The effect of fresh versus standard blood transfusion on microvascular endothelial function

BACKGROUND

The duration of red blood cell (RBC) storage may have a negative impact on endothelial nitric oxide bioavailability. We tested the hypothesis that transfused fresh blood will have a more favorable effect on microvascular endothelial function as compared to older standard issue blood.

METHODS

Participants requiring chronic RBC transfusions were enrolled in a crossover design study to receive fresh (<7 days of storage) or standard (up to 42 days of storage) blood on 2 separate visits. Endothelial function was assessed by reactive hyperemia peripheral arterial tonometry that was measured before and after transfusions. For each participant, the difference between endothelial function pretransfusion and posttransfusion was assessed in relation to blood storage time.

RESULTS

Twenty-one patients (71 ± 16 years, 52% females) were enrolled. Mean age of fresh blood was 5.5 days (±1.0), and that of standard blood was 24.5 days (±7.9 days). The pretransfusion hemoglobin was 83.1 ± 2.5 g/L; and posttransfusion, 98.9 ± 2.6 g/L. An average of 2 U of packed RBCs was transfused. Microvascular endothelial function decreased more frequently after transfusion of standard blood compared to fresh blood. Standard issue blood transfusion was associated with decrease in reactive hyperemia peripheral arterial tonometry index (-0.25 ± 0.63) compared to fresh blood (+0.03 ± 0.49); P = .026.

CONCLUSION

Transfusions of standard issue blood are associated with less favorable effect on microvascular endothelial function as compared to fresh blood.

Eculizumab in the management of paroxysmal nocturnal hemoglobinuria: patient selection and special considerations

Paroxysmal nocturnal hemoglobinuria (PNH) is a nonmalignant clonal disorder resulting from somatic mutation in the PIG-A gene leading to a deficiency of the membrane-anchoring molecule glycosylphosphatidylinositol. The lack of expression of two glycosylphosphatidylinositol-anchored proteins involved in the regulation of the complement system renders PNH erythrocytes susceptible to complement-mediated lysis. Clinical manifestations include thromboembolic disease, chronic kidney injury, pulmonary hypertension, smooth muscle dysfunction, and chronic hemolysis. Until recently, treatment was mainly supportive with most patients suffering from significant morbidity and shortened survival compared to age-matched controls. The development of eculizumab, a humanized monoclonal antibody directed against the terminal complement protein C5, has resulted in dramatic improvements of survival and reduction in complications. In this paper, we review some special considerations pertaining to the use of eculizumab for PNH.

Reducing inappropriate ESR testing with computerized clinical decision support

Laboratory test overutilization increases health care costs, leads to unwarranted investigations, and may have a negative impact on health outcomes. The American Society of Clinical Pathology, in its Choosing Wisely Campaign, advocates that inflammation be investigated with C-reactive protein (CRP) instead of Erythrocyte Sedimentation Rate (ESR). London Health Sciences Centre (LHSC), a tertiary care hospital organization in Ontario, Canada, set a goal to reduce inappropriate ESR orders by 50%. After developing appropriateness criteria for ESR, we used a series of PDSA cycles to reduce inappropriate ESR ordering and analyzed our results with an interrupted time series design. Our intervention began with an educational bulletin and moved to city-wide implementation of computerized Clinical Decision Support (CDS). After implementation, ESR orders decreased by 40% from 386 orders per week to 241 orders per week. Our results are supported by previous literature on the effectiveness of CDS in reducing overutilization and suggest that provider habit is a significant contributor to inappropriate ordering.

Eculizumab as a bridge to immunosuppressive therapy in severe cold agglutinin disease of anti-Pr specificity

Severe cold agglutinin disease with hemodynamic compromise requires rapid stabilization of the autoimmune hemolytic anemia as a bridge to the immunosuppressive effect of rituximab. Herein, we describe eculizumab treatment of severe complement-mediated hemolysis in a patient whose hemodynamic status deteriorated in spite of supportive blood transfusions and therapeutic plasma exchange.

Novel lymphocyte screening tube using dried monoclonal antibody reagents

We previously developed a 10-color 11-antibody combination including a viability dye, to screen T-, B-, and natural killer (NK)-cell populations in blood, bone marrow, tissue, and body fluids. Recently, Beckman Coulter has introduced a line of dried reagents that, unlike liquid reagents and cocktails, require no refrigeration, titration, or manipulation before using. We evaluated custom tubes based on our standard lymphocyte screening panel, focusing on comparative analysis, ease of use, and advantages compared with our liquid reagent set. We tested 42 samples from blood (n = 15), bone marrow (n = 17), and tissue (n = 10) with the combination CD4/CD8/KAPPA/LAMBDA/CD19/CD56/CD5/CD20/CD10/CD3/CD45 and a vital dye by both methods and compared positivity and staining intensity for each antigen. Of the 42 samples, 5 were normal samples, 3 were red cell disorders, 20 were B-cell malignancies, 5 T-cell malignancies, 4 myeloid malignancies, and the remaining 5 were other diagnoses. Dried reagents gave equivalent staining intensity results to our standard panel in a variety of sample types, with diagnoses including reactive lymphocytosis, chronic lymphocytic leukemia, and various lymphomas. Our standard panel for evaluation of mature lymphoid malignancies allows rapid assessment of any sample type while providing direct assessment of viability. The dried reagent tube reduces preanalytical work, with simple addition of sample and the viability dye to the tube, saving time, reducing potential errors, and obviating need to titrate and monitor individual antibodies. With a shelf life of at least 12 months, the reagents also offer potential savings in reagent costs by reducing wastage due to expiration or tandem breakdown in standard liquid formulation.

Screening of patients with idiopathic venous thromboembolism for paroxysmal nocturnal hemoglobinuria clones

Paroxysmal nocturnal hemoglobinuria (PNH) is an uncommon disorder characterized by hemolysis, thrombosis and marrow failure. Whereas venous and arterial thrombosis is a very common symptom of the disease, the frequency of PNH clones in patients with unexplained venous thromboembolism, including deep vein thrombosis and pulmonary embolism, has not been studied. We conducted a cross sectional study evaluating the presence of PNH clones in patients with prevalent venous thromboembolism using a high sensitivity flow cytometry assay for erythrocytes and neutrophils. Among the 388 patients enrolled in the study one patient had a detectable PNH clone of 0.02% in the neutrophil population (0.26%; 95% CI 0.05 to 1.45) and no detectable erythrocyte clone. We conclude that the presence of PNH clones in patients with idiopathic venous thrombosis is rare. Screening for PNH clones among VTE patients might be better reserved for patients with signs of hemolysis.

Response to "Need to minimize bias when surveying patient attitudes to stopping cml treatment"

We thank Villemagne et al. for their comments, and we will address some of the issues that they raised.[...]

Patient preferences for stopping tyrosine kinase inhibitors in chronic myeloid leukemia

BACKGROUND

We used an interview-assisted survey of patients with chronic myeloid leukemia (cml) at a single tertiary care centre to explore patient reactions to and preferences for, and the risk-acceptability of, stopping tyrosine kinase inhibitor (tki) treatment.

METHODS

The study included patients with confirmed cml currently being treated with a tki. The survey was conducted by structured interview using a standard form. Patient preferences were explored in a case-based scenario using 0%-100% visual analog scales and 5-point Likert scales. Data were analyzed using proportions for dichotomous variables and medians and interquartile ranges for continuous variables.

RESULTS

Of 63 patients approached, 56 completed the survey. Participant responses suggest that the idea of stopping tki use is appealing to many patients if there is a chance of long-term stable disease and a high probability of response upon restarting a tki. Participants were more likely to stop their tki as the risk of relapse decreased. Participants reported loss of disease control and failure of disease to respond to treatment as important concerns if they chose to stop their tki.

CONCLUSIONS

Given the current 60% estimated rate of relapse after discontinuation of tki therapy, most patients with cml chose to continue with tki. However, at the lower relapse rates reported with second-generation tkis, participants were more undecided, demonstrating a basic understanding of risk. Contrary to our hypothesis, neither compliance nor occurrence of side effects significantly affected patient willingness to stop their tki.

Initial performance evaluation of the UniCel® DxH 800 Coulter® cellular analysis system

The Beckman Coulter UniCel® DxH 800 is a hematology analyzer incorporating new electronic and mechanical design with advanced algorithm technology to perform CBC, white blood cell (WBC) differential, nucleated red blood cell (NRBC), and reticulocyte analysis. Evaluation of this instrument was performed in our 800-bed tertiary care hospital and specifically centered upon the correlation of WBC, NRBC, and platelet (PLT) enumeration when compared to a predicate analyzer, the Coulter® LH 780, and flow cytometry (FCM) reference methods. Of particular interest were those samples with morphologically confirmed interference and extreme leukocytosis (evaluated with respect to red blood cell parameter correction). The sample set (n=272) consisted of morphologically normal and hematologically abnormal patients. Correlation of the WBC, PLT, and NRBC showed r(2) values of 0.994, 0.985, and 0.910 for the DxH 800 vs. FCM, respectively. The presence of interfering particles did not affect the accuracy of the DxH 800 with respect to WBC counts. The DxH 800 showed accurate PLT and NRBC counts in the clinically significant low range when compared to FCM. Compared to the LH 780, flagging rates were significantly reduced (NRBC flag), or equivalent (WBC, PLT flag) on the DxH 800. The DxH 800 demonstrated higher sensitivity and specificity for PLTs and NRBCs and achieved a lower NRBC false negative rate compared to the LH 780. The UniCel® DxH 800 represents a significant improvement to previous impedance analyzers in accurately detecting the presence of NRBCs at counts >1/100 WBC. Furthermore, it provides accurate PLT and WBC counts in the presence of interference and improved NRBC flagging efficiency when compared to the LH 780. Correction of red blood cell parameters is appropriate and accurate in cases of extreme leukocytosis.

Access to thalidomide for the treatment of multiple myeloma in Canada: physician behaviours and ethical implications

BACKGROUND

Multiple myeloma is an incurable malignancy. Since the late 1990s, its management has changed with the introduction of novel agents. Thalidomide, which is often called a "novel" therapy, has significantly prolonged survival in multiple myeloma and is considered worldwide to be part of standard of care in this disease. However, thalidomide is not approved in Canada, leading to problems with drug access for patients.

METHODS

Our study surveyed Canadian hematologists on their thalidomide prescribing practices and difficulties with drug access. We address some of the ethical issues facing patients and their doctors who are unable to obtain or afford the drug, and who therefore resort to alternative means such as illegal importation.

RESULTS

Of the 411 Canadian hematologists contacted, 122 completed the survey, 97 reported that they did not treat myeloma, and 192 did not respond. Assuming that all non-responders treat myeloma, our estimated overall response rate from physicians who treat this disease was 39%. Survey participants indicated that, in Canada, access to thalidomide is a major issue for physicians and myeloma patients alike, and that 81% of respondents are dissatisfied or very dissatisfied with the drug access process. Many physicians felt that the special access process for thalidomide is unduly onerous, influences treatment decisions, and invades patient privacy. We found that 20% of physicians were unaware of the legal implications of obtaining thalidomide from other countries and that at least 23% overtly or covertly support patients in obtaining the drug from a non-Health-Canada-approved source.

CONCLUSIONS

The current lack of access to thalidomide in Canada is a concerning problem for patients and health care providers dealing with myeloma. Regulatory changes at the federal level (Health Canada) need to be re-examined to promptly resolve this issue.

Engagement of glycosylphosphatidylinositol-anchored proteins results in enhanced mouse and human invariant natural killer T cell responses

Invariant natural killer T (iNKT) cells are a small subset of lymphocytes that recognize glycolipid antigens in the context of CD1d and consequently produce large quantities of pro-inflammatory and/or anti-inflammatory cytokines. Several transmembrane glycoproteins have been implicated in the co-stimulation of iNKT cell responses. However, whether glycosylphosphatidylinositol (GPI)-anchored proteins can function in this capacity is not known. Here, we demonstrate that antibody-mediated cross-linking of the prototype mouse GPI-anchored protein Thy-1 (CD90) on the surface of a double-negative (CD4⁻CD8⁻) iNKT cell line leads to cytokine production at both the mRNA and protein levels. In addition, Thy-1 triggering enhanced cytokine secretion by iNKT cells that were concomitantly stimulated with α-galactosylceramide (αGC), consistent with a co-stimulatory role for Thy-1 in iNKT cell activation. This was also evident when a CD4+ mouse iNKT cell line or primary hepatic NKT cells were stimulated with αGC and/or anti-Thy-1 antibody. Cross-linking Ly-6A/E, another GPI-anchored protein, could also boost cytokine secretion by αGC-stimulated iNKT cells, suggesting that the observed effects reflect a general property of GPI-anchored proteins. To extend these results from mouse to human cells, we focused on CD55, a GPI-anchored protein that, unlike Thy-1, is expressed on human iNKT cells. Cross-linking CD55 augmented αGC-induced iNKT cell responses as judged by more vigorous proliferation and higher CD69 expression. Collectively, these findings demonstrate for the first time that GPI-anchored proteins are able to co-stimulate CD1d-restricted, glycolipid-reactive iNKT cells in both mice and humans.

Flow cytometric assessment of monocyte activation markers and circulating endothelial cells in patients with localized or metastatic breast cancer

BACKGROUND

Monocyte activation in cancer patients may be reflective of anticancer activity. However, studies indicate that recruitment of macrophages can actually promote tumor growth and angiogenesis. Assessment of other microenvironmental cells such as circulating endothelial cells (CECs) may provide additional information regarding disease progression. The objective of this study was to assess monocyte activation and CECs in breast cancer patients and determine the potential clinical relevance during disease progression.

METHODS

Patients (n = 41) with localized or metastatic breast cancer who were not currently receiving treatment were eligible for study inclusion. Peripheral blood was collected and analyzed by flow cytometry for monocyte activation (Leuko64 assay kit), and for CECs (CD146(+)CD45(-) phenotype).

RESULTS

Metastatic breast cancer patients demonstrated a higher monocyte CD64 index relative to normal donors and localized breast cancer patients (P < 0.05). Furthermore, breast cancer patients had a lower monocyte CD163 index relative to normal donors (P = 0.008). Localized breast cancer patients demonstrated higher levels of CD146(+)CD45(-) cells CECs relative to metastatic breast cancer patients and normal donors. Within the localized breast cancer population, levels of CD146(+)CD45(-) cells increased with disease stage (P < 0.05).

CONCLUSIONS

These results suggest that monocyte activation and CECs may play a role in breast cancer progression. We speculate that monocyte activation may reflect a reaction to metastatic cells and/or response to tissue damage caused by metastatic growth in distant organs. Furthermore, the observation that CECs increase with disease stage in localized breast cancer suggests that CECs could be a useful surrogate marker for disease progression in this patient population.

Flow cytometric reticulocyte analysis using thiazole orange; clinical experience and technical limitations

Flow cytometric (FCM) reticulocyte analysis using thiazole orange (TO) is becoming an increasingly popular method for routine quantification of reticulocytes. The methodology is accurate, cost-effective and shows a high correlation with manual techniques. We describe our experience with the clinical application of FCM reticulocyte analysis in a general hospital setting over a 20-month period with special emphasis on technical limitations.

Diagnosing PNH with FLAER and multiparameter flow cytometry

BACKGROUND

PNH is an acquired hematopoietic stem cell disorder leading to a partial or absolute deficiency of all glycophosphatidyl-inositol (GPI)-linked proteins. The classical approach to diagnosis of PNH by cytometry involves the loss of at least two GPI-linked antigens on RBCs and neutrophils. While flow assays are more sensitive and specific than complement-mediated lysis or the Hams test, they suffer from several drawbacks. Bacterial aerolysin binds to the GPI moiety of cell surface GPI-linked molecules and causes lysis of normal but not GPI-deficient PNH cells. FLAER is an Alexa488-labeled inactive variant of aerolysin that does not cause lysis of cells. Our goals were to develop a FLAER-based assay to diagnose and monitor patients with PNH and to improve detection of minor populations of PNH clones in other hematologic disorders.

METHODS

In a single tube assay, we combined FLAER with CD45, CD33, and CD14 allowing the simultaneous analysis of FLAER and the GPI-linked CD14 structure on neutrophil and monocyte lineages.

RESULTS

Comparison to standard CD55 and CD59 analysis showed excellent agreement. Because of the higher signal to noise ratio, the method shows increased sensitivity in our hands over single (CD55 or CD59) parameter analysis. Using this assay, we were able to detect as few as 1% PNH monocytes and neutrophils in aplastic anemia, that were otherwise undetectable using CD55 and CD59 on RBC's. We also observed abnormal FLAER staining of blast populations in acute leukemia. In these cases, the neutrophils stained normally with FLAER, while the gated CD33bright cells failed to express normal levels of CD14 and additionally showed aberrant CD45 staining and bound lower levels of FLAER.

CONCLUSION

FLAER combined with multiparameter flow cytometry offers an improved assay for diagnosis and monitoring of PNH clones and may have utility in detection of unsuspected myeloproliferative disorders.

Consenting to blood: what do patients remember?

We sought to characterize the consent process for transfusion and determine its impact on patients' knowledge and level of comfort with receiving blood. We identified all adult patients who had received blood transfusion at a tertiary care centre over 3 months. Patients who were discharged each received a survey that assessed their (1) recall of the consent process, (2) recall of information conveyed, (3) assessment of the discussion's understandability and (4) perceived knowledge of as well as comfort level with transfusion as a result of the discussion. Overall, 80% of respondents recalled discussing and signing an informed consent. Information was mostly conveyed by attending physicians (35%) and consent obtained in the patient's hospital room (38%) or the preadmission clinic (19%). Although the majority recalled the consent process, many did not recall the discussion of specific transfusion risks or alternatives to donor blood (88%). Although the majority felt the discussion was at least somewhat understandable (77%), only 35% felt better informed and more comfortable with accepting blood. Despite implementation of written informed consent for transfusion, patients' recollection and understanding of risks and alternatives remain poor. This suggests the need for improving risk communication.

A retrospective study evaluating single-unit red blood cell transfusions in reducing allogeneic blood exposure

Although guidelines recommend the use of single-unit red blood cell (RBC) transfusions to minimize allogeneic blood exposure, clinical practice remains dominated by two-unit transfusions. This study assesses the potential impact of a single-unit transfusion policy on reducing RBC utilization. We performed a retrospective analysis of adult patients admitted to a tertiary care hospital who received one or two RBC units. In subjects transfused two units, the effect of one unit was estimated by dividing the change in haemoglobin by 2. The proportion of patients reaching a haemoglobin threshold of 70, 75, 80, 85 and 90 g L(-1) with a single RBC unit was estimated. Of 302 included patients, only 65 received a one-unit transfusion. Based on thresholds of > or = 90, > or = 80 and > or = 70 g L(-1), a single-unit transfusion would be sufficient in 42.0% (RRR = 0.54), 79.6% (RRR = 0.23) and 98.0% (RRR = 0.02) of cases, respectively. This corresponds to 0.21, 0.57 and 0.82 mean RBC units saved per patient. In the orthopaedic subpopulation, the mean RBC units saved are 0.53, 0.88 and 1.00 for the same haemoglobin targets. Adopting a policy of transfusing RBC in single-unit aliquots could significantly improve RBC utilization and decrease patient exposure to allogeneic blood.

A pilot trial evaluating the clinical effects of prolonged storage of red cells

The clinical consequences of prolonged storage of red cells have not been established. In this pilot study, we evaluated whether it would be feasible to provide a continuous supply of red cells stored <8 days. In addition, we examined the potential benefits attributed to "fresh" as compared to standard red cells in 66 critically ill and cardiac surgical patients. Nine patients were issued red cells but were not transfused. From the 57 remaining patients, the number of units transfused averaged 5.5 +/- 8.43 red cell units in the experimental group compared to 3.3 +/- 3.27 red cell units in the standard group (P = 0.25). The median storage time was 4 days in the experimental group compared to 19 days in the standard group (difference of 15 days; interquartile range of 12-16 days; P < 0.001). Overall, 73% of patients received red cells with storage times that corresponded to the treatment allocation more than 90% of the time. The group receiving red cells <8 days old tended to be older on average (68 +/- 8.54 yr versus 63 +/- 15.30 yr; P = 0.13) and have more comorbid illnesses (85% versus 65%; P = 0.09). In total, 27% of patients in the experimental group died or had a life-threatening complication as compared to 13% in the standard group (P = 0.31). There were no differences in prolonged respiratory, cardiovascular, or renal support after randomization (P > 0.05). A large clinical trial comparing red cell storage times is feasible and warranted given the limited available evidence.

Hemolysis with rapid transfusion systems in the trauma setting

OBJECTIVE

Rapid infusion system allows rapid infusion of resuscitation fluids at body temperature in trauma patients. Packed red blood cells are subjected to high external pneumatic pressure (up to 300 mm Hg) and rapid infusion rates through a 170-microm filter. This study was conducted to outline hemolysis that may occur in the setting of massive transfusion (> 10 units).

METHODS AND MATERIALS

Measurements of various parameters were made before and after infusion of 17 units of outdated (38-82 d) packed red blood cells through a Level 1 Rapid Infuser, including lactate dehydrogenase (LDH), potassium, plasma hemoglobin, hematocrit and total hemoglobin. Hemolysis, expressed as a percentage, was calculated from these parameters.

RESULTS

Hemolysis observed in this experiment ranged from near 0 to 0.05%. All the units had plasma potassium concentrations of 15 mmol/L or more.

CONCLUSION

Transfusion of 17 units with the Level 1 Rapid Infuser did not cause a clinically significant amount of hemolysis.

Critical oxygen delivery in conscious septic rats under stagnant or anemic hypoxia

Although evidence shows that critical O2 delivery (QO2crit), the point at which oxygen consumption becomes limited by O2 delivery (QO2), is not affected by the method used to decrease QO2 in healthy subjects, microcirculatory injury caused by sepsis may modify QO2crit in a unique manner. We therefore designed this study to compare QO2crit in anemic and stagnant hypoxia in conscious septic rats. Rats were randomized to control or sepsis induced by cecal ligation and perforation; 24 hours later, oxygen consumption was measured using expired gas analysis, whereas QO2 was calculated from standard formula. Rats were further randomized to anemic hypoxia by isovolemic hemodilution or stagnant hypoxia by stepwise inflation of a balloon-tip catheter in the right atrium. QO2crit and critical hemoglobin concentration were calculated by dual linear regression analysis. We found that (1) QO2crit was not different between anemic and stagnant hypoxia in sepsis and that (2) the critical hemoglobin concentration in anemic hypoxia was similar between sepsis and control, indicating that tolerance to acute anemia is not altered by sepsis. Further studies are needed before the clinical relevance of these conclusions can be fully understood.