Restrictive Versus Liberal Transfusion Strategies for Older Mechanically Ventilated Critically Ill Patients: A Randomized Pilot Trial*

Red Blood Cell Transfusion in Critically Ill Adults: An American College of Chest Physicians Clinical Practice Guideline

BACKGROUND

Blood products frequently are administered to critically ill patients. Considering recent trials and practice variability, a comprehensive review of current evidence was deemed essential to offer pertinent guidance to critical care practitioners. This American College of Chest Physicians (CHEST) guidelines panel examined the literature on RBC transfusions among critically ill patients overall and specific subgroups, including patients with gastrointestinal bleeding, acute coronary syndrome (ACS), cardiac surgery, isolated troponin elevation, and septic shock, to provide evidence-based recommendations.

STUDY DESIGN AND METHODS

A panel of experts developed 6 Population, Intervention, Comparator, and Outcome questions addressing RBC transfusions in critically ill patients and performed a comprehensive evidence review. The panel applied the Grading of Recommendations, Assessment, Development, and Evaluations approach to assess the certainty of evidence and to formulate and grade recommendations. A modified Delphi technique was used to reach consensus on the recommendations.

RESULTS

The initial search identified a total of 3,082 studies, and after the initial screening, 38 articles were reviewed. Among them, 23 studies met inclusion criteria, comprising 22 randomized controlled trials and 1 cohort study. Based on the analysis of these studies, the panel formulated 2 strong and 4 conditional recommendations. The overall quality of evidence for recommendations ranged from very low to moderate.

CONCLUSIONS

In most critically ill patients, a restrictive strategy was preferable to a permissive approach because it does not increase the risk of death or complications, but does decrease RBC use significantly. Data from critically ill subpopulations also supported a restrictive approach, except in patients with ACS, for whom favoring a restrictive approach could increase adverse outcomes.

A Contemporary Review of Blood Transfusion in Critically Ill Patients

Blood transfusion is a common therapeutic intervention in hospitalized patients. There are numerous indications for transfusion, including anemia and coagulopathy with deficiency of single or multiple coagulation components such as platelets or coagulation factors. Nevertheless, the practice of transfusion in critically ill patients has been controversial mainly due to a lack of evidence and the need to consider the appropriate clinical context for transfusion. Further, transfusion carries many risk factors that must be balanced with benefits. Therefore, transfusion practice in ICU patients has constantly evolved, and we endeavor to present a contemporary review of transfusion practices in this population guided by clinical trials and expert guidelines.

Does red blood cell transfusion affect clinical outcomes in critically ill patients? A report from a large teaching hospital in south Iran

BACKGROUND

Despite the beneficial effects, RBC transfusion can be associated with infectious and non-infectious complications in critically ill patients.

OBJECTIVES

Investigate current RBC transfusion practices and their effect on the clinical outcomes of patients in intensive care units (ICUs).

DESIGN

Retrospective observational study.

SETTING

Three mixed medical-surgical adult ICUs of a large academic tertiary hospital.

PATIENTS AND METHODS

From March 2018 to February 2020, all adult patients admitted to medical or surgical ICU. Patients who received one or more RBC transfusions during the first month of ICU admission were included in the "transfusion" group, while the remaining patients were assigned to the "non-transfusion" group.

MAIN OUTCOME MEASURES

Mortality and length of ICU and hospital stay.

SAMPLE SIZE

2159 patients.

RESULTS

Of 594 patients who recieved transfusions, 27% of patients received red blood cell (RBC) products. The mean pre-transfusion hemoglobin (Hb) level was 8.05 (1.46) g/dL. There was a significant relationship between higher APACHE II scores and ICU mortality in patients with Hb levels of 7-9 g/dL (OR adjusted=1.05). Also, ICU mortality was associated with age (OR adjusted=1.03), APACHE II score (OR adjusted=1.08), and RBC transfusion (OR adjusted=2.01) in those whose Hb levels were >9 (g/dl).

CONCLUSION

RBC transfusion was associated with an approximately doubled risk of ICU mortality in patients with Hb>9 g/dL. High APACHE II score and age increase the chance of death in the ICU by 8% and 3%, respectively. Hence, ICU physicians should consider a lower Hb threshold for RBC transfusion, and efforts must be made to optimize RBC transfusion practices.

LIMITATIONS

Single-center and retrospective study.

Assessing the impact of transfusion thresholds in patients with septic acute kidney injury: a retrospective study

Background

Sepsis is a severe condition that often leads to complications such as acute kidney injury, which significantly increases morbidity and mortality rates. Septic AKI (S-AKI) is common in ICU patients and is associated with poor outcomes. However, there is no consensus on the optimal transfusion threshold for achieving the best clinical results. This retrospective study aims to investigate the relationship between different transfusion thresholds during hospitalization and the prognosis of septic AKI.

Methods

Data from patients with S-AKI was extracted from MIMIC-IV. Based on the lowest hemoglobin level 24 h before transfusion, patients were divided into high-threshold (≥7 g/L) and low-threshold (<7 g/L) groups. We compared the outcomes between these two groups, including hospital and ICU mortality rates as primary outcomes, and 30 days, 60 days, and 90 days mortality rates, as well as duration of stay in ICU and hospital as secondary outcomes.

Results

A total of 5,654 patients were included in our study. Baseline characteristics differed significantly between the two groups, with patients in the low-threshold group generally being younger and having higher SOFA scores. After performing propensity score matching, no significant differences in survival rates were found between the groups. However, patients in the low-threshold group had a longer overall hospital stay.

Conclusion

A lower transfusion threshold does not impact the mortality rate in S-AKI patients, but it may lead to a longer hospital stay.

Red Blood Cell Transfusion: 2023 AABB International Guidelines

Importance

Red blood cell transfusion is a common medical intervention with benefits and harms.

Objective

To provide recommendations for use of red blood cell transfusion in adults and children.

Evidence Review

Standards for trustworthy guidelines were followed, including using Grading of Recommendations Assessment, Development and Evaluation methods, managing conflicts of interest, and making values and preferences explicit. Evidence from systematic reviews of randomized controlled trials was reviewed.

Findings

For adults, 45 randomized controlled trials with 20 599 participants compared restrictive hemoglobin-based transfusion thresholds, typically 7 to 8 g/dL, with liberal transfusion thresholds of 9 to 10 g/dL. For pediatric patients, 7 randomized controlled trials with 2730 participants compared a variety of restrictive and liberal transfusion thresholds. For most patient populations, results provided moderate quality evidence that restrictive transfusion thresholds did not adversely affect patient-important outcomes. Recommendation 1: for hospitalized adult patients who are hemodynamically stable, the international panel recommends a restrictive transfusion strategy considering transfusion when the hemoglobin concentration is less than 7 g/dL (strong recommendation, moderate certainty evidence). In accordance with the restrictive strategy threshold used in most trials, clinicians may choose a threshold of 7.5 g/dL for patients undergoing cardiac surgery and 8 g/dL for those undergoing orthopedic surgery or those with preexisting cardiovascular disease. Recommendation 2: for hospitalized adult patients with hematologic and oncologic disorders, the panel suggests a restrictive transfusion strategy considering transfusion when the hemoglobin concentration is less than 7 g/dL (conditional recommendations, low certainty evidence). Recommendation 3: for critically ill children and those at risk of critical illness who are hemodynamically stable and without a hemoglobinopathy, cyanotic cardiac condition, or severe hypoxemia, the international panel recommends a restrictive transfusion strategy considering transfusion when the hemoglobin concentration is less than 7 g/dL (strong recommendation, moderate certainty evidence). Recommendation 4: for hemodynamically stable children with congenital heart disease, the international panel suggests a transfusion threshold that is based on the cardiac abnormality and stage of surgical repair: 7 g/dL (biventricular repair), 9 g/dL (single-ventricle palliation), or 7 to 9 g/dL (uncorrected congenital heart disease) (conditional recommendation, low certainty evidence).

Conclusions and Relevance

It is good practice to consider overall clinical context and alternative therapies to transfusion when making transfusion decisions about an individual patient.

An analysis of quality of life and functional outcomes as reported in randomized trials for red cell transfusions

BACKGROUND

Meta-analyses of randomized controlled trials (RCTs) evaluating thresholds for red blood cell (RBC) transfusion typically focus on mortality; however, other outcomes are highly relevant. The aim of this study is to summarize the effects of different transfusion thresholds on the outcomes of quality of life (QoL) and function.

STUDY DESIGN

We extracted data from RCTs identified in a recently published Cochrane systematic review. Primary analysis was descriptive.

RESULTS

A total of 23 RCTs with 13,743 adult participants were included. Fifteen RCTs included patients in the postoperative period, of which 9 RCTs were conducted in hip (n = 3024) and 6 (n = 8672) in cardiac surgeries; 5 RCTs (n = 489) were in patients with hematological malignancies; 2 in the setting of bleeding (gastrointestinal bleed [n = 936] and postpartum [n = 521]); and one RCT (n = 936) included critically ill patients. QoL and function were reported using a variety of questionnaires and tools. The timing of assessments varied between trials. No clear clinical differences in QoL outcomes were identified in comparisons between restrictive and liberal transfusion thresholds.

DISCUSSION

There is no evidence that a liberal transfusion strategy improves QoL and functional outcomes. However, the substantial limitations of many included studies indicate the need for further well-designed and adequately powered trials.

Perioperative Fluid Management

The medical complexity of the geriatric patients has been steadily rising. Still, as outcomes of surgical procedures in the elderly are improving, centers are pushing boundaries. There is also a growing appreciation of the importance of perioperative fluid management on postoperative outcomes, especially in the elderly. Optimal fluid management in this cohort is challenging due to the combination of age-related physiological changes in organ function, increased comorbid burden, and larger fluid shifts during more complex surgical procedures. The current state-of-the-art approach to fluid management in the perioperative period is outlined.

How I treat anemia with red blood cell transfusion and iron

Severe anemia is commonly treated with red blood cell transfusion. Clinical trials have demonstrated that a restrictive transfusion strategy of 7 to 8 g/dL is as safe as a liberal transfusion strategy of 9 to 10 g/dL in many clinical settings. Evidence is lacking for subgroups of patients, including those with preexisting coronary artery disease, acute myocardial infarction, congestive heart failure, and myelodysplastic neoplasms. We present 3 clinical vignettes that highlight the clinical challenges in caring for patients with coronary artery disease with gastrointestinal bleeding, congestive heart failure, or myelodysplastic neoplasms. We emphasize that transfusion practice should be guided by patient symptoms and preferences in conjunction with the patient's hemoglobin concentration. Along with the transfusion decision, evaluation and management of the etiology of the anemia is essential. Iron-restricted erythropoiesis is a common cause of anemia severe enough to be considered for red blood cell transfusion but diagnosis and management of absolute iron deficiency anemia, the anemia of inflammation with functional iron deficiency, or their combination may be problematic. Intravenous iron therapy is generally the treatment of choice for absolute iron deficiency in patients with complex medical disorders, with or without coexisting functional iron deficiency.

Patient Blood Management, Anemia, and Transfusion Optimization Across Surgical Specialties

Patient blood management (PBM) is a systematic, evidence-based approach to improve patient outcomes by managing and preserving a patient's own blood and minimizing allogenic transfusion need and risk. According to the PBM approach, the goals of perioperative anemia management include early diagnosis, targeted treatment, blood conservation, restrictive transfusion except in cases of acute and massive hemorrhage, and ongoing quality assurance and research efforts to advance overall blood health.

Mortality and its associated factors in transfused patients at a tertiary hospital in Uganda

Blood transfusion is life-saving but sometimes also associated with morbidity and mortality. There is limited data on mortality in patients transfused with whole blood in sub-Saharan Africa. We described the 30-day all-cause mortality and its associated factors in patients transfused with whole blood to inform appropriate clinical intervention and research priorities to mitigate potential risks. A retrospective study was performed on purposively sampled patients transfused with whole blood at the Uganda Cancer Institute (UCI) and Mulago hospital in the year 2018. Two thousand twelve patients with a median (IQR) age of 39 (28–54) years were enrolled over a four month period. There were 1,107 (55%) females. Isolated HIV related anaemia (228, 11.3%), gynaecological cancers (208, 10.3%), unexplained anaemia (186, 9.2%), gastrointestinal cancers (148, 7.4%), and kidney disease (141, 7.0%) were the commonest diagnoses. Most patients were transfused with only one unit of blood (n = 1232, 61.2%). The 30 day all-cause mortality rate was 25.2%. Factors associated with mortality were isolated HIV related anaemia (HR 3.2, 95% CI, 2.3–4.4), liver disease (HR 3.0, 95% CI, 2.0–4.5), kidney disease (HR 2.2, 95% CI, 1.5–3.3; p<0.01), cardiovascular disease (HR 2.9, 95% CI, 1.6–5.4; p<0.01), respiratory disease (HR 3.0, 95% CI 1.8–4.9; p<0.01), diabetes mellitus (HR 4.1, 95% CI, 2.3–7.4; p<0.01) and sepsis (HR 6.2, 95% CI 3.7–10.4; p<0.01). Transfusion with additional blood was associated with survival (HR 0.8, 95% CI 0.7–0.9, p<0.01). In conclusion, the 30-day all-cause mortality was higher than in the general inpatients. Factors associated with mortality were isolated HIV related anaemia, kidney disease, liver disease, respiratory disease, cardiovascular disease, diabetes mellitus and sepsis. Transfusion with additional blood was associated with survival. These findings require further prospective evaluation.

Haemoglobin value and red blood cell transfusions in prolonged weaning from mechanical ventilation: a retrospective observational study

INTRODUCTION

The role of haemoglobin (Hb) value and red blood cell (RBC) transfusions in prolonged weaning from mechanical ventilation (MV) is still controversial. Pathophysiological considerations recommend a not too restrictive transfusion strategy, whereas adverse effects of transfusions are reported. We aimed to investigate the association between Hb value, RBC transfusion and clinical outcome of patients undergoing prolonged weaning from MV.

METHODS

We performed a retrospective, single-centred, observational study including patients being transferred to a specialised weaning unit. Data on demographic characteristics, comorbidities, current and past medical history and the current course of treatment were collected. Weaning failure and mortality were chosen as primary and secondary endpoint, respectively. Differences between transfused and non-transfused patients were analysed. To evaluate the impact of different risk factors including Hb value and RBC transfusion on clinical outcome, a multivariate logistic regression analysis was used.

RESULTS

184 patients from a specialised weaning unit were analysed, of whom 36 (19.6%) failed to be weaned successfully. In-hospital mortality was 18.5%. 90 patients (48.9%) required RBC transfusion during the weaning process, showing a significantly lower Hb value (g/L) (86.3±5.3) than the non-transfusion group (95.8±10.5). In the multivariate regression analysis (OR 3.24; p=0.045), RBC transfusion was associated with weaning failure. However, the transfusion group had characteristics indicating that these patients were still in a more critical state of disease.

CONCLUSIONS

In our analysis, the need for RBC transfusion was independently associated with weaning failure. However, it is unclear whether the transfusion itself should be considered an independent risk factor or an additional symptom of a persistent critical patient condition.

Impact of restrictive red blood cell transfusion strategy on thrombosis-related events: A meta-analysis and systematic review

BACKGROUND AND OBJECTIVES

There is an ongoing controversy regarding the risks of restrictive and liberal red blood cell (RBC) transfusion strategies. This meta-analysis assessed whether transfusion at a lower threshold was superior to transfusion at a higher threshold, with regard to thrombosis-related events, that is, whether these outcomes can benefit from a restrictive transfusion strategy is debated.

MATERIALS AND METHODS

We searched PubMed, Cochrane Central Register of Controlled Trials and Scopus from inception up to 31 July 2021. We included randomized controlled trials (RCTs) in any clinical setting that evaluated the effects of restrictive versus liberal RBC transfusion in adults. We used random-effects models to calculate the risk ratios (RRs) and 95% confidence intervals (CIs) based on pooled data.

RESULTS

Thirty RCTs involving 17,334 participants were included. The pooled RR for thromboembolic events was 0.65 (95% CI 0.44-0.94; p = 0.020; I²  = 0.0%, very low-quality evidence), favouring the restrictive strategy. There were no significant differences in cerebrovascular accidents (RR = 0.83; 95% CI 0.64-1.09; p = 0.180; I²  = 0.0%, very low-quality evidence) or myocardial infarction (RR = 1.05; 95% CI 0.87-1.26; p = 0.620; I²  = 0.0%, low-quality evidence). Subgroup analyses showed that a restrictive (relative to liberal) strategy reduced (1) thromboembolic events in RCTs conducted in North America and (2) myocardial infarctions in the subgroup of RCTs where the restrictive transfusion threshold was 7 g/dl but not in the 8 g/dl subgroup (with a liberal transfusion threshold of 10 g/dl in both subgroups).

CONCLUSIONS

A restrictive (relative to liberal) transfusion strategy may be effective in reducing venous thrombosis but not arterial thrombosis.

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.

Association between blood transfusion and ventilator-associated events: a nested case-control study

OBJECTIVES

The association between blood transfusion and ventilator-associated events (VAEs) has not been fully understood. We sought to determine whether blood transfusion increases the risk of a VAE.

DESIGN

Nested case-control study.

SETTING

This study was based on a registry of healthcare-associated infections in intensive care units at West China Hospital system.

PATIENTS

1,657 VAE cases and 3,293 matched controls were identified.

METHODS

For each case, 2 controls were randomly selected using incidence density sampling. We defined blood transfusion as a time-dependent variable, and we used weighted Cox models to calculate hazard ratios (HRs) for all 3 tiers of VAEs.

RESULTS

Blood transfusion was associated with increased risk of ventilator-associated complication-plus (VAC-plus; HR, 1.47; 95% CI, 1.22-1.77; P <.001), VAC-only (HR, 1.29; 95% CI, 1.01-1.65; P = .038), infection-related VAC-plus (IVAC-plus; HR, 1.78; 95% CI, 1.33-2.39; P < .001), and possible ventilator-associated pneumonia (PVAP; HR, 2.10; 95% CI, 1.10-3.99; P = .024). Red blood cell (RBC) transfusion was also associated with increased risk of VAC-plus (HR, 1.34; 95% CI, 1.08-1.65; P = .007), IVAC-plus (HR, 1.70; 95% CI, 1.22-2.36; P = .002), and PVAP (HR, 2.49; 95% CI, 1.17-5.28; P = .018). Compared to patients without transfusion, the risk of VAE was significantly higher in patients with RBC transfusions of >3 units (HR, 1.73; 95% CI, 1.25-2.40; P = .001) but not in those with RBC transfusions of 0-3 units.

CONCLUSION

Blood transfusions were associated with increased risk of all tiers of VAE. The risk was significantly higher among patients who were transfused with >3 units of RBCs.

Lower versus higher hemoglobin threshold for transfusion in ARDS patients with and without ECMO

BACKGROUND

Efficacy and safety of different hemoglobin thresholds for transfusion of red blood cells (RBCs) in adults with an acute respiratory distress syndrome (ARDS) are unknown. We therefore assessed the effect of two transfusion thresholds on short-term outcome in patients with ARDS.

METHODS

Patients who received transfusions of RBCs were identified from a cohort of 1044 ARDS patients. After propensity score matching, patients transfused at a hemoglobin concentration of 8 g/dl or less (lower-threshold) were compared to patients transfused at a hemoglobin concentration of 10 g/dl or less (higher-threshold). The primary endpoint was 28-day mortality. Secondary endpoints included ECMO-free, ventilator-free, sedation-free, and organ dysfunction-free composites.

MEASUREMENTS AND MAIN RESULTS

One hundred ninety-two patients were eligible for analysis of the matched cohort. Patients in the lower-threshold group had similar baseline characteristics and hemoglobin levels at ARDS onset but received fewer RBC units and had lower hemoglobin levels compared with the higher-threshold group during the course on the ICU (9.1 [IQR, 8.7-9.7] vs. 10.4 [10-11] g/dl, P < 0.001). There was no difference in 28-day mortality between the lower-threshold group compared with the higher-threshold group (hazard ratio, 0.94 [95%-CI, 0.59-1.48], P = 0.78). Within 28 days, 36.5% (95%-CI, 27.0-46.9) of the patients in the lower-threshold group compared with 39.5% (29.9-50.1) of the patients in the higher-threshold group had died. While there were no differences in ECMO-free, sedation-free, and organ dysfunction-free composites, the chance for successful weaning from mechanical ventilation within 28 days after ARDS onset was lower in the lower-threshold group (subdistribution hazard ratio, 0.36 [95%-CI, 0.15-0.86], P = 0.02).

CONCLUSIONS

Transfusion at a hemoglobin concentration of 8 g/dl, as compared with a hemoglobin concentration of 10 g/dl, was not associated with an increase in 28-day mortality in adults with ARDS. However, a transfusion at a hemoglobin concentration of 8 g/dl was associated with a lower chance for successful weaning from the ventilator during the first 28 days after ARDS onset.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03871166.

7 Is the New 8: Improving Adherence to Restrictive PRBC Transfusions in the Pediatric ICU

Up to 30%-40% of children admitted to the pediatric intensive care unit (PICU) have anemia, and approximately 15% receive packed red blood cell (pRBC) transfusions. Current literature supports a pRBC transfusion threshold of hemoglobin less than or equal to seven for most PICU patients. Our objective was to determine pRBC transfusion rates, assess compliance with transfusion guidelines, understand patient-level variables that affect transfusion practices, and use cross-industry innovation to implement a practice strategy. This was a pre-post study of pediatric patients admitted to our PICU. We collected baseline data on pRBC transfusion practices. Next, we organized an innovation platform, which generated multi-industry ideas and produced an awareness campaign to effect pRBC ordering behavior. Innovative educational interventions were implemented, and postintervention transfusion practices were monitored. Statistical analysis was performed using linear mixed models. A p value < .05 was considered statistically significant. At baseline, 41% of pRBC transfusions met restrictive transfusion guidelines with a pretransfusion hemoglobin less than or equal to 7 g/dl. In the postintervention period, 53% of transfusions met restrictive transfusion guidelines (odds ratio 1.66, 95% confidence interval 1.21-2.28). Implementation of a behavioral campaign using multi-industry innovation led to improved adherence to pRBC transfusion guidelines in a tertiary care PICU.

Critical Care Society of Southern Africa adult patient blood management guidelines: 2019 Round-table meeting, CCSSA Congress, Durban, 2018

The CCSSA PBM Guidelines have been developed to improve patient blood management in critically ill patients in southern Africa. These consensus recommendations are based on a rigorous process by experts in the field of critical care who are also practicing in South Africa (SA). The process comprised a Delphi process, a round-table meeting (at the CCSSA National Congress, Durban, 2018), and a review of the best available evidence and international guidelines. The guidelines focus on the broader principles of patient blood management and incorporate transfusion medicine (transfusion guidelines), management of anaemia, optimisation of coagulopathy, and administrative and ethical considerations. There are a mix of low-middle and high-income healthcare structures within southern Africa. Blood products are, however, provided by the same not-for-profit non-governmental organisations to both private and public sectors. There are several challenges related to patient blood management in SA due most notably to a high incidence of anaemia, a frequent shortage of blood products, a small donor population, and a healthcare system under financial strain. The rational and equitable use of blood products is important to ensure best care for as many critically ill patients as possible. The summary of the recommendations provides key practice points for the day-to-day management of critically ill patients. A more detailed description of the evidence used to make these recommendations follows in the full clinical guidelines section.

Differences among hemoglobin thresholds for red blood cell transfusions in patients with hematological diseases in teaching hospitals: a real world data in Japan

A hemoglobin (Hb) threshold level of 7 g/dL has been proposed for red blood cell (RBC) transfusion in patients with chronic anemia in the Japanese guideline since 2005. However, Hb thresholds for hematological diseases in clinical practice and factors responsible for higher Hb thresholds remain unclear. Hb thresholds were collected for patients with hematological diseases from 32 Japanese teaching hospitals. Uni- and multivariate analyses were used to analyze relationships between Hb threshold level and various patient and hospital factors. In total, 4996 units of RBC were transfused to 1054 patients with hematological diseases in 2421 transfusions. Median age was 68 years. Myelodysplastic syndrome was the most frequent diagnosis. Overall median Hb threshold level was 6.9 g/dL. Multivariate linear regression analysis detected the following variables associated with Hb threshold level: hospital; cardiovascular disease; symptomatic anemia; and hematopoietic stem cell transplantation. Hospital was the most significant factor. Collectively, median Hb threshold level in clinical practice in Japan was similar to the guidelines. Higher Hb threshold level depended on the hospitals at which the transfusions were performed as well as patient condition. Educational approaches directed toward hospitals may be useful to promote transfusion guidelines.

Heterogenous treatment effects of transfusion thresholds by patient age: Post-hoc analysis of the TRISS trial

BACKGROUND

Use of a lower haemoglobin (Hb) threshold to guide red blood cell (RBC) transfusion is now generally recommended in critically ill patients, but uncertainty remains regarding the optimal Hb threshold for RBC transfusion in patients of different ages.

METHODS

We conducted a post-hoc analysis of 998 patients with septic shock and anaemia randomised to RBC transfusion at a Hb threshold of 7 g/dl [4.3 mmol/l] vs 9 g/dl [5.6 mmol/l] in the Transfusion Requirements in Septic Shock (TRISS) trial. We assessed if there were heterogeneous effects between the allocated Hb threshold and patient age categorised and on the continuous scale. The primary outcome was 1-year mortality; the secondary outcome was 90-day mortality. Both outcomes were analysed using logistic regression models and in sensitivity analyses with additional adjusting for site of enrolment, presence of haematological malignancy and the Sequential Organ Failure Assessment (SOFA) score. The secondary analyses were Kaplan-Meier curves with corresponding log-rank tests.

RESULTS

We found no heterogeneity between patient age and the allocated Hb thresholds for RBC transfusion for 1-year mortality or 90-day mortality in the primary analyses. The sensitivity analyses suggested heterogeneity between age groups regarding 90-day mortality, however, this was not consistent for 1-year mortality or when assessing age on the continuous scale.

CONCLUSION

In this post-hoc study of ICU patients with septic shock, we found no reliable heterogeneous effects of transfusion at a Hb threshold of 7 vs 9 g/dl according to patient age on mortality. However, due to low power, this study should only be considered as hypothesis generating.

Transfusion strategies in non-bleeding critically ill adults: a clinical practice guideline from the European Society of Intensive Care Medicine

OBJECTIVE

To develop evidence-based clinical practice recommendations regarding transfusion practices in non-bleeding, critically ill adults.

DESIGN

A task force involving 13 international experts and three methodologists used the GRADE approach for guideline development.

METHODS

The task force identified four main topics: red blood cell transfusion thresholds, red blood cell transfusion avoidance strategies, platelet transfusion, and plasma transfusion. The panel developed structured guideline questions using population, intervention, comparison, and outcomes (PICO) format.

RESULTS

The task force generated 16 clinical practice recommendations (3 strong recommendations, 13 conditional recommendations), and identified five PICOs with insufficient evidence to make any recommendation.

CONCLUSIONS

This clinical practice guideline provides evidence-based recommendations and identifies areas where further research is needed regarding transfusion practices and transfusion avoidance in non-bleeding, critically ill adults.

Liberal Transfusion versus Restrictive Transfusion and Outcomes in Critically Ill Adults: A Meta-Analysis

Objective

We aimed to determine whether the restrictive red-cell transfusion strategy was superior to the liberal one in reducing all-cause mortality in critically ill adults.

Methods

The MEDLINE, EMBASE, PubMed, Web of Science, and Cochrane Library Central Register of Controlled Trials databases were searched from inception to January 2019 to identify meta-analyses or systematic reviews and published randomized controlled trials which were restrictive versus liberal blood transfusion with mortality as the endpoint in critically ill adults. We used two search routes whereby one search was restricted to systematic reviews, reviews, or meta-analysis, and the other was not restricted. There were no date restrictions, but language was limited to English and the population was restricted to critically ill adults. The data of study methods, participant characteristics, and outcomes were extracted and analyzed independently by 2 reviewers. The main outcome was all-cause mortality.

Results

Through screening the obtained records, we enrolled 7 randomized clinical trials that included information on restrictive versus liberal red-cell transfusion and mortality of intensive care unit (ICU) patients. Involving a total of 7,363 ICU adult patients, ICU mortality (risk ratio [RR] 0.82, 95% confidence interval [CI] 0.62, 1.08, p = 0.15), 28/30-day mortality (RR 0.98, 95% CI 0.84, 1.13, p = 0.74), 60-day mortality (RR 1.01, 95% CI 0.87, 1.16, p = 0.91), 90-day mortality (RR 1.02, 95% CI 0.92, 1.14, p = 0.69), 120-day mortality (RR 1.29, 95% CI 0.67, 2.47, p = 0.44), and 180-day mortality (RR 0.91, 95% CI 0.75, 1.12, p = 0.38) were not statistically significantly different when the restrictive transfusion strategy was compared with the liberal transfusion strategy. However, we surprisingly discovered that 112 out of 469 (24%) patients who received a unit RBC transfusion when hemoglobin was less than 7 g/dL, and 142 out of 469 (30.3%) who received a unit of RBC transfused with hemoglobin less than 9 g/dL, had died during hospitalization (RR 0.79, 95% CI 0.64, 0.97, p = 0.03). The results showed that the restrictive transfusion strategy could decrease in-hospital mortality compared with the liberal transfusion strategy. It was safe to utilize a restrictive transfusion threshold of less than 7 g/dL in stable critically ill adults.

Conclusions

In this study, we found that the restrictive red-cell transfusion strategy potentially reduced in-hospital mortality in critically ill adults with anemia compared with the liberal strategy.

Is haemoglobin below 7.0 g/dL an optimal trigger for allogenic red blood cell transfusion in patients admitted to intensive care units? A meta-analysis and systematic review

OBJECTIVES

We employed a comprehensive systematic review and meta-analysis to assess benefits and risks of a threshold of haemoglobin level below 7 g/dL versus liberal transfusion strategy among critically ill patients, and even patients with septic shock.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

We performed systematical searches for relevant randomised controlled trials (RCTs) in the Cochrane Library, EMBASE and PubMed databases up to 1 September 2019.

ELIGIBILITY CRITERIA

RCTs among adult intensive care unit (ICU) patients comparing 7 g/dL as restrictive strategy with liberal transfusion were incorporated.

DATA EXTRACTION AND SYNTHESIS

The clinical outcomes, including short-term mortality, length of hospital stay, length of ICU stay, myocardial infarction (MI) and ischaemic events, were screened and analysed after data collection. We applied odds ratios (ORs) to analyse dichotomous outcomes and standardised mean differences (SMDs) to analyse continuous outcomes with fixed or random effects models based on heterogeneity evaluation for each outcome.

RESULTS

Eight RCTs with 3415 patients were included. Compared with a more liberal threshold, a red blood cell (RBC) transfusion threshold <7 g/dL haemoglobin showed no significant difference in short-term mortality (OR: 0.90, 95% CI: 0.67 to 1.21, p=0.48, I²=53%), length of hospital stay (SMD: -0.11, 95% CI: -0.30 to 0.07, p=0.24, I²=71%), length of ICU stay (SMD: -0.03, 95% CI: -0.14 to 0.08, p=0.54, I²=0%) or ischaemic events (OR: 0.80, 95% CI: 0.43 to 1.48, p=0.48, I²=51%). However, we found that the incidence of MI (OR: 0.54, 95% CI: 0.30 to 0.98, p=0.04, I²=0%) was lower in the group with the threshold <7 g/dL than that with the more liberal threshold.

CONCLUSIONS

An RBC transfusion threshold <7 g/dL haemoglobin is incapable of decreasing short-term mortality in ICU patients according to currently published evidences, while it might have potential role in reducing MI incidence.

Anemia and red blood cell transfusion practice in prolonged mechanically ventilated patients admitted to a specialized weaning center: an observational study

Background

The impact of anemia and red blood cell (RBC) transfusion on weaning from mechanical ventilation is not known. In theory, transfusions could facilitate liberation from the ventilator by improving oxygen transport capacity. In contrast, retrospective studies of critically ill patients showed a positive correlation of transfusions with prolonged mechanical ventilation, increased mortality rates, and increased risk of nosocomial infections, which in turn could adversely affect weaning outcome.

Methods

Retrospective, observational study on prolonged mechanically ventilated, tracheotomized patients (n = 378), admitted to a national weaning center over a 5 year period. Medical records were reviewed to obtain data on patients’ demographics, comorbidities, blood counts, transfusions, weaning outcome, and nosocomial infections, defined according to the criteria of the U.S. Centers for Disease Control and Prevention. The impact of RBC transfusion on outcome measures was assessed using regression models.

Results

Ninety-eight percent of all patients showed anemia on admission to the weaning center. Transfused and non-transfused patients differed significantly regarding disease severity and comorbidities. In multivariate analyses, RBC transfusion, but not mean hemoglobin concentration in the course of weaning, was independently correlated with weaning duration (adjusted β 12.386, 95% CI 9.335–15.436; p <  0.001) and hospital length of stay (adjusted β 16.116, 95% CI 8.925–23.306; p <  0.001); there was also a trend toward increased hospital mortality (adjusted odds ratio [OR] 2.050, 95% CI 0.995–4.224; p = 0.052), but there was no independent correlation with weaning outcome or nosocomial infections. In contrast, hemoglobin level on the day of admission to the weaning center was independently associated with hospital mortality (adjusted OR 0.956, 95% CI 0.924–0.989; p = 0.010), appearing significantly elevated at values below 8.5 g/dl (AUC 0.670, 95% CI 0.593–0.747; p <  0.001).

Conclusions

A high percentage of prolonged mechanically ventilated patients showed anemia on admission to the weaning center. RBC transfusion was independently correlated with worse outcomes. Since transfused patients differed significantly regarding their clinical characteristics and comorbidities, RBC transfusion might be an indicator of disease severity rather than directly impacting patient prognosis.

Use of red blood cells in Danish intensive care units: A population-based register study

BACKGROUND

Red blood cell (RBC) transfusion is common in the intensive care unit (ICU). Recent trials have shown that a restrictive transfusion strategy is safe in most patients, and recent guidelines recommend such a strategy in most ICU patients. It is unknown if this has translated into a change in clinical practice.

METHODS

We conducted a population-based register study of RBC transfusions in ICUs in the Danish Capital Region between 1st of January 2011 and 31st of December 2016 by linking data from the regional blood bank and the Danish Intensive Care Database. We used crude data and run- and control-charts to analyse changes in the number of RBC transfusions.

RESULTS

We included 27 835 ICU admissions of which 6936 received 40 889 RBC units. The crude use was 36.2 RBC units per one-hundred patient bed-days in 2011 vs 29.8 in 2016. The run-chart analysis did not confirm a change in the total use of RBC units in all ICUs combined, and we observed no change in the proportion of transfused patients or in the use of RBCs among transfused patients. Sensitivity analyses showed decreased use of RBC units in two general ICUs, and a reduced use of RBC units among medical ICU patients.

CONCLUSIONS

In this population-based register study, we did not with certainty observe changes over time in the use of RBC transfusions in all patients in all ICUs in the Danish Capital Region. A reduction in RBC use may have occurred in some general ICUs and in medical ICU patients.

Lower vs higher transfusion threshold in septic shock patients of different ages: A study protocol

BACKGROUND

Current evidence indicates that it is safe to use a lower haemoglobin (Hb) threshold for red blood cell (RBC) transfusion as compared to a higher Hb-threshold. However, the recent Transfusion Requirements in Cardiac Surgery (TRICS-3) trial reported a significant interaction between patient age and the effect of lower vs higher Hb-thresholds for RBC transfusion. The interaction between patient age and transfusion strategy appears to differ between trials.

METHODS

This is the protocol and statistical analysis plan for a post hoc analysis of the Transfusion Requirements in Septic Shock (TRISS) trial. We will assess the effect of a lower vs a higher Hb-threshold for RBC transfusion in patients of different ages with septic shock. The primary and secondary outcomes are 1-year mortality and 90-day mortality respectively. We will assess age divided into six age groups and as a continuous variable and present baseline characteristics and odds ratios derived from both simple and adjusted (for the Sequential Organ Failure Assessment score, haematological malignancy, age and trial site) logistic regression models and P-values for the test-of-interaction. Furthermore, we will compare outcomes according to Hb-threshold in each age group using Kaplan-Meier curves and log-rank tests.

DISCUSSION

The outlined study will make a detailed assessment of potential interaction of patient age with transfusion strategy in patients with septic shock. This may inform future trials on the benefits and harms of RBC transfusion.

Should Transfusion Trigger Thresholds Differ for Critical Care Versus Perioperative Patients? A Meta-Analysis of Randomized Trials

Supplemental Digital Content is available in the text.

Objective:

To address the significant uncertainty as to whether transfusion thresholds for critical care versus surgical patients should differ.

Design:

Meta-analysis of randomized controlled trials.

Setting:

Medline, EMBASE, and Cochrane Library searches were performed up to 15 June 2016.

Patients:

Trials had to enroll adult surgical or critically ill patients for inclusion.

Interventions:

Studies had to compare a liberal versus restrictive threshold for the transfusion of allogeneic packed RBCs.

Measurements and Main Results:

The primary outcome was 30-day all-cause mortality, sub-grouped by surgical and critical care patients. Secondary outcomes included myocardial infarction, stroke, renal failure, allogeneic blood exposure, and length of stay. Odds ratios and weighted mean differences were calculated using random effects meta-analysis. To assess whether subgroups were significantly different, tests for subgroup interaction were used. Subgroup analysis by trials enrolling critically ill versus surgical patients was performed. Twenty-seven randomized controlled trials (10,797 patients) were included. In critical care patients, restrictive transfusion resulted in significantly reduced 30-day mortality compared with liberal transfusion (odds ratio, 0.82; 95% CI, 0.70–0.97). In surgical patients, a restrictive transfusion strategy led to the opposite direction of effect for mortality (odds ratio, 1.31; 95% CI, 0.94–1.82). The subgroup interaction test was significant (p = 0.04), suggesting that the effect of restrictive transfusion on mortality is statistically different for critical care (decreased risk) versus surgical patients (potentially increased risk or no difference). Regarding secondary outcomes, for critically ill patients, a restrictive strategy resulted in reduced risk of stroke/transient ischemic attack, packed RBC exposure, transfusion reactions, and hospital length of stay. In surgical patients, restrictive transfusion resulted in reduced packed RBC exposure.

Conclusions:

The safety of restrictive transfusion strategies likely differs for critically ill patients versus perioperative patients. Further trials investigating transfusion strategies in the perioperative setting are necessary.

Anemia at Discharge in Elderly Trauma Patients is Not Associated with Six-Month Mortality

Few studies have evaluated outcomes in geriatric trauma patients discharged with anemia. Our hypothesis was that anemia at discharge was not associated with six-month mortality. A 22-month retrospective study of trauma patients ≥ 65 years was conducted from 2015 to 2016. The end point was six-month mortality. The degree of anemia at admission (admission hemoglobin [AHb]) and discharge (discharge hemoglobin [DHb]) was categorized as follows based on hemoglobin (Hb) (g/dL): I (>10), II (>9 and ≤10), III (>8 and ≤9), and IV (≤8). Univariate analysis and multivariate analysis were performed to determine the association of AHb and DHb with the end point. Nine hundred forty-nine patients were analyzed (median age, 82 years). Six-month mortality was 11 per cent. Mortality was associated with AHb by univariate analysis (I:10% [84/831]; II: 13% [9/67]; III: 22% [7/32]; and IV: 26% [5/19]) ( P = 0.003). DHb was not associated with mortality (I:11% [65/613]; II: 12% [21/183]; III: 10% [12/116]; and IV: 18% [7/39]) ( P = 0.37). Logistic regression found that AHb category IV, age, and chronic kidney disease were independently associated with the end point. In geriatric patients, the severity of anemia at admission and not at discharge predicted six-month mortality. Discharging patients with an Hb of ≤8 g/dL was not adversely associated with mortality.

A retrospective observational analysis of red blood cell transfusion practices in stable, non-bleeding adult patients admitted to nine medical-surgical intensive care units

Background

Red blood cell (RBC) transfusions are common procedures performed in the intensive care unit (ICU). However, conservative transfusion approaches have been recommended to avoid RBC transfusions that are not clinically necessary and to achieve optimal patient outcomes. The objective of this study was to examine the utilization and costs of RBC transfusions in medical-surgical ICUs and to compare this information against clinical guideline recommendations for best practice.

Methods

Retrospective observational analysis of RBC transfusions in stable, non-bleeding adult patients was examined in a geographically-defined, population-based cohort of nine integrated ICUs between April 1, 2014 and December 31, 2016. RBC transfusions associated with a pre-transfusion hemoglobin value of 70 g/L or more were examined through linear and logistic regression. The total costs of RBC transfusions, based on the RBC unit cost, were estimated.

Results

A total of 4632 RBC transfusions (2287 ICU admissions) were included. Pre-transfusion hemoglobin values were identified for 4487 transfusions. On average, 61% occurred at or above a hemoglobin value of 70 g/L (mean 73.4 ± 9.2 g/L). Factors associated with such transfusions included being male, age over 75, Sequential Organ Failure Assessment (SOFA) score greater or equal to 10, transfer from operating room, gastrointestinal bleeding, and trauma. A pre-transfusion hemoglobin value at or above 70 g/L was associated with increased odds of ICU mortality; there was no impact on overall hospital mortality. The total estimated cost of RBC transfusions was $2.99M Canadian dollars (CAD), with $1.82M CAD attributed to those with a hemoglobin value at or above 70 g/L.

Conclusions

Over half of the examined RBC transfusions may not have aligned with recommended best practice; this suggests significant opportunity for improvement. The present findings are an essential step towards optimizing RBC transfusions in the ICU.

Electronic supplementary material

The online version of this article (10.1186/s40560-019-0375-3) contains supplementary material, which is available to authorized users.

Patient Blood Management: Recommendations From the 2018 Frankfurt Consensus Conference

IMPORTANCE

Blood transfusion is one of the most frequently used therapies worldwide and is associated with benefits, risks, and costs.

OBJECTIVE

To develop a set of evidence-based recommendations for patient blood management (PBM) and for research.

EVIDENCE REVIEW

The scientific committee developed 17 Population/Intervention/Comparison/Outcome (PICO) questions for red blood cell (RBC) transfusion in adult patients in 3 areas: preoperative anemia (3 questions), RBC transfusion thresholds (11 questions), and implementation of PBM programs (3 questions). These questions guided the literature search in 4 biomedical databases (MEDLINE, EMBASE, Cochrane Library, Transfusion Evidence Library), searched from inception to January 2018. Meta-analyses were conducted with the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) methodology and the Evidence-to-Decision framework by 3 panels including clinical and scientific experts, nurses, patient representatives, and methodologists, to develop clinical recommendations during a consensus conference in Frankfurt/Main, Germany, in April 2018.

FINDINGS

From 17 607 literature citations associated with the 17 PICO questions, 145 studies, including 63 randomized clinical trials with 23 143 patients and 82 observational studies with more than 4 million patients, were analyzed. For preoperative anemia, 4 clinical and 3 research recommendations were developed, including the strong recommendation to detect and manage anemia sufficiently early before major elective surgery. For RBC transfusion thresholds, 4 clinical and 6 research recommendations were developed, including 2 strong clinical recommendations for critically ill but clinically stable intensive care patients with or without septic shock (recommended threshold for RBC transfusion, hemoglobin concentration <7 g/dL) as well as for patients undergoing cardiac surgery (recommended threshold for RBC transfusion, hemoglobin concentration <7.5 g/dL). For implementation of PBM programs, 2 clinical and 3 research recommendations were developed, including recommendations to implement comprehensive PBM programs and to use electronic decision support systems (both conditional recommendations) to improve appropriate RBC utilization.

CONCLUSIONS AND RELEVANCE

The 2018 PBM International Consensus Conference defined the current status of the PBM evidence base for practice and research purposes and established 10 clinical recommendations and 12 research recommendations for preoperative anemia, RBC transfusion thresholds for adults, and implementation of PBM programs. The relative paucity of strong evidence to answer many of the PICO questions supports the need for additional research and an international consensus for accepted definitions and hemoglobin thresholds, as well as clinically meaningful end points for multicenter trials.

The optimal use of blood components in the management of gastrointestinal bleeding

Acute gastrointestinal bleeding accounts for 5,000 deaths per annum in the UK and is the second-most common indication for transfusion of blood components. Transfusion of blood components is integral to management of these patients. Recent years have seen an expansion in the evidence base for their use in this population and this review aims to provide up-to-date guidance on the use of red cells, plasma, platelets, sources of concentrated fibrinogen and adjuncts such as antifibrinolytic agents in patients with acute gastrointestinal haemorrhage. Key considerations include whether or not it is appropriate to extrapolate from studies in trauma patients to the GI bleeding population, whether restrictive red cell transfusion is appropriate for all patients and whether the presence or absence of liver disease has implications for our transfusion practice. Clinical evidence now favours restrictive transfusion of red blood cells in the haemodynamically stable bleeding patient, but there remain significant evidence gaps concerning the use of plasma, platelets and adjunctive measures.

Red Blood Cell Transfusion Thresholds in Critically Ill Patients

Anemia of multifactorial etiology is common among critically ill patients and several arbitrary transfusion thresholds have been proposed. Transfusion of red blood cells has been well established to increase morbidity and even mortality among critically ill patients. Several randomized controlled studies have evaluated the use of a restrictive compared to a more liberal transfusion strategy in the critically ill. A transfusion threshold of 7 g/dL appears to be generally safe, especially in the younger age group without significant comorbidities. Besides, a restrictive transfusion strategy reduces the incidence of transfusion-related complications. However, the decision to transfuse needs to be individualized depending on the clinical situation, balancing putative benefits against possible complications.

How to cite this article

Chacko J, Brar G. Red Blood Cell Transfusion Thresholds in Critically Ill Patients. Indian J Crit Care Med 2019;23(Suppl 3):S181-S184.

The Age of BLood Evaluation (ABLE) randomised controlled trial: description of the UK-funded arm of the international trial, the UK cost-utility analysis and secondary analyses exploring factors associated with health-related quality of life and health-care costs during the 12-month follow-up

BACKGROUND

At present, red blood cells (RBCs) are stored for up to 42 days prior to transfusion. The relative effectiveness and safety of different RBC storage times prior to transfusion is uncertain.

OBJECTIVE

To assess the clinical effectiveness and cost-effectiveness of transfusing fresher RBCs (stored for ≤ 7 days) compared with current standard-aged RBCs in critically ill patients requiring blood transfusions.

DESIGN

The international Age of BLood Evaluation (ABLE) trial was a multicentre, randomised, blinded trial undertaken in Canada, the UK, the Netherlands and France. The UK trial was funded to contribute patients to the international trial and undertake a UK-specific health economic evaluation.

SETTING

Twenty intensive care units (ICUs) in the UK, as part of 64 international centres.

PARTICIPANTS

Critically ill patients aged ≥ 18 years (≥ 16 years in Scotland) expected to require mechanical ventilation for ≥ 48 hours and requiring a first RBC transfusion during the first 7 days in the ICU.

INTERVENTIONS

All decisions to transfuse RBCs were made by clinicians. One patient group received exclusively fresh RBCs stored for ≤ 7 days whenever transfusion was required from randomisation until hospital discharge. The other group received standard-issue RBCs throughout their hospital stay.

MAIN OUTCOME MEASURES

The primary outcome was 90-day mortality. Secondary outcomes included development of organ dysfunction, new thrombosis, infections and transfusion reactions. The primary economic evaluation was a cost-utility analysis.

RESULTS

The international trial took place between March 2009 and October 2014 (UK recruitment took place between January 2012 and October 2014). In total, 1211 patients were assigned to receive fresh blood and 1219 patients to receive standard-aged blood. RBCs were stored for a mean of 6.1 days [standard deviation (SD) ± 4.9 days] in the group allocated to receive fresh blood and 22.0 days (SD ± 8.4 days) in the group allocated to receive standard-aged blood. Patients received a mean of 4.3 RBC units (SD ± 5.2 RBC units) and 4.3 RBC units (SD ± 5.5 RBC units) in the groups receiving fresh blood and standard-aged blood, respectively. At 90 days, 37.0% of patients in the group allocated to receive fresh blood and 35.3% of patients in the group allocated to receive standard-aged blood had died {absolute risk difference 1.7% [95% confidence interval (CI) -2.1% to 5.5%]}. There were no between-group differences in any secondary outcomes. The UK cohort comprised 359 patients randomised and followed up for 12 months for the cost-utility analysis. UK patients had similar characteristics and outcomes to the international cohort. Mean total costs per patient were £32,346 (95% CI £29,306 to £35,385) in the group allocated to receive fresh blood and £33,353 (95% CI £29,729 to £36,978) in the group allocated to receive standard-aged blood. Approximately 85% of the total costs were incurred during the index hospital admission. There were no significant cost differences between the two groups [mean incremental costs for those receiving fresh vs. standard-aged blood: -£231 (95% CI -£4876 to £4415)], nor were there significant differences in outcomes (mean difference in quality-adjusted life-years -0.010, 95% CI -0.078 to 0.057).

LIMITATIONS

Adverse effects from the exclusive use of older RBCs compared with standard or fresh RBCs cannot be excluded.

CONCLUSIONS

The use of RBCs aged ≤ 7 days confers no clinical or economic benefit in critically ill patients compared with standard-aged RBCs.

FUTURE WORK

Future studies should address the safety of RBCs near the end of the current permitted storage age.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN44878718.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 21, No. 62. See the NIHR Journals Library website for further project information. The international ABLE trial was also supported by peer-reviewed grants from the Canadian Institutes of Health Research (177453), Fonds de Recherche du Québec - Santé (24460), the French Ministry of Health Programme Hospitalier de Recherche Clinique (12.07, 2011) and by funding from Établissement Français du Sang and Sanquin Blood Supply.

Clinical trials evaluating red blood cell transfusion thresholds: An updated systematic review and with additional focus on patients with cardiovascular disease

BACKGROUND

Several new trials evaluating transfusion strategies in patients with cardiovascular disease have recently been published, increasing the number of enrolled patients by over 30%. The objective was to evaluate transfusion thresholds in patients with cardiovascular disease.

METHODS

We conducted an updated systematic review of randomized trials that compared patients assigned to maintain a lower (restrictive transfusion strategy) or higher (liberal transfusion strategy) hemoglobin concentration. We focused on new trial data in patients with cardiovascular disease. The primary outcome was 30-day mortality. Specific subgroups were patients undergoing cardiac surgery and with acute myocardial infarction.

RESULTS

A total of 37 trials that enrolled 19,049 patients were appraised. In cardiac surgery, mortality at 30days was comparable between groups (risk ratio 0.99; 95% confidence interval 0.74-1.33). In 2 small trials (n=154) in patients with myocardial infarction, the point estimate for the mortality risk ratio was 3.88 (95% CI, 0.83-18.13) favoring the liberal strategy. Overall, from 26 trials enrolling 15,681 patients, 30-day mortality was not different between restrictive and liberal transfusion strategies (risk ratio 1.0, 95% CI, 0.86-1.16). Overall and in the cardiovascular disease subgroup, there were no significant differences observed across a range of secondary outcomes.

CONCLUSIONS

New trials in patients undergoing cardiac surgery establish that a restrictive transfusion strategy of 7 to 8g/dL is safe and decreased red cell use by 24%. Further research is needed to define the optimal transfusion threshold in patients with acute myocardial infarction.

Risks of restrictive red blood cell transfusion strategies in patients with cardiovascular disease (CVD): a meta-analysis

AIM

To evaluate the risks of restrictive red blood cell transfusion strategies (haemoglobin 7-8 g dL^-1 ) in patients with and without known cardiovascular disease (CVD).

BACKGROUND

Recent guidelines recommend restrictive strategies for CVD patients hospitalised for non-CVD indications, patients without known CVD and patients hospitalised for CVD corrective procedures.

METHODS/MATERIALS

Database searches were conducted through December 2017 for randomised clinical trials that enrolled patients with and without known CVD, hospitalised either for CVD-corrective procedures or non-cardiac indications, comparing effects of liberal with restrictive strategies on major adverse coronary events (MACE) and death.

RESULTS

In CVD patients not undergoing cardiac interventions, a liberal strategy decreased (P = 0·01) the relative risk (95% CI) (RR) of MACE [0·50 (0·29-0·86)] (I²  = 0%). Among patients without known CVD, the incidence of MACE was lower (1·7 vs 3·9%), and the effect of a liberal strategy on MACE [0·79, (0·39-1·58)] was smaller and non-significant but not different from CVD patients (P = 0·30). Combining all CVD and non-CVD patients, a liberal strategy decreased MACE [0·59, (0·39-0·91); P = 0·02]. Conversely, among studies reporting mortality, a liberal strategy decreased mortality in CVD patients (11·7% vs·13·3%) but increased mortality (19·2% vs 18·0%) in patients without known CVD [interaction P = 0·05; ratio of RR 0·73, (0·53-1·00)]. A liberal strategy also did not benefit patients undergoing cardiac surgery; data were insufficient for percutaneous cardiac procedures.

CONCLUSIONS

In patients hospitalised for non-cardiac indications, liberal transfusion strategies are associated with a decreased risk of MACE in both those with and without known CVD. However, this only provides a survival benefit to CVD patients not admitted for CVD-corrective procedures.

Comprehensive Analysis of Liberal and Restrictive Transfusion Strategies in Pediatric Intensive Care Unit

BACKGROUND

We prospectively compared restrictive and liberal transfusion strategies for critically ill children regarding hemodynamic and laboratory parameters.

METHODS

A total of 180 children requiring packed red blood cells (PRBCs) were randomized into two groups: the liberal transfusion strategy group (transfusion trigger < 10 g/dL, Group 1) and the restrictive transfusion strategy group (transfusion trigger ≤ 7 g/dL, Group 2). Basal variables including venous/arterial hemoglobin, hematocrit and lactate levels; stroke volume; and cardiac output were recorded at the beginning and end of the transfusion. Oxygen saturation, noninvasive total hemoglobin, noninvasive total oxygen content, perfusion index (PI), heart rate and systolic and diastolic blood pressures were assessed via the Radical-7 Pulse co-oximeter (Masimo, Irvine, CA, USA) with the Root monitor, initially and at 4 h.

RESULTS

In all, 160 children were eligible for final analysis. The baseline hemoglobin level for the PRBC transfusion was 7.38 ± 0.98 g/dL for all patients. At the end of the PRBC transfusion, cardiac output decreased by 9.9% in Group 1 and by 24% in Group 2 (p  < 0.001); PI increased by 10% in Group 1 and by 45% in Group 2 (p  < 0.001). Lactate decreased by 9.8% in Group 1 and by 31.68% in Group 2 (p < 0.001).

CONCLUSION

Restrictive blood transfusion strategy is better than liberal transfusion strategy with regard to the hemodynamic and laboratory values during the early period. PI also provides valuable information regarding the efficacy of PRBC transfusion in clinical practice.

Blood Product Administration in the Critical Care and Perioperative Settings

The critical care and perioperative settings are high consumers of blood products, with multiple units and different products often given to an individual patient. The recommendation of this review is always to consider the risks and benefits for a specific blood product for a specific patient in a specific clinical setting. Optimize patient status by treating anemia and preventing the need for red blood cell transfusion. Consider other options for correction of anemia and coagulation disorders and use an imperative non-overtransfusion policy for all blood products.

Patient blood management programs: how to spread the word?

Red blood cell (RBC) transfusions save lives and improve health; however, unnecessary transfusion practice exposes patients to immediate and long-term negative consequences. Indirect consequences of unnecessary transfusions are the reduced availability of RBC units for patients who are in need. Accumulating evidence shows that restricting RBC transfusions improves outcomes and current guidelines suggest limiting RBC transfusion to the minimum number of units required to relieve symptoms of anemia or to return the patient to a safe hemoglobin range (7-8 g/dl in stable, non-cardiac inpatients). Still, studies show that there is over-utilization of RBC transfusion, partly due to low level of knowledge of physicians regarding restrictive RBC transfusion policy across a broad range of professions and specialties. Patient blood management (PBM) programs have been developed to promote clear hospital transfusion guidelines, strive for optimization of patient hemoglobin and iron stores and, most importantly, improve education regarding restrictive RBC policy. Understanding what and where the gaps of knowledge are, as was done in the study by Dr. Koren and his colleagues, is an important step for developing effective PBM programs.

High-Dose Vitamin D3 Administration Is Associated With Increases in Hemoglobin Concentrations in Mechanically Ventilated Critically Ill Adults: A Pilot Double-Blind, Randomized, Placebo-Controlled Trial

BACKGROUND

Anemia and vitamin D deficiency are highly prevalent in critical illness, and vitamin D status has been associated with hemoglobin concentrations in epidemiologic studies. We examined the effect of high-dose vitamin D therapy on hemoglobin and hepcidin concentrations in critically ill adults.

MATERIALS AND METHODS

Mechanically ventilated critically ill adults (N = 30) enrolled in a pilot double-blind, randomized, placebo-controlled trial of high-dose vitamin D3 (D3 ) were included in this analysis. Participants were randomized to receive placebo, 50,000 IU D3 , or 100,000 IU D3 daily for 5 days (totaling 250,000 IU D3 and 500,000 IU D3 , respectively). Blood was drawn weekly throughout hospitalization for up to 4 weeks. Linear mixed-effects models were used to assess change in hemoglobin and hepcidin concentrations by treatment group over time.

RESULTS

At enrollment, >75% of participants in all groups had plasma 25-hydroxyvitamin D (25(OH)D) concentrations <30 ng/mL, and >85% of participants across groups were anemic. In the 500,000-IU D3 group, hemoglobin concentrations increased significantly over time (Pgroup × time = .01) compared with placebo but did not change in the 250,000-IU D3 group (Pgroup × time = 0.59). Hepcidin concentrations decreased acutely in the 500,000-IU D3 group relative to placebo after 1 week (P = .007). Hepcidin did not change significantly in the 250,000-IU D3 group.

CONCLUSION

In these critically ill adults, treatment with 500,000 IU D3 was associated with increased hemoglobin concentrations over time and acutely reduced serum hepcidin concentrations. These findings suggest that high-dose vitamin D may improve iron metabolism in critical illness and should be confirmed in larger studies.

Impact of transfusion on patients with sepsis admitted in intensive care unit: a systematic review and meta-analysis

Red blood cell transfusion (RBCT) threshold in patients with sepsis remains a matter of controversy. A threshold of 7 g/dL for stabilized patients with sepsis is commonly proposed, although debated. The aim of the study was to compare the benefit and harm of restrictive versus liberal RBCT strategies in order to guide physicians on RBCT strategies in patients with severe sepsis or septic shock. Four outcomes were assessed: death, nosocomial infection (NI), acute lung injury (ALI) and acute kidney injury (AKI). Studies assessing RBCT strategies or RBCT impact on outcome and including intensive care unit (ICU) patients with sepsis were assessed. Two systematic reviews were achieved: first for the randomized controlled studies (RCTs) and second for the observational studies. MEDLINE, EMBASE, Web of Science Core Collection, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews and Clinical Trials.gov were analyzed up to March 01, 2015. Der Simonian and Laird random-effects models were used to report pooled odds ratios (ORs). Subgroup analyses and meta-regressions were performed to explore studies heterogeneity. One RCT was finally included. The restrictive RBCT strategy was not associated with harm or benefit compared to liberal strategy. Twelve cohort studies were included, of which nine focused on mortality rate. RBCT was not associated with increased mortality rate (overall pooled OR was 1.10 [0.75, 1.60]; I 2 = 57%, p = 0.03), but was associated with the occurrence of NI (2 studies: pooled OR 1.25 [1.04-1.50]; I 2 = 0%, p = 0.97), the occurrence of ALI (1 study: OR 2.75 [1.22-6.37]; p = 0.016) and the occurrence of AKI (1 study: OR 5.22 [2.1-15.8]; p = 0.001). Because there was only one RCT, the final meta-analyses were only based on the cohort studies. As a result, the safety of a RBCT restrictive strategy was confirmed, although only one study specifically focused on ICU patients with sepsis. Then, RBCT was not associated with increased mortality rate, but was associated with increased in occurrence of NI, ALI and AKI. Nevertheless, the data on RBCT in patients with sepsis are sparse and the high heterogeneity between studies prevents from drawing any definitive conclusions.

Anemia and Red Blood Cell Transfusion: Advances in Critical Care

Anemia is common in the intensive care unit (ICU), resulting in frequent administration of red blood cell (RBC) transfusions. Significant advances have been made in understanding the pathophysiology of anemia in the ICU, which is anemia of inflammation. This anemia is related to high hepcidin concentrations resulting in iron-restricted erythropoiesis, and decreased erythropoietin concentrations. A new hormone (erythroferrone) has been identified, which mediates hepcidin suppression to allow increased iron absorption and mobilization from iron stores. RBC transfusions are most commonly administered to ICU patients for treatment of anemia. All strategies to reduce anemia in the ICU should be implemented.

From Donor to Recipient: Considerations for Blood Transfusion Outcomes Research

Donated blood can be broken down into blood components for use in patient care. This article focuses primarily on packed red blood cells (PRBCs), as they experience breakdown during storage that may adversely impact patient outcomes. Patients require PRBC transfusions for a number of clinical reasons. Although transfusions of PRBCs provide some clinical benefit, they are also associated with increased morbidity and mortality across multiple patient populations, albeit the mechanisms underlying this relationship remain unclear. With an aging, more acutely ill population requiring aggressive treatment and a lack of transfusion alternatives, research focused on PRBCs has gained momentum. Proper interpretation of research findings on the part of clinicians depends on accurate data collection that includes aspects of both the transfused blood components and the recipients. The purpose of this article is to examine stored PRBC factors, blood-donor characteristics, transfusion-specific factors, and patient-specific characteristics as they relate to patient outcomes research. Challenges associated with performing and interpreting outcomes of transfusion-related research are presented. Implications of current evidence for patient care, such as awareness of benefits as well as risks associated with blood component transfusion, are also provided.

Effect of restrictive versus liberal red cell transfusion strategies on haemostasis: systematic review and meta-analysis

Red cells play a key role in normal haemostasis in vitro but their importance clinically is less clear. The objective of this meta-analysis was to assess if correction of anaemia by transfusing red cells at a high haemoglobin threshold (liberal transfusion) is superior to transfusion at a lower haemoglobin threshold (restrictive transfusion) for reducing the risk of bleeding or thrombotic events. We searched for randomised controlled trials in any clinical setting that compared two red cell transfusion thresholds and investigated the risk of bleeding. We searched for studies published up to October 19, 2016 in The Cochrane Central Register of Controlled Trials, MEDLINE, PubMed, Embase, and the Transfusion Evidence Library and ISI Web of Science. Relative risks (RR) or Peto Odds Ratios (pOR) were pooled using a random-effect model. Nineteen randomised trials with 9852 participants were eligible for inclusion in this review. Overall there was no difference in the risk of any bleeding between transfusion strategies (RR 0.91, 95 % confidence interval [CI] 0.74 to 1.12). The risk of severe or life-threatening bleeding was lower with a restrictive strategy (RR 0.75, 95 % CI 0.57 to 0.99). There was no difference in the risk of thrombotic events (RR 0.83, 95 % CI 0.61 to 1.13). The risk of any bleeding was not reduced with liberal transfusion and there was no overall difference in the risk of thrombotic events. Data from the included trials do not support aiming for a high haemoglobin threshold to improve haemostasis. PROSPERO registration number CRD42016035519.

Anemia and blood transfusion in the critically ill patient with cardiovascular disease

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2017. Other selected articles can be found online at http://ccforum.com/series/annualupdate2017 . Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901 .

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.