC POF, with a mean WBC count of 0.2 x 10(6) POF. Mean platelet (PLT) yields POF ranged from 3.1 to 3.4 x 10(11). A PRF rest decreased mean POF WBC counts in products filtered with LRF6. The LRF10 consistently produced PPH with < 5 x 10(6) WBC POF. Blood centers must thoroughly validate equipment utilized in the production of blood components.

Resolution of refractory, classic thrombotic thrombocytopenic purpura after staphylococcal protein A immunoadsorption

BACKGROUND

Multiple therapeutic interventions are available for treatment of thrombotic thrombocytopenic purpura. Resolution of thrombotic thrombocytopenic purpura may require use of several of these interventions.

CASE REPORT

A patient presenting with classic (non-cancer chemotherapy-associated) thrombotic thrombocytopenic purpura had an initial response to intensive, daily plasma exchange with fresh-frozen plasma and cryosupernatant. Multiple attempts over a period of 2 months to decrease the frequency of plasma exchange resulted in exacerbations of disease activity, indicated by increased schistocytosis, decreased hematocrit, increased serum lactate dehydrogenase, and decreased platelet counts. After a total of 39 plasma exchanges, the patient was begun on immunoadsorption therapy utilizing a staphylococcal protein A immunoadsorption treatment column. After six 2000-mL protein A immunoadsorption treatments, the patient's platelet count, lactate dehydrogenase, and peripheral smear normalized, and they have remained normal over nearly 4 months of follow-up.

CONCLUSION

Treatment by protein A immunoadsorption may be of benefit in patients with classic thrombotic thrombocytopenic purpura who are not achieving a sustained remission with conventional plasma exchange therapy.

An introductory orientation to clinical pathology core and on-call responsibilities

An introductory 4-week orientation for clinical pathology is described. There were 76 hours of lectures, 74 hours of conferences, and 68 hours of laboratories for a total of 221 hours. During the orientation, all calls handled by the residents were evaluated as to resolution, patient outcome, and interaction required. Eighty calls were received during the orientation from 57 technologists (71%), 16 physicians (20%), and seven nurses (9%). The calls originated concerning the following: blood banking, 37 (46%); hematology, 21 (27%); chemistry, 14 (18%); microbiology, five (6%); and administration, three (4%). Sixty percent of the calls were consultative and 40% were supervisory. Ninety-nine percent were handled appropriately by the residents. Patient outcome was moderately or significantly affected in 44% of all calls, divided between 67% of all consultative calls and 9% of all supervisory calls. Significant pathologist interaction was required in 49% of all calls, divided between 71% of the consultative calls and 16% of the supervisory calls. Using this integrated, dynamic system of resident instruction, on-call experience, and evaluation, residents quickly gain confidence in handling call, didactic clinical consultation, and patient management. The orientation and on-call system described provides for a relevant and dynamic system for resident education.

The effects of exercise on ventilation-perfusion relationship in patients with mitral stenosis

Exercise limitation is common in patients with chronic pulmonary venous hypertension. One postulated mechanism is ventilation-perfusion inequality secondary to vascular congestion and edema formation. To investigate this possibility, five patients with symptomatic, chronic mitral stenosis were studied at rest, during 10 min of steady-state exercise and during recovery from exercise. Both conventional indices of gas exchange and the multiple inert gas elimination method were used. Hypoxemia was not present in patients at any stage in the study and negligible shunt or low VA/Q lung units were demonstrated by the inert gas method. Instead, regions with high VA/Q ratio appeared toward the end of exercise and immediately after exercise. We postulate that this was the result of a marked redistribution of pulmonary blood flow, possibly due to an accumulation of interstitial edema fluid. It is concluded that the excessive ventilatory response to exercise observed in patients with mitral stenosis may, in part, be explained by an unequal distribution of ventilation and perfusion.