Transfusing red blood cells stored in citrate phosphate dextrose adenine-1 for 28 days fails to improve tissue oxygenation in rats

Collection and administration of blood products in horses: Transfusion indications, materials, methods, complications, donor selection, and blood testing

BACKGROUND

Blood transfusion is a lifesaving treatment for horses with acute hemorrhage and other causes of anemia. Transfusions improve oxygen delivery to the tissues via increased blood volume and hemoglobin concentration. Certain aspects of equine blood transfusion are challenging, especially in the field situation, and practitioners may be unfamiliar or feel overwhelmed with the process. An understanding of the indications, materials, methods, and techniques as well as donor selection and possible complications will help practitioners successfully implement blood transfusion in clinical practice.

PROCEDURES

Blood transfusion involves several steps including appropriate donor selection, cross-matching, blood collection, and administration, as well as monitoring and handling of transfusion reactions. Guidance for each of these steps are detailed in this review.

SUMMARY

Blood transfusion is an effective and often lifesaving treatment for managing diseases of blood loss, hemolysis, and decreased RBC production. Equine practitioners require a thorough understanding of the indications for blood transfusion, the immunological principles behind compatibility testing and transfusion reactions, and the technical skills to aseptically collect and administer blood products KEY POINTS: Equine practitioners require a thorough understanding of the indications for blood transfusion, the immunological principles behind compatibility testing and transfusion reactions, and the technical skills to aseptically collect and administer blood products. Because there are over 400,000 possible equine RBC phenotypes, no universal donor exists, and some blood type incompatibilities are likely between any donor and recipient. Therefore, prior to any blood transfusion, donor and recipient blood should be cross-matched Inadequate delivery of oxygen (Do₂ ) to the tissues, resulting from low hemoglobin (Hb) concentration, is the most important indication for blood transfusion Neonatal isoerythrolysis most commonly occurs following an anamnestic response in late gestation; it rarely occurs following a primary exposure because the immune response is not strong enough to produce clinically significant alloantibody titers.

Restrictive vs. Liberal Red Blood Cell Transfusion Strategy in Patients With Acute Myocardial Infarction and Anemia: A Systematic Review and Meta-Analysis

Objective: Anemia is frequent in patients with acute myocardial infarction (AMI), and the optimal red blood cell transfusion strategy for AMI patients with anemia is still controversial. We aimed to compare the efficacy of restrictive and liberal red cell transfusion strategies in AMI patients with anemia.

Methods: We systematically searched PubMed, EMBASE, Web of Science, Cochrane Library, and Clinicaltrials.gov, from their inception until March 2021. Studies designed to compare the efficacy between restrictive and liberal red blood cell transfusion strategies in patients with AMI were included. The primary outcome was all-cause mortality, including overall mortality, in-hospital or follow-up mortality. Risk ratios (RR) with 95% confidence intervals (CI) were presented and pooled by random-effects models.

Results: The search yielded a total of 6,630 participants in six studies. A total of 2,008 patients received restrictive red blood cell transfusion while 4,622 patients were given liberal red blood cell transfusion. No difference was found in overall mortality and follow-up mortality between restrictive and liberal transfusion groups (RR = 1.07, 95% CI = 0.82–1.40, P = 0.62; RR = 0.89, 95% CI = 0.56–1.42, P = 0.62). However, restrictive transfusion tended to have a higher risk of in-hospital mortality compared with liberal transfusion (RR = 1.22, 95% CI = 1.00–1.50, P = 0.05). No secondary outcomes, including follow-up reinfarction, stroke, and acute heart failure, differed significantly between the two groups. In addition, subgroup analysis showed no differences in overall mortality between the two groups based on sample size and design.

Conclusion: Restrictive and liberal red blood cell transfusion have a similar effect on overall mortality and follow-up mortality in AMI patients with anemia. However, restrictive transfusion tended to have a higher risk of in-hospital mortality compared with liberal transfusion. The findings suggest that transfusion strategy should be further evaluated in future studies.

Improved survival in critically injured combat casualties treated with fresh whole blood by forward surgical teams in Afghanistan

BACKGROUND

The objective of this study was to assess transfusion strategies and outcomes, stratified by the combat mortality index, of casualties treated by small surgical teams in Afghanistan. Resuscitation that included warm fresh whole blood (FWB) was compared to blood component resuscitation.

STUDY DESIGN AND METHODS

Casualties treated by a Role 2 surgical team in Afghanistan from 2008 to 2014 who received 1 or more units of red blood cells (RBCs) or FWB were included. Patients were excluded if they had incomplete data or length of stay less than 30 minutes. Patients were separated into two groups: 1) received FWB and 2) did not receive FWB; moreover, both groups potentially received plasma, RBCs, and platelets. The analysis was stratified by critically versus noncritically injured patients using the prehospital combat mortality index. Kaplan-Meier plot, log-rank test, and multivariable Cox regression were performed to compare survival.

RESULTS

In FWB patients, median units of FWB and total blood product were 4.0 (interquartile range [IQR], 2.0-7.0) and 16.0 (IQR, 10.0-28.0), respectively. The Kaplan-Meier plot demonstrated that survival was similar between FWB (79.1%) and no-FWB (74.5%) groups (p = 0.46); after stratifying patients by the combat mortality index, the risk of mortality was increased in the no-FWB group (hazard ratio, 2.8; 95% confidence interval, 1.2-6.4) compared to the FWB cohort.

CONCLUSION

In forward-deployed environments, where component products are limited, FWB has logistical advantages and was associated with reduced mortality in casualties with a critical combat mortality index. Additional analysis is needed to determine if these effects of FWB are appreciable in all trauma patients or just in those with severe physiologic derangement.

Ferroportin inhibition attenuates plasma iron, oxidant stress, and renal injury following red blood cell transfusion in guinea pigs

BACKGROUND

Red blood cell (RBC) transfusions result in the sequestration and metabolism of storage-damaged RBCs within the spleen and liver. These events are followed by increased plasma iron concentrations that can contribute to oxidant stress and cellular injury. We hypothesized that administration of a ferroportin inhibitor (FPN-INH) immediately after acute RBC exchange transfusion could attenuate posttransfusion circulatory compartment iron exposure, by retaining iron in spleen and hepatic macrophages.

STUDY DESIGN AND METHODS

Donor guinea pig blood was leukoreduced, and RBCs were preserved at 4°C. Recipient guinea pigs (n = 5/group) were exchange transfused with donor RBCs after refrigerator preservation and dosed intravenously with a small-molecule FPN-INH. Groups included transfusion with vehicle (saline), 5 mg/kg or 25 mg/kg FPN-INH. A time course of RBC morphology, plasma non-transferrin-bound iron (NTBI) and plasma hemoglobin (Hb) were evaluated. End-study spleen, liver, and kidney organ iron levels, as well as renal tissue oxidation and injury, were measured acutely (24-hr after transfusion).

RESULTS

RBC transfusion increased plasma NTBI, with maximal concentrations occurring 8 hours after transfusion. Posttransfusion iron accumulation resulted in tubule oxidation and acute kidney injury. FPN inhibition increased spleen and liver parenchymal/macrophage iron accumulation, but attenuated plasma NTBI, and subsequent renal tissue oxidation/injury.

CONCLUSION

In situations of acute RBC transfusion, minimizing circulatory NTBI exposure by FPN inhibition may attenuate organ-specific adverse consequences of iron exposure.

Role of Nitric Oxide Carried by Hemoglobin in Cardiovascular Physiology: Developments on a Three-Gas Respiratory Cycle

A continuous supply of oxygen is essential for the survival of multicellular organisms. The understanding of how this supply is regulated in the microvasculature has evolved from viewing erythrocytes (red blood cells [RBCs]) as passive carriers of oxygen to recognizing the complex interplay between Hb (hemoglobin) and oxygen, carbon dioxide, and nitric oxide-the three-gas respiratory cycle-that insures adequate oxygen and nutrient delivery to meet local metabolic demand. In this context, it is blood flow and not blood oxygen content that is the main driver of tissue oxygenation by RBCs. Herein, we review the lines of experimentation that led to this understanding of RBC function; from the foundational understanding of allosteric regulation of oxygen binding in Hb in the stereochemical model of Perutz, to blood flow autoregulation (hypoxic vasodilation governing oxygen delivery) observed by Guyton, to current understanding that centers on S-nitrosylation of Hb (ie, S-nitrosohemoglobin; SNO-Hb) as a purveyor of oxygen-dependent vasodilatory activity. Notably, hypoxic vasodilation is recapitulated by native S-nitrosothiol (SNO)-replete RBCs and by SNO-Hb itself, whereby SNO is released from Hb and RBCs during deoxygenation, in proportion to the degree of Hb deoxygenation, to regulate vessels directly. In addition, we discuss how dysregulation of this system through genetic mutation in Hb or through disease is a common factor in oxygenation pathologies resulting from microcirculatory impairment, including sickle cell disease, ischemic heart disease, and heart failure. We then conclude by identifying potential therapeutic interventions to correct deficits in RBC-mediated vasodilation to improve oxygen delivery-steps toward effective microvasculature-targeted therapies. To the extent that diseases of the heart, lungs, and blood are associated with impaired tissue oxygenation, the development of new therapies based on the three-gas respiratory system have the potential to improve the well-being of millions of patients.

Intraoperativer Volumenersatz, Transfusion und Behandlung von Gerinnungsstörungen

Sowohl der operative Eingriff als auch die Narkose führen zu Veränderungen des intravasalen Volumenstatus des Patienten. Ziele der perioperativen Flüssigkeits- bzw. Volumentherapie sind die Aufrechterhaltung des zirkulierenden intravasalen Volumen (Normovolämie), einer adäquaten Gewebeperfusion und -oxygenierung, des Gleichgewichts im Elektrolythaushalt sowie die Aufrechterhaltung der Normoglykämie.

Hemolysis in In-Date RBC Concentrates

OBJECTIVES

Hemolysis is one of the most prominent changes that occur during the liquid storage of RBCs in additive solution (AS), but most studies have measured hemolysis only on day 42.

METHODS

Prestorage leukoreduced RBCs in AS-1 and AS-3 were studied, one group on day 42 and a second group between day 0 and day 40. Each product was sampled for direct measurement of supernatant hemoglobin and hematocrit.

RESULTS

Ninety day 42 and 218 day 7 to day 39 RBCs showed a mean ± SD supernatant hemoglobin of 75 ± 100 vs 25.5 ± 16 mg/dL respectively (P < .01). Supernatant hemoglobin correlated weakly with storage age (r = 0.2, P < .01) but more strongly with hematocrit (r = 0.4, P < .01).

CONCLUSIONS

There are minimal differences in supernatant hemoglobin until the final days of liquid storage when some high hematocrit RBCs show excessive hemolysis.

Critical Care Medicine: Major Changes in Dogma of the Past Decade

Critical care medicine is a young specialty that has experienced an expansion of research efforts in the last decade. Many physiologic and therapeutic principles or “dogmas” have been challenged, resulting in major “shifts” and minor “drifts” in thinking. This article reviews the available literature about some of these important and sometimes controversial changes, with emphasis on the practical implications of the concepts. Specific areas discussed include supply-dependent oxygen consumption in critical illness, manipulation of the cytokine cascade in sepsis, ventilation in the acute respiratory distress syndrome (ARDS), blood transfusion in the critically ill, the concept of the multiple organ dysfunction syndrome (MODS), the need for nutritional support in the critically ill, and others. Many of the changes discussed involve the recognition that the host response to a severe insult is exceedingly complex, and the understanding of this response and the effects of it at a tissue and cellular level are incomplete. As a result, the ability to impact the outcome of sepsis and MODS has thus far been disappointing, with the possible exception of “lung-protective” ventilation. The final challenge in critical care medicine is to gain information that will allow the practitioner to better understand, prevent, and treat the complex events that result in organ and cellular dysfunction. Future changes in dogma are welcome if they help achieve these goals.

Retrospective evaluation of the effect of red blood cell product age on occurrence of acute transfusion-related complications in dogs: 210 cases (2010-2012)

OBJECTIVE

To determine whether red blood cell (RBC) product age influences the occurrence of acute transfusion-related complications and mortality in dogs. The hypothesis was that acute transfusion-related complications and mortality would increase with age of product.

DESIGN

Retrospective study (2010-2012).

SETTING

University teaching hospital.

ANIMALS

Two hundred and ten clinical canine patients.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Medical records were reviewed for dogs receiving RBC-containing products. Patient signalment; reason for transfusion; product type, dose, age, and source; pretransfusion compatibility; rate, route, and method of administration; administration of multiple transfusions; underlying disease; occurrence of transfusion-related complications (eg, fever, hemolysis, gastrointestinal distress, cardiovascular, neurologic, and respiratory complications); various hematologic parameters; and survival were recorded. Data were analyzed for association between potential risk factors and occurrence of transfusion-related complications as well as between transfusion-related complications and survival. Of 333 transfusion events in 210 patients, 84 transfusion-related complications occurred. Fever was most common (41/333), followed by hemolysis (21/333). For every additional day of product age, the odds of hemolysis increased significantly (odds ratio, 1.11; 95% confidence interval, 1.06-1.16; P < 0.0001). Transfusion-related complications when considered as a whole were associated with higher dose of product, longer duration of administration per transfusion event, and immune-mediated disease, but not with source of product or general category of anemia. Administration rate was significantly slower in patients with febrile transfusion-related complications (P < 0.0001). Product age was not associated with increased mortality.

CONCLUSIONS

Age of stored RBC products is associated with increased risk of transfusion-related hemolysis, but not with fever. Prospective clinical studies evaluating the influence of storage duration on development of in vitro versus in vivo hemolysis are warranted.

Blood Transfusion Policy among European Pediatric Intensive Care Physicians

The objective of this study was to define current blood transfusion practices among European pediatric intensive care physicians treating critically ill children. A questionnaire of case scenarios was administered to members of the European Society of Pediatric and Neonatal Intensive Care (ESPNIC). Of the 258 members of the ESPNIC, 134 (51.9%) pediatric intensive care physicians completed the questionnaire. The suggested blood transfusion thresholds for case scenario 1 (post–orthopedic surgery child) ranged from <7.0 g/dl to 11 g/dl. A total of 57.3% suggested 7 g/dl, 33.6% suggested 8 g/dl, and 6.9% suggested 9 g/dl as a hemoglobin threshold for transfusion (mean, 7.54 ± 0.75). For case scenarios 2 to 4, the suggested hemoglobin thresholds were 7 g/dl to 12 g/dl. For case scenario 2 (a child with acute respiratory distress syndrome), 22.4% suggested 8 g/dl, 15.7% suggested 9 g/dl, and 41% suggested 10 g/dl as a hemoglobin threshold for transfusion (mean, 9.40 ± 1.27 g/dl). For case scenario 3 (a post–cardiac surgery infant), 20.1% suggested 7 g/dl, 24.6% suggested 8 g/dl, 21.6% suggested 9 g/dl, and 23.9% suggested 10 g/dl as a hemoglobin threshold for transfusion (mean, 8.72 ± 1.24 g/dl). For case scenario 4 (a child with septic shock), 23.1% suggested 8 g/dl, 16.4% suggested 9 g/dl, and 41% suggested 10 g/dl as a hemoglobin threshold for transfusion (mean, 9.45 ± 1.24 g/dl). The threshold for transfusion was not statistically different ( P> .05) between the physicians according to their subspecialty, years of experience, or country of origin. The suggested volume of transfused blood was 10 to 15 ml/kg in 427 responses (82.6%) and 20 ml/kg in 89 responses (17.2%). Most physicians, 78/128 (60.9%), did not consider the age of the transfused blood an important factor in their decision to transfuse. Of the 106 (79.1%) physicians who detailed their considerations for elevating the thresh- old for transfusion, 82 (77.3%) gave a general nonspecific indication, 47 (44.3%) stated hemodynamic instability and shock, and 40 (37.7%) an ongoing bleeding. The hemoglobin threshold for blood transfusion and transfusion volume varies among European pediatric intensive care physicians, for the same patient.

[The ABLE study: A randomized controlled trial on the efficacy of fresh red cell units to improve the outcome of transfused critically ill adults]

Red blood cell units are stored up to 42 days post-collection. The standard policy of blood banks is to deliver the oldest units in order to limit blood wastage. Many caregivers believe that giving fresh rather than old units can improve the outcome of their transfused patients. The ABLE study aims to check if the transfusion of red blood cell units stored seven days or less (fresh arm) improve the outcome of transfused critically ill adults compared to patients who received units delivered according to the standard delivery policy (control arm). From March 2009 to May 2014, 1211 patients were allocated to the fresh arm, 1219 to the control arm (length of storage: 6.1 ± 4.9 and 22.0 ± 8.4 days respectively, P<0.001). The primary outcome measure was 90-day all-cause mortality post-randomisation: there were 448 deaths (37.0%) in the fresh arm and 430 (35.3%) in the control arm (absolute risk difference: 1.7%; 95% confidence interval: -2.1% to 5.5%). In a survival analysis, the risk of death was higher in the fresh arm (hazard ratio: 1.1; 95%CI: 0.9 to 1.2), but the difference was not statistically significant (P=0.38). The same trend against the fresh arm was observed with all but one secondary outcome measures. The conclusion is that the transfusion of red blood cell units stored seven days or less does not improve the outcome of critically ill adults compared to the transfusion of units stored about three weeks (22.0 ± 8.4 days).

Red blood cell storage lesion

OBJECTIVE

To summarize current understanding of the mechanisms responsible for changes occurring during red blood cell (RBC) storage, collectively known as the storage lesion, and to review the biological and clinical consequences of increasing storage time of RBCs.

DATA SOURCES

Human and veterinary clinical studies, experimental animal model studies, and reviews of the RBC storage lesion with no date restrictions.

HUMAN DATA SYNTHESIS

Experimental studies have characterized the evolution of human RBC and supernatant changes that occur during storage and form the basis for concern about the potential for harm from long-term storage of RBCs. Although 4 randomized controlled trials of varying sizes failed to find an association between RBC storage time and negative clinical outcomes, a recent meta-analysis and numerous observational clinical studies have demonstrated that transfusion of old versus fresh stored RBCs is associated with an increased risk of morbidity and mortality, particularly among trauma victims and cardiac surgery patients. Potential clinical consequences of RBC transfusion following development of the storage lesion include risk of organ dysfunction, organ failure, infections, and death.

VETERINARY DATA SYNTHESIS

Experimental animal models have contributed to the evidence supporting adverse consequences of the RBC storage lesion. Studies on relevant RBC storage issues such as the effect of different preservative solutions and leukoreduction have been completed. Transfusion with RBCs stored for 42 days increases mortality in dogs with experimental sepsis.

CONCLUSION

Storage of RBCs induces progressive biochemical, biomechanical, and immunologic changes that affect red cell viability, deformability, oxygen carrying capacity, microcirculatory flow, and recipient response. Most reports in the human and veterinary literature support the concept that there are deleterious effects of the RBC storage lesion, but additional studies with improved experimental design are needed to identify compelling reasons to modify current blood banking and transfusion practices.

Transfusion strategy: impact of haemodynamics and the challenge of haemodilution

Blood transfusion is associated with increased morbidity and mortality and numerous reports have emphasised the need for reduction. Following this there is increased attention to the concept of patient blood management. However, bleeding is relatively common following cardiac surgery and is further enhanced by the continued antiplatelet therapy policy. Another important issue is that cardiopulmonary bypass leads to haemodilution and a potential blood loss. The basic role of blood is oxygen transport to the organs. The determining factors of oxygen delivery are cardiac output, haemoglobin, and saturation. If oxygen delivery/consumption is out of balance, the compensation mechanisms are simple, as a decrease in one factor results in an increase in one or two other factors. Patients with coexisting cardiac diseases may be of particular risk, but studies indicate that patients with coexisting cardiac diseases tolerate moderate anaemia and may even benefit from a restrictive transfusion regimen. Further it has been shown that patients with reduced left ventricular function are able to compensate with increased cardiac output in response to bleeding and haemodilution if normovolaemia is maintained. In conclusion the evidence supports that each institution establishes its own patient blood management strategy to both conserve blood products and maximise outcome.

The impact of two different transfusion strategies on patient immune response during major abdominal surgery: a preliminary report

Blood transfusion is associated with well-known risks. We investigated the difference between a restrictive versus a liberal transfusion strategy on the immune response, as expressed by the production of inflammatory mediators, in patients subjected to major abdominal surgery procedures. Fifty-eight patients undergoing major abdominal surgery were randomized preoperatively to either a restrictive transfusion protocol or a liberal transfusion protocol (with transfusion if hemoglobin dropped below 7.7 g dL(-1) or 9.9 g dL(-1), respectively). In a subgroup of 20 patients randomly selected from the original allocation groups, blood was sampled for measurement of IL-6, IL-10, and TNFα. Postoperative levels of IL-10 were higher in the liberal transfusion group on the first postoperative day (49.82 ± 29.07 vs. 15.83 ± 13.22 pg mL(-1), P < 0.05). Peak postoperative IL-10 levels correlated with the units of blood transfused as well as the mean duration of storage and the storage time of the oldest unit transfused (r(2) = 0.38, P = 0.032, r(2) = 0.52, P = 0.007, and r(2) = 0.68, P<0.001, respectively). IL-10 levels were elevated in patients with a more liberal red blood cell transfusion strategy. The strength of the association between anti-inflammatory IL-10 and transfusion variables indicates that IL-10 may be an important factor in transfusion-associated immunomodulation. This trial is registered under ClinicalTrials.gov Identifier: NCT02020525.

The deleterious effect of red blood cell storage on microvascular response to transfusion

BACKGROUND

The transfusion of relatively older red blood cells (RBCs) has been associated with both morbidity and mortality in trauma patients in observational studies. Although the mechanisms responsible for this phenomenon remain unclear, alterations in the microcirculation as a result of the transfusion of relatively older blood may be a causative factor. To assess this hypothesis, we evaluated microvascular perfusion in trauma patients during RBC transfusion.

METHODS

Anemic but otherwise stable trauma intensive care unit patients with orders for transfusion were identified. Thenar muscle tissue oxygen saturation (StO(2)) was measured continuously by near-infrared spectroscopy during the course of transfusion of one RBC unit. Sublingual microcirculation was observed by sidestream dark-field illumination microscopy before and after transfusion of one RBC unit. Thenar muscle StO(2) was recorded during the course of transfusion. Pretransfusion and posttransfusion perfused capillary vascular density (PCD) was determined by semiquantitative image analysis. Changes in StO(2) and PCD relative to age of RBC unit were evaluated using mixed models that adjusted for baseline StO(2) and Spearman correlation, respectively.

RESULTS

Overall, 93 patients were recruited for study participation, 69% were male, and average Injury Severity Score (ISS) was 26.4. The average pretransfusion hemoglobin was 7.5 mg/dL, and the average age of RBC unit transfused was 29.4 days. The average peritransfusion StO(2) was negatively associated with increasing RBC age (slope, -0.11; p = 0.0014). Change in PCD from pretransfusion to posttransfusion period was found to correlate negatively with RBC storage age (Spearman correlation, -0.27; p = 0.037).

CONCLUSION

The transfusion of relatively older RBC units was associated with a decline in both StO(2) and PCD. Collectively, these observations demonstrate that transfusions of older RBC units are associated with the inhibition of regional microvascular perfusion. In patients requiring multiple units of RBCs, alteration of the microcirculation by relatively older units could potentially contribute to adverse outcomes.

LEVEL OF EVIDENCE

Prognostic study, level III.

Effect of birth weight on the association between necrotising enterocolitis and red blood cell transfusions in <=1500 g infants

CONTEXT

Reports evaluating a possible association between necrotising enterocolitis (NEC) and blood transfusion have been predominantly case-control studies. As the possible associations of disease with any variable on which cases and controls have been matched cannot be explored, a cohort study would offer a solution to this problem.

OBJECTIVE

Our objective was to evaluate the association between exposure to a packed red blood cell (PRBC) transfusion and development of NEC in a cohort where biases of matching are omitted.

DESIGN

In a retrospective cohort, exposed infants were defined as those who received a transfusion and did not develop NEC or developed NEC within 48 h of the transfusion. All others were considered unexposed.

SETTING

A single regional perinatal centre in Memphis, Tennessee, USA.

PATIENTS

3060 ≤1500 g birth weights (BW) were included.

OUTCOME MEASURES

The relative risk of developing NEC after exposure to a PRBC transfusion was measured.

RESULTS

3060 infants were identified. 174 infants (5.7%) developed NEC; 116 of the 174 infants (67%) were exposed. NEC infants had a significantly lower BW (924 vs 1042 g) and required a longer stay on a ventilator (7 vs 2 days). Divided into groups, infants with BW ≤750 , 751-1000 , 1001-1250 g and 1251-1500 g (n=52, 51, 46 and 25, respectively) had a relative risk of 0.14, 0.46, 1.83 and 1.78 (p<0.01, 0.02, 0.07 and 0.17), respectively, to develop NEC after an exposure. Infants with longest ventilator days were also significantly less likely to develop NEC after an exposure; relative risk=0.11 (p<0.01).

CONCLUSIONS

Exposure to transfusions was less likely associated with NEC in ≤1000 g infants and remained a risk factor in 1001-1500 infants. BW has to be factored in any study evaluating the association between PRBC transfusions and NEC.

Effects of non-leukocyte-reduced and leukocyte-reduced packed red blood cell transfusions on oxygenation of rat spinotrapezius muscle

Leukoreduction of blood used for transfusion alleviates febrile transfusion reactions, graft versus host disease and alloimmunization to leukocyte antigen. However, the actual clinical benefit of leukoreduction in terms of microcirculatory tissue O2 delivery after packed red blood cell (pRBC) transfusion has not been investigated. As such, the aim of this study was to determine the effects of non-leukoreduced (NLR) and leukoreduced (LR) fresh pRBC transfusion on interstitial oxygenation in anesthetized male Sprague-Dawley rats. Interstitial fluid PO2 and arteriolar diameters in spinotrapezius muscle preparations were monitored before and after transfusion with NLR- or LR-pRBCs. The major findings were that (1) transfusion of NLR-pRBCs significantly decreased interstitial oxygenation whereas transfusion of LR-pRBCs did not, and (2) transfusion with LR-pRBCs elicited a substantially greater increase in arterial blood pressure (ABP) than did transfusion with NLR-pRBCs. These changes in PO2 and ABP were not associated with changes in the diameters of resistance arterioles in the spinotrapezius muscle. These data suggest that transfusion of fresh NLR-pRBCs may negatively affect tissue oxygenation via enhanced leukocyte influx and decreased O2 delivery. They also suggest that leukocytes diminish the capability of transfused pRBCs to increase cardiac output. As such, transfusion of LR-pRBCs may be less deleterious on tissue PO2 levels than NLR-pRBCs although a concomitantly greater increase in ABP may accompany transfusion of LR-pRBCs.

Microhemodynamic aberrations created by transfusion of stored blood

BACKGROUND

Human red blood cells (RBCs) can be stored for up to 42 days under controlled conditions. Physical and chemical changes occur during RBC storage, altering their function. This study links stored cell mechanical changes with hemodynamic functional alterations upon transfusion.

STUDY DESIGN AND METHODS

Mechanical properties of fresh and stored RBCs were evaluated in vitro. Their transfusion effects were evaluated in vivo using intravital microscopy of the rat's cremaster muscle preparation. Rats were hemodiluted to 30% hematocrit, to mimic an anemic state before transfusion, and then exchange-transfused with fresh or stored cells.

RESULTS

In vitro studies on rheology and oxygen affinity of stored cells confirmed previously published results. Storage was found to modify static and dynamic RBC mechanic behavior. After transfusion, systemic hemodynamics were similar for fresh and stored cells; however, microvascular hemodynamics were drastically affected by stored cells. Stored cells reduced blood flow and oxygen delivery. Additionally, the presence of stored cells in circulation affected cell-to-cell and cell-to-wall interactions and affected cell hydrodynamics. Stored cells disrupted the RBC cell-free layer and wall shear stress signals.

CONCLUSION

The reduced cell deformability due to RBC "storage lesions" caused pathologic changes in microvascular hemodynamics, endothelial cell mechanotransduction, and RBC dynamics. Thus, the mechanical changes of blood-banked cells can limit transfusion ability to achieve its intended goal.

Resuscitation with aged blood exacerbates liver injury in a hemorrhagic rat model

OBJECTIVE

Blood loss and transfusion are frequent among patients undergoing liver surgery. Concerns have been raised about the safety and efficacy of transfusing stored blood. The influence of transfusing fresh vs. stored blood on the liver has not been studied to date. We tested the hypothesis that transfusion of stored, but not fresh blood, adversely affects liver outcome in vivo following acute hemorrhage. Additionally, possible mechanisms linking adverse liver outcome with increased storage duration were evaluated.

DESIGN

Prospective, controlled, animal study.

SETTING

University research laboratory.

SUBJECTS

Adult male Sprague-Dawley rats

INTERVENTIONS

Anesthetized rats were randomized to control, hemorrhagic and shock group (acute bleeding; HSG), or hemorrhagic and blood resuscitation groups (BR) (with fresh blood [BR-d0], blood stored for 4 [BR-d4] or 7 [BR-d7] days, or packed RBCs stored for 7 days [packed RBC-d7]).

MEASUREMENTS AND MAIN RESULTS

Administration of blood or packed RBC stored for 7 days exacerbated liver injury as reflected by liver necrosis and enhanced apoptosis (p < 0.001). Functional MRI analysis of the liver demonstrated significant improvement in liver perfusion with fresh blood (% change in functional MRI signal intensity due to hyperoxia was 16% ± 3% in BR-d0 vs. 4% ± 3% in hemorrhagic group, p < 0.001) but not with stored blood (12% ± 2% and 9% ± 5% for BR-d4 and BR-d7, respectively). Analysis of stored blood showed reduction in RBC deformability at 7 days of storage, reflecting a five-fold increase in the number of undeformable cells.

CONCLUSION

Liver injury is exacerbated by the transfusion of stored blood, primarily due to the change in the rheological properties of RBC. This data call for clinical studies in patients undergoing liver resection or transplantation.

Decreased erythrocyte deformability after transfusion and the effects of erythrocyte storage duration

BACKGROUND

Erythrocyte cell membranes undergo morphologic changes during storage, but it is unclear whether these changes are reversible. We assessed erythrocyte cell membrane deformability in patients before and after transfusion to determine the effects of storage duration and whether changes in deformability are reversible after transfusion.

METHODS

Sixteen patients undergoing posterior spinal fusion surgery were studied. Erythrocyte deformability was compared between those who required moderate transfusion (≥ 5 units erythrocytes) and those who received minimal transfusion (0-4 units erythrocytes). Deformability was measured in samples drawn directly from the blood storage bags before transfusion and in samples drawn from patients before and after transfusion (over 3 postoperative days). In samples taken from the blood storage bags, we compared deformability of erythrocytes stored for a long duration (≥ 21 days), those stored for a shorter duration (<21 days), and cell-salvaged erythrocytes. Deformability was assessed quantitatively using the elongation index (EI) measured by ektacytometry, a method that determines the ability for the cell to elongate when exposed to shear stress.

RESULTS

Erythrocyte deformability was significantly decreased from the preoperative baseline in patients after moderate transfusion (EI decreased by 12% ± 4% to 20% ± 6%; P = 0.03) but not after minimal transfusion (EI decreased by 3% ± 1% to 4% ± 1%; P = 0.68). These changes did not reverse over 3 postoperative days. Deformability was significantly less in erythrocytes stored for ≥ 21 days (EI = 0.28 ± 0.02) than in those stored for <21 days (EI = 0.33 ± 0.02; P = 0.001) or those drawn from patients preoperatively (EI = 0.33 ± 0.02; P = 0.001). Cell-salvaged erythrocytes had intermediate deformability (EI = 0.30 ± 0.03) that was greater than that of erythrocytes stored ≥ 21 days (P = 0.047), but less than that of erythrocytes stored <21 days (P = 0.03).

CONCLUSIONS

The findings demonstrate that increased duration of erythrocyte storage is associated with decreased cell membrane deformability and that these changes are not readily reversible after transfusion.

The effects of non-leukoreduced red blood cell transfusions on microcirculation in mixed surgical patients

BACKGROUND

The impact of the storage process on oxygen-carrying properties of red blood cells and the efficacy of red blood cell (RBC) transfusions concerning tissue oxygenation remain an issue of debate in transfusion medicine. Storage time and leukocyte content probably interact since longer storage duration is thought to cause greater accumulation of leukocyte-derived cytokines and red blood cell injury.

OBJECTIVES

The aim of this study was to investigate the effects of storage and the efficacy of fresh (stored for less than 1 week) versus aged (stored for more than 3 weeks) non-leukoreduced RBC transfusions on sublingual microvascular density and flow in mixed surgical patients.

METHODS

Eighteen surgical patients were included in this study. Patients were randomly assigned into two groups receiving fresh (Group A) and aged (Group B) RBC transfusions. Sublingual microcirculatory functional capillary density (FCD) and microvascular flow index (MFI) were assessed using orthogonal polarization spectral (OPS) imaging. Measurements and collection of blood samples were performed after induction of general anesthesia, before RBC transfusion and 30 min after the RBC transfusion ended.

RESULTS

In both groups RBC transfusions caused an increase in hemoglobin concentration (p<0.001). RBC transfusions increased FCD in Group A (p<0.001), while FCD remained unaffected in Group B. Changes in MFI following RBC transfusion in both groups remained unaltered.

CONCLUSIONS

Fresh non-leukoreduced RBC transfusions but not RBCs stored for more than 3weeks, were effective in improving microciruculatory perfusion by elevating the number of perfused microvessels in mixed surgical patients.

Anemia and blood transfusions in critically ill patients

Anemia is common in critically ill patients. As a consequence packed red blood cell (PRBC) transfusions are frequent in the critically ill. Over the past two decades a growing body of literature has emerged, linking PRBC transfusion to infections, immunosuppression, organ dysfunction, and a higher mortality rate. However, despite growing evidence that risk of PRBC transfusion outweighs its benefit, significant numbers of critically ill patients still receive PRBC transfusion during their intensive care unit (ICU) stay. In this paper, we summarize the current literature concerning the impact of anemia on outcomes in critically ill patients and the potential complications of PRBC transfusions.

Effect of processing and storage on red blood cell function in vivo

Red blood cell (RBC) transfusion is indicated to improve oxygen delivery to tissue, and for no other purpose. We have come to appreciate that donor RBCs are fundamentally altered during processing and storage in a manner that both impairs oxygen transport efficacy and introduces additional risk by perturbing both immune and coagulation systems. The protean biophysical and physiological changes in RBC function arising from storage are termed the "storage lesion;" many have been understood for some time; for example, we know that the oxygen affinity of stored blood rises during the storage period and that intracellular allosteric regulators, notably 2,3-bisphosphoglyceric acid and ATP, are depleted during storage. Our appreciation of other storage lesion features has emerged with improved understanding of coagulation, immune, and vascular signaling systems. Here, we review key features of the "storage lesion." Additionally, we call particular attention to the newly appreciated role of RBCs in regulating linkage between regional blood flow and regional O(2) consumption by regulating the bioavailability of key vasoactive mediators in plasma, and discuss how processing and storage disturb this key signaling function and impair transfusion efficacy.

Coagulopathy and shock on admission is associated with mortality for children with traumatic injuries at combat support hospitals

OBJECTIVE

In adults, early traumatic coagulopathy and shock are both common and independently associated with mortality. There are little data regarding both the incidence and association of early coagulopathy and shock on outcomes in pediatric patients with traumatic injuries. Our objective was to determine whether coagulopathy and shock on admission are independently associated with mortality in children with traumatic injuries.

METHODS

A retrospective review of the Joint Theater Trauma Registry from U.S. combat support hospitals in Iraq and Afghanistan from 2002 to 2009 was performed. Coagulopathy was defined as an international normalized ratio of ≥1.5 and shock as a base deficit of ≥6. Laboratory values were measured on admission. Primary outcome was inhospital mortality. Univariate analyses were performed on all admission variables followed by reverse stepwise multivariate logistic regression to determine independent associations.

SETTING

Combat support hospitals in Iraq and Afghanistan.

PATIENTS

Patients <18 yrs of age with Injury Severity Score, international normalized ratio, base deficit, and inhospital mortality were included. Of 1998 in the cohort, 744 (37%) had a complete set of data for analysis.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

The incidence of early coagulopathy and shock were 27% and 38.3% and associated with mortality of 22% and 16.8%, respectively. After multivariate logistic regression, early coagulopathy had an odds ratio of 2.2 (95% confidence interval 1.1-4.5) and early shock had an odds ratio of 3.0 (95% confidence interval 1.2-7.5) for mortality. Patients with coagulopathy and shock had an odds ratio of 3.8 (95% confidence interval 2.0-7.4) for mortality.

CONCLUSIONS

In children with traumatic injuries treated at combat support hospitals, coagulopathy and shock on admission are common and independently associated with a high incidence of inhospital mortality. Future studies are needed to determine whether more rapid and accurate methods of measuring coagulopathy and shock as well as if early goal-directed treatment of these states can improve outcomes in children.

Hemoglobin-driven pathophysiology is an in vivo consequence of the red blood cell storage lesion that can be attenuated in guinea pigs by haptoglobin therapy

Massive transfusion of blood can lead to clinical complications, including multiorgan dysfunction and even death. Such severe clinical outcomes have been associated with longer red blood cell (rbc) storage times. Collectively referred to as the rbc storage lesion, rbc storage results in multiple biochemical changes that impact intracellular processes as well as membrane and cytoskeletal properties, resulting in cellular injury in vitro. However, how the rbc storage lesion triggers pathophysiology in vivo remains poorly defined. In this study, we developed a guinea pig transfusion model with blood stored under standard blood banking conditions for 2 (new), 21 (intermediate), or 28 days (old blood). Transfusion with old but not new blood led to intravascular hemolysis, acute hypertension, vascular injury, and kidney dysfunction associated with pathophysiology driven by hemoglobin (Hb). These adverse effects were dramatically attenuated when the high-affinity Hb scavenger haptoglobin (Hp) was administered at the time of transfusion with old blood. Pathologies observed after transfusion with old blood, together with the favorable response to Hp supplementation, allowed us to define the in vivo consequences of the rbc storage lesion as storage-related posttransfusion hemolysis producing Hb-driven pathophysiology. Hb sequestration by Hp might therefore be a therapeutic modality for enhancing transfusion safety in severely ill or massively transfused patients.

Intraoperativer Volumenersatz, Transfusion und Behandlung von Gerinnungsstörungen

Sowohl der operative Eingriff als auch die Narkose führen zu Veränderungen des intravasalen Volumenstatus des Patienten.

The effect of red blood cell transfusion on tissue oxygenation and microcirculation in severe septic patients

BACKGROUND

Microcirculation plays a vital role in the development of multiple organ failure in severe sepsis. The effects of red blood cell (RBC) transfusions on these tissue oxygenation and microcirculation variables in early severe sepsis are not well defined.

METHODS

This is a prospective, observational study of patients with severe sepsis requiring RBC transfusions of one to two units of non-leukoreduced RBCs for a hemoglobin < 7.0, or for a hemoglobin between 7.0 and 9.0 with lactic acidosis or central venous oxygen saturation < 70%. This study took place in a 54-bed, medical-surgical intensive care unit of a university-affiliated hospital. Thenar tissue oxygen saturation was measured by using a tissue spectrometer on 21 patients, and a vaso-occlusive test was performed before and 1 hour after transfusion. The sublingual microcirculation was assessed with a Sidestream Dark Field device concomitantly on 11 of them.

RESULTS

RBC transfusion resulted in increase in hemoglobin (7.23 (± 0.87) to 8.75 (± 1.06) g/dl; p < 0.001). RBC transfusion did not globally affect near-infrared spectrometry (NIRS)-derived variables. However, percent change in muscle oxygen consumption was negatively correlated with baseline (r = - 0.679, p = 0.001). There was no statistically significant correlation between percent change in vascular reactivity and baseline (p = 0.275). There was a positive correlation between percent change in oxygen consumption and percent change in vascular reactivity (r = 0.442, p = 0.045). In the 11 patients, RBC transfusion did not globally affect NIRS-derived variables or SDF-derived variables. There was no statistically significant correlation between percent change in small vessel perfusion and baseline perfusion (r = -0.474, p = 0.141), between percent change in small vessel flow and baseline flow (r = -0.418, p = 0.201), or between percent change in small vessel perfusion and percent change in small vessel flow (r = 0.435, p = 0.182).

CONCLUSIONS

In a small sample population, muscle tissue oxygen consumption, microvascular reactivity and sublingual microcirculation were globally unaltered by RBC transfusion in severe septic patients. However, muscle oxygen consumption improved in patients with low baseline and deteriorated in patients with preserved baseline. Future research with larger samples is needed to further examine the association between RBC transfusion and outcomes of patients resuscitated early in severe sepsis, with an emphasis on elucidating the potential contribution of microvascular factors.

Red blood cell storage lesions and related transfusion issues: a Canadian Blood Services research and development symposium

For centuries, man has been trying to figure out how to revive sick and traumatized individuals using fluids of various types, even from animals. In the 17th century, it was determined that blood was the best fluid to use and, in the early 1900s, after the discovery of the ABO blood groups, human blood was found to provide significant benefit for patients with shock and/or anemia. In the 1950s and 1960s, various ways to obtain, process, and store human blood were developed. It soon became apparent that storage of human blood for transfusion was problematic because red cells, as they aged in vitro, underwent a multitude of physicochemical changes that greatly affected their shelf life, the so-called storage lesion. More recently, the question has arisen as to the potential detrimental effects of the storage lesion and suggestions that older blood may induce increased morbidity and even mortality despite its acceptable in vivo survival. To address this issue of the efficacy and safety of transfusion of aged stored blood, a number of controlled clinical trials have been instituted to determine if older blood is significantly detrimental compared with fresher blood in transfusion recipients.

Stored red blood cell supernatant facilitates thrombin generation

BACKGROUND

Observational studies have reported that patients transfused with red blood cells (RBCs) have a worse clinical outcome than untransfused patients and that storage age of RBCs at the time of transfusion may be an independent predictor of this adverse clinical outcome.

STUDY DESIGN AND METHODS

Eight RBC concentrates in additive solution were studied over an 8-week storage period. The RBC supernatant was ultracentrifuged to concentrate microvesicles (RCMVs). RCMVs were studied by flow cytometry to identify phosphatidylserine (PS)-expressing RCMVs and in a thromboelastograph (TEG) using a modified assay to detect a thrombin facilitation effect.

RESULTS

For all products, the percentage of RCMVs that exhibited PS expression on Day 1 was 50 ± 13%, which increased with storage, and on Day 31 was 90 ± 4%. After 31 days, four of the eight products showed a thrombin facilitation effect as evidenced by a shortening of the TEG reaction (R) time of 1.3 ± 1.1 minutes, which persisted to Day 41. Data are the mean ± 1 SD. This TEG R shortening effect was neutralized by annexin V. No such effect was observed on, or before, Day 21.

CONCLUSIONS

Some stored RBCs release RCMVs, which express PS and are capable of facilitating thrombin generation in vitro. This provides a possible mechanism by which stored RBCs could promote adverse thrombotic or inflammatory effects.

Duration of red cell storage influences mortality after trauma

BACKGROUND

Although previous studies have identified an association between the transfusion of relatively older red blood cells (RBCs) (storage ≥ 14 days) and adverse outcomes, they are difficult to interpret because the majority of patients received a combination of old and fresh RBC units. To overcome this limitation, we compared in-hospital mortality among patients who received exclusively old versus fresh RBC units during the first 24 hours of hospitalization.

METHODS

Patients admitted to a Level I trauma center between January 2000 and May 2009 who received ≥ 1 unit of exclusively old (≥ 14 days) vs. fresh (< 14 days) RBCs during the first 24 hours of hospitalization were identified. Risk ratios (RRs) and 95% confidence intervals (CIs) were calculated for the association between mortality and RBC age, adjusted for patient age, Injury Severity Score, gender, receipt of fresh frozen plasma or platelets, RBC volume, brain injury, and injury mechanism (blunt or penetrating).

RESULTS

One thousand six hundred forty-seven patients met the study inclusion criteria. Among patients who were transfused 1 or 2 RBC units, no difference in mortality with respect to RBC age was identified (adjusted RR, 0.97; 95% CI, 0.72-1.32). Among patients who were transfused 3 or more RBC units, receipt of old versus fresh RBCs was associated with a significantly increased risk of mortality, with an adjusted RR of 1.57 (95% CI, 1.14-2.15). No difference was observed concerning the mean number of old versus fresh units transfused to patients who received 3 or more units (6.05 vs. 5.47, respectively; p = 0.11).

CONCLUSION

In trauma patients undergoing transfusion of 3 or more RBC units within 24 hour of hospital arrival, receipt of relatively older blood was associated with a significantly increased mortality risk. Reservation of relatively fresh RBC units for the acutely injured may be advisable.

Controversies related to red blood cell transfusion in critically ill patients

OBJECTIVE

To review the evolution of and controversies associated with allogenic blood transfusion in critically ill patients.

DATA SOURCES

Veterinary and human literature review.

HUMAN DATA SYNTHESIS

RBC transfusion practices for ICU patients have come under scrutiny in the last 2 decades. Human trials have demonstrated relative tolerance to severe, euvolemic anemia and a significant outcome advantage following implementation of more restricted transfusion therapy. Investigators question the ability of RBCs stored longer than 2 weeks to improve tissue oxygenation, and theorize that both age and proinflammatory or immunomodulating effects of transfused cells may limit efficacy and contribute to increased patient morbidity and mortality. Also controversial is the ability of pre- and post-storage leukoreduction of RBCs to mitigate adverse transfusion-related events.

VETERINARY DATA SYNTHESIS

While there are several studies evaluating the transfusion trigger, the RBC storage lesion and transfusion-related immunomodulation in experimental animal models, there is little research pertaining to clinical veterinary patients.

CONCLUSIONS

RBC transfusion is unequivocally indicated for treatment of anemic hypoxia. However, critical hemoglobin or Hct below which all critically ill patients require transfusion has not been established and there are inherent risks associated with allogenic blood transfusion. Clinical trials designed to evaluate the effects of RBC age and leukoreduction on veterinary patient outcome are warranted. Implementation of evidence-based transfusion guidelines and consideration of alternatives to allogenic blood transfusion are advisable.

Impact of blood transfusion on short- and long-term mortality in patients with ST-segment elevation myocardial infarction

OBJECTIVES

We sought to examine the short- and long-term outcomes of blood transfusion in patients presenting with ST-segment elevation myocardial infarction (STEMI).

BACKGROUND

The short- and long-term consequences of blood transfusion in anemic patients with recent STEMI remain controversial.

METHODS

We evaluated 30-day, 6-month, and 1-year all-cause mortality among 4,131 STEMI patients enrolled in the GUSTO (Global Use of Strategies to Open Occluded Coronary Arteries) IIb trial. Patients were categorized according to whether they received a blood transfusion during hospitalization. Cox proportional hazards survival models with transfusion as a time-dependent covariate were conducted for the whole and for the propensity-matched groups. Additionally, a series of sensitivity analyses assessed the magnitude of hidden bias that would need to be present to explain the associations actually observed.

RESULTS

Death at 30 days (13.7% vs. 5.5%), 6 months (19.7% vs. 6.9%), and 1 year (21.8% vs. 8.7%) was significantly higher for transfused patients than for nontransfused patients, respectively. After adjusting for over 25 baseline characteristics, nadir hemoglobin, and propensity score for transfusion, and using transfusion as a time-dependent covariate, transfusion remained significantly associated with increased risk of mortality at 30 days (hazard ratio [HR]: 3.89, 95% confidence interval [CI]: 2.66 to 5.68, p < 0.001), 6 months (HR: 3.63, 95% CI: 2.67 to 4.95, p < 0.001), and 1 year (HR: 3.03, 95% CI: 2.25 to 4.08, p < 0.001). Similar results were observed in the propensity-matched patients.

CONCLUSIONS

Blood transfusion is associated with increased short- and long-term mortality in the setting of STEMI.

The optimal hematocrit

Nearly 15 million units of packed red blood cells and whole blood are transfused annually in the United States alone. Until recently, the major risks from blood transfusion were thought to be transmission of viral infections, and overall, blood transfusion was believed by most providers to be safe. A safe hemoglobin threshold above which red cell transfusion is clearly unnecessary has not been established. This article addresses the numerous problems that surround the use and consequences of blood transfusion, such as hemoglobin and hematocrit levels, oxygenation, storage time, immunomodulation, infection, and anemia. The relevant literature is comprehensively reviewed.

Perfusion vs. oxygen delivery in transfusion with "fresh" and "old" red blood cells: the experimental evidence

We review the experimental evidence showing systemic and microvascular effects of blood transfusions instituted to support the organism in extreme hemodilution and hemorrhagic shock, focusing on the use of fresh vs. stored blood as a variable. The question: "What does a blood transfusion remedy?" was analyzed in experimental models addressing systemic and microvascular effects showing that oxygen delivery is not the only function that must be addressed. In extreme hemodilution and hemorrhagic shock blood transfusions simultaneously restore blood viscosity and oxygen carrying capacity, the former being critically needed for re-establishing a functional mechanical environment of the microcirculation, necessary for obtaining adequate capillary blood perfusion. Increased oxygen affinity due to 2,3 DPG depletion is shown to have either no effect or a positive oxygenation effect, when the transfused red blood cells (RBCs) do not cause additional flow impairment due to structural malfunctions including increased rigidity and release of hemoglobin. It is concluded that fresh RBCs are shown to be superior to stored RBCs in transfusion, however increased oxygen affinity may be a positive factor in hemorrhagic shock resuscitation. Although experimental studies seldom reproduce emergency and clinical conditions, nonetheless they serve to explore fundamental physiological mechanisms in the microcirculation that cannot be directly studied in humans.

Should fresh blood be recommended for intensive care patients?

Fresh blood has many potential advantages over older blood, but there is no evidence that these properties translate into clinical benefit for intensive care patients. The observational multicenter study by Karam and colleagues provides some evidence suggesting that blood stored for less than 14 days is better than older blood in terms of new organ failure and reduction in length of stay in pediatric intensive care units. Though in favor of using young blood, this study suffers from several limitations. As a consequence, it is ethical and certainly pertinent to conduct a randomized clinical trial in order to test the hypothesis that fresh blood might reduce mortality. The rationale is strong and the potential benefit of fresh blood is substantial.

The effect of blood transfusion on brain oxygenation in children with severe traumatic brain injury

OBJECTIVE

The indications for blood transfusion in traumatic brain injury are controversial. In particular, little is known about the effect of blood transfusion in childhood traumatic brain injury. This study aimed to examine the influence of blood transfusion on brain tissue oxygen tension in children with severe traumatic brain injury.

DESIGN

A retrospective analysis of a prospective observational database of children with severe traumatic brain injury who received brain tissue oxygen tension monitoring and a blood transfusion.

SETTING

University-affiliated pediatric hospital.

PATIENTS

Children with severe traumatic brain injury and blood transfusion.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Brain tissue oxygen tension was measured in normal-appearing white matter with a commercially available polarographic Clarke-type electrode. Brain tissue oxygen tension values after blood transfusion were compared with pre-transfusion values in hemodynamically stable patients. Limited interventions were allowed during the studied period. Brain tissue oxygen tension values were examined for early (1-4 hrs) and late (24 hrs) changes after blood transfusion, controlling for multiple clinical and physiologic variables with regression techniques. Further comparison was made with matched non-transfused controls to examine the influence of time after injury. Nineteen blood transfusions in 17 patients were evaluated. Brain tissue oxygen tension increased significantly in the early period after blood transfusion (p = .0018; 79% increased, 21% decreased) in comparison with baseline values and matched controls, but the overall changes were small and, in part, influenced by accompanying cerebral perfusion pressure changes. Also, this effect was limited to the early period after blood transfusion and was not significant after 24 hrs. In general, the brain tissue oxygen tension increase was larger in patients with higher baseline brain tissue oxygen tension and lower initial hemoglobin; however, no factors associated with the magnitude of the brain tissue oxygen tension change were significant in multivariate analysis. Increased age of blood did not appear to impair brain tissue oxygen tension changes, but most blood transfusion were <14 days old.

CONCLUSIONS

Brain tissue oxygen tension increased transiently in 79% of blood transfusion in pediatric traumatic brain injury patients, and decreased transiently in 21%. Brain tissue oxygen tension returned to baseline within 24 hrs. Reliable predictors of this brain tissue oxygen tension response to blood transfusion, however, remain elusive.

Resuscitation and transfusion principles for traumatic hemorrhagic shock

The transfusion approach to massive hemorrhage has continually evolved since it began in the early 1900s. It started with fresh whole blood and currently consists of virtually exclusive use of component and crystalloid therapy. Recent US military experience has reinvigorated the debate on what the most optimal transfusion strategy is for patients with traumatic hemorrhagic shock. In this review we discuss recently described mechanisms that contribute to traumatic coagulopathy, which include increased anti-coagulation factors and hyperfibrinolysis. We also describe the concept of damage control resuscitation (DCR), an early and aggressive prevention and treatment of hemorrhagic shock for patients with severe life-threatening traumatic injuries. The central tenants of DCR include hypotensive resuscitation, rapid surgical control, prevention and treatment of acidosis, hypothermia, and hypocalcemia, avoidance of hemodilution, and hemostatic resuscitation with transfusion of red blood cells, plasma, and platelets in a 1:1:1 unit ratio and the appropriate use of coagulation factors such as rFVIIa and fibrinogen-containing products (fibrinogen concentrates, cryoprecipitate). Fresh whole blood is also part of DCR in locations where it is available. Additional concepts to DCR since its original description that can be considered are the preferential use of "fresh" RBCs, and when available thromboelastography to direct blood product and hemostatic adjunct (anti-fibrinolytics and coagulation factor) administration. Lastly we discuss the importance of an established massive transfusion protocol to rapidly employ DCR and hemostatic resuscitation principles. While the majority of recent trauma transfusion papers are supportive of these general concepts, there is no Level 1 or 2 data available. Taken together, the preponderance of data suggests that these concepts may significantly decrease mortality in massively transfused trauma patients.

Duration of red blood cell storage is associated with increased incidence of deep vein thrombosis and in hospital mortality in patients with traumatic injuries

Introduction

In critically ill patients the relationship between the storage age of red blood cells (RBCs) transfused and outcomes are controversial. To determine if duration of RBC storage is associated with adverse outcomes we studied critically ill trauma patients requiring transfusion.

Methods

This retrospective cohort study included patients with traumatic injuries transfused ≥5 RBC units. Patients transfused ≥ 1 unit of RBCs with a maximum storage age of up to 27 days were compared with those transfused 1 or more RBC units with a maximum storage age of ≥ 28 days. These study groups were also matched by RBC amount (+/- 1 unit) transfused. Primary outcomes were deep vein thrombosis and in-hospital mortality.

Results

Two hundred and two patients were studied with 101 in both decreased and increased RBC age groups. No differences in admission vital signs, laboratory values, use of DVT prophylaxis, blood products or Injury Severity Scores were measured between study groups. In the decreased compared with increased RBC storage age groups, deep vein thrombosis occurred in 16.7% vs 34.5%, (P = 0.006), and mortality was 13.9% vs 26.7%, (P = 0.02), respectively. Patients transfused RBCs of increased storage age had an independent association with mortality, OR (95% CI), 4.0 (1.34 - 11.61), (P = 0.01), and had an increased incidence of death from multi-organ failure compared with the decreased RBC age group, 16% vs 7%, respectively, (P = 0.037).

Conclusions

In trauma patients transfused ≥5 units of RBCs, transfusion of RBCs ≥ 28 days of storage may be associated with deep vein thrombosis and death from multi-organ failure.

Blood transfusion in the critically ill: does storage age matter?

Morphologic and biochemical changes occur during red cell storage prior to product expiry, and these changes may hinder erythrocyte viability and function following transfusion. Despite a relatively large body of literature detailing the metabolic and structural deterioration that occurs during red cell storage, evidence for a significant detrimental clinical effect related to the transfusion of older blood is relatively less conclusive, limited primarily to observations in retrospective studies. Nonetheless, the implication that the transfusion of old, but not outdated blood may have negative clinical consequences demands attention. In this report, the current understanding of the biochemical and structural changes that occur during storage, known collectively as the storage lesion, is described, and the clinical evidence concerning the detrimental consequences associated with the transfusion of relatively older red cells is critically reviewed. Although the growing body of literature demonstrating the deleterious effects of relatively old blood is compelling, it is notable that all of these reports have been retrospective, and most of these studies have evaluated patients who received a mixture of red cell units of varying storage age. Until prospective studies have been completed and produce confirmative results, it would be premature to recommend any modification of current transfusion practice regarding storage age.

In 1917, Frances Payton Rous and J.R. Turner identified that a citrate-glucose solution allowed for the preservation of a whole blood unit for up to five days, thus facilitating the formative practice of blood banking[1]. Later, Loutit and Mollison of Great Britain developed the first anticoagulant of the modern era, known as acid-citrate-dextrose (ACD)[1]. ACD extended the shelf life of refrigerated blood to 21 days, and ACD remained in wide spread usage until the 1960s, when it was replaced by citrate-phosphate-dextrose (CPD) and citrate-phosphate-dextrose-adenine (CPDA) solutions that increased shelf life to 35 days and 42 days respectively. More recently, additive solutions containing saline, adenine, and dextrose have been developed to augment red cell survival following transfusion, although without any direct increase in storage duration[1,2].

It is now well appreciated, however, that a number of morphologic and biochemical changes occur during red cell storage prior to product expiry, and these changes may hinder erythrocyte viability and function following transfusion. Despite a relatively large body of literature detailing the metabolic and structural deterioration that occurs during red cell storage, evidence for a significant detrimental clinical effect related to the transfusion of older blood is relatively less conclusive, limited primarily to observations in retrospective studies. Nonetheless, the implication that the transfusion of old, but not outdated blood may have negative clinical consequences demands attention. The purpose of this report is to describe the current understanding of the biochemical and structural changes that occur during storage, known collectively as the storage lesion, and to critically review the clinical evidence concerning the detrimental consequences associated with the transfusion of relatively older red cells.

Microbiology, time course and clinical characteristics of infection in critically ill patients receiving packed red blood cell transfusion

BACKGROUND AND OBJECTIVES

Packed red blood cell transfusion has been associated with increased infection in a variety of critically ill patient populations. We evaluated the microbiology and time course of infection in transfused patients in the intensive care unit (ICU) as no data exist on these parameters.

MATERIALS AND METHODS

We performed a retrospective review of data for all patients admitted to a 24-bed medical-surgical ICU at Cooper University Hospital from July 2003 to September 2006 and entered in the Project Impact database.

RESULTS

A total of 2432 patients were admitted during the study period, of which 609 underwent transfusion. Transfused patients were more likely to develop a nosocomial infection (10.5% vs. 4.9%, P < 0.001). ICU and hospital length of stay were longer in the transfused group (P < 0.001 for both). Mortality was also greater (13.1% vs. 8.7%, P = 0.001). Transfused patients had a shorter time from hospital admission to first infection (P < 0.001) and ICU admission to first infection (P < 0.001). Multivariate analysis confirmed transfusion as an independent risk factor for infection, mortality, hospital and ICU length of stay. Methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococcus and Acinetobacter occurred more often in transfused patients. Acinetobacter accounted for a disproportionate share of infections among transfused patients (P < 0.001).

CONCLUSIONS

Transfused ICU patients have a higher incidence of nosocomial infection and worse outcomes. Transfused patients had a shorter onset of infection. Acinetobacter infection appears to be particularly common among these patients. Further investigation is merited to better elucidate the mechanism for these findings and their therapeutic and clinical implications.

Transfusion of aged packed red blood cells results in decreased tissue oxygenation in critically injured trauma patients

BACKGROUND

Blood transfusion is a common event in the treatment of injured patients. The effect of red blood cell transfusion on tissue oxygenation is unclear. The transfusion of older blood has been shown to be detrimental in retrospective studies. This study aims to study the effect of the age of the blood transfused on the tissue oxygenation using near infrared spectroscopy.

METHODS

Thirty-two critically injured trauma patients for whom a blood transfusion had been ordered were recruited. Each patient had a transcutaneous probe placed on the thenar eminence. The probe was placed 1 hour before the transfusion and left in place until 4 hours after transfusion. Tissue oxygen saturation (Sto2) was recorded every 2 minutes. The Sto2 area under the curve (AUC) over time periods was calculated. A control group (n = 16), not transfused, was recruited. The transfusion group was divided into two groups by blood age. One group received blood less than 21 days old, (new blood, n = 15) and the other received blood 21 days old or greater (old blood, n = 17). The data were analyzed for significance with Kendall's W and Wilcoxon's signed rank test (p < 0.05).

RESULTS

Baseline characteristics such were not significantly different between groups. The baseline AUC did not differ between groups. The old blood group demonstrated a significant decline in Sto2 comparing its baseline period to its transfusion period (p < 0.05). There was no similar decline in the control group or the new blood group. The posttransfusion period AUC for the old blood group was also lower versus baseline (p = 0.06). There was a moderate correlation between increasing age of blood and decrease in oxygenation (r = 0.5).

CONCLUSIONS

There was a decrease in peripheral tissue oxygenation in patients receiving older red blood cells. There was no oxygenation decrease in patients receiving blood less than 21 days. This indicates that factors in stored blood may influence the peripheral vasculature and oxygen delivery.

Warm fresh whole blood is independently associated with improved survival for patients with combat-related traumatic injuries

BACKGROUND

Increased understanding of the pathophysiology of the acute coagulopathy of trauma has lead many to question the current transfusion approach to hemorrhagic shock. We hypothesized that warm fresh whole blood (WFWB) transfusion would be associated with improved survival in patients with trauma compared with those transfused only stored component therapy (CT).

METHODS

We retrospectively studied US Military combat casualty patients transfused >or=1 unit of red blood cells (RBCs). The following two groups of patients were compared: (1) WFWB, who were transfused WFWB, RBCs, and plasma but not apheresis platelets and (2) CT, who were transfused RBC, plasma, and apheresis platelets but not WFWB. The primary outcomes were 24-hour and 30-day survival.

RESULTS

Of 354 patients analyzed there were 100 in the WFWB and 254 in the CT group. Patients in both groups had similar severity of injury determined by admission eye, verbal, and motor Glasgow Coma Score, base deficit, international normalized ratio, hemoglobin, systolic blood pressure, and injury severity score. Both 24-hour and 30-day survival were higher in the WFWB cohort compared with CT patients, 96 of 100 (96%) versus 223 of 254 (88%), (p = 0.018) and 95% to 82%, (p = 0.002), respectively. An increased amount (825 mL) of additives and anticoagulants were administered to the CT compared with the WFWB group, (p < 0.001). Upon multivariate logistic regression the use of WFWB and the volume of WFWB transfused was independently associated with improved 30-day survival.

CONCLUSIONS

In patients with trauma with hemorrhagic shock, resuscitation strategies that include WFWB may improve 30-day survival, and may be a result of less anticoagulants and additives with WFWB use in this population.