Computerized quality assurance of decisions to transfuse blood components to critically ill patients

BACKGROUND: In critically ill patients optimal transfusion therapy for most clinical settings has not been determined. The objective of this study was to evaluate the impact of a computerized audit on transfusion decisions of red blood cells (RBC), fresh frozen plasma (FFP), and platelets among critically ill patients. METHODS: Two hundred and ninety consecutive patients admitted to nine-bed medical-surgical intensive care unit at a university hospital were included in this prospective study. Prior to the study, the criteria for transfusions of RBCs, FFP and platelets were established. Phase I, the first 3-month period served as a control period. During phase II the fulfilment of these criteria was prospectively monitored by an audit software belonging to the computerized blood request program. If the predefined transfusion criteria were not met the audit software was automatically activated. The last 3-month period, phase III, was to assess if possible effects on transfusion decisions were permanent. RESULTS: The proportion of RBC transfusions administered according to predefined trigger during the study phases I, II, and III were 55.9%, 75.1% and 67.9%, respectively (P < 0.001). The proportion of FFP and platelet transfusions according to a predefined trigger did not differ statistically significantly between the study phases. Logistic multiple regression analysis revealed an independent effect of the audit phase on the decision to transfuse RBCs and FFP. CONCLUSIONS: The data suggests that a computerized prospective transfusion audit has impact on the realisation of predefined transfusion decisions.     

Duration of red blood cell storage and outcomes following orthotopic liver transplantation

Liver transplantation may be complicated by massive intraoperative bleeding, and red blood cell (RBC) transfusions may be required. The storage duration or age of transfused RBCs has been shown to affect the morbidity and mortality of critically ill, trauma, and cardiac surgery patients. Here we investigate the effect of RBC age on the outcomes of liver transplant patients. Five hundred thirty-one patients underwent orthotopic liver transplantation between January 1, 2000 and August 15, 2010. The patient demographics, the Model for End-Stage Liver Disease-sodium (MELD-Na) score, and the number and age of RBC units were evaluated with univariate and multivariate models of outcomes, which included mortality rates 2 years after transplantation, postoperative infections, and organ rejection. In a univariate analysis, the number of RBC units (but not the RBC age) was associated with increased 2-year mortality, an increased risk of infection, and a decreased risk of organ rejection. Only the number of RBC units was associated with increased 2-year mortality in a multivariate Cox regression model. The mortality risk was decreased by two-thirds for patients who received <10 U of RBCs versus those who received ≥10 U (hazard ratio = 0.33, 95% confidence interval = 0.16-0.69, P = 0.003). The number of transfused RBC units was not associated with the risk of infection or organ rejection in a multivariate logistic regression model. In conclusion, the RBC age is not associated with infection, organ rejection, or death in liver transplant patients. Patients who receive more blood have an increased risk of death. In a multivariate model, the MELD-Na score was not associated with increased mortality, and this is consistent with previous studies demonstrating that the MELD-Na score is a poor predictor of long-term survival after transplantation.     

The association between duration of storage of transfused red blood cells and morbidity and mortality after reoperative cardiac surgery

Red blood cells (RBCs) undergo numerous changes during storage; however, the clinical relevance of these storage "lesions" is unclear. We hypothesized that the duration of storage of transfused RBCs is associated with mortality after repeat sternotomy for cardiac surgery, because these patients are at high risk for both RBC transfusion and adverse outcome. We retrospectively analyzed 434 patients who underwent repeat median sternotomy for coronary artery bypass graft or valve surgery and who received allogeneic RBCs. Three-hundred-twenty-one (74%) patients met the criteria for eligibility. After adjusting for the effects of confounders and the total number of RBC transfusions, the duration of storage of the oldest RBC unit transfused was found to be associated with both in-hospital mortality (Cox proportional hazard ratio (HR) = 1.151; P < 0.0001) and out-of-hospital mortality (HR = 1.116; P < 0.0001). The mean duration of storage of transfused RBCs was also an independent predictor of in-hospital mortality (HR = 1.036; P < 0.0001). Independent associations between the duration of storage of transfused RBCs and acute renal dysfunction and intensive care unit and hospital length of stay were also observed. The duration of storage of RBCs is associated with adverse outcome after repeat sternotomy for cardiac surgery. The clinical significance of this finding should be investigated in a large, randomized, blinded clinical trial.     

Determination of autofluorescence of red blood cells (RbCs) in uremic patients as a marker of oxidative damage

AIM: It is suggested that the red blood cells (RBCs) of uremic patients have increased oxidative damage. The activities of different antioxidant enzymes and the levels of several antioxidants or lipid peroxidation products in RBCs are usually determined to estimate the oxidative stress in uremia. The autofluorescence of RBCs as measured by flow cytometry is caused by the formation of conjugated Schiff base compounds from aldehydes derived from lipid peroxidation and amino groups of phospholipids or cell proteins, and has been proposed as a marker of oxidative stress. The aim of this study was to evaluate if this method is suitable for estimation of oxidative stress in the RBCs of patients with different degrees of renal insufficiency. PATIENTS AND METHODS: To determine the oxidative damage in RBCs in uremia, the autofluorescence of RBCs was measured by flow cytometry in the following 3 groups of patients: group A: 16 patients with chronic renal failure (CRF); group B: 16 hemodialysis (HD) patients; group C: 16 patients with a well-functioning renal allograft. Twenty-four healthy volunteers served as controls. The basal value of RBC autofluorescence and the autofluorescence of RBCs after oxidative damage by treatment with 0.1 mM hydrogen peroxide (H2O2)/0.7 mM sodium azide were determined. RESULTS: In basal RBC autofluorescence values, no differences were found between the 3 groups and the controls. However, there was a significant correlation between the increase of serum creatinine and RBC autofluorescence in the group of patients with CRF (r = 0.521; p = 0.038). After H2O2 treatment, the RBC autofluorescence rose markedly in all individuals. This increase in RBC autofluorescence was significantly higher in the patients with CRF (p = 0.003) and in the HD patients (p = 0.001) compared to the controls. In contrast, there was no difference in RBC autofluorescence between the patients with renal allograft and the controls after H2O2 treatment. CONCLUSIONS: In conclusion, flow cytometry is a useful tool for determining oxidative damage in RBCs. The RBCs of uremic patients are more susceptible to oxidative damage induced by H2O2, likely caused by diminished antioxidant defense in the RBC membrane. Successful renal transplantation leads to a normal autofluorescence response in the RBCs after H2O2 treatment.     

Immunologic profiles of red blood cells using in vitro models of transfusion

Background

Transfusion of packed red blood cells (RBCs) produces a myriad of immunologic derangements, from suppressive to stimulatory. Proliferation of human T cells is suppressed in vitro after exposure to processed red blood cells (PRBCs). We hypothesized that this effect would be mitigated by using fresh RBCs. We also hypothesized that this suppressive effect was a generalized effect on lymphocyte proliferation and would be observed in both CD4+ and CD8+ T-cell subpopulations as well as B cells.

Materials and methods

We isolated human T cells from donor peripheral blood mononuclear cells and exposed them to either blood bank PRBCs or fresh RBCs from volunteer donors and stimulated them with anti-CD3/anti-CD28. Human B cells were stimulated with lipopolysaccharide and exposed to PRBCs or fresh RBCs. We measured proliferation of B cells by thymidine incorporation assays. We also treated RBCs with citrate-phosphate-dextrose (CPD) at different time points before culture them with stimulated T cells to determine the role of this common RBC storage solution in lymphocyte proliferation.

Results

In vitro proliferation of CD4+ and CD8+ T cells was suppressed by blood bank RBCs. This suppression is eliminated when fresh RBCs were used. The B cells showed inhibition of proliferation when exposed to similar conditions, which appeared to be consistent over serial dilutions. Fresh RBCs exposed to CPD did not appear suppressive in the first 6 h after exposure.

Conclusions

T-cell and B-cell proliferation inhibition by blood banked RBCs suggests a generalized effect of RBCs on cellular proliferation. The lack of suppression by fresh RBCs further suggests that something involved in blood banking alters RBC properties such that they attain a suppressive phenotype. One such blood banking component, CPD, does not appear to affect this suppressive phenotype within the first 6 h.     

Blood Utilization After Primary Total Joint Arthroplasty in a Large Hospital Network

Background

Since a study in orthopedic hip fracture patients demonstrated that a liberal hemoglobin (Hb) threshold does not improve patient morbidity and mortality relative to a restrictive Hb threshold, the standard of care in total joint arthroplasty (TJA) should be examined to understand the variability of red blood cell (RBC) transfusion following TJA.

Questions/purposes

The study aimed to answer the following questions: (1) What is the blood utilization rate after primary TJA for individual surgeons within a large hospital network? (2) What is the comparison of hospital charges, length of stay (LOS), and discharge locations among TJA patients who were and were not transfused?

Methods

A retrospective study was conducted on 3,750 primary total knee arthroplasties (TKAs) and 2,070 primary total hip arthroplasties (THAs), and data was retrospectively collected over a 15-month period on the number of RBCs transfused per patient, along with demographic and cost details. The number of patients who received at least 1 RBC unit and the number of RBCs transfused per patient was calculated and stratified by surgeon.

Results

In the postoperative period, 19.3% TKA patients and 38.5% THA patients received a RBC transfusion. Transfusion rates following TJA varied widely between surgeons (TKA 4.8–63.8%, THA 4.3–86.8%). Transfused TKA patients received an average of 1.65 ± 0.03 RBCs, and THA patients received an average of 1.97 ± 0.14 RBCs. LOS and hospital charges for blood transfusion patients were higher than nontransfused patients.

Conclusion

Blood utilization after primary TJA varies greatly among surgeons, suggesting that resources may be misallocated. These findings highlight the need to standardize RBC transfusion practice following TJA.

Electronic supplementary material

The online version of this article (doi:10.1007/s11420-013-9327-y) contains supplementary material, which is available to authorized users.     

Determination of eicosanoid and cytokine production in salvaged blood, stored red blood cell concentrates, and whole blood

STUDY OBJECTIVE: To determine the production of the eicosanoids prostaglandin 2 (PGE2) and thromboxane 2 (TxB2) and the cytokines interleukin 1 beta (IL-1-beta) and interleukin 6 (IL-6) in whole blood (WB), unfiltered red blood cell (RBC), and filtered RBC concentrates, and salvaged blood. DESIGN: Prospective study. SETTING: University hospital of Erlangen. PATIENTS: 32 healthy volunteers and 14 ASA physical status I, II, and III radical prostatectomy patients (mean age 65 yrs). INTERVENTIONS: Sixteen WB units and 16 RBC units (divided into 16 filtered and unfiltered units each) were taken from 32 volunteers. Fourteen salvaged RBC units were obtained from the 14 radical prostatectomy patients. Sixteen WB units were stored for 35 days. From the 16 WB donations, RBC concentrates (PAGGS-M) were prepared. The RBC concentrates were halved, one half had its leukocytes removed at day 0; both halves were stored for 49 days. Salvaged blood (n = 14) was stored up to 2 hours during surgery and then retransfused. MEASUREMENTS AND MAIN RESULTS: Immediately at the start of the study, in all blood units (WB, RBC filtered, and RBC unfiltered units) at days 0 and 21, and at the end of the storage period (WB: 35 days, RBC concentrates: 49 days) and in the salvaged RBC units, the following parameters were measured: PGE2, TxB2, IL-1-beta, IL-6, hematocrit, platelet number, leukocytes, blood volume, and hemoglobin. During storage, different levels of PGE2, TxB2, IL-1-beta, IL-6 for WB, filtered RBC concentrates, and unfiltered RBCs were found. The higher levels of PGE2, TxB2, IL-1-beta, and IL-6 were found in the WB and RBC salvaged units than the filtered RBCs or unfiltered RBC units. There was no statistically significant difference between WB and salvaged RBCs. Higher levels of leukocytes and platelets were found in WB units and salvaged RBCs as compared to filtered or unfiltered RBCs. CONCLUSIONS: The eicosanoid and cytokine levels in the salvaged, filtered RBC, unfiltered RBC, and WB units stayed within physiological limits, suggesting that these levels do not contribute to the risk of nonhemolytic, immunomodulated transfusion reactions, even in massive transfusions.     

Benefits and risks of red blood cell transfusion in pediatric patients undergoing cardiac surgery

As the number of neonates and young infants undergoing cardiac surgery requiring cardiopulmonary bypass (CPB) increases, red blood cell (RBC) transfusion will continue to be an integral part of the practice of pediatric cardiac anesthesiology. The decision of when to transfuse RBCs to these patients is complex and influenced by multiple factors such as size, presence of cyanotic heart disease, complexity of the surgical procedure, and the hemostatic alterations induced by CPB. The known benefits of RBC transfusion include an increase in the oxygen-carrying capacity of blood, improved tissue oxygenation, and improved hemostasis. Unfortunately, there is no minimum hemoglobin level that serves as a transfusion trigger for all pediatric patients undergoing cardiac surgery. Physiologic signs such as tachycardia, hypotension, low mixed venous oxygen saturation and increased oxygen extraction ratios can provide objective evidence of the need to augment a given hemoglobin level. Nevertheless, the benefits of RBC transfusion must be balanced against its risks and, in recent years, RBC transfusion has been subjected to intense scrutiny. The adverse consequences of RBC transfusion include the transmission of infectious diseases and immune-mediated and nonimmune-mediated complications. Advances in donor selection, infectious disease testing of donated blood, use of leukocyte reduction and irradiation of blood in defined situations have improved the safety of the blood supply in terms of infection transmission. However, a growing number of prospective randomized clinical trials are finding an association between RBC transfusion and an increased risk of morbidity and mortality even with the use of leuko-reduced blood. Thus, it is becoming increasingly important that the decision to transfuse RBCs be made with a thorough understanding of the benefit-to-risk ratio. This review addresses the benefits and risks of RBC transfusion, pertinent data acquired in the setting of congenital cardiac surgery and techniques designed to minimize the need for RBC transfusion.     

Influence of storage on red blood cell rheological properties.

BACKGROUND: It is known that the age of transfused blood is a risk factor for the development of multiple organ failure in surgical patients. However, the character of hemorrheological changes in stored blood as well as the time when they appear remains disputable. We assumed that blood storage was accompanied by a progressive decrease of RBC deformability and rheological disorders. The degree of rheological disturbances should be directly proportional to the number of RBC with altered geometry. MATERIALS AND METHODS: Nine packages of RBC kept in adenine saline solution were examined from the 5th to the 42nd day of storage. RBC deformability index (DI) was determined by micropore filtration technique. RBC shape was estimated by means of scanning electron microscopy. Blood clotting time was measured by Sonoclot coagulation analyzer. RESULTS: Significant alterations of RBC shape started at the second week of storage and progressed during the rest of the storage period. RBC shape changes were accompanied by progressive decrease in DI and increase in hemolysis and acidosis. The correlation index between the percentage of abnormally shaped RBC and DI was -0.81 (P = 0.0258). Blood clotting progressively decreased after 2 weeks of storage, probably due to the exhaustion of some procoagulant plasma factors. CONCLUSIONS: Serious hemorrheological disorders, including the decrease in RBC deformability secondary to shape abnormalities, acidosis, and the decrease of blood clotting, start already at the second week of storage and progress up to the end of the storage period. Transfusion of packed RBC older than 7 days may contribute to hemorrheological disorders in critically ill patients.     

Red blood cell age, pyruvate kinase activity, and insulin receptors. Evidence that monocytes and RBCs may behave differently

Data emerging from insulin receptor studies performed on red blood cells (RBCs) and monocytes from the same subject are not always in agreement; dichotomy might occur since variations in mean RBC age are not taken into account or because insulin receptors on the two cell types behave differently. In the present investigation RBCs from normal male subjects were separated into five populations of different mean age by means of centrifugation of RBCs on a discontinuous gradient of buffered Percoll for 10 min at 1000 X g. Insulin binding varied significantly depending upon the RBC population tested and was closely correlated to the activity of pyruvate kinase (r2 = 0.86), a well-known marker of RBC age. These data suggested that pyruvate kinase assay might be helpful in studies of RBCs. To confirm this hypothesis, RBCs from 10 normal male subjects and 13 male patients with hemolytic anemia were studied; insulin binding was correlated to pyruvate kinase activity. By adjusting insulin binding to 2 X 10(9) RBCs/ml the range of data was abnormally high, but it became acceptable after adjusting insulin binding to pyruvate kinase activity (0.75 U/2 X 10(9) RBCs). The overall data indicated that insulin binding was highly correlated to pyruvate kinase activity (r2 = 0.82) but only slightly to reticulocyte number (r2 = 0.56) since not only reticulocytes but also erythrocytes lose receptors during maturation. Pyruvate kinase activity was measured in RBCs from normal men and from normally menstruating women at the seventh and twenty-fourth days of the cycle; results demonstrated that adjustment of data, according to mean RBC age, broadens dichotomy of monocyte and RBC data.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of vitamin E-bonded dialyzer membrane on red blood cell survival in hemodialyzed patients

Reduced red blood cell (RBC) survival due to oxidative damage is one of the causes of anemia in patients under long-term hemodialysis. Recently, it has been shown that vitamin E-bonded dialyzer membrane is able to reduce the oxidative stress during hemodialysis. In humans, creatine content in RBC is used to measure RBC life span and erythropoietic capacity, since it rapidly declines as the RBCs become old. Therefore this study aimed to elucidate the effect of vitamin E-bonded dialyzer membrane on RBC life span by measuring creatine content in RBC.     

A Red Blood Cell Model to Estimate the Hemolysis Fingerprint of Cardiovascular Devices

One of the most relevant and open issues within cardiovascular prosthetic hemodynamic performance is a realistic quantification of the damage sustained by red blood cells (RBCs). Specifically, the optimal design of bileaflet mechanical heart valves (BMHVs) requires both low shear stresses along the leaflets and short particle resident times. This study approaches RBC damage estimation by developing a numerical model of RBCs and computing the damage sustained by a set of passive RBCs immersed within in vitro flows. The RBC is modeled as an ellipsoidal shell with size dependent on age. Mechanically, a viscous hyper‐elastic model was adopted to compute the stress‐deformation transmitted by the experimental flow field to the RBC layer. The rupture parameters were calibrated using experimental results on real RBCs submitted to Couette flow. Moreover, the integrated hemolysis index (HI) through a BMHV was computed for a set of RBCs injected in a flow field derived from an in vitro study and for multiple RBC passages. The main results are (1) a good capability of the RBC model to replicate in vitro experiments performed with real RBCs, finding realistic rupture parameters; (2) the spatial distribution for the HI, maximal along the leaflet boundary layer and for long resident times; (3) 90% of HI is produced by the less damaging trajectories, which are favored by local flow dynamics; (4) cumulated HI in 8 days is about 0.01% smaller than the clinical warning threshold, the latter being obtained only after a period of time comparable with the RBC lifetime.     

Determination of erythrocyte antioxidant capacity in haemodialysis patients using electron paramagnetic resonance.

BACKGROUND: The increased oxidative stress of uraemia is caused both by an increased generation of oxygen-free radicals and a decrease of antioxidative forces. There are, however, conflicting data concerning disturbances of the radical-scavenging power of red blood cells (RBCs) in uraemic patients. METHODS: The antioxidant capacities of the RBCs of 10 haemodialysis (HD) patients and 10 controls were examined after treatment with 0.324 mM tert-butylhydroperoxide (t-BOOH) in phosphate-buffered saline at 37 degrees C using electron paramagnetic resonance (EPR) with 5,5-dimethylpyrroline-N-oxide (DMPO) as a spin trap and glutathione (GSH) regeneration as an indicator of hexose monophosphate shunt (HMPS) activity. EPR investigations were also done after pre-incubation with N-ethylmaleimide (NEM) to inhibit the GSH system. Furthermore, we determined the RBC redox state in 15 HD patients and 15 controls. RESULTS: There was no difference between HD patients and controls in the elimination of t-BOOH-generated free radicals in the RBCs. A more than 20-fold increase in radical concentration was observed after GSH trapping with NEM. In this case, we found a delayed decrease of the relative radical concentration in HD patients compared with controls with a significant difference after 7 min (2.2+/-0.26 vs 1.60+/-0.21; P=0.005) and after 10 min (1.82+/-0.41 vs 0.83+/-0.44; P=0.001). GSH regeneration via HMPS did not differ between the RBCs of HD patients (99.5+/-13.5 nmol/min x ml RBC) and those of the controls (94.2+/-16.9 nmol/min x ml RBC). There were no differences in the RBC concentrations of GSH, GSSG, NADP, NADPH, and in the GSH/GSSG and NADP/NADPH ratios between HD patients and controls. CONCLUSIONS: These data suggest a strong antioxidant potential in the GSH system of erythrocytes without any evidence of a disturbance in HD patients. The HMPS pathway also appears not to be impaired in the RBCs of HD patients. However, the slower radical elimination in the RBCs of HD patients after inhibition of GSH-depending radical scavengers as compared with controls indicates a defect in the antioxidant forces outside the GSH system, and could be one reason for the reduced lifespan of RBCs in HD patients.     

Plasma from aged stored red blood cells delays neutrophil apoptosis and primes for cytotoxicity: abrogation by poststorage washing but not prestorage leukoreduction

BACKGROUND: Blood transfusion-particularly that of older stored red blood cells (RBCs)--is an independent risk factor for postinjury multiple organ failure. Immunomodulatory effects of RBC transfusion include neutrophil (PMN) priming for cytotoxicity, an effect exacerbated by longer RBC storage times. We have found that delayed PMN apoptosis in trauma patients is provoked by transfusion, independent of injury severity. We hypothesized that aged stored RBCs delay PMN apoptosis, but that prestorage leukodepletion or poststorage washing could abrogate the effect. METHODS: Healthy volunteers each donated 1 unit of blood. One half was leukodepleted, and RBC units were processed in the usual fashion and stored at 4 degrees C. Aliquots were removed on days 1, 14, 21, and 42 and the plasma fraction isolated. Selected aliquots were washed with normal saline before plasma isolation. PMNs harvested from healthy controls were incubated (5% CO2, 37 degrees C) with unmodified, leukoreduced, or washed RBC plasma (20% plasma/80% RPMI 1640), and apoptosis assessed by morphology after 24 hours. Apoptotic index (apoptotic PMNs/total PMNs) was compared. PMN priming for superoxide release was also assessed after plasma exposure. RESULTS: PMN apoptosis was delayed by RBCs stored for 21 or 42 days. Prestorage leukodepletion did not alter the effect. However, washing 42-day-old RBCs abrogated the effect. PMN priming for superoxide was provoked by stored packed RBCs in an identical pattern to delayed apoptosis. CONCLUSION: Plasma from stored RBCs-even if leukoreduced-delays apoptosis and primes PMNs. The effect becomes evident at 21 days and worsens through product outdate (42 days), but may be prevented by poststorage washing. Inflammatory agents contaminating stored blood likely mediate the effect. Modification of transfusion practices (e.g., giving fresher or washed RBCs or blood substitutes) may attenuate adverse immunomodulatory effects of transfusion in trauma patients.     

An unusual haemolytic reaction following plasma transfusions

Plasma transfusions in a patient with severe burn injuries transiently neutralized Lewis blood group antibodies and obscured the serological incompatibility of a unit of red blood cell (RBC) concentrate. An acute haemolytic reaction occurred 6 days later when the RBCs were transfused. The case illustrates an unusual complication of plasma therapy which may be prevented by repeating compatibility tests with fresh blood specimens in patients receiving multiple transfusion of plasma, as well as RBCs.     

Hyperglycemia in the intensive care unit: no longer just a marker of illness severity

BACKGROUND: Hyperglycemia is a common occurrence in critically ill patients. Recent evidence has demonstrated improved survival in patients in surgical intensive care units (SICUs) receiving "tight glycemic control." The mechanisms of this survival advantage are not well understood. METHODS: A review of the English language literature pertaining to potential mechanisms affecting outcome in critically ill patients receiving insulin therapy, including recently published human trials evaluating mortality outcomes. RESULTS: This review discusses the results of clinical trials of "tight glycemic control," considers mechanisms of hyperglycemia in critical illness, and reviews potential mechanisms of improved outcome related in the critically ill patient. CONCLUSIONS: A number of human studies have demonstrated improved outcomes in critically ill patient populations receiving insulin therapy with a target of euglycemia, suggesting at least part of the benefit of this therapy is normal blood sugar and not the effects of insulin. An important population not studied to date is patients in the medical ICU. However, aggressive control of hyperglycemia now remains an important component of care for all surgical patients in the ICU.     

Numerical investigation of the effect of blade geometry on blood trauma in a centrifugal blood pump

Fluid dynamic forces in centrifugal blood pump impellers are of key importance in destruction of red blood cells (RBCs) because high rotational speed leads to strong interaction between the impeller and the RBCs. In this paper, three-dimensional models of five different blade geometries are investigated numerically using the commercial software CFX-TASCflow, and the streaklines of RBCs are obtained using the Lagrangian particle tracking method. In reality, RBCs pass through the pump along complicated paths resulting in a highly irregular loading condition for each RBC. In order to enable the prediction of blood damage under the action of these complex-loading conditions, a cumulative damage model for RBCs was adopted in this paper. The numerically simulated percent hemoglobin (%HB) released as RBCs traversed the impeller and volute was examined. It was observed that the residence time of particles in the blade passage is a critical factor in determining hemolytic effects. This, in turn, is a function of the blade geometry. In addition, it was observed that the volute profile is an important influence on the computed HB% released.     

Blood transfusion and increased risk for vasospasm and poor outcome after subarachnoid hemorrhage

OBJECT: Nitric oxide (NO) metabolism may influence vasospasm after subarachnoid hemorrhage (SAH). It has been demonstrated in recent studies that erythrocytes carry NO for release in vessels, whereas transfused erythrocytes may lack stored NO. Several converging lines of evidence also indicate that blood transfusion may exacerbate poor outcomes in some critically ill patients. In this study the authors hypothesized that patients with SAH who received red blood cell (RBC) transfusions were at greater risk for vasospasm and poor outcome. METHODS: The authors retrospectively reviewed a prospective observational database, including hospital records, computerized tomography (CT) scans, and pre- and postoperative four-vessel angiograms, in which the management methods used in 441 patients undergoing surgery for ruptured cerebral aneurysms were described. Two hundred seventy patients (61.2%) received an RBC transfusion during their hospital stay. After adjustment for Hunt and Hess grade, SAH grade on CT scans, delay between rupture and surgery, smoking status, and intraoperative aneurysm rupture, a worse outcome was more likely in patients who received intraoperative blood (odds ratio [OR] 2.44, confidence interval [CI] 1.32-4.52; 120 patients). Intraoperative RBC transfusion did not influence subsequent angiographically confirmed vasospasm (OR 0.92, CI 0.6-1.4). Worse outcome was observed in patients who received blood postoperatively (OR 1.81, CI 1.21-2.7), but not after adjustments were made for confounding variables (OR 1.48, CI 0.83-2.63). Angiographic vasospasm was observed in 217 patients and, after adjusting for confounding variables, was more frequent among patients who received postoperative RBC transfusion (OR 1.68, CI 1.02-2.75). Among patients in whom angiographically confirmed vasospasm developed there was a tendency to have received more blood than in those with no vasospasm; however, a clear dose-dependent response was not observed. CONCLUSIONS: Development of angiographically confirmed vasospasm after SAH is associated with postoperative RBC transfusion and worse outcome is associated with intraoperative RBC transfusion. Before blood is transfused, patients with SAH should be carefully assessed to determine if they are symptomatic because of anemia.     

Anemia and blood transfusion in trauma patients admitted to the intensive care unit

BACKGROUND: Anemia is a common occurrence in the intensive care unit (ICU). Although resuscitation, including the use of blood, is a mainstay of early treatment of trauma victims, the safety and efficacy of red blood cell (RBC) transfusion has come under scrutiny recently. The issue of blood use in critically injured patients requires evaluation. METHODS: This was a post hoc analysis of a subset of trauma patients (> or =18 years in age) from a prospective, multicenter, observational, cohort study in the United States. Patients were enrolled within 48 hours after ICU admission and followed for up to 30 days, or until hospital discharge or death. RESULTS: Five hundred seventy-six patients from 111 ICUs in 100 hospitals were enrolled between August 2000 and April 2001. At baseline, mean age was 44.1 +/- 20.2 years, 73.6% were men, and mean APACHE II score was 16.9 +/- 8.2. Mean baseline hemoglobin was 11.1 +/- 2.4 g/dL and patients remained anemic throughout the study either with or without transfusion; 55.4% of patients were transfused (mean, 5.8 +/- 5.5 units) during the ICU stay and 43.8% of patients had an ICU length of stay > or = 7 days. Mean pretransfusion hemoglobin was 8.9 +/- 1.8 g/dL. Mean age of RBCs transfused was 20.1 +/- 11.4 days. As compared with the full study population, patients in the trauma subset were more likely to be transfused and received an average of 1 additional unit of blood. CONCLUSION: Anemia is common in critically injured trauma patients and persists throughout the duration of critical illness. These patients receive a large number of RBC transfusions during their ICU course with aged blood.     

Minor antigens on transfused RBCs crossprime CD8 T cells but do not induce full effector function

HLA-matched bone marrow transplantation (BMT) is a cure for nonmalignant hematological disorders; however, rejection rates are high and correlate with the number of antecedent transfusions. Recently, using murine models, we reported that minor antigens (mHAs) in transfused leukoreduced red blood cell (RBC) or platelet units induce rejection of subsequent BMT. To study RBCs as an immunogen, we utilized transgenic donors that express a model mHA selectively on RBCs (HOD mouse). Transfusion of HOD blood did not induce BMT rejection of marrow that shared mHAs with the HOD RBCs. Similarly, no endogenous anti-HOD CD8(+) T-cell response was detected with antigen-specific tetramer reagents. Adoptively transferred OT-I T cells rapidly expanded after HOD blood transfusion; however, only a semi-effector phenotype was observed (tumor necrosis factor-α and interferon-γ secretion, but essentially no Granzyme B). After initial expansion, OT-I T cells contracted rapidly to very low levels. A similar trend was observed by in vivo CTL assay, with only transient lytic activity. Together, these data indicate that RBCs may not be the component of RBC units that induces BMT rejection, and suggest that contaminating platelets or leukocytes may be responsible.