Carboxyhemoglobinemia in a pediatric cardiopulmonary bypass patient derived from a contaminated unit of allogenic blood.

A 4.3 kg, three-month-old patient, diagnosed with a perimembranous ventricular septal defect, presented for cardiac surgery. Upon initiation of cardiopulmonary bypass (CPB), the patient developed carboxyhemoglobinemia (11.1%). Potential sources for the unexpected acquired carboxyhemoglobinemia were sought quickly. Testing of residual blood from the unit of packed red blood cells (PRBCs) used to prime the CPB circuit revealed a carboxyhemoglobin (COHb) of 15.1 %. A decrease in cerebral oximetry (rSO(2)) on CPB was initially felt to be a result of the elevated COHb levels. When ventilation of the oxygenator with 100% oxygen (O(2)) failed to decrease COHb levels, a partial exchange transfusion was performed with reduction in COHb to 7.1%. The operation was completed successfully and the patient's COHb levels returned to normal within 75 minutes. Post case analysis of events and data collected during the case revealed a broader differential for explaining the compromised patient's O(2) delivery than the transient acquired carboxyhemoglobinemia. A partial obstruction of the superior vena cava could have triggered the drop in rSO(2) on CPB. Follow-up of the donor blood confirmed the donor had previously undiagnosed carboxyhemoglobinemia as a result of chronic carbon monoxide exposure from a faulty vehicle exhaust system.

Transfusion practices for patients with sickle cell disease at a major academic medical center.

The University of North Carolina at Chapel Hill (UNC) is a tertiarycare, academic university hospital and a major referral center for patients across the state of North Carolina. This 700-bed, Level 1 trauma center transfuses more than 22,000 RBC units to patients annually. Clinical services and areas of the hospital which rely most heavily on transfusion support for their activities are transplantation (bone marrow and solid organ), hematology, critical care (medical and surgical intensive care units), cardiothoracic surgery, pediatrics, the operating room, the emergency department, labor and delivery, dialysis, and outpatient services. UNC is recognized for its expertise in coagulation, transfusion medicine, and hematology, particularly in sickle cell disease (SCD). The sickle cell center at UNC, which began in 1980 and continues today, in conjunction with our neighboring institution,Duke University Medical Center, is designated as part of a National Institutes of Health comprehensive sickle cell center. Several of the physicians are dedicated to the care of pediatric and adult patients with SCD, as well as to research on transfusion management of these patients and recruitment of African American blood donors. This article describes the practices of this institution for transfusion management of patients with SCD, as well as some of its efforts related to this challenging area of transfusion medicine.

Cardiogenic shock complicates successful treatment of refractory thrombotic thrombocytopenia purpura with rituximab.

BACKGROUND: Treatment of thrombotic thrombo-cytopenia purpura (TTP) with daily therapeutic plasma exchange (TPE) may be accompanied by a variety of adjunctive interventions including most recently rituximab. Rituximab, a murine and human monoclonal antibody directed against CD20 antigen on B lymphocytes, is primarily used for treatment of non-Hodgkin's lymphomas. Because of severe and fatal infusion reactions including heart failure, rituximab carries a boxed warning. CASE REPORT: A 20-year-old female presented with TTP. She underwent 17 daily (1 day skipped) TPE. Her platelet (PLT) count reached 150 x 10(9) per L and then gradually declined to 36 x 10(9) per L despite continuing TPE. Because of the refractory behavior of her disease, rituximab was administered. After the rituximab infusion, she developed a nonproductive cough which progressed to a productive cough, acute respiratory failure, chest pain, and hypotension and was moved to intensive care for management of biventricular cardiogenic shock (ejection fraction was 5%-10%). Once stable in the intensive care unit, TPE was resumed. Her PLT count reached 241 x 10(9) per L, and her lactate dehydrogenase decreased to normal after four TPEs. Her heart failure completely resolved and she was discharged. Rituximab was added to her medical record as a drug allergy. CONCLUSION: Refractory TTP has been reported to respond favorably to rituximab when used as an adjunct. Interventions, however, can also carry significant risk as illustrated by the cardiogenic shock in our patient. Use of rituximab for refractory TTP should follow a careful assessment of benefits.

Differentiating thrombotic microangiopathies induced by severe hypertension from anemia and thrombocytopenia seen in thrombotic thrombocytopenia purpura.

Thrombotic microangiopathy (TMA) is a recognized complication of malignant hypertension (HTN). Such patients have blood pressures > or = 200/140 mmHg but the condition is defined by the presence of papilledema and is frequently complicated by acute renal failure. Here we report two patients with severe HTN (systolic > or = 180 mmHg or diastolic > or = 120 mmHg), TMA, thrombocytopenia, renal failure, and, in one case, neurological changes (4 of 5 manifestations of the TTP pentad). A 50-year-old male with HTN presented with blurred vision, dizziness, headache, confusion, renal failure, and a TMA (PLT = 39 x 10(9)/L and LD = 2,781 normal <600 U/L). On presentation, BP was 214/133 mmHg and an ophthalmic exam demonstrated no papilledema. With HTN control over 7 days, his platelet count rebounded (220 x 10(9)/L), LD declined (1,730 U/L), and mental status improved. A 60-year-old female with diabetes, HTN, Lupus erythematosus, mild chronic anemia, and thrombocytopenia presented with abdominal pain, shortness of breath, renal failure, and a TMA (PLT = 83 x 10(9)/L and LD = 2,929 U/L). Blood pressures were 180-210/89-111 mmHg and ophthalmic exam demonstrated no papilledema. With HTN control over 8 days, her platelet count rebounded (147 x 10(9)/L), and LD declined (1,624 U/L). Although in both cases a diagnosis of TTP was considered because of overlap with the classic diagnostic pentad, neither received plasmapheresis. TTP is a diagnosis of exclusion, where there is no other likely diagnosis to explain the TMA. In cases of severe HTN (with or without papilledema), the diagnosis of TTP should be held in abeyance until the effect of HTN control can be assessed.

Incidence of allergic reactions with fresh frozen plasma or cryo-supernatant plasma in the treatment of thrombotic thrombocytopenic purpura.

Plasma replacement for thrombotic thrombocytopenic purpura (TTP) is accomplished with various plasma products. This study sought to determine the incidence of allergic reactions with FFP or CPP as replacement in therapeutic plasma exchange (TPE). Forty-one TTP patients were identified retrospectively who received TPE replacement with either FFP (n=21) or CPP (n=20). Anti-histamine was administered prophylactically following the initial occurrence of an allergic reaction (urticaria, respiratory distress, or anaphylaxis with hypotension). Fifty-one allergic reactions occurred in 65.8% of patients. Urticaria comprised 49 of 51 (96%) of reactions and respiratory distress the remaining 4%. No anaphylaxis occurred. Nineteen urticarial reactions occurred in 50% of CPP recipients compared to 71% of FFP recipients (P=0.28). Anti-histamine breakthrough occurred in 36.3% of patients who experienced a previous allergic reaction with CPP and 37.5% with FFP (P=1.0). The overall risk of allergy per unit of plasma was 1.37% (1.23 % CPP, 1.48% FFP), comparable to estimates in non-TTP recipients. The median number of donor exposures preceding the first allergic reaction was 35 and 32, CPP and FFP, respectively (P=0.63). The mean volume of plasma transfused prior to reaction was 9,883 mL for CPP and 9,348 mL for FFP (P=0.85). Neither product was advantageous in preventing allergic complications. Because of the large volume, the number of donor exposures, and prolonged duration of therapy, allergic reactions to plasma are common (65.8%) in the treatment of TTP.

In vivo and in vitro characteristics of double units of RBCs collected by apheresis with a single in-line WBC-reduction filter.

BACKGROUND: A novel apheresis procedure for a blood separator (MCS+, Haemonetics) enables the collection of 2 WBC-reduced RBC units in a single donation by using one disposable set with one in-line WBC-reduction filter (RC2H, Pall Corp.). The objective of this study was to evaluate the filtration performance in connection with different prefiltration RBC storage conditions and with the in vitro and in vivo storage quality of the filtered units. STUDY DESIGN AND METHODS: Sixty-six 2-unit RBC collection and gravity-filtration procedures were completed at three sites, resulting in 132 RBC units. Filtration of the double RBC units was performed at room temperature (RT) within 8 hours of collection (n = 36) and under refrigeration (1-6 degrees C) for up to 24 hours (n = 10) and 72 hours (n = 20) before filtration. RBC quality was compared to that of nonfiltered apheresis RBC units (n = 10). RESULTS: Median filtration time was 6.5 and 14 minutes for units stored at RT and under refrigeration, respectively. All 132 RBC units had residual WBC counts <0.4 x 10(6). The refrigerated units showed a greater mean log reduction in WBCs: 5.06 +/- 0.16 (24 hour) and 4.74 +/- 0.48 (72 hour), respectively, than did RT units: 4.47 +/- 0.28 (p<0.05). RBC loss was less than 12 percent in all cases (mean, 7.8 +/- 1.8%). Minimal differences in volume were observed between the paired RBC units. In vitro RBC storage characteristics of the filtered units were as expected and similar to those of the nonfiltered units. For RBC units held at RT (n = 24), the mean in vivo 24-hour recovery was 81.8 +/- 8.4 percent (double-label). CONCLUSION: Satisfactory filter performance in terms of WBC removal and RBC loss was observed with all 66 procedures, irrespective of storage conditions before filtration.

Likelihood of D heterozygosity in Mestizo Mexicans and Mexican Americans.

Information on the gene frequencies of the Rh system in the Mexican or Mexican American population is currently not available in the medical literature, thus hindering management of pregnancies at risk for development of hemolytic disease of the newborn. Data from four recent large studies in the broader scientific literature of Mestizo Mexicans and Mexican Americans is reviewed. Gene frequencies are calculated from the pooled data. A table of gene frequencies in the Caucasian and African American population is provided for comparison.

Apheresis and the thrombotic thrombocytopenic purpura syndrome: current advances in diagnosis, pathophysiology, and management.

Endeavors to optimize the management of thrombotic thrombocytopenic purpura (TTP) syndrome and improve mortality and relapse rates are hindered by its poorly understood pathophysiology. Variability in the application of therapeutic plasma exchange (TPE), including replacement fluid strategies, desirable endpoints in the platelet count, serum lactate dehydrogenase concentration, and the use of a TPE taper, limit comparisons among published studies. The diversity of adjunctive therapies such as antiplatelet agents, steroids, and splenectomy further clouds comparisons. Recent progress in the diagnosis, pathophysiology, and management of TTP syndrome are summarized. The possible role of occult infection and newly emerging associations such as ticlopidine therapy are discussed. Advances in possible pathogenic mechanisms, the rationale for different replacement fluids including the recently licensed solvent-detergent treated plasma, and progress in the apheresis management of TTP syndrome are presented.

United States Thrombotic Thrombocytopenic Purpura Apheresis Study Group (US TTP ASG): multicenter survey and retrospective analysis of current efficacy of therapeutic plasma exchange.

Thrombotic thrombocytopenic purpura (TTP) remains enigmatic from the perspective of its etiology, pathophysiology, and treatment. Once recognized, the accepted standard of care for TTP is daily therapeutic plasma exchange (TPE). However, the diversity in TPE treatment protocols has made comparisons of clinical research between institutions difficult. This study strived to assess the current practice of TPE in order to provide direction for prospective controlled clinical trials. Twenty large apheresis centers within the United States comprising the US TTP ASG responded to a survey to establish the current status of TPE in TTP. A retrospective analysis from data provided by 14 of 20 centers included 115 initial presentations of primary TTP with an overall mortality rate of 10% and relapse rate of 37%. The majority of deaths (58%) occurred within 48 hours of presentation. Variation in therapeutic targets (platelet count [plt] and serum LDH) and the number of plasma volumes exchanged per procedure did not affect the relapse rate. Initial plt and LDH were not predictive of mortality. Response, relapse, and mortality rates with the combination of 5% albumin for the initial 50% of TPE followed by plasma for the final 50% of TPE as replacement were comparable or possibly better than plasma-only replacement strategies. Forty percent of centers routinely used a TPE taper; however, there was no statistical difference in relapse rates comparing the taper and non-taper sub-groups. By controlling for adjunctive modalities such as steroids and anti-platelet agents, it is hoped that future prospective clinical trials may optimize the role of TPE in TTP, minimize patient exposure to blood products and procedures, shorten the clinical course of TTP, and reduce mortality.

Lack of efficacy for conventional gamma irradiation of platelet concentrates to abrogate bacterial growth.

The maximum storage time for platelet concentrates is 5 days, owing to the higher risk bacterial contamination with longer storage. The expiration date could potentially be extended if a rapid system to detect microbial contamination or a safe sterilization technique could be developed and easily implemented. Gamma irradiation has decreased bacterial contamination in food products. Conventional doses of gamma irradiation were tested for their efficacy in decreasing bacterial growth during the 5-day platelet shelf life. An initial pilot study determined that bacteria suspended in normal saline at concentrations of 1 to 2 x 10(7) colony-forming units per milliliter showed a dose-related susceptibility to gamma irradiation. Subsequently, four platelet concentrates were pooled, inoculated with a known concentration of Staphylococcus autreus or Serratia marcescens, and divided. The concentrates were exposed to varying amounts of gamma irradiation, ie, no irradiation (control), 25, 50, and 75 Gy, and subjected to typical blood bank storage conditions. The platelet concentrates were sampled daily for 7 consecutive days to monitor bacterial growth by quantitative cultures. An inverse linear dose-related extinction of bacteria was evident in the pilot study with an extrapolated total kill in the 100 to 150 Gy range. There is no difference in bacterial growth with S aureus using irradiation levels from 0 to 75 Gy. A 1-day delay in bacterial growth at 75 Gy was found with S marcescens compared with units irradiated with 0 through 50 Gy. Exposure of bacteria-contaminated platelet concentrates on storage day zero to gamma irradiation at levels up to 75 Gy is ineffective at sterilizing the platelet concentrates. Higher levels of irradiation may be effective in sterilizing platelet concentrates. Function, survival, and sterility after higher than conventional levels of irradiation need further study.

Thrombotic thrombocytopenic purpura that is refractory to therapeutic plasma exchange in two patients with occult infection.

BACKGROUND: The etiology of thrombotic thrombocytopenic purpura (TTP) remains undetermined. TTP has been associated with a number of secondary causes including infections, drugs, menses, pregnancy, autoimmune diseases, and bone marrow transplantation. Regardless of the inciting factors, it is widely accepted that endothelial injury and platelet aggregation are integral components. The morbidity and mortality have been significantly reduced with the use of plasmapheresis. However, refractory forms of TTP remain a clinical management challenge. Refractory TTP has not previously been associated with occult bacterial infection. CASE REPORT: Two patients had classic TTP that was refractory to daily plasma exchange with fresh-frozen plasma. Multiple attempts over a period of months to wean these patients off plasma exchange resulted in exacerbations of disease activity, as indicated by increased schistocytosis, decreased hematocrit, increased serum lactate dehydrogenase, and decreased platelet counts. Both patients were empirically treated for infections during hospitalization, although microbial cultures failed to isolate an organism. Discontinuation of antimicrobial therapy on multiple occasions in one patient was associated with recurrence of disease. In the other patient, dental extraction with drainage of an occult periodontal abscess resulted in sustained remission of disease. CONCLUSION: Occult bacterial infection may play a role in triggering and sustaining TTP that is refractory to conventional treatment. A careful search for such an infection and appropriate antimicrobial therapy should be considered in the management of these patients.

Cellular source of serum lactate dehydrogenase elevation in patients with thrombotic thrombocytopenic purpura.

Elevated serum lactate dehydrogenase (LDH) is a characteristic finding in patients with thrombotic thrombocytopenic purpura (TTP). It is widely accepted that total serum LDH principally rises due to the release of red blood cell LDH as a consequence of intravascular hemolysis. To identify the cellular source of serum LDH in TTP, we prospectively analyzed total serum LDH and LDH isoenzyme profiles in 10 consecutive patients with classic, acute idiopathic TTP within 5 days of clinical presentation. Total LDH was quantitated on a Hitachi 911 Analyzer (Indianapolis, IN), using the lactate to pyruvate reaction. LDH isoenzymes were measured by serum protein electrophoresis, using the Beckman LDH Isoenzyme Kit (Anaheim, CA). Isoenzymes attributable to erythrocytes (LDH1, LDH2) were not disproportionately elevated in 9 of 10 patients. LDH3 was below or within normal limits for all 10 patients, and one patient showed a slightly increased LDH4. Serum LDH5, the isoenzyme derived primarily from liver and skeletal muscle, was elevated 1-2 times normal in all patients. Evidence supporting hemolysis as the major contribution to the elevated total serum LDH frequently encountered in acute TTP was not identified in this study. The isoenzyme fractions LDH and LDH2 elevated by erythrocyte injury were not disproportionately elevated in this series. LDH 5, the isoenzyme found in skeletal muscle and liver, was consistently 1- to 2-fold greater than normal in all patients. We propose that the elevation of serum LDH seen in patients with TTP is due to release of LDH from a variety of tissues damaged as a result of systemic ischemia.

Alternatives to albumin: starch replacement for plasma exchange.

Today, albumin, or a combination of saline and albumin, is used and widely accepted as a replacement for routine plasma exchange. However, decreased availability (due to market recalls secondary to Creutzfeld-Jacob or bacterial contamination risk) rising costs, recognition of drug interactions with albumin (i.e., ACE inhibitors) and a fear of disease transmission have led several groups to reconsider the use of colloid starches as partial or full replacement for plasma during plasma exchange. There are two hydroxyethyl starches: hetastarch (Hespan and Pentaspan) currently licensed for human use in the United States. While both are approved for granulocyte collection only Hespan is approved as a plasma volume expander. Anecdotal experience and limited reports in the literature with the use of starches as a replacement for plasma exchange suggest that such starch products are a reasonable replacement for albumin as an initial wash-out fluid or in combination with either albumin or saline. Kinetic modeling of the wash-out of starch used as a replacement fluid demonstrate that relatively little residual starch remains compared to the total amount infused. Hydroxyethyl starches are biochemically similar to glycogen, which likely explains the lack of immunogenicity and lack of adverse reactions. Substantial cost savings are associated with the substitution of starch for albumin. It is concluded that HES is well-tolerated and cost-effective as full or partial volume replacement with plasma exchange. It is anticipated that the use of HES will emerge as a standard of care in apheresis.

Apheresis. New opportunities.

Recent advances in apheresis have emerged in a variety of clinical settings. Improvements in granulocyte and peripheral blood stem cell collection and mobilization, the changing role of intravenous gamma globulin, the importance of patient assessment and selection of replacement fluids, and the progress in both affinity apheresis and photopheresis are presented. These current trends, their limitation, and their promise in treating a diversity of diseases inspire the future of this technology.

Tissue transglutaminase expression in human breast cancer.

Tissue transglutaminase (tTG) is postulated to play a role in apoptosis, cell adhesion, metastasis, and extracellular matrix (ECM) assembly. In this study, the distribution and expression of tissue transglutaminase was investigated in normal human mammary tissue and in intraductal and invasive human breast cancer by immunohistochemistry and in situ hybridization. Frozen and formalin-fixed paraffin-embedded sections of normal, intraductal, and invasive human breast carcinoma were examined with an avidin-biotin complex immunoperoxidase method for tTG antigen and by in situ hybridization to determine the cell types expressing tTG mRNA. The expression of tTG in normal and malignant mammary epithelium in culture was evaluated by quantitative immunoblot analysis. Low-level expression of tTG was found in normal tissues with the antigen located in the ECM surrounding the ducts and in the endothelium. In intraductal cancer, there was a marked increased expression of the tTG antigen, and the increased staining was found in the ECM and was also localized in a distinct pattern at the boundary between the in situ tumor cells and the normal tissue. Further immunohistochemical analysis revealed that the cells in this boundary also stained for the endothelial cell markers CD31, CD34, and von Willebrand factor. In invasive tumors, the tTG antigen was no longer localized to the normal tissue/tumor boundary but dispersed around the tumor cells. In situ hybridization studies revealed three distinct compartments of tTG synthesis: (a) tumor cells, (b) endothelial cells, and (c) stromal cells. In addition, normal and malignant epithelial cells in culture expressed variable amounts of tTG, and the expression of tTG in these epithelial cells was at least 17-fold less than endothelial cells. The up-regulation of tTG in intraductal and invasive human breast cancer and its localization to the ECM and neovasculature suggest that tTG may regulate tumor growth and metastasis.

Overexpression of p53 and HER-2/neu proteins as prognostic markers in early stage breast cancer.

OBJECTIVE: Overexpression of the p53 and HER-2/neu oncogenes are the two most common genetic abnormalities associated with breast cancer. Shorter survival time has been reported in patients with tumors with p53 or HER-2/neu. This report analyzes a retrospective cohort of early stage breast cancers for both oncogenes and relates overexpression to clinicopathologic parameters and survival. METHODS: Immunostaining for p53 and HER-2/neu was performed on 230 paraffin-embedded specimens of stage I and II breast cancers diagnosed and treated at Duke University Medical Center between 1984 and 1987. Positive staining for both p53 and HER-2/neu in paraffin-embedded tissues indicates an underlying genetic abnormality: point mutations in the p53 gene and amplification of the HER-2/neu gene. RESULTS: In this cohort of patients, 24% were positive for p53 and 17% for HER-2/neu. Four per cent were positive for both oncogenes. Significant correlations were found between p53 immunostaining and increasing tumor size, stage, and low estrogen and progesterone receptor contents. Univariate analysis showed that p53 and HER-2/neu were indicators of overall and failure-free survival. An additive effect on survival was observed in patients with both oncogene abnormalities. Nodal status, HER-2/neu, and p53 all attained independent prognostic value in a multivariate analysis. CONCLUSIONS: The p53 and HER-2/neu oncogenes have proven but limited prognostic value. An approach that combines several molecular genetic markers with established pathologic criteria may help physicians to make more accurate predictions of prognosis in patients with early stage breast cancer.