Clinical practice guideline: Red blood cell transfusion in adult trauma and critical care*:

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.

Perioperative Transfusion Practices in Adults Having Noncardiac Surgery

Surgical patients are often transfused to manage bleeding and anemia. Best practices for red blood cell (RBC) transfusion administration in patient having noncardiac surgery remains controversial and a robust evaluation and description of perioperative transfusion practices is lacking. We characterized perioperative hemoglobin concentrations and transfusion practices from the prospective VISION cohort which included 39,222 patients aged ≥45 years who had inpatient noncardiac surgery. Variations in transfusion practices were analyzed using hierarchical mixed models, and associations with mortality and complications were evaluated using a nested frailty survival model. Within the cohort, 16.1% (n = 6296) were given perioperative RBC transfusions, with the fraction declining from 20% to 13% over the 6-year study period. The proportion of patients transfused varied by surgery type from 6.4% for low-risk operations (i.e., minor surgery) to 31.5% for orthopedic surgeries. Variations were largely associated with patient hemoglobin concentrations, but also with center (range: 3.7%-27.3%) and country (0.4%-25.3%). Even after adjusting for baseline hemoglobin, comorbidities and type of surgery, both center and country were significant sources of variation in transfusion practices. Among transfused participants, 60.4% (n = 3728/6170) had at least 1 hemoglobin concentration ≤80g/L and 86.0% (n = 5305/6170) had at least 1 hemoglobin concentration ≤90g/L, suggesting that relatively restrictive transfusion strategies were used in most. The proportion of patients receiving at least 1 RBC transfusion declined from 20% to 13% over 6 years. However, there was considerable unexplained variation in transfusion practices.

Resuscitating the macro- vs. microcirculation in septic shock

PURPOSE OF REVIEW

This review summarizes current literature about the relationships between macro and microcirculation and their practical clinical implications in children with septic shock.

RECENT FINDINGS

Current evidence from experimental and clinical observational studies in children and adults with septic shock reveals that the response to treatment and resuscitation is widely variable. Furthermore, there is a loss of hemodynamic coherence, as resuscitation-induced improvement in macrocirculation (systemic hemodynamic parameters) does not necessarily result in a parallel improvement in the microcirculation. Therefore, patient-tailored monitoring is essential in order to adjust treatment requirements during resuscitation in septic shock. Optimal monitoring must integrate macrocirculation (heart rate, blood pressure, cardiac output, and ultrasound images), microcirculation (videomicroscopy parameters and capillary refill time) and cellular metabolism (lactic acid, central venous blood oxygen saturation, and difference of central venous to arterial carbon dioxide partial pressure).

SUMMARY

There is a dire need for high-quality studies to assess the relationships between macrocirculation, microcirculation and tissue metabolism in children with septic shock. The development of reliable and readily available microcirculation and tissue perfusion biomarkers (other than lactic acid) is also necessary to improve monitoring and treatment adjustment in such patients.

Efficacy and safety of restrictive versus liberal blood transfusion strategies in acute myocardial infarction and anemia: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Blood transfusion strategies in patients with acute myocardial infarction (AMI) and anemia are yet to be conclusively identified. Thus, we aim to assess the efficacy and safety of restrictive versus liberal blood transfusion strategies for AMI and anemia.

METHODS

A systematic review and meta-analysis of randomized controlled trials (RCTs) retrieved from PubMed, web of science, SCOPUS, EMBASE, and Cochrane Central Register of Controlled Trials were performed through November 2023. We used RevMan V. 5.4 to pool dichotomous data using risk ratio (RR) and continuous data using mean difference (MD) with a 95% confidence interval (CI). (PROSPERO): ID: CRD42023490692.

RESULTS

We included four RCTs with 4.325 patients. There was no significant difference between both groups regarding MACE whether at 30 days (RR: 0.93 with 95% CI [0.57-1.51], P  = 0.76) or ≥ six months (RR: 1.17 with 95% CI [0.95-1.45], P  = 0.14), all-cause mortality at 30 days (RR: 1.16 with 95% CI [0.95-1.40], P  = 0.14) or ≥ six months (RR: 1.16 with 95% CI [0.88-1.53], P  = 0.28). However, the liberal strategy was significantly associated with increased hemoglobin level change (MD: -1.44 with 95% CI [-1.68 to -1.20], P  < 0.00001). However, the restrictive strategy was significantly associated with a lower incidence of acute lung injury (RR: 0.11 with 95% CI [0.02-0.60], P  = 0.01).

CONCLUSION

There was no significant difference between the restrictive blood transfusion strategy and the liberal blood transfusion strategy regarding the clinical outcomes. However, restrictive blood transfusion strategy was significantly associated with a lower incidence of acute lung injury than liberal blood transfusion strategy.

Predicting the complexity and mortality of polytrauma patients with machine learning models

We aim to develop machine learning (ML) models for predicting the complexity and mortality of polytrauma patients using clinical features, including physician diagnoses and physiological data. We conducted a retrospective analysis of a cohort comprising 756 polytrauma patients admitted to the intensive care unit (ICU) at Pizhou People's Hospital Trauma Center, Jiangsu, China between 2020 and 2022. Clinical parameters encompassed demographics, vital signs, laboratory values, clinical scores and physician diagnoses. The two primary outcomes considered were mortality and complexity. We developed ML models to predict polytrauma mortality or complexity using four ML algorithms, including Support Vector Machine (SVM), Random Forest (RF), Artificial Neural Network (ANN) and eXtreme Gradient Boosting (XGBoost). We assessed the models' performance and compared the optimal ML model against three existing trauma evaluation scores, including Injury Severity Score (ISS), Trauma Index (TI) and Glasgow Coma Scale (GCS). In addition, we identified several important clinical predictors that made contributions to the prognostic models. The XGBoost-based polytrauma mortality prediction model demonstrated a predictive ability with an accuracy of 90% and an F-score of 88%, outperforming SVM, RF and ANN models. In comparison to conventional scoring systems, the XGBoost model had substantial improvements in predicting the mortality of polytrauma patients. External validation yielded strong stability and generalization with an accuracy of up to 91% and an AUC of 82%. To predict polytrauma complexity, the XGBoost model maintained its performance over other models and scoring systems with good calibration and discrimination abilities. Feature importance analysis highlighted several clinical predictors of polytrauma complexity and mortality, such as Intracranial hematoma (ICH). Leveraging ML algorithms in polytrauma care can enhance the prognostic estimation of polytrauma patients. This approach may have potential value in the management of polytrauma patients.

Red blood cell transfusion in neurocritical patients: a systematic review and meta-analysis

BACKGROUND

Anemia can lead to secondary brain damage by reducing arterial oxygen content and brain oxygen supply. Patients with acute brain injury have impaired self-regulation. Brain hypoxia may also occur even in mild anemia. Red blood cell (RBC) transfusion is associated with increased postoperative complications, poor neurological recovery, and mortality in critically ill neurologic patients. Balancing the risks of anemia and red blood cell transfusion-associated adverse effects is challenging in neurocritical settings.

METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), Embase, and MEDLINE (PubMed) from inception to January 31, 2024. We included all randomized controlled trials (RCTs) assessing liberal versus restrictive RBC transfusion strategies in neurocritical patients. We included all relevant studies published in English. The primary outcome was mortality at intensive care unit (ICU), discharge, and six months.

RESULTS

Of 5195 records retrieved, 84 full-text articles were reviewed, and five eligible studies were included. There was no significant difference between the restrictive and liberal transfusion groups in ICU mortality (RR: 2.53, 95% CI: 0.53 to 12.13), in-hospital mortality (RR: 2.34, 95% CI: 0.50 to 11.00), mortality at six months (RR: 1.42, 95% CI: 0.42 to 4.78) and long-term mortality (RR: 1.22, 95% CI: 0.64 to 2.33). The occurrence of neurological adverse events and most major non-neurological complications was similar in the two groups. The incidence of deep venous thrombosis was lower in the restrictive strategy group (RR: 0.41, 95% CI: 0.18 to 0.91).

CONCLUSIONS

Due to the small sample size of current studies, the evidence is insufficiently robust to confirm definitive conclusions for neurocritical patients. Therefore, further investigation is encouraged to define appropriate RBC transfusion thresholds in the neurocritical setting.

Reducing Unnecessary Transfusions of RBCs in Inpatients Admitted Across Niagara Health Community Hospitals

BACKGROUND AND OBJECTIVES

Blood products are scarce resources. Audits on the use of red blood cells (RBCs) in tertiary centers have repeatedly highlighted inappropriate use. Earlier retrospective audit at our local community hospitals has demonstrated that only 85% and 54% of all requests met Choosing Wisely Canada guidelines for pre-transfusion hemoglobin (Hb) of 80 g/L or less and single unit, respectively.We sought to improve RBC utilization by 15% over a period of 12 months (meeting Choosing Wisely Canada criteria of pre-transfusion Hb ≤80g/L by >80% and single-unit transfusion by >65%).

METHODS

Following repeated PDSA (Plan-Do-Study-Act) cycles, we implemented educational strategies, prospective transfusion medicine (TM) technologist-led screening of orders, and an RBC order set.

RESULTS

The 3-month median percentages of appropriate RBC use for pre-transfusion Hb and single unit (September-November 2021) across all 3 hospitals were 90% and 71%, respectively. Overall, the rate of appropriate RBCs based on pre-transfusion Hb remained above target (>80%), with minimal improvement across all hospitals (median percentage at pre- and post-technologist screening periods of 87% and 90%, respectively). The median percentage of appropriate RBCs based on single-unit transfusion orders has improved across all Niagara Health hospitals with sustained targets (3-month median percentage at pre- and post-technologist screening and most recent time periods of 54%, 56%, and 71%, respectively).

CONCLUSIONS

We have taken a collaborative, multifaceted approach to optimizing utilization of RBCs across the Niagara Health hospitals. The rates of appropriate RBC use were comparable with the provincial and national accreditation benchmark standards. In particular, the TM technologist-led screening was effective in producing sustained improvement with respect to single-unit transfusion. One of the balancing outcomes was increasing workload on technologists. Local and provincial efforts are needed to facilitate recruitment and retention of laboratory technologists, especially in community hospitals.

Trauma Anesthesiology Perioperative Management Update

Anesthesia for patients with life-threatening injuries is an essential part of post-accident care. Unfortunately, there is variability in trauma anesthesia care and numerous nonstandardized methods of working with patients remain. Uncertainty exists as to when and how best to intubate trauma patients, the use of vasopressors, and the appropriate management of severe traumatic brain injury. Some physicians recommend prehospital rapid sequence intubation, whereas others use bag-mask ventilation at lower pressures with no cricoid pressure and early transport to a trauma center. Overall, the absence of uniformity in trauma anesthesia care underlines the need for continued study and dialogue to define best practices and optimize patient outcomes.

Transfusion Strategies in the 21st Century: A Case-Based Narrative Report

The transfusion of all blood components (red blood cells, plasma, and platelets) has been associated with increased morbidity and mortality in children. It is essential that pediatric providers weigh the risks and benefits before transfusing a critically ill child. A growing body of evidence has demonstrated the safety of restrictive transfusion practices in critically ill children.

Outcomes of Transfusion With Whole Blood, Component Therapy, or Both in Adult Civilian Trauma Patients: A Systematic Review and Meta-Analysis

INTRODUCTION

This systematic review and meta-analysis was conducted to compare outcomes, including transfusion volume, complications, intensive care unit length of stay, and mortality for adult civilian trauma patients transfused with whole blood (WB), components (COMP), or both (WB + COMP).

METHODS

A systematic review and meta-analysis were conducted using studies that evaluated outcomes of transfusion of WB, COMP, or WB + COMP for adult civilian trauma patients. A search of PubMed, Embase, and Cochrane from database inception to March 3, 2022 was conducted. The search resulted in 18,400 initial articles with 16 studies remaining after the removal of duplicates and screening for inclusion and exclusion criteria.

RESULTS

This study identified an increased risk of 24-h mortality with COMP versus WB + COMP (relative risk: 1.40 [1.10, 1.78]) and increased transfusion volumes of red blood cells with COMP versus WB at 6 and 24 h, respectively (-2.26 [-3.82, -0.70]; -1.94 [-3.22, -0.65] units). There were no differences in the calculated rates of infections or intensive care unit length of stay between WB and COMP, respectively (relative risks: 1.35 [0.53, 3.46]; -0.91 [-2.64, 0.83]).

CONCLUSIONS

Transfusion with WB + COMP is associated with lower 24-h mortality versus COMP and transfusion with WB is associated with a lower volume of red blood cells transfused at both 6 and 24 h. Based on these findings, greater utilization of whole blood in civilian adult trauma resuscitation may lead to improved mortality and reduced transfusion requirements.

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.

Traumatic Brain Injury: Intraoperative Management and Intensive Care Unit Multimodality Monitoring

Traumatic brain injury is a devastating event associated with substantial morbidity. Pathophysiology involves the initial trauma, subsequent inflammatory response, and secondary insults, which worsen brain injury severity. Management entails cardiopulmonary stabilization and diagnostic imaging with targeted interventions, such as decompressive hemicraniectomy, intracranial monitors or drains, and pharmacological agents to reduce intracranial pressure. Anesthesia and intensive care requires control of multiple physiologic variables and evidence-based practices to reduce secondary brain injury. Advances in biomedical engineering have enhanced assessments of cerebral oxygenation, pressure, metabolism, blood flow, and autoregulation. Many centers employ multimodality neuromonitoring for targeted therapies with the hope to improve recovery.

Outcomes of Patients Treated with Blood Transfusion in a Contemporary Tertiary Care Medical Center Intensive Cardiac Care Unit

BACKGROUND

Acutely ill patients treated with blood transfusion (BT) have unfavorable prognoses. Nevertheless, data regarding outcomes in patients treated with BT admitted into a contemporary tertiary care medical center intensive cardiac care unit (ICCU) are limited. The current study aimed to assess the mortality rate and outcomes of patients treated with BT in a modern ICCU.

METHODS

Prospective single center study where we evaluated mortality, in the short and long term, of patients treated with BT between the period of January 2020 and December 2021 in an ICCU.

OUTCOMES

A total of 2132 consecutive patients were admitted to the ICCU during the study period and were followed-up for up to 2 years. In total, 108 (5%) patients were treated with BT (BT-group) during their admission, with 305 packed cell units. The mean age was 73.8 ± 14 years in the BT-group vs. 66.6 ± 16 years in the non-BT (NBT) group, p < 0.0001. Females were more likely to receive BT as compared with males (48.1% vs. 29.5%, respectively, p < 0.0001). The crude mortality rate was 29.6% in the BT-group and 9.2% in the NBT-group, p < 0.0001. Multivariate Cox analysis found that even one unit of BT was independently associated with more than two-fold the mortality rate [HR = 2.19 95% CI (1.47-3.62)] as compared with the NBT-group, p < 0.0001]. Receiver operating characteristic (ROC) curve was plotted for multivariable analysis and showed area under curve (AUC) of 0.8 [95% CI (0.760-0.852)].

CONCLUSIONS

BT continues to be a potent and independent predictor for both short- and long-term mortality even in a contemporary ICCU, despite the advanced technology, equipment and delivery of care. Further considerations for refining the strategy of BT administration in ICCU patients and guidelines for different subsets of high-risk patients may be warranted.

A positive blood culture is associated with a lower haemoglobin increment in hospitalized patients after red blood cell transfusion

BACKGROUND AND OBJECTIVES

Abundant clinical evidence supports the safety of red blood cell (RBC) concentrates for transfusion irrespective of storage age, but still, less is known about how recipient characteristics may affect post-transfusion RBC recovery and function. Septic patients are frequently transfused. We hypothesized that the recipient environment in patients with septicaemia would blunt the increase in post-transfusion blood haemoglobin (Hb). The main objective was to compare the post-transfusion Hb increment in hospitalized patients with or without a positive blood culture.

MATERIALS AND METHODS

A retrospective cohort study using data from the Transfusion Research, Utilization, Surveillance, and Tracking database (TRUST) was performed. All adult non-trauma in-patients transfused between 2010 and 2017 with ≥1 RBC unit, and for whom both pre- and post-transfusion complete blood count and pre-transfusion blood culture data were available were included. A general linear model with binary blood culture positivity was fit for continuous Hb increment after transfusion and was adjusted for patient demographic parameters and transfusion-related covariates.

RESULTS

Among 210,263 admitted patients, 6252 were transfused: 596 had positive cultures, and 5656 had negative blood cultures. A modelled Hb deficit of 1.50 g/L in blood culture-positive patients was found. All covariates had a significant effect on Hb increment, except for the age of the transfused RBC.

CONCLUSION

Recipient blood culture positivity was associated with a statistically significant but modestly lower post-transfusion Hb increment in hospitalized patients. In isolation, the effect is unlikely to be clinically significant, but it could become so in combination with other recipient characteristics.

Prediction of red blood cell transfusion after orthopedic surgery using an interpretable machine learning framework

Objective

Postoperative red blood cell (RBC) transfusion is widely used during the perioperative period but is often associated with a high risk of infection and complications. However, prediction models for RBC transfusion in patients with orthopedic surgery have not yet been developed. We aimed to identify predictors and constructed prediction models for RBC transfusion after orthopedic surgery using interpretable machine learning algorithms.

Methods

This retrospective cohort study reviewed a total of 59,605 patients undergoing orthopedic surgery from June 2013 to January 2019 across 7 tertiary hospitals in China. Patients were randomly split into training (80%) and test subsets (20%). The feature selection method of recursive feature elimination (RFE) was used to identify an optimal feature subset from thirty preoperative variables, and six machine learning algorithms were applied to develop prediction models. The Shapley Additive exPlanations (SHAP) value was employed to evaluate the contribution of each predictor towards the prediction of postoperative RBC transfusion. For simplicity of the clinical utility, a risk score system was further established using the top risk factors identified by machine learning models.

Results

Of the 59,605 patients with orthopedic surgery, 19,921 (33.40%) underwent postoperative RBC transfusion. The CatBoost model exhibited an AUC of 0.831 (95% CI: 0.824-0.836) on the test subset, which significantly outperformed five other prediction models. The risk of RBC transfusion was associated with old age (>60 years) and low RBC count (<4.0 × 10¹²/L) with clear threshold effects. Extremes of BMI, low albumin, prolonged activated partial thromboplastin time, repair and plastic operations on joint structures were additional top predictors for RBC transfusion. The risk score system derived from six risk factors performed well with an AUC of 0.801 (95% CI: 0.794-0.807) on the test subset.

Conclusion

By applying an interpretable machine learning framework in a large-scale multicenter retrospective cohort, we identified novel modifiable risk factors and developed prediction models with good performance for postoperative RBC transfusion in patients undergoing orthopedic surgery. Our findings may allow more precise identification of high-risk patients for optimal control of risk factors and achieve personalized RBC transfusion for orthopedic patients.

National analysis of whole blood and component versus component transfusions in civilian trauma patients who underwent a thoracotomy or laparotomy: Toward improving patient outcomes and quality of care

BACKGROUND

This study aimed to investigate the associations of whole blood and component versus component transfusions with in-hospital mortality, complication rates, intensive care unit length of stay, and packed red blood cells transfusion volumes in adult civilian trauma patients.

METHODS

We performed a retrospective cohort study of the American College of Surgeons Trauma Quality Program Participant Use File 2016 to 2019 dataset. Adult civilian trauma patients (aged >18 years) sustaining injuries of at least moderate severity who received whole blood and component or component within 4 hours of arrival and underwent thoracotomy or laparotomy were included. Multivariable regression analysis was used to compare outcomes between whole blood and component and component groups.

RESULTS

A total of 37,384 patients met eligibility criteria, of which 218 received whole blood and component and 37,166 received component. There was no significant difference in in-hospital mortality between whole blood and component and component groups for those who underwent thoracotomy (adjusted odds ratio = 0.408, P = .413) or laparotomy (adjusted odds ratio = 1.046, P = .857). Thoracotomy patients who received whole blood and component had no difference in 4-hour or 24-hour pack red blood cell volumes (3336 mL vs 3106 mL, P = .754; 3 658mL vs 3,636mL, P = .982), intensive care unit length of stay (10.68 days vs 8.63 days, P = .542), or complications rates compared to those who received component. Laparotomy patients who received whole blood and component had no difference in 4 hour or 24-hour packed red blood cell volumes (2,758 mL vs 2,721mL, P = .927; 3,538 mL vs 3,385 mL, P = .754), intensive care unit length of stay (11.78 days vs 9.90 days, P = .177), or complications rates compared to those who received component.

CONCLUSION

Study findings have indicated that a combined resuscitation with whole blood and component transfusion in adult civilian trauma patients is a viable alternative to component transfusion alone.

Evaluation and Management of Heavy Vaginal Bleeding (Noncancerous)

Heavy vaginal bleeding is a common, life-altering condition affecting around 30% of women at some point in their reproductive lives. Initial evaluation should focus on hemodynamic stability. A thorough history including the patient's menstrual cycle and personal and family bleeding history should be obtained. Causes are stratified using the structural and nonstructural International Federation of Gynecology and Obstetrics classification system. Further consideration of the patient's age is essential because this can help to narrow the differential diagnosis. Work-up includes laboratory and imaging studies. Treatment approach includes acute stabilization and long-term treatment with medical and surgical modalities.

Recovery of organ-specific tissue oxygen delivery at restrictive transfusion thresholds after fluid treatment in ovine haemorrhagic shock

Background

Fluid resuscitation is the standard treatment to restore circulating blood volume and pressure after massive haemorrhage and shock. Packed red blood cells (PRBC) are transfused to restore haemoglobin levels. Restoration of microcirculatory flow and tissue oxygen delivery is critical for organ and patient survival, but these parameters are infrequently measured. Patient Blood Management is a multidisciplinary approach to manage and conserve a patient’s own blood, directing treatment options based on broad clinical assessment beyond haemoglobin alone, for which tissue perfusion and oxygenation could be useful. Our aim was to assess utility of non-invasive tissue-specific measures to compare PRBC transfusion with novel crystalloid treatments for haemorrhagic shock.

Methods

A model of severe haemorrhagic shock was developed in an intensive care setting, with controlled haemorrhage in sheep according to pressure (mean arterial pressure 30–40 mmHg) and oxygen debt (lactate > 4 mM) targets. We compared PRBC transfusion to fluid resuscitation with either PlasmaLyte or a novel crystalloid. Efficacy was assessed according to recovery of haemodynamic parameters and non-invasive measures of sublingual microcirculatory flow, regional tissue oxygen saturation, repayment of oxygen debt (arterial lactate), and a panel of inflammatory and organ function markers. Invasive measurements of tissue perfusion, oxygen tension and lactate levels were performed in brain, kidney, liver, and skeletal muscle. Outcomes were assessed during 4 h treatment and post-mortem, and analysed by one- and two-way ANOVA.

Results

Each treatment restored haemodynamic and tissue oxygen delivery parameters equivalently (p > 0.05), despite haemodilution after crystalloid infusion to haemoglobin concentrations below 70 g/L (p < 0.001). Recovery of vital organ-specific perfusion and oxygen tension commenced shortly before non-invasive measures improved. Lactate declined in all tissues and correlated with arterial lactate levels (p < 0.0001). The novel crystalloid supported rapid peripheral vasodilation (p = 0.014) and tended to achieve tissue oxygen delivery targets earlier. PRBC supported earlier renal oxygen delivery (p = 0.012) but delayed peripheral perfusion (p = 0.034).

Conclusions

Crystalloids supported vital organ oxygen delivery after massive haemorrhage, despite haemodilution to < 70 g/L, confirming that restrictive transfusion thresholds are appropriate to support oxygen delivery. Non-invasive tissue perfusion and oximetry technologies merit further clinical appraisal to guide treatment for massive haemorrhage in the context of Patient Blood Management.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40635-022-00439-6.

Technologies for measuring red blood cell deformability

Human red blood cells (RBCs) are approximately 8 μm in diameter, but must repeatedly deform through capillaries as small as 2 μm in order to deliver oxygen to all parts of the body. The loss of this capability is associated with the pathology of many diseases, and is therefore a potential biomarker for disease status and treatment efficacy. Measuring RBC deformability is a difficult problem because of the minute forces (∼pN) that must be exerted on these cells, as well as the requirements for throughput and multiplexing. The development of technologies for measuring RBC deformability date back to the 1960s with the development of micropipette aspiration, ektacytometry, and the cell transit analyzer. In the past 10 years, significant progress has been made using microfluidics by leveraging the ability to precisely control fluid flow through microstructures at the size scale of individual RBCs. These technologies have now surpassed traditional methods in terms of sensitivity, throughput, consistency, and ease of use. As a result, these efforts are beginning to move beyond feasibility studies and into applications to enable biomedical discoveries. In this review, we provide an overview of both traditional and microfluidic techniques for measuring RBC deformability. We discuss the capabilities of each technique and compare their sensitivity, throughput, and robustness in measuring bulk and single-cell RBC deformability. Finally, we discuss how these tools could be used to measure changes in RBC deformability in the context of various applications including pathologies caused by malaria and hemoglobinopathies, as well as degradation during storage in blood bags prior to blood transfusions.

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.

Hemoglobin matters: Perioperative blood management for oncology patients

As the number of cancer cases rise each year in Canada, so does the number of surgical oncology cases. Surgery presents a unique and heightened stressor for the body already experiencing volatility from factors such as disease and treatments. Perioperative red blood cell (RBC) transfusions are critical to stabilize hemoglobin levels and correct anemia, as well as provide a buffer against anticipated intraoperative blood loss. Thoroughly examining and anticipating risk factors related to the potential need for perioperative blood transfusions is necessary to improve outcomes. Research evidence in recent years related to perioperative blood management of oncology patients has specifically recommended active, coordinated programs to reduce the need and amount of blood transfusions administered pre-, intra-, and post-surgery. Coordination between surgical oncologists and a local or provincial patient blood management (PBM) program is an important strategy that allows patients at risk of perioperative complications to be identified and receive early interventions and ongoing observation.

L’importance de l’hémoglobine : gestion périopératoire du sang pour les patients en oncologie

Au Canada, le nombre de cas de cancer augmente chaque année et, par conséquent, le nombre de patients en oncologie qui subissent une opération. La chirurgie cause un stress particulièrement intense à l’organisme déjà fragilisé par la maladie et les traitements. Les transfusions périopératoires de globules rouges sont essentielles pour stabiliser le taux d’hémoglobine et soigner l’anémie, ainsi que pour gérer la perte de sang attendue pendant l’opération. Il est nécessaire d’examiner en profondeur et d’anticiper les facteurs de risque associés aux transfusions sanguines périopératoires pour améliorer le devenir des patients. Ces dernières années, la recherche sur la gestion périopératoire du sang des patients en oncologie recommande tout spécialement la création de programmes d’intervention coordonnés pour réduire la nécessité et le nombre de transfusions sanguines administrées avant, pendant et après l’opération. Pour recenser les patients à risque de complications périopératoires et leur faire bénéficier d’interventions rapides et d’une observation continue, la bonne stratégie est de mettre en lien les chirurgiens oncologues avec un programme local ou provincial de conservation du sang.

Ability of a Machine Learning Algorithm to Predict the Need for Perioperative Red Blood Cells Transfusion in Pelvic Fracture Patients: A Multicenter Cohort Study in China

Background: Predicting the perioperative requirement for red blood cells (RBCs) transfusion in patients with the pelvic fracture may be challenging. In this study, we constructed a perioperative RBCs transfusion predictive model (ternary classifications) based on a machine learning algorithm.

Materials and Methods: This study included perioperative adult patients with pelvic trauma hospitalized across six Chinese centers between September 2012 and June 2019. An extreme gradient boosting (XGBoost) algorithm was used to predict the need for perioperative RBCs transfusion, with data being split into training test (80%), which was subjected to 5-fold cross-validation, and test set (20%). The ability of the predictive transfusion model was compared with blood preparation based on surgeons' experience and other predictive models, including random forest, gradient boosting decision tree, K-nearest neighbor, logistic regression, and Gaussian naïve Bayes classifier models. Data of 33 patients from one of the hospitals were prospectively collected for model validation.

Results: Among 510 patients, 192 (37.65%) have not received any perioperative RBCs transfusion, 127 (24.90%) received less-transfusion (RBCs < 4U), and 191 (37.45%) received more-transfusion (RBCs ≥ 4U). Machine learning-based transfusion predictive model produced the best performance with the accuracy of 83.34%, and Kappa coefficient of 0.7967 compared with other methods (blood preparation based on surgeons' experience with the accuracy of 65.94%, and Kappa coefficient of 0.5704; the random forest method with an accuracy of 82.35%, and Kappa coefficient of 0.7858; the gradient boosting decision tree with an accuracy of 79.41%, and Kappa coefficient of 0.7742; the K-nearest neighbor with an accuracy of 53.92%, and Kappa coefficient of 0.3341). In the prospective dataset, it also had a food performance with accuracy 81.82%.

Conclusion: This multicenter retrospective cohort study described the construction of an accurate model that could predict perioperative RBCs transfusion in patients with pelvic fractures.

Hemoglobin levels as a transfusion criterion in moderate to severe traumatic brain injury: a systematic review and meta-analysis

BACKGROUND

Several factors can influence the outcome of severe head injuries including the patient's hemoglobin levels. There has often been a dilemma regarding levels of hemoglobin at which red cell blood transfusion (RCBT) should be performed.

OBJECTIVE

To systematically review the literature to determine the usefulness of management protocols that have hemoglobin levels <10 g/dL vs <7 g/dL as an RCBT criterion.

METHODS

Following the PRISMA statement, the search was constructed using terms and descriptors of the Medical Subject Heading (MeSH), combined with Boolean operators. Full text of these articles was studied, and outcome measures at 3-6 months were considered for patients who were given a RCBT at <10 g/dL or at 7 g/dL hemoglobin levels.

RESULTS

A total of 4 articles were found suitable for inclusion in the meta-analysis. RCBT below 7 g/dL was not associated with an increased risk of mortality as compared to RCBT using the value of less than 10 g/dL. RCBT at lower levels of hemoglobin was also not associated with a poor neurological outcome (GOS 4-5) but rather RCBT at lower levels lead to better outcomes (GOS 1-3) and the association was significant.

CONCLUSION

Allogenic RCBT was associated with poorer neurological outcomes, within a wide range of reported differences in the hemoglobin threshold to decide for RCBT in TBI patients. Restrictive RCBT strategy may be useful in moderate to severe TBI cases although the risk of anemia-induced cerebral injury needs further investigation regarding the risks and complications inherent to RCBT.

Nationwide analysis of cryopreserved packed red blood cell transfusion in civilian trauma

BACKGROUND

Liquid packed red blood cells (LPRBCs) have a limited shelf life and worsening quality with age. Cryopreserved packed red blood cells (CPRBCs) can be stored up to 10 years with no quality deterioration. The effect of CPRBCs on outcomes in civilian trauma is less explored. This study aims to evaluate the safety and efficacy of CPRBCs in civilian trauma patients.

METHODS

We analyzed the (2015-2016) Trauma Quality Improvement Program, including adult (age, ≥18 years) patients who received a RBC transfusion within 4 hours of admission. Patients were stratified, those who received LPRBC and those who received CPRBC. Primary outcomes were 24-hour and in-hospital mortality. Secondary outcomes were major complications. Propensity matching was performed adjusting for demographics, vitals, blood components, injury parameters, comorbidities, and center parameters.

RESULTS

A total of 39,975 patients were identified, and a matched cohort of 483 was obtained. A total of 161 received CPRBC (CPRBC, 2 [2-4]; plasma, 2 [0-5]; platelets, 1 [0-2]) and 322 received LPRBC (LPRBC, 3 [2-6]; plasma, 3 [0-6]; platelets, 1 [0-2]). The mean age was 43 ± 22 years, 62% were men, Injury Severity Score was 18 (12-27), and 65% had a blunt injury. Patients who received CPRBC had similar 24-hour mortality (1.8% vs. 2.3%; p = 0.82) and in-hospital mortality (4.9% vs. 5.2%; p = 0.88). No difference was found in terms of complications (15.3% vs. 17.2%; p = 0.21) between the two groups.

CONCLUSION

Transfusion of CPRBCs may be as safe and effective as transfusion of LPRBCs in moderately injured trauma patients. Cryopreservation has the potential to expand our transfusion armamentarium in diverse settings, such as periods of increased usage, disaster scenarios, and rural areas.

LEVEL OF EVIDENCE

Therapeutic study, level III.

Preoperative Risk Factors for Postoperative Urinary Tract Infection After Primary Total Hip and Knee Arthroplasties

BACKGROUND

Establishing clear risk factors for complications such as urinary tract infection (UTI) after arthroplasty procedures helps guide clinical practice and provides more information to both surgeons and patients. This study aims to assess selected preoperative patient characteristics as risk factors for postoperative UTI after primary total hip and knee arthroplasties (THA and TKA).

METHODS

This was a retrospective analysis using current procedural terminology codes to investigate the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database for patients who underwent THA or TKA from 2010 to 2017. Patients were classified for UTI by NSQIP guidelines. Patient samples with all possible covariates were included for multivariate logistic regression analysis and assessed for independent associations.

RESULTS

In a cohort of 983 identified patients (983 of 119,096; 0.83%): ages 57+ years, preoperative red blood cell (RBC) transfusion, perioperative RBC transfusion, bleeding disorders, operative time 110+ minutes, preoperative steroid use, diabetes, pulmonary comorbidities, body mass index 30+ kg/m² were independent risk factors for postoperative UTI after THA. In a cohort of 1503 identified patients (1503 of 189,327; 0.8%): ages 60+ years, preoperative RBC transfusion, perioperative RBC transfusion, anemia, platelets less than 150k, preoperative steroid use, diabetes, and body mass index 30+ kg/m² were independent risk factors for postoperative UTI after TKA. Male sex was associated with a decreased risk of UTI in both THA and TKA.

CONCLUSION

This study provides novel evidence on risk factors associated with the development of UTI after THA or TKA. Clinicians should be aware of risk factors in the manifestation of postoperative UTI after primary THA or TKA procedures.

Paroxysmal nocturnal hemoglobinuria: patient journey and burden of disease

Patients with paroxysmal nocturnal hemoglobinuria (PNH) often experience a lengthy path to diagnosis. Fewer than 40% of patients with PNH receive a diagnosis within 12 months of symptom onset, and 24% of all PNH diagnoses can take 5 years or longer. Diagnostic delay is a source of distress and can affect emotional well-being for patients with PNH. In PNH disease management, patients and care providers focus on risk of organ failure and mortality related to disease progression; nonetheless, patients' health-related quality of life (HRQOL) is largely affected by extensive treatment requirements and nonfatal complications of disease, such as fatigue. In particular, thrombosis is associated with significant impairments in physical and social functioning and global health status and significant fatigue. Among patients with anemia who are transfusion dependent, the burden of transfusion is considerable. Transfusion dependence has a negative effect on HRQOL; is associated with risks and complications, including iron overload; and results in lost productivity due to travel times to and time spent at infusion centers. DISCLOSURES: This research was developed under a research contract between RTI Health Solutions and Apellis Pharmaceuticals and was funded by Apellis Pharmaceuticals. Bektas, Copley-Merriman, and Khan are employees of RTI Health Solutions. Sarda is an employee of Apellis Pharmaceuticals. Shammo consults for Apellis Pharmaceuticals.

Transfusion in critical care: Past, present and future

Anaemia and coagulopathy are common in critically ill patients and are associated with poor outcomes, including increased risk of mortality, myocardial infarction, failure to be liberated from mechanical ventilation and poor physical recovery. Transfusion of blood and blood products remains the corner stone of anaemia and coagulopathy treatment in critical care. However, determining when the benefits of transfusion outweigh the risks of anaemia may be challenging in some critically ill patients. Therefore, the European Society of Intensive Care Medicine prioritised the development of a clinical practice guideline to address anaemia and coagulopathy in non-bleeding critically ill patients. The aims of this article are to: (1) review the evolution of transfusion practice in critical care and the direction for future developments in this important area of transfusion medicine and (2) to provide a brief synopsis of the guideline development process and recommendations in a format designed for busy clinicians and blood bank staff. These clinical practice guidelines provide recommendations to clinicians on how best to manage non-bleeding critically ill patients at the bedside. More research is needed on alternative transfusion targets, use of transfusions in special populations (e.g., acute neurological injury, acute coronary syndromes), use of anaemia prevention strategies and point-of-care interventions to guide transfusion strategies.

The effect of time on packed cell volume following packed red blood cell transfusion in anemic dogs

OBJECTIVE

To compare the PCV at several timepoints following packed red blood cell (pRBC) administration to anemic dogs and to assess if underlying cause of anemia or regenerative status significantly affects these measurements.

DESIGN

Prospective, observational study from November 2016 to October 2017.

SETTING

A small animal emergency and specialty hospital.

ANIMALS

Forty-six anemic client-owned dogs that received a total of 50 pRBC transfusions for management of anemia.

INTERVENTIONS

Blood was collected, and a PCV was obtained prior to pRBC transfusion (T0), immediately after (T1), 30 minutes after (T2), 1 hour after (T3), 2 hours after (T4), and 4 hours after (T5) the transfusion. Underlying causes of anemia were classified as hemorrhage, hemolysis, and ineffective erythropoiesis. Dogs were also categorized in regard to regenerative status of anemia and the presence or absence of expected continued blood loss or destruction.

MEASUREMENTS AND MAIN RESULTS

The mean PCV at T0 was 0.15 L/L (15%). After administration of a pRBC transfusion, the mean PCV at T1 was 0.28 L/L (28%). For all other timepoints (T2, T3, T4, and T5), the mean PCV was 0.27 L/L (27%). The PCV did not change significantly over time post-transfusion (P = 0.184), and no pairwise combinations of times differed significantly (paired t-tests; P > 0.05 for all). When dogs were categorized via regeneration status and continued blood loss or hemolysis, results were consistent.

CONCLUSIONS

There was no significant change in PCV from the value obtained immediately after pRBC transfusion up to 4 hours post-transfusion in dogs with several different causes of anemia. These results suggest that obtaining a PCV immediately after administering a pRBC transfusion to an anemic dog may be just as reliable as obtaining a measurement 2 hours after the transfusion. This remains true for dogs with expected continued red blood cell loss or destruction.

Hemoglobin-based Oxygen Carriers: Current State-of-the-art and Novel Molecules

In blood, the primary role of red blood cells (RBCs) is to transport oxygen via highly regulated mechanisms involving hemoglobin (Hb). Hb is a tetrameric porphyrin protein comprising of two α- and two β-polypeptide chains, each containing an iron-containing heme group capable of binding one oxygen molecule. In military as well as civilian traumatic exsanguinating hemorrhage, rapid loss of RBCs can lead to suboptimal tissue oxygenation and subsequent morbidity and mortality. In such cases, transfusion of whole blood or RBCs can significantly improve survival. However, blood products including RBCs present issues of limited availability and portability, need for type matching, pathogenic contamination risks, and short shelf-life, causing substantial logistical barriers to their prehospital use in austere battlefield and remote civilian conditions. While robust research is being directed to resolve these issues, parallel research efforts have emerged toward bioengineering of semisynthetic and synthetic surrogates of RBCs, using various cross-linked, polymeric, and encapsulated forms of Hb. These Hb-based oxygen carriers (HBOCs) can potentially provide therapeutic oxygenation when blood or RBCs are not available. Several of these HBOCs have undergone rigorous preclinical and clinical evaluation, but have not yet received clinical approval in the USA for human use. While these designs are being optimized for clinical translations, several new HBOC designs and molecules have been reported in recent years, with unique properties. The current article will provide a comprehensive review of such HBOC designs, including current state-of-the-art and novel molecules in development, along with a critical discussion of successes and challenges in this field.

Massive transfusion protocol in adult trauma population

BACKGROUND

Acute blood loss in trauma requires quick identification and action to restore circulating volume and save the patient. Massive transfusion protocols (MTPs) have become standard at Trauma Centers, in order to rapidly deliver blood products to bleeding patients. This literature review presents current standards of transfusion ratios, as well as insights into adjuncts during massive transfusions.

METHODS

PubMED was searched for articles from 2005 to 2020 on MTPs, the article were assessed for single vs. multi-institutional, mechanism of injury, type of MTP, timing in which blood products should be administered, timing of delivery of blood products to trauma bay, pre-hospital treatment and adjuncts, and outcomes.

RESULTS

Eleven studies addressed transfusion ratios. Seven studies looked at timing of blood products. Nine studies addressed MTP pre-hospital treatment and adjuncts. Prior to 2015, studies supported the benefits of a balanced transfusion ratio, which was then confirmed by the PROPPR randomized controlled trial. The shorter the time to blood product delivery the better the outcomes. New advances in technology have allowed us to measure different patterns of coagulation, allowing more individualized approaches to the bleeding patient.

CONCLUSION

Current massive transfusion protocols should utilize between 1:1:1 and 1:1:2 ratios of the 3 main products; plasma, platelets, and red blood cells. Massive transfusion protocols are effective in decreasing mortality. Better resuscitation efforts were seen when blood products were readily available in the trauma bay when the patient arrived and the faster the replacement of blood, the better the outcomes.

Evaluation of blood product transfusion therapies in acute injury care in low- and middle-income countries: a systematic review

BACKGROUND

Worldwide, injuries account for approximately five million mortalities annually, with 90% occurring in low- and middle-income countries (LMICs). Although guidelines characterizing data for blood product transfusion in injury resuscitation have been established for high-income countries (HICs), no such information on use of blood products in LMICs exists. This systematic review evaluated the available literature on the use and associated outcomes of blood product transfusion therapies in LMICs for acute care of patients with injuries.

METHODS

A systematic search of PubMed, EMBASE, Global Health, CINAHL and Cochrane databases through November 2018 was performed by a health sciences medical librarian. Prospective and cross-sectional reports of injured patients from LMICs involving data on blood product transfusion therapies were included. Two reviewers identified eligible records (κ=0.92); quality was assessed using Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria. Report elements, patient characteristics, injury information, blood transfusion therapies provided and mortality outcomes were extracted and analyzed.

RESULTS

Of 3411 records, 150 full-text reports were reviewed and 17 met inclusion criteria. Identified reports came from the World Health Organization regions of Africa, the Eastern Mediterranean, and South-East Asia. A total of 6535 patients were studied, with the majority from exclusively inpatient hospital settings (52.9%). Data on transfusion therapies demonstrated that packed red blood cells were given to 27.0% of patients, fresh frozen plasma to 13.8%, and unspecified product types to 50.1%. Among patients with blunt and penetrating injuries, 5.8% and 15.7% were treated with blood product transfusions, respectively. Four reports provided data on comparative mortality outcomes, of which two found higher mortality in blood transfusion-treated patients than in untreated patients at 17.4% and 30.4%. The overall quality of evidence was either low (52.9%) or very low (41.2%), with one report of moderate quality by GRADE criteria.

CONCLUSION

There is a paucity of high-quality data to inform appropriate use of blood transfusion therapies in LMIC injury care. Studies were geographically limited and did not include sufficient data on types of therapies and specific injury patterns treated. Future research in more diverse LMIC settings with improved data collection methods is needed to inform injury care globally.

RBC Transfusion Strategies in the ICU: A Concise Review

OBJECTIVES

To critically assess available high-level clinical studies regarding RBC transfusion strategies, with a focus on hemoglobin transfusion thresholds in the ICU.

DATA SOURCES

Source data were obtained from a PubMed literature review.

STUDY SELECTION

English language studies addressing RBC transfusions in the ICU with a focus on the most recent relevant studies.

DATA EXTRACTION

Relevant studies were reviewed and the following aspects of each study were identified, abstracted, and analyzed: study design, methods, results, and implications for critical care practice.

DATA SYNTHESIS

Approximately 30-50% of ICU patients receive a transfusion during their hospitalization with anemia being the indication for 75% of transfusions. A significant body of clinical research evidence supports using a restrictive transfusion strategy (e.g., hemoglobin threshold < 7 g/dL) compared with a more liberal approach (e.g., hemoglobin threshold < 10 g/dL). A restrictive strategy (hemoglobin < 7 g/dL) is recommended in patients with sepsis and gastrointestinal bleeds. A slightly higher restrictive threshold is recommended in cardiac surgery (hemoglobin < 7.5 g/dL) and stable cardiovascular disease (hemoglobin < 8 g/dL). Although restrictive strategies are generally supported in hematologic malignancies, acute neurologic injury, and burns, more definitive studies are needed, including acute coronary syndrome. Massive transfusion protocols are the mainstay of treatment for hemorrhagic shock; however, the exact RBC to fresh frozen plasma ratio is still unclear. There are also emerging complimentary practices including nontransfusion strategies to avoid and treat anemia and the reemergence of whole blood transfusion.

CONCLUSIONS

The current literature supports the use of restrictive transfusion strategies in the majority of critically ill populations. Continued studies of optimal transfusion strategies in various patient populations, coupled with the integration of novel complementary ICU practices, will continue to enhance our ability to treat critically ill patients.

Respiratory conditions in coronavirus disease 2019 (COVID-19): Important considerations regarding novel treatment strategies to reduce mortality

A novel virus named 2019 novel coronavirus (2019-nCoV/SARS-CoV-2) causes symptoms that are classified as coronavirus disease (COVID-19). Respiratory conditions are extensively described among more serious cases of COVID-19, and the onset of acute respiratory distress syndrome (ARDS) is one of the hallmark features of critical COVID-19 cases. ARDS can be directly life-threatening because it is associated with low blood oxygenation levels and can result in organ failure. There are no generally recognized effective treatments for COVID-19, but treatments are urgently needed. Anti-viral medications and vaccines are in the early developmental stages and may take many months or even years to fully develop. At present, management of COVID-19 with respiratory and ventilator support are standard therapeutic treatments, but unfortunately such treatments are associated with high mortality rates. Therefore, it is imperative to consider novel new therapeutic interventions to treat/ameliorate respiratory conditions associated with COVID-19. Alternate treatment strategies utilizing clinically available treatments such as hyperbaric oxygen therapy (HBOT), packed red blood cell (pRBC) transfusions, or erthropoiesis-stimulating agent (ESA) therapy were hypothesized to increase oxygenation of tissues by alternative means than standard respiratory and ventilator treatments. It was also revealed that alternative treatments currently being considered for COVID-19 such as chloroquine and hydroxychloroquine by increasing hemoglobin production and increasing hemoglobin availability for oxygen binding and acetazolamine (for the treatment of altitude sickness) by causing hyperventilation with associated increasing levels of oxygen and decreasing levels of carbon dioxide in the blood may significantly ameliorate COVID-19 respiratory symptoms. In conclusion, is recommend, given HBOT, pRBC, and ESA therapies are currently available and routinely utilized in the treatment of other conditions, that such therapies be tried among COVID-19 patients with serious respiratory conditions and that future controlled-clinical trials explore the potential usefulness of such treatments among COVID-19 patients with respiratory conditions.

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.

Transfusion rates in emergency general surgery: high but modifiable

BACKGROUND

Transfusion of red blood cells (RBC) increases morbidity and mortality, and emergency general surgery (EGS) cases have increased risk for transfusion and complication given case complexity and patient acuity. Transfusion reduction strategies and blood-conservation technology have been developed to decrease transfusions. This study explores whether transfusion rates in EGS have decreased as these new strategies have been implemented.

METHODS

This is a retrospective review of the American College of Surgeons' National Surgical Quality Improvement Program (ACS NSQIP) data from three academic medical centers. Operations performed by general surgeons on adults (aged ≥18 years) were selected. Data were analyzed from two periods: 2011-2013 and 2014-2016. Cases were grouped by the first four digits of the primary procedure Current Procedural Terminology code. Transfusion was defined as any RBC transfusion during or within 72 hours following the operation. Composite morbidity was defined as any NSQIP complication within 30 days following the operation.

RESULTS

Overall general surgery transfusion rates decreased from 6.4% to 4.8% from period 1 to period 2 (emergent: 16.6%-11.5%; non-emergent 4.9%-3.7%; Fisher's exact p values <0.001). Among patients transfused, the number of units received decreased slightly (median 2 U (IQR 2-3) to median 2 U (IQR 1-3), Mann-Whitney U test p=0.005). Morbidity decreased (overall: 13.8%-12.3%, p=0.001; emergent: 26.3%-20.6%, p<0.001) while mortality did not change.

DISCUSSION

Rates of RBC transfusion decreased in both emergent and non-emergent cases. Efforts to reduce transfusion may have been successful in the EGS population. Morbidity improved over the time periods while mortality was unchanged.

LEVEL OF EVIDENCE

Level III.

Impact of Genitourinary Injuries on Patients Requiring an Emergency Laparotomy for Trauma

Introduction

In patients having emergency abdominal surgery for trauma, the presence of urologic injury tends to increase mortality and morbidity.

Methods

This retrospective study evaluated patients requiring emergency surgery for abdominal trauma at a Level 1 Trauma Center over 30 years (1980-2010). Special attention was given to patients with concomitant genitourinary (GU) injuries.

Results

Of 1105 patients requiring an emergency laparotomy for trauma, 242 (22%) had urologic injuries including kidney 178 (16%), ureter 47 (4%), and bladder 46 (4%). Of the 242 patients, 50 (20%) died early (<48 hours) and 13 (5%) died later, primarily due to infection. A concept of “seven deadly signs” of hypoperfusion was developed. In patients with GU injuries, the presence of any deadly sign of hypoperfusion increased the mortality rate from 4% (6/152) to 63% (56/90), p<0.001. Of the 53 patients having a nephrectomy, 36 (68%) had one or more deadly signs and 27 (75%) died. Of 17 without deadly signs, only 2 (12%) died (p=0.001). Of 167 GU patients receiving blood, 59 (35%) developed infection vs 3/75(4%) in those receiving no blood (p<0.001).

Conclusions

The presence of deadly signs of severe injury and hypoperfusion on admission was the major factor determining mortality. With a severely injured kidney plus any deadly signs of hypoperfusion, special efforts should be made to avoid a nephrectomy.

Transfusion in children with acute respiratory distress syndrome

Transfusion is a frequent treatment in pediatric patients with acute respiratory distress syndrome (PARDS) although evidence to support transfusion decision-making is lacking. The purpose of this review is to review the current state of knowledge on the issue of transfusion in children with PARDS and to detail the possible beneficial effects and potential deleterious impacts of transfusion in this patient population. Based on the current literature and recent guidelines, a restrictive red blood cell (RBC) transfusion strategy (avoidance of transfusion when the haemoglobin level is above 7 g/dL) is indicated in stable patients without severe PARDS, as these were excluded from the large trials. In children with severe PARDS, further research is needed to determine if factors other than the haemoglobin level might guide RBC transfusion decision-making by better characterizing the presence of low oxygen delivery (DO₂). Additionally, appropriate indications for prophylactic transfusion of hemostatic products (plasma or platelets) in children with PARDS are lacking.

Determinants of transfusion decisions in the ICU: haemoglobin concentration, what else? - a retrospective cohort study

BACKGROUND AND OBJECTIVES

The aim of this study was to assess potentially relevant clinical characteristics which influence the decision to transfuse red cells in critically ill patients with low haemoglobin concentrations (6.0-10.0 g/dl).

MATERIALS AND METHODS

This was a retrospective observational cohort study of patients admitted between November 2004 and May 2016 at the intensive care unit (ICU) of the Leiden University Medical Center, Netherlands. Haemoglobin measurements, clinical variables and the subsequent transfusion decision were extracted from the electronic health records. Clinical variables were grouped by organ system. We first examined the association of each of the clinical variables with the decision to transfuse during the following 6 h after a haemoglobin measurement using generalized estimating equations. We then compared the predictive abilities of single variables within an organ system and the predictive ability of an organ system's combined variables using the change in Akaike information criterion (AIC).

RESULTS

A total of 83 394 haemoglobin measurements of 10 947 ICU admissions were included. Haemoglobin concentration was the most predictive for red cell transfusion. After the haemoglobin concentration, the combined variables for General Health, followed by the organ systems Cardiovascular and Pulmonary, were most predictive for red cell transfusion. Within these organ systems, the APACHE II score, referring department, APACHE admission diagnosis subgroup, troponin concentration, lactate concentration, respiratory rate, PaO₂ /FiO₂ and ventilation mode had the highest predictive ability.

CONCLUSION

Haemoglobin concentration is the dominant predictor for red cell transfusion. Other clinical characteristics are also predictive, though to a lesser extent.

Clinical application of auricular point sticking in perioperative hemostasis for elderly patients with intertrochanteric fractures of the femur

We investigated the clinical application of auricular point sticking (APS) combined with tranexamic acid in perioperative hemostasis in elderly patients with intertrochanteric fractures of the femur.This is a prospective cohort study, and we analyzed 86 elderly patients with intertrochanteric fractures of the femur who underwent closed reduction and internal fixation with proximal femoral nail antirotation (PFNA) between January 2016 and December 2016. The patients were divided into auricular point combined with tranexamic acid group (APS group, n = 43) and tranexamic acid alone group (Control group, n = 43). APS was performed for patients using Vaccaria seeds 1 to 2 days before the operation. The 4 acupoints of hemostasis, including spleen, diaphragm, pituitary, and adrenal gland, as well as acupoint of hip joint, were selected. Routine treatment was performed using tranexamic acid alone in the control group. Blood transfusion, intraoperative, postoperative, and total blood loss were compared between the 2 groups.This study enrolled 36 males and 50 females aged 71 to 93 years (average age: 78.5 years). There were no significant differences in gender, age, height, weight, preoperative hematocrit level, fracture classification, operative time, and hospitalization stay (P > .05). Total blood loss was lower in the APS group than the control group (244.26, 197.87-258.50 ml vs 533.94, 424.00-598.09 ml, P < .01). The blood transfusion rate was 14.0% in the APS group and 34.9% in the control group (P = .02).APS can reduce perioperative bleeding and decrease the need for blood transfusion in elderly patients with intertrochanteric fractures of the femur. This noninvasive method can be applied clinically. Randomized trials may be needed to confirm the findings.

Anesthetic considerations for extracranial injuries in patients with associated brain trauma

Patients with severe traumatic brain injury often presents with extracranial injuries, which may contribute to fatal outcome. Anesthetic management of such polytrauma patients is extremely challenging that includes prioritizing the organ system to be dealt first, reducing on-going injury, and preventing secondary injuries. Neuroprotective and neurorescue measures should be instituted simultaneously during extracranial surgeries. Selection of anesthetic drugs that minimally interferes with cerebral dynamics, maintenance of hemodynamics and cerebral perfusion pressure, optimal utilization of multimodal monitoring techniques, and aggressive rehabilitation approach are the key factors for improving overall patient outcome.

Quality of clinical practice guidelines about red blood cell transfusion

BACKGROUND

Red blood cell (RBC) transfusions are essential in health care. The quality of recommendations included in clinical practice guidelines (CPG), regarding this intervention, has not been systematically evaluated. This paper systematically assessed CPGs for RBC-transfusion, to appraise their methodological quality, to explore changes in quality over time, and to assess the consistency of the hemoglobin threshold (HT) recommendations.

METHODS

We searched for CPGs that included recommendations of RBC-transfusion in generic databases, compiler entities, registries, clearinghouses and guideline developers. Three reviewers extracted data on CPGs characteristics and HT recommendations, independently appraised the quality of the studies using AGREE II and resolved disagreements by consensus.

RESULTS

We examined 16 CPGs. Mean scores (mean ± SD) were: scope and purpose (59.4% ± 19.8%), stakeholder involvement (43.2% ± 22.6%), rigor of development (50% ± 25%), clarity of presentation (74.4% ± 12.6%), applicability (19.4% ± 18.8%), and editorial independence (41% ± 30%). Seven CPGs recommended a restrictive strategy for RBC transfusion; four CPGs gave a guarded statement considering an HT of 7 g/dL, as safe to prescribe an RBC transfusion. Eight CPGs did not provide an HT stating that RBC transfusions should not be prescribed by HT alone.

CONCLUSIONS

Only 3 out of the 16 evaluated CPGs were "recommended" by the independent evaluators. Four domains "stakeholder involvement," "rigor of development," applicability," and "editorial independence" had serious shortcomings. Recommendations about the use of an HT for RBC-transfusion were heterogeneous among guidelines. Greater efforts are needed to provide high-quality CPGs in the RBC-transfusion practice.

Outcomes following restrictive or liberal red blood cell transfusion in patients with lower gastrointestinal bleeding

BACKGROUND

Restrictive red blood cell (RBC) transfusion reduces mortality and rebleeding after upper gastrointestinal bleeding (UGIB). However, there is no evidence to guide transfusion strategies in lower gastrointestinal bleeding (LGIB).

AIM

To assess the association between RBC transfusion strategies and outcomes in patients with LGIB METHODS: This was a post hoc analysis of the UK National Comparative Audit of LGIB and the Use of Blood. The relationships between liberal RBC transfusion and clinical outcomes of rebleeding, mortality and a composite outcome for safe discharge were examined. Transfusion strategy was dichotomised and defined as "liberal" when transfusion was administered for haemoglobin (Hb) ≥80 g/L (or ≥90 g/L in patients with acute coronary syndrome) or major haemorrhage, and "restrictive" otherwise. Multivariable logistic regression models were used to assess the independent association between liberal RBC transfusion and outcomes.

RESULTS

Of 2528 consecutive patients enrolled from 143 hospitals in the original study, 666 (26.3%) received RBC transfusion (mean age 73.3 ± 16 years, 49% female, initial mean haemoglobin 90 ± 24 g/L, 2.3% had haemodynamic instability). The rebleeding rate in transfused patients was 42.3%. After adjusting for potential confounders, there was no difference between liberal and restrictive RBC transfusion strategies for the odds of rebleeding (OR 0.89, 95% CI 0.6-1.22), in-hospital mortality (OR 0.54, 95% CI 0.3-1.1) or of achieving the composite outcome (OR 0.72, 95% CI 0.5-1.1).

CONCLUSION

Although these results could be due to residual confounding, they provide an important foundation for the design of randomised trials to evaluate transfusion strategies for LGIB.

Red blood cell transfusion threshold after pediatric cardiac surgery: A systematic review and meta-analysis

BACKGROUND

Restrictive red blood cell transfusion strategy is implemented to minimize risk following allogeneic blood transfusion in adult cardiac surgery. However, it is still unclear if it can be applied to pediatric cardiac patients. The purpose of this systematic review and meta-analysis was to determine the effect of postoperative restrictive transfusion thresholds on clinical outcomes based on up-to-date results of randomized controlled trials (RCTs) and observational studies in pediatric cardiac surgery.

METHOD

We searched for RCTs and observational studies in the following databases: the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, and ClinicalTrials.gov from their inception to October 26, 2017. We also searched reference lists of published guidelines, reviews, and relevant articles, as well as conference proceedings. No language restrictions were applied and no observational study met the inclusion criteria.

RESULTS

Four RCTs on cardiac surgery involving 454 patients were included. There were no differences in the pooled fixed effects of intensive care unit (ICU) stay between the liberal and restrictive transfusion thresholds (standardized mean difference SMD, 0.007; 95% confidence interval CI, -0.18-0.19; P = .94). There were also no differences in the length of hospital stay (SMD, -0.062; 95% CI, -0.28-0.15; P = .57), ventilation duration (SMD, -0.015; 95% CI, -0.25-0.22; P = .90), mean arterial lactate level (SMD, 0.071; 95% CI, -0.22-0.36; P = .63), and mortality (risk ratio, 0.49; 95% CI, 0.13-1.94; P = .31). There was no inter-trial heterogeneity for any pooled analysis. Publication bias was tested using Egger, Begg, or the trim-and-fill test, and the results indicated no significant publication bias.

CONCLUSION

Evidence from RCTs in pediatric cardiac surgery, though limited, showed non-inferiority of restrictive thresholds over liberal thresholds in length of ICU stay and other outcomes following red blood cell transfusion. Further high-quality RCTs are necessary to confirm the findings.