Transfusion thresholds and other strategies for guiding allogeneic red blood cell transfusion

Mid-Term Mortality in Older Anemic Patients with Type 2 Myocardial Infarction: Does Blood Transfusion sImprove Prognosis?

(1) Anemia often predisposes older patients to type 2 myocardial infarction (T2MI). However, the management of this frequent association remains uncertain. We aimed to evaluate the impact of red blood cell transfusion during the acute phase of T2MI in older anemic inpatients. (2) Methods and results: We performed a retrospective study using a French regional database. One hundred and seventy-eight patients aged 65 years or older, presenting with a T2MI and anemia, were selected. Patients were split into two groups: one that received a red blood cell transfusion (≥1 red blood cell unit) and one that did not. A propensity score was built to adjust for potential confounders, and the association between transfusion and 30-day mortality was evaluated with an inverse propensity score weighted Cox model. Transfusion was not associated with 30-day all-cause mortality (propensity score weighted hazard ratio (HR) 1.59 (0.55-4.56), p = 0.38). However, 1-year all-cause mortality was significantly higher in the transfusion group (propensity score weighted HR 2.47 (1.22-4.97), p = 0.011). (3) Conclusion: Our findings in older adults with anemia suggest that blood transfusion in the acute phase of T2MI could not be associated with improved short-term prognosis. Prospective studies are urgently needed to assess the impact of transfusion on longer-term prognosis.

Transfusion thresholds for guiding red blood cell transfusion

BACKGROUND

The optimal haemoglobin threshold for use of red blood cell (RBC) transfusions in anaemic patients remains an active field of research. Blood is a scarce resource, and in some countries, transfusions are less safe than in others because of inadequate testing for viral pathogens. If a liberal transfusion policy does not improve clinical outcomes, or if it is equivalent, then adopting a more restrictive approach could be recognised as the standard of care.  OBJECTIVES: The aim of this review update was to compare 30-day mortality and other clinical outcomes for participants randomised to restrictive versus liberal red blood cell (RBC) transfusion thresholds (triggers) for all clinical conditions. The restrictive transfusion threshold uses a lower haemoglobin concentration as a threshold for transfusion (most commonly, 7.0 g/dL to 8.0 g/dL), and the liberal transfusion threshold uses a higher haemoglobin concentration as a threshold for transfusion (most commonly, 9.0 g/dL to 10.0 g/dL).

SEARCH METHODS

We identified trials through updated searches: CENTRAL (2020, Issue 11), MEDLINE (1946 to November 2020), Embase (1974 to November 2020), Transfusion Evidence Library (1950 to November 2020), Web of Science Conference Proceedings Citation Index (1990 to November 2020), and trial registries (November 2020). We  checked the reference lists of other published reviews and relevant papers to identify additional trials. We were aware of one trial identified in earlier searching that was in the process of being published (in February 2021), and we were able to include it before this review was finalised.

SELECTION CRITERIA

We included randomised trials of surgical or medical participants that recruited adults or children, or both. We excluded studies that focused on neonates. Eligible trials assigned intervention groups on the basis of different transfusion schedules or thresholds or 'triggers'. These thresholds would be defined by a haemoglobin (Hb) or haematocrit (Hct) concentration below which an RBC transfusion would be administered; the haemoglobin concentration remains the most commonly applied marker of the need for RBC transfusion in clinical practice. We included trials in which investigators had allocated participants to higher thresholds or more liberal transfusion strategies compared to more restrictive ones, which might include no transfusion. As in previous versions of this review, we did not exclude unregistered trials published after 2010 (as per the policy of the Cochrane Injuries Group, 2015), however, we did conduct analyses to consider the differential impact of results of trials for which prospective registration could not be confirmed.   DATA COLLECTION AND ANALYSIS: We identified trials for inclusion and extracted data using Cochrane methods. We pooled risk ratios of clinical outcomes across trials using a random-effects model. Two review authors independently extracted data and assessed risk of bias. We conducted predefined analyses by clinical subgroups. We defined participants randomly allocated to the lower transfusion threshold as being in the 'restrictive transfusion' group and those randomly allocated to the higher transfusion threshold as being in the 'liberal transfusion' group.

MAIN RESULTS

A total of 48 trials, involving data from 21,433 participants (at baseline), across a range of clinical contexts (e.g. orthopaedic, cardiac, or vascular surgery; critical care; acute blood loss (including gastrointestinal bleeding); acute coronary syndrome; cancer; leukaemia; haematological malignancies), met the eligibility criteria. The haemoglobin concentration used to define the restrictive transfusion group in most trials (36) was between 7.0 g/dL and 8.0 g/dL.  Most trials included only adults; three trials focused on children. The included studies were generally at low risk of bias for key domains including allocation concealment and incomplete outcome data. Restrictive transfusion strategies reduced the risk of receiving at least one RBC transfusion by 41% across a broad range of clinical contexts (risk ratio (RR) 0.59, 95% confidence interval (CI) 0.53 to 0.66; 42 studies, 20,057 participants; high-quality evidence), with a large amount of heterogeneity between trials (I² = 96%). Overall, restrictive transfusion strategies did not increase or decrease the risk of 30-day mortality compared with liberal transfusion strategies (RR 0.99, 95% CI 0.86 to 1.15; 31 studies, 16,729 participants; I² = 30%; moderate-quality evidence) or any of the other outcomes assessed (i.e. cardiac events (low-quality evidence), myocardial infarction, stroke, thromboembolism (all high-quality evidence)). High-quality evidence shows that the liberal transfusion threshold did not affect the risk of infection (pneumonia, wound infection, or bacteraemia). Transfusion-specific reactions are uncommon and were inconsistently reported within trials. We noted less certainty in the strength of evidence to support the safety of restrictive transfusion thresholds for the following predefined clinical subgroups: myocardial infarction, vascular surgery, haematological malignancies, and chronic bone-marrow disorders.

AUTHORS' CONCLUSIONS

Transfusion at a restrictive haemoglobin concentration decreased the proportion of people exposed to RBC transfusion by 41% across a broad range of clinical contexts. Across all trials, no evidence suggests that a restrictive transfusion strategy impacted 30-day mortality, mortality at other time points, or morbidity (i.e. cardiac events, myocardial infarction, stroke, pneumonia, thromboembolism, infection) compared with a liberal transfusion strategy. Despite including 17 more randomised trials (and 8846 participants), data remain insufficient to inform the safety of transfusion policies in important and selected clinical contexts, such as myocardial infarction, chronic cardiovascular disease, neurological injury or traumatic brain injury, stroke, thrombocytopenia, and cancer or haematological malignancies, including chronic bone marrow failure.  Further work is needed to improve our understanding of outcomes other than mortality. Most trials compared only two separate thresholds for haemoglobin concentration, which may not identify the actual optimal threshold for transfusion in a particular patient. Haemoglobin concentration may not be the most informative marker of the need for transfusion in individual patients with different degrees of physiological adaptation to anaemia. Notwithstanding these issues, overall findings provide good evidence that transfusions with allogeneic RBCs can be avoided in most patients with haemoglobin thresholds between the range of 7.0 g/dL and 8.0 g/dL. Some patient subgroups might benefit from RBCs to maintain higher haemoglobin concentrations; research efforts should focus on these clinical contexts.

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.

Transfusion practice in anemic, non-bleeding patients: Cross-sectional survey of physicians working in general internal medicine teaching hospitals in Switzerland

Background

Transfusion practice might significantly influence patient morbidity and mortality. Between European countries, transfusion practice of red blood cells (RBC) greatly differs. Only sparse data are available on transfusion practice of general internal medicine physicians in Switzerland.

Methods

In this cross-sectional survey, physicians working in general medicine teaching hospitals in Switzerland were investigated regarding their self-reported transfusion practice in anemic patients without acute bleeding. The definition of anemia, transfusion triggers, knowledge on RBC transfusion, and implementation of guidelines were assessed.

Results

560 physicians of 71 hospitals (64%) responded to the survey. Anemia was defined at very diverging hemoglobin values (by 38% at a hemoglobin <130 g/L for men and by 57% at <120 g/L in non-pregnant women). 62% and 43% respectively, did not define anemia in men and in women according to the World Health Organization. Fifty percent reported not to transfuse RBC according to international guidelines. Following factors were indicated to influence the decision to transfuse: educational background of the physicians, geographical region of employment, severity of anemia, and presence of known coronary artery disease. 60% indicated that their knowledge on Transfusion-related Acute Lung Injury (TRALI) did not influence transfusion practice. 50% of physicians stated that no local transfusion guidelines exist and 84% supported the development of national recommendations on transfusion in non-acutely bleeding, anemic patients.

Conclusion

This study highlights the lack of adherence to current transfusion guidelines in Switzerland. Identifying and subsequently correcting this deficit in knowledge translation may have a significant impact on patient care.

Transfusion practice patterns in patients with anemia receiving myelosuppressive chemotherapy for nonmyeloid cancer: results from a prospective observational study

Purpose

The decision to prescribe packed red blood cell (PRBC) transfusions in patients with chemotherapy-induced anemia (CIA) includes assessment of clinical features such as the patient’s cancer type and treatment regimen, severity of anemia symptoms, and presence of comorbidities. We examined contemporary transfusion practices in patients with nonmyeloid cancer and CIA.

Methods

Key inclusion criteria were age ≥ 18 years with nonmyeloid cancer, receiving first/second-line myelosuppressive chemotherapy, baseline hemoglobin (Hb) ≤ 10.0 g/dL, and planned to receive ≥ 1 PRBC transfusions. Exclusion criteria were receipt of erythropoiesis-stimulating agents within 8 weeks of screening and/or chronic renal insufficiency. Data were collected from patients’ medical records, laboratory values, and physician/provider questionnaires. Proportion of patients for each clinical consideration leading to a decision to prescribe a PRBC transfusion and 95% exact binomial confidence intervals were determined.

Results

The study enrolled 154 patients at 18 sites in USA; 147 (95.5%) received a PRBC transfusion. Fatigue was the most common symptom affecting the decision to prescribe a PRBC transfusion (101 [69.2%] patients). Of the three reasons selected as primary considerations for prescribing a PRBC transfusion, anemia symptoms (106 [72.1%] patients) was the most frequently reported, followed by Hb value (37 [25.2%] patients) and medical history (4 [2.7%] patients).

Conclusions

In this study, the primary consideration for prescribing a PRBC transfusion was anemia symptoms in 72.1% of patients, with only 25.2% of patients prescribed a transfusion based exclusively on Hb value. Results indicate that clinical judgment and patient symptoms, not just Hb value, were used in decisions to prescribe PRBC transfusions.

Electronic supplementary material

The online version of this article (10.1007/s00520-017-4035-7) contains supplementary material, which is available to authorized users.

Transfusion thresholds and other strategies for guiding allogeneic red blood cell transfusion

BACKGROUND

There is considerable uncertainty regarding the optimal haemoglobin threshold for the use of red blood cell (RBC) transfusions in anaemic patients. Blood is a scarce resource, and in some countries, transfusions are less safe than others because of a lack of testing for viral pathogens. Therefore, reducing the number and volume of transfusions would benefit patients.

OBJECTIVES

The aim of this review was to compare 30-day mortality and other clinical outcomes in participants randomized to restrictive versus liberal red blood cell (RBC) transfusion thresholds (triggers) for all conditions. The restrictive transfusion threshold uses a lower haemoglobin level to trigger transfusion (most commonly 7 g/dL or 8 g/dL), and the liberal transfusion threshold uses a higher haemoglobin level to trigger transfusion (most commonly 9 g/dL to 10 g/dL).

SEARCH METHODS

We identified trials by searching CENTRAL (2016, Issue 4), MEDLINE (1946 to May 2016), Embase (1974 to May 2016), the Transfusion Evidence Library (1950 to May 2016), the Web of Science Conference Proceedings Citation Index (1990 to May 2016), and ongoing trial registries (27 May 2016). We also checked reference lists of other published reviews and relevant papers to identify any additional trials.

SELECTION CRITERIA

We included randomized trials where intervention groups were assigned on the basis of a clear transfusion 'trigger', described as a haemoglobin (Hb) or haematocrit (Hct) level below which a red blood cell (RBC) transfusion was to be administered.

DATA COLLECTION AND ANALYSIS

We pooled risk ratios of clinical outcomes across trials using a random-effects model. Two people extracted the data and assessed the risk of bias. We conducted predefined analyses by clinical subgroups. We defined participants randomly allocated to the lower transfusion threshold as 'restrictive transfusion' and to the higher transfusion threshold as 'liberal transfusion'.

MAIN RESULTS

A total of 31 trials, involving 12,587 participants, across a range of clinical specialities (e.g. surgery, critical care) met the eligibility criteria. The trial interventions were split fairly equally with regard to the haemoglobin concentration used to define the restrictive transfusion group. About half of them used a 7 g/dL threshold, and the other half used a restrictive transfusion threshold of 8 g/dL to 9 g/dL. The trials were generally at low risk of bias .Some items of methodological quality were unclear, including definitions and blinding for secondary outcomes.Restrictive transfusion strategies reduced the risk of receiving a RBC transfusion by 43% across a broad range of clinical specialties (risk ratio (RR) 0.57, 95% confidence interval (CI) 0.49 to 0.65; 12,587 participants, 31 trials; high-quality evidence), with a large amount of heterogeneity between trials (I² = 97%). Overall, restrictive transfusion strategies did not increase or decrease the risk of 30-day mortality compared with liberal transfusion strategies (RR 0.97, 95% CI 0.81 to 1.16, I² = 37%; N = 10,537; 23 trials; moderate-quality evidence) or any of the other outcomes assessed (i.e. cardiac events (low-quality evidence), myocardial infarction, stroke, thromboembolism (high-quality evidence)). Liberal transfusion did not affect the risk of infection (pneumonia, wound, or bacteraemia).

AUTHORS' CONCLUSIONS

Transfusing at a restrictive haemoglobin concentration of between 7 g/dL to 8 g/dL decreased the proportion of participants exposed to RBC transfusion by 43% across a broad range of clinical specialities. There was no evidence that a restrictive transfusion strategy impacts 30-day mortality or morbidity (i.e. mortality at other points, cardiac events, myocardial infarction, stroke, pneumonia, thromboembolism, infection) compared with a liberal transfusion strategy. There were insufficient data to inform the safety of transfusion policies in certain clinical subgroups, including acute coronary syndrome, myocardial infarction, neurological injury/traumatic brain injury, acute neurological disorders, stroke, thrombocytopenia, cancer, haematological malignancies, and bone marrow failure. The findings provide good evidence that transfusions with allogeneic RBCs can be avoided in most patients with haemoglobin thresholds above 7 g/dL to 8 g/dL.

A multi-centre randomised controlled trial of Transfusion Indication Threshold Reduction on transfusion rates, morbidity and healthcare resource use following cardiac surgery: study protocol

Thresholds for red blood cell transfusion following cardiac surgery vary by hospital and surgeon. The TITRe2 multi-centre randomised controlled trial aims to randomise 2000 patients from 17 United Kingdom centres, and tests the hypothesis that a restrictive transfusion threshold will reduce postoperative morbidity and health service costs compared to a liberal threshold. Patients consent to take part in the study pre-operatively but are only randomised if their haemoglobin falls below 9 g/dL during their post-operative hospital stay. The primary outcome is a binary composite outcome of any serious infectious or ischaemic event in the first three months after randomisation. Many challenges have been encountered in the set-up and running of the study.

Predicting red blood cell transfusion in hospitalized patients: role of hemoglobin level, comorbidities, and illness severity

Background

Randomized controlled trial evidence supports a restrictive strategy of red blood cell (RBC) transfusion, but significant variation in clinical transfusion practice persists. Patient characteristics other than hemoglobin levels may influence the decision to transfuse RBCs and explain some of this variation. Our objective was to evaluate the role of patient comorbidities and severity of illness in predicting inpatient red blood cell transfusion events.

Methods

We developed a predictive model of inpatient RBC transfusion using comprehensive electronic medical record (EMR) data from 21 hospitals over a four year period (2008-2011). Using a retrospective cohort study design, we modeled predictors of transfusion events within 24 hours of hospital admission and throughout the entire hospitalization. Model predictors included administrative data (age, sex, comorbid conditions, admission type, and admission diagnosis), admission hemoglobin, severity of illness, prior inpatient RBC transfusion, admission ward, and hospital.

Results

The study cohort included 275,874 patients who experienced 444,969 hospitalizations. The 24 hour and overall inpatient RBC transfusion rates were 7.2% and 13.9%, respectively. A predictive model for transfusion within 24 hours of hospital admission had a C-statistic of 0.928 and pseudo-R2 of 0.542; corresponding values for the model examining transfusion through the entire hospitalization were 0.872 and 0.437. Inclusion of the admission hemoglobin resulted in the greatest improvement in model performance relative to patient comorbidities and severity of illness.

Conclusions

Data from electronic medical records at the time of admission predicts with very high likelihood the incidence of red blood transfusion events in the first 24 hours and throughout hospitalization. Patient comorbidities and severity of illness on admission play a small role in predicting the likelihood of RBC transfusion relative to the admission hemoglobin.

Patterns and outcomes of red blood cell transfusion in patients undergoing percutaneous coronary intervention

IMPORTANCE

Studies have shown variation in the use of red blood cell transfusion among patients with acute coronary syndromes. There are no definitive data for the efficacy of transfusion in improving outcomes, and concerning data exist about possible association with harm. Current transfusion practices in patients undergoing percutaneous coronary intervention (PCI) are not well understood.

OBJECTIVE

To determine the current patterns of blood transfusion among patients undergoing PCI and the association of transfusion with adverse cardiac outcomes across hospitals in the United States.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cohort study of all patient visits from the CathPCI Registry from July 2009 to March 2013 that included PCI, excluding those with missing data on bleeding complications or who underwent in-hospital coronary artery bypass graft surgery (N = 2,258,711 visits).

MAIN OUTCOMES AND MEASURES

Transfusion rates in the overall population and by hospital (N = 1431) were the primary outcomes. The association of transfusion with myocardial infarction, stroke, and death after accounting for a patient's propensity for transfusion was also measured.

RESULTS

The overall rate of transfusion was 2.14% (95% CI, 2.13%-2.16%) and quarterly transfusion rates slightly declined from July 2009 to March 2013 (from 2.11% [95% CI, 2.03%-2.19%] to 2.04% [95% CI, 1.97%-2.12%]; P < .001). Patients who were more likely to receive transfusion were older (mean, 70.5 vs 64.6 years), were women (56.3% vs 32.5%), and had hypertension (86.4% vs 82.0%), diabetes (44.8% vs 34.6%), advanced renal dysfunction (8.7% vs 2.3%), prior myocardial infarction (33.0% vs 30.2%), or prior heart failure (27.0% vs 11.8%). Overall, 96.3% of sites gave a transfusion to less than 5% of patients and 3.7% of sites gave a transfusion to 5% of patients or more. Variation in hospital risk-standardized rates of transfusion persisted after adjustment, and hospitals showed variability in their transfusion thresholds. Receipt of transfusion was associated with myocardial infarction (42,803 events; 4.5% vs 1.8%; odds ratio [OR], 2.60; 95% CI, 2.57-2.63), stroke (5011 events; 2.0% vs 0.2%; OR, 7.72; 95% CI, 7.47-7.98), and in-hospital death (31,885 events; 12.5% vs 1.2%; OR, 4.63; 95% CI, 4.57-4.69), irrespective of bleeding complications.

CONCLUSIONS AND RELEVANCE

Among patients undergoing PCI at US hospitals, there was considerable variation in blood transfusion practices, and receipt of transfusion was associated with increased risk of in-hospital adverse cardiac events. These observational findings may warrant a randomized trial of transfusion strategies for patients undergoing PCI.

S-nitrosylation: integrator of cardiovascular performance and oxygen delivery

Delivery of oxygen to tissues is the primary function of the cardiovascular system. NO, a gasotransmitter that signals predominantly through protein S-nitrosylation to form S-nitrosothiols (SNOs) in target proteins, operates coordinately with oxygen in mammalian cellular systems. From this perspective, SNO-based signaling may have evolved as a major transducer of the cellular oxygen-sensing machinery that underlies global cardiovascular function. Here we review mechanisms that regulate S-nitrosylation in the context of its essential role in "systems-level" control of oxygen sensing, delivery, and utilization in the cardiovascular system, and we highlight examples of aberrant S-nitrosylation that may lead to altered oxygen homeostasis in cardiovascular diseases. Thus, through a bird's-eye view of S-nitrosylation in the cardiovascular system, we provide a conceptual framework that may be broadly applicable to the functioning of other cellular systems and physiological processes and that illuminates new therapeutic promise in cardiovascular medicine.

Patient Blood Management: A Patient-Orientated Approach to Blood Replacement with the Goal of Reducing Anemia, Blood Loss and the Need for Blood Transfusion in Elective Surgery

Patient Blood Management (PBM) describes an evidence-based, multidisciplinary therapeutic approach. Its focus is on the treatment of the individual patient and as such comprises transfusion therapy and pharmacotherapy. Furthermore, the applicability of PBM is not limited to the perioperative setting but is applicable also to other therapeutic measures and disciplines where significant blood loss is known to occur and where transfusion of blood products is part of the established treatment. PBM is fundamentally based on 3 pillars: (1) optimization of the (preoperative) erythrocyte volume, (2) reduction of diagnostic, therapeutic, or intraoperative blood loss, and (3) increasing individual tolerance towards anemia and accurate blood transfusion triggers. PBM primarily identifies patients at risk of transfusion and provides a management plan aimed at reducing or eliminating the risk of anemia and the need for allogeneic transfusion, thus reducing the inherent risks, inventory pressures, and the escalating costs associated with transfusion.

Significant reduction of red blood cell transfusion requirements by changing from a double-unit to a single-unit transfusion policy in patients receiving intensive chemotherapy or stem cell transplantation

BACKGROUND

Traditionally, single-unit red blood cell transfusions were believed to be insufficient to treat anemia, but recent data suggest that they may lead to a safe reduction of transfusion requirements. We tested this hypothesis by changing from a double- to a single-unit red blood cell transfusion policy.

DESIGN AND METHODS

We performed a retrospective cohort study in patients with hematologic malignancies receiving intensive chemotherapy or hematopoietic stem cell transplantation. The major end-points were the reduction in the total number of red blood cell units per therapy cycle and per day of aplasia. The study comprised 139 patients who received 272 therapy cycles. Overall 2212 red blood cell units were administered in 1548 transfusions.

RESULTS

During the periods of the double- and single-unit policies, one red blood cell unit was transfused in 25% and 84% of the cases and the median number of red blood cell units per transfusion was two and one, respectively. Single-unit transfusion led to a 25% reduction of red blood cell usage per therapy cycle and 24% per aplasia day, but was not associated with a higher out-patient transfusion frequency. In multivariate analysis, single-unit transfusion resulted in a reduction of 2.7 red blood cell units per treatment cycle (P = 0.001). The pre-transfusion hemoglobin levels were lower during the single-unit period (median 61 g/L versus 64 g/L) and more transfusions were administered to patients with hemoglobin values of 60 gl/L or less (47% versus 26%). There was no evidence of more severe bleeding or more platelet transfusions during the single-unit period and the overall survival was similar in both cohorts.

CONCLUSIONS

Implementing a single-unit transfusion policy saves 25% of red blood cell units and, thereby, reduces the risks associated with allogeneic blood transfusions.

The transfusion problem: role of aberrant S-nitrosylation

Protein S-nitrosylation (the binding of a nitric oxide [NO] group to a cysteine thiol) is a major mechanism through which the ubiquitous cellular influence of NO is exerted. Disruption of S-nitrosylation is associated with a wide range of pathophysiologic conditions. Hemoglobin (Hb) exemplifies both of these concepts. It is the prototypical S-nitrosylated protein in that it binds, activates, and deploys NO. Within red blood cells (RBCs), Hb is S-nitrosylated during the respiratory cycle and thereby conveys NO bioactivity that may be dispensed to regulate local blood flow in the physiologic response known as hypoxic vasodilation. Hb thus both delivers oxygen directly and delivers vasoactivity to potentially optimize tissue perfusion in concert with local metabolic demand. Accordingly, decreased levels of S-nitrosylated Hb (also known as S-nitrosohemoglobin) and/or impaired delivery of RBC-derived NO bioactivity have been observed in a variety of disease states that are characterized by tissue hypoxemia. It has been shown recently that storage of blood depletes S-nitrosylated Hb, accompanied by reduced ability of RBCs to induce vasodilation. This defect appears to account in significant part for the impaired ability of banked RBCs to deliver oxygen. Renitrosylation can correct this impairment and thus may offer a means to ameliorate the disruptions in tissue perfusion produced by transfusion.

An estimate of future transfusion needs in the province of Ravenna made on the basis of Italian national statistics and past consumption

BACKGROUND

After years of surpluses in numerous blood components in the province of Ravenna, there is now evidence that the increased use of such products is leading to an ever less abundant self-sufficiency. The concern about the possible loss of self-sufficiency, in a province in which the population of donors does not seem to be adequate to compensate for transfusion domands, led us to verify consumption and future prospects in greater detail.

MATERIALS AND METHODS

In order to plan future transfusion needs, past consumption was analysed dividing the population into several age groups. This historical use of blood products was projected into the scenario of the population in years to come to estimate needs and their increases over time.

RESULTS

The use of transfusion products is very different in different age groups, increasing notably with age. Age factor was identified as the most important factor determining blood product consumption.

DISCUSSION

It will, therefore, be the aging of the population that causes an increase in blood product requirements. Projections from the Italian Institute of Statistics considering age groups of the population up to 2051 enable predictions of transfusion needs, in the absence of drastic interventions on the appropriateness of transfusion practices. Considering that the public and private hospitals of Ravenna predominantly admit subjects from its own territory, these predictions appear realistic, provided that new reasons for consumption are not introduced.

Platelet-rich-plasmapheresis for minimising peri-operative allogeneic blood transfusion

BACKGROUND

Concerns regarding the safety of transfused blood have generated considerable enthusiasm for the use of technologies intended to reduce the use of allogeneic blood (blood from an unrelated donor). Platelet-rich plasmapheresis (PRP) offers an alternative approach to blood conservation.

OBJECTIVES

To examine the evidence for the efficacy of PRP in reducing peri-operative allogeneic red blood cell (RBC) transfusion, and the evidence for any effect on clinical outcomes such as mortality and re-operation rates.

SEARCH STRATEGY

We identified studies by searching MEDLINE (1950 to 2009), EMBASE (1980 to 2009), The Cochrane Library (Issue 1, 2009), the Internet (to March 2009) and the reference lists of published articles, reports, and reviews.

SELECTION CRITERIA

Controlled parallel group trials in which adult patients, scheduled for non-urgent surgery, were randomised to PRP, or to a control group which did not receive the intervention.

DATA COLLECTION AND ANALYSIS

Primary outcomes measured were: the number of patients exposed to allogeneic RBC transfusion, and the amount of RBC transfused. Other outcomes measured were: the number of patients exposed to allogeneic platelet transfusions, fresh frozen plasma, and cryoprecipitate, blood loss, re-operation for bleeding, post-operative complications (thrombosis), mortality, and length of hospital stay. Treatment effects were pooled using a random-effects model. Trial quality was assessed using criteria proposed by Schulz et al (Schulz 1995).

MAIN RESULTS

Twenty-two trials of PRP were identified that reported data for the number of patients exposed to allogeneic RBC transfusion. These trials evaluated a total of 1589 patients. The relative risk (RR) of exposure to allogeneic blood transfusion in those patients randomised to PRP was 0.73 (95%CI 0.59 to 0.90), equating to a relative risk reduction (RRR) of 27% and a risk difference (RD) of 19% (95%CI 10% to 29%). However, significant heterogeneity of treatment effect was observed (p < 0.00001; I² = 79%). When the four trials by Boldt are excluded, the RR is 0.76 (95% CI 0.62 to 0.93). On average, PRP did not significantly reduce the total volume of RBC transfused (weighted mean difference [WMD] -0.69, 95%CI -1.93 to 0.56 units). Trials provided inadequate data regarding the impact of PRP on morbidity, mortality, and hospital length of stay. Trials were generally small and of poor methodological quality.

AUTHORS' CONCLUSIONS

Although the results suggest that PRP is effective in reducing allogeneic RBC transfusion in adult patients undergoing elective surgery, there was considerable heterogeneity of treatment effects and the trials were of poor methodological quality. The available studies provided inadequate data for firm conclusions to be drawn regarding the impact of PRP on clinically important endpoints.

Well being of obstetric patients on minimal blood transfusions (WOMB trial)

Background

Primary postpartum haemorrhage is an obstetrical emergency often causing acute anaemia that may require immediate red blood cell (RBC) transfusion. This anaemia results in symptoms such as fatigue, which may have major impact on the health-related quality of life. RBC transfusion is generally thought to alleviate these undesirable effects although it may cause transfusion reactions. Moreover, the postpartum haemoglobin level seems to influence fatigue only for a short period of time. At present, there are no strict transfusion criteria for this specific indication, resulting in a wide variation in postpartum policy of RBC transfusion in the Netherlands.

Methods/Design

The WOMB trial is a multicentre randomised non-inferiority trial. Women with acute anaemia due to postpartum haemorrhage, 12-24 hours after delivery and not initially treated with RBC transfusion, are eligible for randomisation. Patients with severe physical complaints are excluded. Patients are randomised for either RBC transfusion or expectant management. Health related quality of life (HRQoL) will be assessed at inclusion, at three days and one, three and six weeks postpartum with three validated measures (Multi-dimensional Fatigue Inventory, ShortForm-36, EuroQol-5D). Primary outcome of the study is physical fatigue three days postpartum. Secondary outcome measures are general and mental fatigue scores and generic health related quality of life scores, the number of RBC transfusions, length of hospital stay, complications and health-care costs.

The primary analysis will be by intention-to-treat. The various longitudinal scores will be evaluated using Repeated Measurements ANOVA. A costs benefit analysis will also be performed. The power calculation is based on the exclusion of a difference in means of 1.3 points or greater in favour of RBC transfusion arm regarding physical fatigue subscale. With missing data not exceeding 20%, 250 patients per arm have to be randomised (one-sided alpha = 0.025, power = 80%).

Discussion

This study will provide evidence for a guideline regarding RBC transfusion in the postpartum patient suffering from acute anaemia. Equivalence in fatigue score, remaining HRQoL scores and physical complications between both groups is assumed, in which case an expectant management would be preferred to minimise transfusion reactions and costs.

Trial registration

ClinicalTrials.gov NCT00335023, Nederlands Trial Register NTR335

Murine blood banking: characterization and comparisons to human blood

Blood transfusion remains an essential treatment of acute anemia. Current storage processes allow the efficient administration of blood products. Erythrocytes undergo morphological and biochemical changes during storage that may affect outcomes after transfusion. A reliable small-animal model would be ideal to examine the effects of stored blood products after transfusion. The objective of this study was to characterize the storage of murine erythrocytes for future application to animal models of acute anemia. Blood samples were collected from male mice and human volunteers, separated into components, and stored. At intervals, morphological and biochemical analysis was performed. Lactate, potassium, hemoglobin, and hemolysis were determined, and cell morphology was evaluated with light microscopy. Murine packed red blood cells (pRBCs) aged more rapidly than human samples. Murine pRBCs exhibited higher lactate levels (34.9 +/- 1.3 mmol/L vs. 18.1 +/- 1.0 mmol/L, mouse vs. human) and more severe acidosis as indicated by pH (6.56 +/- 0.02 vs. 6.79 +/- 0.04, mouse vs. human). Murine pRBCs hemolyzed earlier (11.2 +/- 3.7 g vs. 0.7 +/- 0.3 g, mouse vs. human after 21 days of storage) and more rapidly than human pRBCs. Corpuscular changes consistent with red cell storage lesions appeared earlier in murine samples compared with human stored pRBCs. Compared with human pRBCs, murine pRBCs exhibit similar but more accelerated aging processes under standard storage conditions. Characterization of the murine red cell storage lesion will allow the application of stored blood components to future investigations into the treatment of acute anemia in experimental murine models.

Red cell transfusion triggers in critically ill patients: time for some new TRICCs?

Current evidence suggests that critically ill patients tolerate anaemia well and that blood transfusions may increase the risk of adverse outcomes. Dr Sakr and colleagues present a contradictory analysis of a surgical ICU cohort, finding an association between blood transfusions and lower hospital mortality after adjustment for a range of potential confounders. Analyses of this kind are interesting and provocative, but are limited by residual confounding and bias by indication. The data emphasise the need for additional high quality trials of transfusion practice in critical care.

Cell salvage for minimising perioperative allogeneic blood transfusion

BACKGROUND

Concerns regarding the safety of transfused blood have prompted reconsideration of the use of allogeneic (from an unrelated donor) red blood cell (RBC) transfusion, and a range of techniques to minimise transfusion requirements.

OBJECTIVES

To examine the evidence for the efficacy of cell salvage in reducing allogeneic blood transfusion and the evidence for any effect on clinical outcomes.

SEARCH STRATEGY

We identified studies by searching CENTRAL (The Cochrane Library 2009, Issue 2), MEDLINE (1950 to June 2009), EMBASE (1980 to June 2009), the internet (to August 2009) and bibliographies of published articles.

SELECTION CRITERIA

Randomised controlled trials with a concurrent control group in which adult patients, scheduled for non-urgent surgery, were randomised to cell salvage (autotransfusion) or to a control group who did not receive the intervention.

DATA COLLECTION AND ANALYSIS

Data were independently extracted and the risk of bias assessed. Relative risks (RR) and weighted mean differences (WMD) with 95% confidence intervals (CIs) were calculated. Data were pooled using a random-effects model. The primary outcomes were the number of patients exposed to allogeneic red cell transfusion and the amount of blood transfused. Other clinical outcomes are detailed in the review.

MAIN RESULTS

A total of 75 trials were included. Overall, the use of cell salvage reduced the rate of exposure to allogeneic RBC transfusion by a relative 38% (RR 0.62; 95% CI 0.55 to 0.70). The absolute reduction in risk (ARR) of receiving an allogeneic RBC transfusion was 21% (95% CI 15% to 26%). In orthopaedic procedures the RR of exposure to RBC transfusion was 0.46 (95% CI 0.37 to 0.57) compared to 0.77 (95% CI 0.69 to 0.86) for cardiac procedures. The use of cell salvage resulted in an average saving of 0.68 units of allogeneic RBC per patient (WMD -0.68; 95% CI -0.88 to -0.49). Cell salvage did not appear to impact adversely on clinical outcomes.

AUTHORS' CONCLUSIONS

The results suggest cell salvage is efficacious in reducing the need for allogeneic red cell transfusion in adult elective cardiac and orthopaedic surgery. The use of cell salvage did not appear to impact adversely on clinical outcomes. However, the methodological quality of trials was poor. As the trials were unblinded and lacked adequate concealment of treatment allocation, transfusion practices may have been influenced by knowledge of the patients' treatment status potentially biasing the results in favour of cell salvage.

Determinants of transfusion decisions in a mixed medical-surgical intensive care unit: a prospective cohort study

BACKGROUND

For reasons unknown, a restrictive transfusion policy of red blood cells (RBC) is only gradually being implemented by Intensive Care Unit (ICU) physicians, resulting in a large variation in transfusion practice. Insight into physicians' transfusion decisions may aid efforts to restrict transfusion practice.

STUDY DESIGN AND METHODS

In a prospective cohort study, transfusion triggers were determined in patients consecutively admitted to an ICU during a 10-week period. Using a questionnaire, the reasons why ICU physicians transfused RBC were evaluated.

RESULTS

Among 310 admissions, 90 patients (29%) received a RBC transfusion. Eighty-one of these 90 patients were included in this analysis. RBC were transfused at a mean haemoglobin (Hb) level of 7.4+/-1.1 g/dL. Residents transfused RBC at a higher Hb level compared to senior staff (7.7+/-1.0 versus 6.9+/-1.3, respectively; p<0.05). The most important reason for physicians to transfuse RBC was the suspicion of bleeding. Age and coronary ischaemia were the predominant reasons for transfusing RBC in 4% and 12% of cases, respectively. The average order for RBC transfusion was four units. Of each order, 38% of the units were not administered.

CONCLUSION

RBC transfusion decisions are predominantly based on Hb levels rather than on patients' characteristics. Residents transfuse at a higher Hb level compared to more experienced physicians. The major determinant for physicians to transfuse RBC is bleeding. However, the majority of patients were transfused in the absence of bleeding, and many of these patients received multiple units. The need for RBC may be overestimated, resulting in wasted orders.

Anemia in the preoperative patient

Anemia is commonly encountered in the preoperative patient. Determination of the cause of the anemia can affect perioperative surgical and medical management and outcome. Red blood cell transfusions are often administered during the perioperative time period in patients with preoperative anemia, although evidence to support the optimal transfusion threshold is limited. The authors review the evaluation of anemia and evidence regarding perioperative blood transfusions. Recommendations on the treatment of anemia, including perioperative blood transfusions, are outlined.

The role of blood transfusion in the management of upper and lower intestinal tract bleeding

Patients with gastrointestinal (GI) haemorrhage use 13.8% of all red blood cell transfusions in England. This review addresses the evidence for red blood cell, fresh frozen plasma and platelet transfusions in acute and chronic blood loss, from both the upper and lower intestinal tract. It reviews the indications for transfusion in GI bleeding, the haematological consequences of massive blood loss and massive transfusion, and the importance of managing coagulopathy in bleeding patients. It also looks at the safety and risks of blood transfusion, and provides clinicians with evidence to reduce unnecessary transfusion. Large controlled clinical trials of blood transfusion specifically in GI bleeding are required, along with further research into the use of adjuvant therapies such as recombinant activated factor VIIa. Changing clinician behaviour to reduce inappropriate blood transfusion remains a key target for future transfusion research.

Evolution of adverse changes in stored RBCs

Recent studies have underscored questions about the balance of risk and benefit of RBC transfusion. A better understanding of the nature and timing of molecular and functional changes in stored RBCs may provide strategies to improve the balance of benefit and risk of RBC transfusion. We analyzed changes occurring during RBC storage focusing on RBC deformability, RBC-dependent vasoregulatory function, and S-nitrosohemoglobin (SNO-Hb), through which hemoglobin (Hb) O(2) desaturation is coupled to regional increases in blood flow in vivo (hypoxic vasodilation). Five hundred ml of blood from each of 15 healthy volunteers was processed into leukofiltered, additive solution 3-exposed RBCs and stored at 1-6 degrees C according to AABB standards. Blood was subjected to 26 assays at 0, 3, 8, 24 and 96 h, and at 1, 2, 3, 4, and 6 weeks. RBC SNO-Hb decreased rapidly (1.2 x 10(-4) at 3 h vs. 6.5 x 10(-4) (fresh) mol S-nitrosothiol (SNO)/mol Hb tetramer (P = 0.032, mercuric-displaced photolysis-chemiluminescence assay), and remained low over the 42-day period. The decline was corroborated by using the carbon monoxide-saturated copper-cysteine assay [3.0 x 10(-5) at 3 h vs. 9.0 x 10(-5) (fresh) mol SNO/mol Hb]. In parallel, vasodilation by stored RBCs was significantly depressed. RBC deformability assayed at a physiological shear stress decreased gradually over the 42-day period (P < 0.001). Time courses vary for several storage-induced defects that might account for recent observations linking blood transfusion with adverse outcomes. Of clinical concern is that SNO levels, and their physiological correlate, RBC-dependent vasodilation, become depressed soon after collection, suggesting that even "fresh" blood may have developed adverse biological characteristics.

The impact of bleeding in patients with acute coronary syndromes: how to optimize the benefits of treatment and minimize the risk

Recurrent ischemic events after an acute coronary syndrome (ACS) remain common. Antithrombotic therapy with coronary revascularization reduces the frequency of such life-threatening events. However, with the greater use of antithrombotic medications and early revascularization, bleeding has become an increasingly important problem. Not only does bleeding result in an immediate threat, but it is also associated with increased coronary artery disease mortality and reinfarction, both in the short and long term. Older patients and women, as well as patients with anemia, renal dysfunction, high-risk ACS, diabetes, hypertension and those undergoing invasive procedures, are at especially high risk for bleeding. Major bleeding is associated with a 60% increased risk of in-hospital death, and a fivefold increase in one-year mortality and reinfarction. However, the causal link between bleeding and increased coronary artery disease events is unproven. Although there is no proof that reducing bleeding events improves outcomes, the current paradigm for the management of ACS is a strategy to minimize recurrent ischemic events but also to minimize the risk of bleeding. Such a strategy includes matching the ACS risk to the most appropriate treatment, assessing the bleeding risk, using vascular access techniques to minimize bleeding, selecting the antithrombotic agent that is best for the patient, minimizing the duration of exposure to antithrombotic agents, using the correct dose of medications, recognizing the early signs of bleeding and using gastroprotective agents to minimize upper gastrointestinal bleeding.

Critical care issues in the early management of severe trauma

Violent trauma and road traffic injuries kill more than 2.5 million people in the world every year, for a combined mortality of 48 deaths per 100,000 population per year. Most trauma deaths occur at the scene or in the first hour after trauma, with a proportion from 34% to 50% occurring in hospitals. Preventability of trauma deaths has been reported as high as 76% and as low as 1% in mature trauma systems. Critical care errors may occur in a half of hospital trauma deaths, in most of the cases contributing to the death. The most common critical care errors are related to airway and respiratory management, fluid resuscitation, neurotrauma diagnosis and support, and delayed diagnosis of critical lesions. A systematic approach to the trauma patient in the critical care unit would avoid errors and preventable deaths.

Homologous blood transfusion is not required in surgery for adolescent idiopathic scoliosis

We studied 70 consecutive patients with adolescent idiopathic scoliosis who underwent corrective surgery. They were divided into two groups. In the study group of 38 patients one or more modern blood-conservation measures was used peri-operatively. The 32 patients in the control group did not have these measures. Both groups were similar in regard to age, body-weight, the number of levels fused and the type of surgery.

Only two patients in the study group were transfused with homologous blood and these transfusions were ‘off-protocol’. Wastage of autologous pre-donated units was minimal (6 of 83 units). By contrast, all patients in the control group were transfused with homologous blood. In the study group there was a significant decrease (p = 0.005) in the estimated blood loss when all the blood-conservation methods were used.

The use of blood-conservation measures, the lowering of the haemoglobin trigger for transfusion and the education of the entire team involved in the care of the patient can prevent the need for homologous blood transfusion in patients undergoing surgery for adolescent idiopathic scoliosis.

Scope of the problem: epidemiology of anemia and use of blood transfusions in critical care

Anemia is a common problem in critically ill patients. It is caused, in part, by blood loss related to phlebotomy for diagnostic testing, occult gastrointestinal bleeding, renal replacement therapies, surgical intervention, and traumatic injuries. Reduced red cell life span and nutritional deficiencies (iron, folate, vitamin B₁₂) may be other contributing factors. In addition, critically ill patients have impaired erythropoiesis because of blunted endogenous erythropoietin production and the direct inhibitory effects of inflammatory cytokines on red blood cell production by the bone marrow. Blood transfusions are commonly utilized for treatment of anemia in critical care, resulting in high use of blood transfusions in the intensive care unit (ICU). The percentage of patients transfused in the ICU is inversely related to admission hemoglobin and directly related to age and severity of illness. Patients with an increased length of stay in the ICU are also at increased risk for receiving blood transfusions. Studies are needed to improve our understanding of the pathophysiology of ICU-acquired anemia, to determine the efficacy of blood transfusions in critical care, and to investigate alternatives to blood transfusion for the treatment of anemia in the ICU.

Effect of a flow chart on use of blood transfusions in primary total hip and knee replacement: prospective before and after study

PROBLEM

A suspected high proportion of unnecessary blood transfusions occur in patients undergoing total joint replacement.

DESIGN

Prospective before and after study evaluating the impact of a one page flow chart aimed at reducing the use of blood transfusions.

SETTING

Orthopaedic tertiary care centre in Winterthur, Switzerland. 208 patients underwent primary total joint replacement of hips or knees during the control period (October 1998 to September 1999) and 217 during the intervention period (October 1999 to September 2000).

KEY MEASURES FOR IMPROVEMENT

Proportion of patients receiving allogeneic blood transfusions.

STRATEGIES FOR CHANGE

A simple one page flow chart, which summarised graphically the perioperative decision pathways for anaemic patients, was placed in all charts of patients undergoing total joint replacement and handed out to medical staff from 4 October 1999 onwards. The implementation of the flow chart focused on its endorsement by chief physicians and the development of a sense of "ownership" among physicians and nurses.

EFFECTS OF CHANGE

The proportion of patients receiving allogeneic blood decreased from 35.0% to 19.8% (absolute difference -15.2%, 95% confidence interval -23.3 to -7.0%). The percentage of patients donating and receiving autologous blood also decreased. This led to overall savings of about 23,000 pounds sterling (42,470 dollars; 34,441 euros) (103.50 pounds sterlingper patient undergoing total joint replacement). Differences became more pronounced after adjustment for confounding factors.

LESSONS LEARNT

Allogeneic blood transfusions in primary hip and knee replacement surgery may be reduced cost effectively by implementing a one page flow chart. Five key elements may have contributed: simplicity; wide distribution; no requirement for major changes; endorsement by local opinion leaders; and development of a sense of ownership. These elements may be used in other contexts to achieve sustained change of clinical practice.