Background and Objectives: Respiratory transfusion reactions associate strongly with morbidity and mortality, and transfusion-associated circulatory overload (TACO) is the leading cause of reaction-related deaths. Risk factors for TACO include transfusion speed and volume and cardiorenal comorbidities. Materials and Methods: An academic health network haemovigilance database was interrogated to assess variables associating with 371 cases of TACO and involved-visit outcomes, using univariate and multivariate regression analysis. Results: TACO reactions over 11 years were reported in 179 males and 192 females, median age (interquartile range) 65 (53-75) years. In-hospital and 28-day mortality were 17.5% and 12.9%, respectively. In univariate regression modelling, male sex, injury severity grade, product volume administered, the use of platelets and intensive care admissions were each associated with in-hospital and 28-day mortality (p < 0.05). However, after multivariate regression analysis, only male sex in transfusion recipients independently associated with mortality (p < 0.05). Conclusion: In this cohort, male recipient sex and platelet administration were associated with TACO-involving admissions not ending in survival.

BackgroundIt is uncertain how transfusion knowledge translates to practice. The purpose of the study was to determine if higher scores on a validated Transfusion Camp knowledge assessment test were associated with transfusion order appropriateness.Study Design and MethodsEligible participants included postgraduate trainees and faculty physicians who had prescribed at least four transfusion orders in the preceding 6 months at two hospitals. Participant data and knowledge were collected using a web-based questionnaire with a validated Transfusion Camp knowledge assessment tool. The most recent 4-10 consecutive transfusion orders per prescriber were independently dually adjudicated for appropriateness based on published criteria. The primary outcome was the correlation between the score on six questions on red blood cells (RBCs), platelets (PLTs), and plasma from the validated test and the percentage order appropriateness. Generalized linear regression was conducted to determine if factors (sex, specialty, participation in Transfusion Camp, previous transfusion education, self-rated knowledge) were associated with appropriate orders.ResultsSeventy-four participants (45 trainees, 29 faculty; 31 females, 43 males) completed the test. Median score was 66.7% (interquartile range [IQR]: 50.0, 83.3) for six questions on RBCs, PLTs, and plasma transfusions. Of 546 transfusion orders adjudicated, appropriateness was 90.7% (95% confidence interval [CI]: 87.9%-93.0%). The correlation between prescriber test scores and order appropriateness was very weak (r = -.08). In multivariable analysis, female prescribers (p = .02) and beginner (vs. intermediate) self-rated knowledge (p = .01) were associated with higher transfusion appropriateness.ConclusionTransfusion knowledge test scores did not correlate with order appropriateness. Factors other than knowledge are key to understanding how to improve appropriate blood use.

BACKGROUND: Transfusion-associated circulatory overload (TACO) is a common but under-reported complication of transfusion therapy, and results in significant morbidity and mortality. Pre-transfusion furosemide has been proposed as a mitigating strategy but has not received widespread endorsement, in part due to uncertainty regarding safe and effective dosing. An observational study was therefore conducted with the goal of creating a reliable dose-response curve in patients at high risk of TACO, using the statistical technique of Multiple Comparisons Procedure with Modelling (MCP-MOD). METHODS: Eligible patients were identified by screening bolus intravenous (IV) furosemide orders at two large academic hospitals. Eligibility criteria were selected to mimic those of a planned randomized controlled trial (RCT) of pre-transfusion furosemide for the prevention of TACO. Inclusion criteria were inpatients 50 years of age or older. Exclusion criteria were active bleeding, hemodynamic instability, glomerular filtration rate (GFR) < 30mL/min or need for dialysis, diuretic therapy (other than furosemide) administered less than 24 hours, furosemide (either IV or PO) administered less than 12 hours, or exogenous albumin administered less than 8 hours prior to index furosemide therapy. The primary outcome measure was the total volume of urine output in the six hours following IV furosemide administration. MCP-MOD analysis was performed after every 50 patients and continued until a weight-adjusted dose-response curve could be established with 100 mL precision, using the following covariates: age, sex, mean arterial pressure (MAP), serum albumin, GFR and history of chronic furosemide use. RESULTS: A total of 149 participants (53 female and 96 male) were enrolled over 2 years. As too few patients received doses exceeding 0.6 mg/kg to allow for a precise dose-response curve, only 132 patients receiving weight-adjusted doses ranging from 0.1 to 0.6 mg/kg were included in the MCP-MOD analysis. The characteristics of these patients are shown in Table 1. The dose-response curve formula that was derived from these patients was: Urine Output at 6 hours (mL) = 717.21 + 191.33 ln(dose (mg)/weight (kg)) + 0.73 × Age (years) + 103.37 × Sex (M=1/F=0) + 1.63 × GFR (ml/min) + 5.45 × MAP (mmHg) - 9.56 × albumin (g/L) - 62.31 × chronic diuretic use (Y=1/N-0) The curve with accompanying 95% confidence intervals is shown in Figure 1 This formula suggests that in an 80 kg patient with a GFR of 75 mL/min, a MAP of 85 mmHg, albumin of 40 g/L and no history of chronic diuretic use, 10 mg of IV furosemide should produce a diuresis of approximately 600 mL, sufficient to prevent circulatory overload from the transfusion of 1 unit of RBCs. A dose of 20 mg would be required to achieve a similar diuresis in patients with either a MAP < 60 mmHg, or a combination of both a GFR < 45 mL/min and a history of chronic diuretic use. CONCLUSIONS: A statistically precise dose-response curve for IV furosemide is possible with the inclusion of relevant clinical covariates, and can be used to guide dosing decisions in patients at risk of transfusion-associated circulatory overload. This formula derived from this study will inform the dosing recommendations of a planned RCT: Transfusion-Associated Circulatory Overload: Best Eliminated by Lasix® (TACO-BEL).

Background: Cardiorespiratory transfusion reactions drive most transfusion-related morbidity and mortality. Transfusion-associated circulatory overload and transfusion-related acute lung injury have established causes, important impacts, mitigation options, and revised definitions, while non-conforming CRTRs fall into a category known as transfusion-associated dyspnea. Though procedures to investigate high-risk febrile transfusion reactions are typically rooted in detecting incompatibility or bacterial contamination, a common standard for examining CRTRs is lacking. CRTRs are further challenged by charting limitations, confounding (or enhanced susceptibility) by comorbidities, and/or overlapping insults. Deeper profiling of CRTRs could improve categorizations, reveal best-value diagnostics, and decipher the nature of (and/or minimize) reactions coded as TAD. Methods: The primary objective of this multi-center study is to reduce uncertainty in final conclusions drawn on CRTRs (cases), defined by dyspnea with objective disturbances and/or significant hemodynamic insults, with/without fever (±F). HRFTRs (controls) represent higher-grade F (T≥39°C or chills/rigors or lower-grade F (≥38°C by +Δ1°C) with non-respiratory effects). Patients (goal: 200) consent to additional sampling (≤24h post-TR) to identify contributing factors in case/control presentations, and in diagnostic groups (TRALI, TACO±F, TAD). Mechanistic axes of interest are cardiorenal, hemolytic, leukoagglutinating, biolipid, vasoactive, and inflammatory. Secondary goals include elucidation of real-life “insult-multiplicity” in CRTRs, tests of greatest yield, and distinguishing features in TRALI/TACO/TAD. Conclusions: A deep systematic CRTR probe may not only reduce diagnostic uncertainty but frame biomarker performance and pathologic signatures in definition-specific CRTRs. The re-classifiability or biology of TAD may be better understood. High-quality, mechanistic, true-to-quantity hemovigilance better exposes burdens and management options. Trial Registration: The trial is registered with ClinicalTrials.gov. with registry number NCT04267029.

BACKGROUND: B-type natriuretic peptide (BNP) is a hormone secreted in response to volume-related ventricular stretch, and as a biomarker is both diagnostic and prognostic in heart failure. Elevation in BNP or its equimolar N-terminal prohormone fragment (NT-proBNP, noteworthy for its longer half-life) qualifies as a criterion in ISBT-IHN-AABB guidelines for the diagnosis of transfusion-associated circulatory overload (TACO). However, real-life range comparisons in TACO vs. non-respiratory transfusion reactions (TR) are lacking. In the Transfusion Associated Dyspnea-Prospective Observation and Laboratory Assessment (TADPOL) study of acute TRs requiring laboratory investigation (cardiorespiratory events +/- fever [CRTR+/-F] vs. standalone high-risk fevers [HRFTR]), patients consented to NT-proBNP testing as part of a multi-dimensional assessment of presentation archetypes and final diagnoses (e.g., TACO, transfusion-associated dyspnea [TAD], febrile non-hemolytic TR [FNHTR]). METHODS: Blood samples were collected within 24h of reaction onset from patients enrolled across 6 centers in the study's first 134 weeks. NT-proBNP (ng/L) was quantified by chemiluminescence immunoassay (Roche Diagnostics) in real-time (3 sites) or by batched testing (3 sites); reference cut-off values to rule in a cardiac cause for dyspnea in the acute care setting were >450 (age <50y), >900 (age 50-75y), and >1800 (age >75y). Summary statistics are reported. Relationships to provisional reaction diagnosis and clinical features were also explored using appropriate tests (Student's t-test, Mann-Whitney U, Pearson's correlation, and/or Fisher's exact test). Discrimination between possible-to-definite TACO and doubtful or ruled-out TACO was assessed using receiver operating characteristic (ROC) curve analysis with logistic regression. RESULTS: At the study mid-point, 1180 TR (604 TADPOL-eligible) occurred, with NT-proBNP tested in 77/100 enrolled patients. NT-proBNP was significantly higher in patients enrolled in the CRTR arms compared to HRFTR (p=0.0009), with no difference between CRTR+F and CRTR-F (p=0.4). NT-proBNP was also significantly higher in patients with dyspnea in the TR (p=0.005). There was no correlation between NT-proBNP and systolic blood pressure change (p=0.1) or at baseline (p=0.1). Provisional reaction diagnoses were available for 55 patients including 32/39 in the CRTR arms: for possible-to-definite TACO (n=14) and TAD (n=19), vs. standalone FNHTR (n=38), the median NT-proBNP (IQR) was 3,439 (1,587-10,668) and 1,893 (674-5,361), vs. 710 (124-10,542), respectively. Transfusion-related acute lung injury was considered possible in 3 cases, all with TACO. Among CRTR, there was a trend towards higher NT-proBNP values in patients with TACO (p=0.05), with no difference in ages (p=0.8). Using the age-adjusted reference cut-off, the sensitivity of high NT-proBNP for TACO was 86%; specificity was 54% when differentiating TACO from all enrolled TR and 38% between TACO and non-TACO CRTR. In ROC curve analysis (Fig. 1), the area under the curve was 72% (95% CI 55-88%) and the threshold value for discriminating TACO from other TR was 1606 with 60% sensitivity and 65% specificity (Fig. 2). CONCLUSIONS: NT-proBNP is strongly correlated with dyspneic TRs compared to isolated febrile TRs. Elevations appeared more marked in TACO, with a sensitivity of 86% using existing laboratory reference values. However, specificity and discrimination within CRTR were poor. These results affirm that NT-proBNP is helpful in ruling out TACO, whereas ruling in TACO continues to demand a more integrated approach. Whether cardiac strain in unclassified CRTR and TAD is evidence of missed TACO or other insults remains to be determined. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

In the current dogma, immune hemolysis is considered an exclusively humorally-mediated state. However, in some cases, serological investigations are negative and without alternative explanations. In such a subset of unexplained seronegative hemolysis (SNH), we investigated for potentially attributable cellular mechanisms. Release of chromium-51(Cr51) was selected as the most sensitive method. Effector cells of the immune system (NK cells, neutrophils, monocytes) were purified by negative selection and evaluated as mediators of RBC lysis. Anti-D-opsonized R2R2 RBCs were selected as positive control RBCs for standardization of cytotoxicity assays and evaluation of the killing capacity of different immune cells. We observed that PBMCs were the least sensitive at lysing control RBC while NK cells, used at an effector/target ratio of 10:1, were the most efficient in killing control RBC, followed by monocytes and neutrophils. Neutrophils, used at an effector/target ratio of 25:1, are also capable of lysing control RBCs but required priming with GM-CSF. By informed consent, ten patients with unexplained SNH were tested for cellular-mediated hemolysis using autologous, purified immune cells (NK or neutrophils), against autologous RBCs with or without opsonization with autologous serum. Evidence of cell-mediated RBC lysis occurred in 60% (6/10) of the patients analysed (PBMCs, 1; NK, 4; neutrophils, 1). We also observed that RBC from patients with SNH display a significant reduction in the expression of CD47 when compared to healthy individuals. With CD47 being a “do not eat me” signal, its reduction is plausibly contributing to enhanced RBC clearance. These initial results suggest that cellular mechanisms beside extravascular antibody-mediated phagocytosis may play a role in seronegative hemolytic anemias.

Abstract BACKGROUND: RBC transfusions play a role in organ- and life-preservation for patients with sickle cell disease (SCD). These in turn are subject to higher-fidelity matches to offset the particularly high condition-specific odds of seroconversion events. Adverse outcomes may be as severe as hyperhemolysis, and/or undertransfusion from the scarcity of suitable antigen profiles. In a woman with HbSS SCD and multiple alloantibodies (-K, -E, Jkb-, -Fya, -S), correspondingly antigen-negative units had nevertheless become invariably crossmatch-incompatible (iXM) owing to the development of an antibody to -Kna, a high-prevalence (but clinically insignificant) target antigen on CR1/CD35. Genotyping ruled out the absence of other rare antigen-negative states at risk of high-frequency antibodies (hrB, hrS, Joa, U). Due to uncertainties on the in-vivo effects of iXM RBC in this patient, the infeasibility of sourcing of complete antigen matches, and challenges ruling out other emerging (and potentially more harmful) antibodies, a prolonged period of transfusion-avoidance ensued. This deferral correlated with progression of SCD-associated dilated non-ischemic cardiomyopathy and restrictive interstitial pulmonary fibrosis. In order to qualify Kna-unselected iXM that were otherwise target-negative for her clinically significant antibodies, a monocyte monolayer assay (MMA) approach was taken to identify, transfuse, and maintain a personalized roster of RBCs for monthly top-up transfusions. METHODS: Selected donors (group O, ±D, ±C, E- K- Jkb- Fya-) were assessed at least once in the MMA by a 4:1 (patient serum) to (candidate unit RBC) ratio, incubated at 37°C for 1 hour. The total number of RBCs phagocytosed in 100 patient monocytes was reported as a phagocytic index (PI), with a significance cut-off of 5 (or lower, if rosettes were noted, and/or a noticeably more incompatible [≥3+] crossmatch was observed compared with other prepared units). Antibody screens (automated solid phase) and manual serologic crossmatches (by both conventional tube- and gel microtube- technique) were performed at each RBC sitting. Interval/pre-RBC tests incorporated hemolytic markers and hemoglobin electrophoresis (HbS%). RESULTS: Of 26 donors examined in 8 MMA arrays over 3 years, 10 were excluded due to high PI (median 6 [range 3.3-54]) and/or differential iXM. Of the remaining 16 (PI 0.9 [0.2-4.5]), RBCs have been transfused from 13, with 56 units [u] (51 fresh/5 frozen-deglycerolized) given in 27 sittings over 113 weeks. Most have donated >1u (7/13 with ≥1u transfused to this recipient, median 4u [range 1-8]). The HbS% fell from 91% to 45% [39-48] (median [IQR], pre-3rd-to-27th sitting) with improved hemolytic markers and freedom from overt incompatibility reactions. A minor allergic reaction on the 1 st sitting (with 2u from the same donor) led to a default mitigation strategy of supernatant reduction and antihistamine-premedication thereafter. All sittings (including 5u from the index donor) were reaction-free until a 2 nd minor allergic reaction 2 years later (associated with 2 other donors). Improvements occurred in cardiac function, performance status, pain, and quality of life over the 1 st 20 months of transfusions, though an acute pulmonary embolism and progressive iron overload have reversed the initial gains. Of 11 donors re-examined in 3 repeat MMA (29-112 weeks later), 10 were re-qualified; the 1 st donor was excluded due to an unexplained PI surge (2.5 to 5.6). Host tolerance otherwise increased to most re-qualified donors in a PI downtrend over time (in 8/10, median 1 st PI 2.1, vs median 2 nd PI 1.0, P=0.006 [paired, 2-sided t-test]). A new sensitization (anti-Cob) was noted before the 14 th sitting, with donor genotypes imputing and disqualifying donor 9. CONCLUSIONS: An MMA-vetted pipeline of RBCs in a once-prohibitively alloimmunized patient with SCD has re-enabled transfusion care by the coordinated efforts of the national blood collector with its donors, its MMA laboratory, and the supervising hospital transfusion service. An unexpected finding in repeated exposures to a limited number of donors was increased tolerance. When the viability of transfusions is restored in SCD, so too are opportunities in disease control and in transfusion-requiring curative treatment options. The number of similarly constrained patients, and the scalability of this innovation, remain to be determined. Disclosures No relevant conflicts of interest to declare.