Transfusion practices for acute traumatic brain injury: a survey of physicians at US trauma centers

Anemia and Optimal Transfusion Thresholds in Brain-Injured Patients: A Narrative Review of the Literature

Anemia is a highly prevalent condition that may compromise oxygen delivery to vital organs, especially among the critically ill. Although current evidence supports the adoption of a restrictive transfusion strategy and threshold among the nonbleeding critically ill patient, it remains unclear whether this practice should apply to the brain-injured patient, given the predisposition to cerebral ischemia in this patient population, in which even nonprofound anemia may exert a detrimental effect on clinical outcomes. The purpose of this review is to provide an overview of the pathophysiological changes related to impaired cerebral oxygenation in the brain-injured patient and to present the available evidence on the effect of anemia and varying transfusion thresholds on the clinical outcomes of patients with acute brain injury.

Development and Performance Evaluation of a Clinical Predictive Model to Estimate the Risk of Red Blood Cell Requirements in Brain Tumor Surgery

BACKGROUND

The identification of factors associated with perioperative red blood cell (RBC) transfusion provides an opportunity to optimize the patient and surgical plan, and to guide perioperative crossmatch and RBC orders. We examined the association among potential bleeding risk factors and RBC requirements to develop a novel predictive model for RBC transfusion in patients undergoing brain tumor surgery.

METHODS

This retrospective study included 696 adults who underwent brain tumor surgery between 2008 and 2018. Multivariable logistic regression with backward stepwise selection for predictor selection was used during modeling. Model performance was evaluated using area under the receiver operating characteristic curve, and calibration was evaluated with Hosmer-Lemeshow goodness-of-fit χ 2 -estimate.

RESULTS

Preoperative hemoglobin level was inversely associated with the probability of RBC transfusion (odds ratio [OR]: 0.50; 95% confidence interval [CI]: 0.39-0.63; P <0.001). The need for RBC transfusion was also greater in patients who had a previous craniotomy (OR: 2.71; 95% CI: 1.32-5.57; P =0.007) and in those with larger brain tumor volume (OR: 1.01; 95% CI: 1.00-1.02; P =0.009). The relationship between number of planned craniotomy sites and RBC transfusion was not statistically significant (OR: 2.11; 95% CI: 0.61-7.32; P =0.238). A predictive model for RBC requirements was built using these 4 variables. The area under the receiver operating characteristic curve was 0.79 (95% CI: 0.70-0.87; P <0.001) showing acceptable calibration for predicting RBC transfusion requirements.

CONCLUSIONS

RBC requirements in patients undergoing brain tumor surgery can be estimated with acceptable accuracy using a predictive model based on readily available preoperative clinical variables. This predictive model could help to optimize both individual patients and surgical plans, and to guide perioperative crossmatch orders.

Restrictive transfusion strategy for critically injured patients (RESTRIC) trial: a study protocol for a cluster-randomised, crossover non-inferiority trial

INTRODUCTION

Resuscitation using blood products is critical during the acute postinjury period. However, the optimal target haemoglobin (Hb) levels have not been adequately investigated. With the restrictive transfusion strategy for critically injured patients (RESTRIC) trial, we aim to compare the restrictive and liberal red blood cell (RBC) transfusion strategies.

METHODS AND ANALYSIS

This is a cluster-randomised, crossover, non-inferiority trial of patients with severe trauma at 22 hospitals that have been randomised in a 1:1 ratio based on the use of a restrictive or liberal transfusion strategy with target Hb levels of 70-90 or 100-120 g/L, respectively, during the first year. Subsequently, after 1-month washout period, another transfusion strategy will be applied for an additional year. RBC transfusion requirements are usually unclear on arrival at the emergency department. Therefore, patients with severe bleeding, which could lead to haemorrhagic shock, will be included in the trial based on the attending physician's judgement. Each RBC transfusion strategy will be applied until 7 days postadmission to the hospital or discharge from the intensive care unit. The outcomes measured will include the 28-day survival rate after arrival at the emergency department (primary), the cumulative amount of blood transfused, event-free days and frequency of transfusion-associated lung injury and organ failure (secondary). Demonstration of the non-inferiority of restrictive transfusion will emphasise its clinical advantages.

ETHICS AND DISSEMINATION

The trial will be performed according to the Japanese and International Ethical guidelines. It has been approved by the Ethics Committee of each participating hospital and The Japanese Association for the Surgery of Trauma (JAST). Written informed consent will be obtained from all patients or their representatives. The results of the trial will be disseminated to the participating hospitals and board-certified educational institutions of JAST, submitted to peer-reviewed journals for publication, and presented at congresses.

TRIAL REGISTRATION NUMBER

UMIN Clinical Trials Registry; UMIN000034405. Registered 8 October 2018.

Management of moderate and severe traumatic brain injury

Traumatic brain injury (TBI) is a common disorder with high morbidity and mortality, accounting for one in every three deaths due to injury. Older adults are especially vulnerable. They have the highest rates of TBI-related hospitalization and death. There are about 2.5 to 6.5 million US citizens living with TBI-related disabilities. The cost of care is very high. Aside from prevention, little can be done for the initial primary injury of neurotrauma. The tissue damage incurred directly from the inciting event, for example, a blow to the head or bullet penetration, is largely complete by the time medical care can be instituted. However, this event will give rise to secondary injury, which consists of a cascade of changes on a cellular and molecular level, including cellular swelling, loss of membrane gradients, influx of immune and inflammatory mediators, excitotoxic transmitter release, and changes in calcium dynamics. Clinicians can intercede with interventions to improve outcome in the mitigating secondary injury. The fundamental concepts in critical care management of moderate and severe TBI focus on alleviating intracranial pressure and avoiding hypotension and hypoxia. In addition to these important considerations, mechanical ventilation, appropriate transfusion of blood products, management of paroxysmal sympathetic hyperactivity, using nutrition as a therapy, and, of course, venous thromboembolism and seizure prevention are all essential in the management of moderate to severe TBI patients. These concepts will be reviewed using the recent 2016 Brain Trauma Foundation Guidelines to discuss best practices and identify future research priorities.

Red blood cell transfusion in critically ill patients with traumatic brain injury: an international survey of physicians' attitudes

INTRODUCTION

Restrictive transfusion strategies have been advocated in critically ill patients. Nevertheless, considerable uncertainty exists regarding optimal transfusion thresholds in traumatic brain injury (TBI) patients because the injured brain is susceptible to hypoxemic damage. We aimed to identify the determinants of red blood cell (RBC) transfusion and the perceived optimal transfusion thresholds in adult patients with moderate-to-severe TBI.

METHODS

We conducted an electronic, self-administered survey targeting critical care specialists and neurosurgeons from Canada, Australia, and the United Kingdom caring for TBI patients. The questionnaire was initially developed by a panel of experts using a structured process (domains/items generation and reduction). The questionnaire was validated for clinical sensibility, reliability, and content.

RESULTS

The response rate was 28.7% (218/760). When presented with the hypothetical scenario of a young adult TBI patient, a wide range of transfusion practices was observed, with 47 (95% confidence interval [CI], 41 to 54)% favouring RBC transfusion at a hemoglobin level of ≤ 70 g·L^-1 in the acute phase of care, while 73 (95% CI, 67 to 79)% would use this trigger in the plateau phase of care. Multiple trauma, neuro-monitoring data, hemorrhagic shock, and planned surgery were the main factors that influenced the need for transfusion. The lack of clinical evidence and guidelines was responsible for uncertainty regarding RBC transfusion strategies in this patient population.

CONCLUSION

In our survey about critically ill TBI patients, transfusion practice was found to be mainly influenced by the acuity of care, patient characteristics, and neuro-monitoring. Clinical equipoise regarding optimal transfusion strategy is believed to be mainly attributed to the lack of clear clinical evidence and guidelines. Appropriate randomized-controlled trials are required to determine the optimal transfusion strategies in TBI patients.

Transfusion requirements after head trauma: a randomized feasibility controlled trial

Background

Anemia is frequent among patients with traumatic brain injury (TBI) and is associated with an increased risk of poor outcome. The optimal hemoglobin concentration to trigger red blood cell (RBC) transfusion in patients with TBI is not clearly defined.

Methods

All eligible consecutive adult patients admitted to the intensive care unit (ICU) with moderate or severe TBI were randomized to a “restrictive” (hemoglobin transfusion threshold of 7 g/dL), or a “liberal” (threshold 9 g/dL) transfusion strategy. The transfusion strategy was continued for up to 14 days or until ICU discharge. The primary outcome was the mean difference in hemoglobin between groups. Secondary outcomes included transfusion requirements, intracranial pressure management, cerebral hemodynamics, length of stay, mortality and 6-month neurological outcome.

Results

A total of 44 patients were randomized, 21 patients to the liberal group and 23 to the restrictive group. There were no baseline differences between the groups. The mean hemoglobin concentrations during the 14-day period were 8.4 ± 1.0 and 9.3 ± 1.3 (p < 0.01) in the restrictive and liberal groups, respectively. Fewer RBC units were administered in the restrictive than in the liberal group (35 vs. 66, p = 0.02). There was negative correlation (r = − 0.265, p < 0.01) between hemoglobin concentration and middle cerebral artery flow velocity as evaluated by transcranial Doppler ultrasound and the incidence of post-traumatic vasospasm was significantly lower in the liberal strategy group (4/21, 3% vs. 15/23, 65%; p < 0.01). Hospital mortality was higher in the restrictive than in the liberal group (7/23 vs. 1/21; p = 0.048) and the liberal group tended to have a better neurological status at 6 months (p = 0.06).

Conclusions

The trial reached feasibility criteria. The restrictive group had lower hemoglobin concentrations and received fewer RBC transfusions. Hospital mortality was lower and neurological status at 6 months favored the liberal group.

Trial registration

ClinicalTrials.gov, NCT02203292. Registered on 29 July 2014.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2273-9) contains supplementary material, which is available to authorized users.

Anaemia and red blood cell transfusion in intracranial neurosurgery: a comprehensive review

Both anaemia and blood transfusion are associated with poor outcomes in the neurosurgical population. Based on the available literature, the optimal haemoglobin concentration for neurologically injured patients appears to be in the range of 9.0-10.0 g dl^-1, although the individual risks and benefits should be weighed. Several perioperative blood conservation strategies have been used successfully in neurosurgery, including correction of anaemia and coagulopathy, use of antifibrinolytics, and intraoperative cell salvage. Avoidance of non-steroidal anti-inflammatory drugs and starch-containing solutions is recommended given the potential for platelet dysfunction.

Variation in Blood Transfusion and Coagulation Management in Traumatic Brain Injury at the Intensive Care Unit: A Survey in 66 Neurotrauma Centers Participating in the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury Study

Our aim was to describe current approaches and to quantify variability between European intensive care units (ICUs) in patients with traumatic brain injury (TBI). Therefore, we conducted a provider profiling survey as part of the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) study. The ICU Questionnaire was sent to 68 centers from 20 countries across Europe and Israel. For this study, we used ICU questions focused on 1) hemoglobin target level (Hb-TL), 2) coagulation management, and 3) deep venous thromboembolism (DVT) prophylaxis. Seventy-eight participants, mostly intensivists and neurosurgeons of 66 centers, completed the ICU questionnaire. For ICU-patients, half of the centers (N = 34; 52%) had a defined Hb-TL in their protocol. For patients with TBI, 26 centers (41%) indicated an Hb-TL between 70 and 90 g/L and 38 centers (59%) above 90 g/L. To treat trauma-related hemostatic abnormalities, the use of fresh frozen plasma (N = 48; 73%) or platelets (N = 34; 52%) was most often reported, followed by the supplementation of vitamin K (N = 26; 39%). Most centers reported using DVT prophylaxis with anticoagulants frequently or always (N = 62; 94%). In the absence of hemorrhagic brain lesions, 14 centers (21%) delayed DVT prophylaxis until 72 h after trauma. If hemorrhagic brain lesions were present, the number of centers delaying DVT prophylaxis for 72 h increased to 29 (46%). Overall, a lack of consensus exists between European ICUs on blood transfusion and coagulation management. The results provide a baseline for the CENTER-TBI study, and the large between-center variation indicates multiple opportunities for comparative effectiveness research.

Hemoglobin concentrations and RBC transfusion thresholds in patients with acute brain injury: an international survey

Background

The optimal hemoglobin (Hb) threshold at which to initiate red blood cell (RBC) transfusion in patients with acute brain injury is unknown. The aim of this survey was to investigate RBC transfusion practices used with these patients.

Methods

We conducted a web-based survey within various societies of critical care medicine for intensive care unit (ICU) physicians who currently manage patients with primary acute brain injury.

Results

A total of 868 responses were obtained from around the world, half of which (n = 485) were from European centers; 204 (24%) respondents had a specific certificate in neurocritical care, and most were specialists in anesthesiology or intensive care and had less than 15 years of practice experience. Four hundred sixty-six respondents (54%) said they used an Hb threshold of 7–8 g/dl to initiate RBC transfusion after acute brain injury, although half of these respondents used a different threshold (closer to 9 g/dl) in patients with traumatic brain injury, subarachnoid hemorrhage, or ischemic stroke. Systemic and cerebral factors were reported as influencing the need for higher Hb thresholds. Most respondents agreed that a randomized clinical trial was needed to compare two different Hb thresholds for RBC transfusion, particularly in patients with traumatic brain injury, subarachnoid hemorrhage, and ischemic stroke.

Conclusions

The Hb threshold used for RBC transfusion after acute brain injury was less than 8 g/dl in half of the ICU clinicians who responded to our survey. However, more than 50% of these physicians used higher Hb thresholds in certain conditions.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-017-1748-4) contains supplementary material, which is available to authorized users.

Transfusion of red blood cells in patients with traumatic brain injuries admitted to Canadian trauma health centres: a multicentre cohort study

BACKGROUND

Optimisation of healthcare practices in patients sustaining a traumatic brain injury is of major concern given the high incidence of death and long-term disabilities. Considering the brain's susceptibility to ischaemia, strategies to optimise oxygenation to brain are needed. While red blood cell (RBC) transfusion is one such strategy, specific RBC strategies are debated. We aimed to evaluate RBC transfusion frequency, determinants of transfusions and associated clinical outcomes.

METHODS

We conducted a retrospective multicentre cohort study using data from the National Trauma Registry of Canada. Patients admitted with moderate or severe traumatic brain injury to participating hospitals between April 2005 and March 2013 were eligible. Patient information on blood products, comorbidities, interventions and complications from the Discharge Abstract Database were linked to the National Trauma Registry data. Relative weights analyses evaluated the contribution of each determinant. We conducted multivariate robust Poisson regression to evaluate the association between potential determinants, mortality, complications, hospital-to-home discharge and RBC transfusion. We also used proportional hazard models to evaluate length of stay for time to discharge from ICU and hospital.

RESULTS

Among the 7062 patients with traumatic brain injury, 1991 patients received at least one RBC transfusion during their hospital stay. Female sex, anaemia, coagulopathy, sepsis, bleeding, hypovolemic shock, other comorbid illnesses, serious extracerebral trauma injuries were all significantly associated with RBC transfusion. Serious extracerebral injuries altogether explained 61% of the observed variation in RBC transfusion. Mortality (risk ratio (RR) 1.23 (95% CI 1.13 to 1.33)), trauma complications (RR 1.38 (95% CI 1.32 to 1.44)) and discharge elsewhere than home (RR 1.88 (95% CI 1.75 to 2.04)) were increased in patients who received RBC transfusion. Discharge from ICU and hospital were also delayed in transfused patients.

CONCLUSIONS

RBC transfusion is common in patients with traumatic brain injury and associated with unfavourable outcomes. Trauma severity is an important determinant of RBC transfusion. Prospective studies are needed to further evaluate optimal transfusion strategies in traumatic brain injury.

Blood transfusion indications in neurosurgical patients: A systematic review

Neurosurgical procedures can be complicated by significant blood losses that have the potential to decrease tissue perfusion to critical brain tissue. Red blood cell transfusion is used in a variety of capacities both inside, and outside, of the operating room to prevent untoward neurologic damage. However, evidence-based guidelines concerning thresholds and indications for transfusion in neurosurgery remain limited. Consequently, transfusion practices in neurosurgical patients are highly variable and based on institutional experiences. Recently, a paradigm shift has occurred in neurocritical intensive care units, whereby restrictive transfusion is increasingly favored over liberal transfusion but the ideal strategy remains in clinical equipoise. The authors of this study perform a systematic review of the literature with the objective of capturing the changing landscape of blood transfusion indications in neurosurgical patients.

Anemia management after acute brain injury

Anemia is frequent among brain-injured patients, where it has been associated with an increased risk of poor outcome. The pathophysiology of anemia in this patient population remains multifactorial; moreover, whether anemia merely reflects a higher severity of the underlying disease or is a significant determinant of the neurological recovery of such patients remains unclear. Interestingly, the effects of red blood cell transfusions (RBCT) in moderately anemic patients remain controversial; although hemoglobin levels are increased, different studies observed only a modest and inconsistent improvement in cerebral oxygenation after RBCT and raised serious concerns about the risk of increased complications. Thus, considering this "blood transfusion anemia paradox", the optimal hemoglobin level to trigger RBCT in brain-injured patients has not been defined yet; also, there is insufficient evidence to provide strong recommendations regarding which hemoglobin level to target and which associated transfusion strategy (restrictive versus liberal) to select in this patient population. We summarize in this review article the more relevant studies evaluating the effects of anemia and RBCT in patients with an acute neurological condition; also, we propose some potential strategies to optimize transfusion management in such patients.

Hemoglobin Area and Time Index Above 90 g/L are Associated with Improved 6-Month Functional Outcomes in Patients with Severe Traumatic Brain Injury

PURPOSE

There is conflicting data on the relationship between anemia and outcomes in patients with traumatic brain injuries (TBI). The objective of this study was to determine if the proportion of time and area under the hemoglobin-time curve of ≥90 g/L are independently associated with 6-month functional outcomes.

METHODS

Retrospective cohort study of 116 patients with a severe TBI who underwent invasive neuromonitoring between June 2006 and December 2013. Hemoglobin area (HAI) and time (HTI) indices were calculated by dividing the total area, or time, under the hemoglobin-time curve at 90 g/L or above by the total duration of monitoring. Multivariable log-binomial regression was used to model the association between HAI or HTI and 6 month favorable neurologic outcome (Glasgow Outcome Score 4 or 5).

RESULTS

Patients had a mean age of 38 years (SD 16) with a median admission Glasgow Coma Scale of 6 (IQR 4-7). There were 1523 hemoglobin measurements and 523 monitoring days. Patients had a hemoglobin ≥90 g/L for a median of 70 % (IQR 37-100) of the time. Each 10 g/L increase in HAI (RR 1.23, 95 %CI 1.04-1.44, P = 0.011), and 10 % increase in HTI (1.10, 95 %CI 1.04-1.16, P < 0.001) were associated with improved neurologic outcome. Thirty-one patients (27 %) received a transfusion with the median pre-transfusion hemoglobin being 81 g/L (IQR 76-87).

CONCLUSIONS

In patients with severe TBI, increased area under the curve and percentage of time that the hemoglobin concentration was ≥90 g/L, were associated with improved neurologic outcomes.

Anemia and Blood Transfusion in Patients with Isolated Traumatic Brain Injury

Rationale. By reducing cerebral oxygen delivery, anemia may aggravate traumatic brain injury (TBI) secondary insult. This study evaluated the impact of anemia and blood transfusion on TBI outcomes. Methods. This was a retrospective cohort study of adult patients with isolated TBI at a tertiary-care intensive care unit from 1/1/2000 to 31/12/2011. Daily hemoglobin level and packed red blood cell (PRBC) transfusion were recorded. Patients with hemoglobin < 10 g/dL during ICU stay (anemic group) were compared with other patients. Results. Anemia was present on admission in two (2%) patients and developed in 48% during the first week with hemoglobin < 7 g/dL occurring in 3.0%. Anemic patients had higher admission Injury Severity Score and underwent more craniotomy (50% versus 13%, p < 0.001). Forty percent of them received PRBC transfusion (2.8 ± 1.5 units per patient, median pretransfusion hemoglobin = 8.8 g/dL). Higher hospital mortality was associated with anemia (25% versus 6% for nonanemic patients, p = 0.01) and PRBC transfusion (38% versus 9% for nontransfused patients, p = 0.003). On multivariate analysis, only PRBC transfusion independently predicted hospital mortality (odds ratio: 6.8; 95% confidence interval: 1.1–42.3). Conclusions. Anemia occurred frequently after isolated TBI, but only PRBC transfusion independently predicted mortality.

Preoperative anemia increases postoperative morbidity in elective cranial neurosurgery

Background:

Preoperative anemia may affect postoperative mortality and morbidity following elective cranial operations.

Methods:

The American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database was used to identify elective cranial neurosurgical cases (2006-2012). Morbidity was defined as wound infection, systemic infection, cardiac, respiratory, renal, neurologic, and thromboembolic events, and unplanned returns to the operating room. For 30-day postoperative mortality and morbidity, adjusted odds ratios (ORs) were estimated with multivariable logistic regression.

Results:

Of 8015 patients who underwent elective cranial neurosurgery, 1710 patients (21.4%) were anemic. Anemic patients had an increased 30-day mortality of 4.1% versus 1.3% in non-anemic patients (P < 0.001) and an increased 30-day morbidity rate of 25.9% versus 14.14% in non-anemic patients (P < 0.001). The 30-day morbidity rates for all patients undergoing cranial procedures were stratified by diagnosis: 26.5% aneurysm, 24.7% sellar tumor, 19.7% extra-axial tumor, 14.8% intra-axial tumor, 14.4% arteriovenous malformation, and 5.6% pain. Following multivariable regression, the 30-day mortality in anemic patients was threefold higher than in non-anemic patients (4.1% vs 1.3%; OR = 2.77; 95% CI: 1.65-4.66). The odds of postoperative morbidity in anemic patients were significantly higher than in non-anemic patients (OR = 1.29; 95% CI: 1.03-1.61). There was a significant difference in postoperative morbidity event odds with a hematocrit level above (OR = 1.07; 95% CI: 0.78-1.48) and below (OR = 2.30; 95% CI: 1.55-3.42) 33% [hemoglobin (Hgb) 11 g/dl].

Conclusions:

Preoperative anemia in elective cranial neurosurgery was independently associated with an increased risk of 30-day postoperative mortality and morbidity when compared to non-anemic patients. A hematocrit level below 33% (Hgb 11 g/dl) was associated with a significant increase in postoperative morbidity.

Haemoglobin management in acute brain injury

PURPOSE OF REVIEW

Anaemia is common among patients in the neurocritical care unit (NCCU) and is thought to exacerbate brain injury. However, the optimal haemoglobin (Hgb) level still remains to be elucidated for traumatic brain injury (TBI), subarachnoid haemorrhage (SAH) and acute ischaemic stroke (AIS). This review outlines recent studies about anaemia and the effects of red blood cell transfusion (RBCT) on outcome in TBI, SAH and AIS patients admitted to the NCCU.

RECENT FINDINGS

Patients with severe SAH, AIS and TBI often develop anaemia and require RBCT. In general critical care, a restrictive RBCT strategy (Hgb ~7 g/dl) is preferable in patients without serious cardiac disease. In severe TBI, AIS and SAH, both anaemia and RBCT may negatively influence clinical outcome. However, the appropriate RBCT trigger remains unclear and there is great variance in how these patients are transfused. There is evidence from PET and microdialysis studies in humans that RBCT can favourably influence brain metabolism and oxygenation. This correction of hypoxia or altered metabolism rather than anaemia may be of greater importance.

SUMMARY

Results from general critical care should not be extrapolated to all patients with acute brain injury. Transfusion is not risk free, but RBCT use needs to be considered also in terms of potential benefit.

Transfusion of red blood cells in patients with a prehospital Glasgow Coma Scale score of 8 or less and no evidence of shock is associated with worse outcomes

BACKGROUND

Red blood cell transfusion practices vary, and the optimal hemoglobin for patients with traumatic brain injury has not been established.

METHODS

A retrospective review of data collected prospectively as part of a randomized, controlled trial involving emergency medical service agencies within the Resuscitation Outcomes Consortium was conducted. In patients with a Glasgow Coma Scale (GCS) score of 8 or less without evidence of shock (defined by a systolic blood pressure [SBP] < 70 or SBP of 70 to 90 with a heart rate ≥108), the association of red blood cell transfusion with 28-day survival, adult respiratory distress syndrome-free survival, Multiple Organ Dysfunction Score (MODs), and 6-month Extended Glasgow Outcome Scale (GOSE) score was modeled using multivariable logistic regression with robust SEs adjusting for age, sex, injury severity (Injury Severity Score [ISS]), initial GCS score, initial SBP, highest field heart rate, penetrating injury, fluid use, study site, and hemoglobin (Hgb) level.

RESULTS

A total of 1,158 patients had a mean age of 40, 76% were male, and 98% experienced blunt trauma. The initial mean GCS score was 5, and the initial mean SBP was 134. The mean head Abbreviated Injury Scale (AIS) score was 3.5. A categorical interaction of red blood cell transfusion stratified by initial Hgb showed that when the first Hgb was greater than 10 g/dL, volume of packed red blood cell was associated with a decreased 28-day survival (odds ratio, 0.83; 95% confidence interval [CI], 0.74-0.93; p < 0.01) and decreased adult respiratory distress syndrome-free survival (odds ratio, 0.82; 95% CI, 0.74-0.92; p < 0.01). When the initial Hgb was greater than 10, each unit of blood transfused increased the MODs by 0.45 (coefficient 95% CI, 0.19-0.70; p < 0.01).

CONCLUSION

In patients with a suspected traumatic brain injury and no evidence of shock, transfusion of red blood cells was associated with worse outcomes when the initial Hgb was greater than 10.

LEVEL OF EVIDENCE

Therapeutic study, level III.

Physiopathology of anemia and transfusion thresholds in isolated head injury

BACKGROUND

Blood transfusion strategies among patients with critical illness use a restrictive hemoglobin threshold. However, among patients with head injury, no outcome differences have been shown between either liberal or restrictive strategies. Several studies and literature reviews suggest that anemia is associated with markers of tissue ischemia. The paucity of prospective data confuses the association between surrogates of tissue ischemia and neurological outcome.

METHODS

A narrative review of transfusion practices among patients in the acute phase of head injury was performed using PubMed, MEDLINE, EMBASE, Cochrane, and WEB of Science databases. A total of 104 articles were reviewed.

RESULTS

There are few data to guide clinical practice. Clinicians use blood hemoglobin concentrations to trigger transfusion. Markers of potential cerebral injury are not in regular use despite experimental and observational data rising from histologic examination, microdialysis, oximetry, and flow-based multimonitoring systems recommending their use to titrate blood transfusion in neurotrauma.

CONCLUSION

The generalization of transfusion triggers is common practice. Evidence-based approaches to transfusions strategies in head injury are lacking and not based on an understanding of cerebral physiopathology.

Red blood cell transfusion in non-bleeding critically ill patients with moderate anemia: is there a benefit?

PURPOSE

This study was undertaken to investigate the efficacy of red blood cell transfusion (RBCT) at reversing the deleterious effects of moderate anemia in critically ill, non-bleeding patients.

METHODS

This was a retrospective, pair-matched (ratio 1:1) cohort study. Non-bleeding critically ill patients with moderate anemia (nadir hemoglobin level between 70 and 95 g/l), admitted to the ICU over a 27-month period, were included. Anemic patients were included upon meeting five matching criteria of having the same nadir hemoglobin (±5 g/l), APACHE II score (±5), SOFA score (±2), admission diagnostic group, and age (±5 years). Outcome events occurring over the whole ICU stay and after RBCT were collected. After hospital discharge, all patients had a 2-year follow-up period.

RESULTS

Two hundred fourteen non-transfused anemic patients (NTAPs) were successfully matched with 214 transfused anemic patients (TAPs). In addition to the matching criteria, at baseline, both groups were homogenous with respect to multiple comorbidities. Compared with TAPs, NTAPs showed significantly lower rates of hospital mortality (21 vs.13 %, respectively; p < 0.05) and ICU re-admission (7.4 vs. 1.9 %, respectively; p < 0.05). Additionally, NTAPs had significantly lower rates of nosocomial infection (12.9 vs. 6.7 %, respectively; p < 0.05) and acute kidney injury (24.8 vs. 16.7 %, respectively; p < 0.05). Similar results were obtained in subgroup analysis where only more anemic patients (68 matched pairs) or patients with cardiovascular comorbidities (63 matched pairs) were considered.

CONCLUSIONS

RBCT does not improve the clinical outcome in non-bleeding critically ill patients with moderate anemia.

Anemia, red blood cell transfusion, and outcomes after severe traumatic brain injury

In the previous issue of Critical Care, Sekhon and colleagues report that mean 7-day hemoglobin concentration <90 g/l was associated with increased mortality among patients with severe traumatic brain injury (TBI). The adverse relationship between reduced hemoglobin concentrations and outcomes among those with TBI has been an inconsistent finding across available studies. However, as anemia is common among adults with severe TBI, and clinical equipoise may exist between specialists as to when to transfuse allogeneic red blood cells, randomized controlled trials of liberal versus restricted transfusion thresholds are indicated.

Association of hemoglobin concentration and mortality in critically ill patients with severe traumatic brain injury

Introduction

The critical care management of traumatic brain injury focuses on preventing secondary ischemic injury. Cerebral oxygen delivery is dependent upon the cerebral perfusion pressure and the oxygen content of blood, which is principally determined by hemoglobin. Despite its importance to the cerebral oxygen delivery, the precise hemoglobin concentration to provide adequate oxygen delivery to injured neuronal tissue in TBI patients is controversial with limited evidence to provide transfusion thresholds.

Methods

We conducted a retrospective cohort study of severe TBI patients, investigating the association between mean 7-day hemoglobin concentration and hospital mortality. Demographic, physiologic, intensive care interventions, clinical outcomes and daily hemoglobin concentrations were recorded for all patients. Patients were all cared for at a tertiary, level 1 trauma center in a mixed medical and surgical intensive unit. Patients were divided into quartiles based on their mean 7-day hemoglobin concentration: < 90 g/L, 90 - 99 g/L, 100 - 109 g/L and > 110 g/L. Multivariable log-binomial regression was used to model the association between mean daily hemoglobin concentration and hospital mortality.

Results

Two hundred seventy-three patients with traumatic brain injury were identified and 169 were included in the analysis based on inclusion/exclusion criteria. Of these, 77% of the patients were male, with a mean age of 38 (SD 17) years and a median best GCS of 6 (IQR 5 - 7). One hundred fifteen patients (68%) received a red blood cell (RBC) transfusion. In RBCs administered in the ICU, the median pre-transfusion hemoglobin was 79 g/L (IQR 73 - 85). Thirty-seven patients (22%) died in hospital. Multivariable analysis revealed that mean 7-day hemoglobin concentration < 90 g/L was independently associated with an increased risk of hospital mortality (RR 3.1, 95% CI 1.5 - 6.3, p = 0.03). Other variables associated with increased mortality on multivariable regression were insertion of external ventricular drain, age and decreased GCS. Red blood cell transfusion was not associated with mortality following multivariable adjustment.

Conclusions

A mean 7-day hemoglobin concentration of < 90g/L is associated with increased hospital mortality in patients with severe traumatic brain injury.

Red blood cell transfusion in neurosurgery

BACKGROUND

The necessity of red blood cell (RBC) transfusions in neurosurgical procedures is under debate. Although detailed recommendations exist for many other surgical disciplines, there are very limited data on the probability of transfusions during neurosurgical procedures.

METHODS

Three-thousand and twenty-six consecutive adult patients undergoing neurosurgical procedures at Saarland University Hospital from December 2006 to June 2008 were retrospectively analyzed for administration of RBCs. The patients were grouped into 11 main diagnostic categories for analysis. The transfusion probability and cross-match to transfusion ratio (C/T ratio) were calculated.

RESULTS

Overall, the transfusion probability for neurosurgical procedures was 1.7 % (52/3,026). The probability was 6.5 % for acute subdural hematoma (7/108), 6.2 % for spinal tumors (5/80), 4.6 % for intracerebral hemorrhage (ICH, 4/98), 2.8 % for abscess (3/108), 2.4 % for traumatic brain injury (4/162), 2.3 % for cerebral ischemia (1/44), 1.9 % for subarachnoid hemorrhage (SAH) /aneurysms (4/206), 1.4 % for brain tumors (10/718), 0.8 % for hydrocephalus (2/196), 0.4 % for degenerative diseases of the spine (5/1290), including 3.6 % (3/82) for posterior lumbar interbody fusion (PLIF) and 0 % for epidural hematoma (0/15). The transfusion probabilities for clipping and coiling of SAH were 2.9 % (2/68) and 1.7 % (2/120) respectively.

CONCLUSIONS

The probability of blood transfusion during neurosurgical procedures is well below the 10 % level which is generally defined as the limit for preoperative appropriation of RBCs. Patients with spinal tumors, acute subdural hematomas or ICH, i.e., patients undergoing large decompressive procedures of bone or soft tissue, had a higher probability of transfusion.

Controversies in neurosciences critical care

Neurocritical care is an evolving subspecialty with many controversial topics. The focus of this review is (1) transfusion thresholds in patients with acute intracranial bleeding, including packed red blood cell transfusion, platelet transfusion, and reversal of coagulopathy; (2) indications for seizure prophylaxis and choice of antiepileptic agent; and (3) the role of specialized neurocritical care units and specialists in the care of critically ill neurology and neurosurgery patients.

Anemia and brain oxygen after severe traumatic brain injury

PURPOSE

To investigate the relationship between hemoglobin (Hgb) and brain tissue oxygen tension (PbtO(2)) after severe traumatic brain injury (TBI) and to examine its impact on outcome.

METHODS

This was a retrospective analysis of a prospective cohort of severe TBI patients whose PbtO(2) was monitored. The relationship between Hgb-categorized into four quartiles (≤9; 9-10; 10.1-11; >11 g/dl)-and PbtO(2) was analyzed using mixed-effects models. Anemia with compromised PbtO(2) was defined as episodes of Hgb ≤ 9 g/dl with simultaneous PbtO(2) < 20 mmHg. Outcome was assessed at 30 days using the Glasgow outcome score (GOS), dichotomized as favorable (GOS 4-5) vs. unfavorable (GOS 1-3).

RESULTS

We analyzed 474 simultaneous Hgb and PbtO(2) samples from 80 patients (mean age 44 ± 20 years, median GCS 4 (3-7)). Using Hgb > 11 g/dl as the reference level, and controlling for important physiologic covariates (CPP, PaO(2), PaCO(2)), Hgb ≤ 9 g/dl was the only Hgb level that was associated with lower PbtO(2) (coefficient -6.53 (95 % CI -9.13; -3.94), p < 0.001). Anemia with simultaneous PbtO(2) < 20 mmHg, but not anemia alone, increased the risk of unfavorable outcome (odds ratio 6.24 (95 % CI 1.61; 24.22), p = 0.008), controlling for age, GCS, Marshall CT grade, and APACHE II score.

CONCLUSIONS

In this cohort of severe TBI patients whose PbtO(2) was monitored, a Hgb level no greater than 9 g/dl was associated with compromised PbtO(2). Anemia with simultaneous compromised PbtO(2), but not anemia alone, was a risk factor for unfavorable outcome, irrespective of injury severity.

Red Blood Cell Transfusion and Transfusion Alternatives in Traumatic Brain Injury

OPINION STATEMENT: Anemia develops in about 50% of patients hospitalized with traumatic brain injury (TBI) and is recognized as a cause of secondary brain injury. This review examines the effects of anemia and transfusion on TBI patients through a literature search to identify original research on anemia and transfusion in TBI, the effects of transfusion on brain physiology, and the role of erythropoietin or hemoglobin-based blood substitutes (HBBSs). However, the amount of high-quality, prospective data available to help make decisions about when TBI patients should be transfused is very small. Randomized transfusion trials have involved far too few TBI patients to reach definitive conclusions. Thus, it is hardly surprising that there is widespread practice variation. In our opinion, a hemoglobin transfusion threshold of 7 g/dL cannot yet be considered safe for TBI patients admitted to hospital, and in particular to the ICU, as it is for other critically ill patients. Red blood cell transfusions often have immediate, seemingly beneficial effects on cerebral physiology, but the magnitude of this effect may depend in part upon how long the cells have been stored before administration. In light of existing physiological data, we generally aim to keep hemoglobin concentrations greater than 9 g/dL during the first several days after TBI. In part, the decision is based on the patient's risk of or development of secondary ischemia or brain injury. An increasing number of centers use multimodal neurologic monitoring, which may help to individualize transfusion goals based on the degree of cerebral hypoxia or metabolic distress. When available, brain tissue oxygen tension values less than 15-20 mm Hg or a lactate:pyruvate ratio greater than 30-40 would influence us to use more aggressive hemoglobin correction (e.g., a transfusion threshold of 10 g/dL). Clinicians can attempt to reduce transfusion requirements by limiting phlebotomy, minimizing hemodilution, and providing appropriate prophylaxis against gastrointestinal hemorrhage. Administration of exogenous erythropoietin may have a small impact in further reducing the need for transfusion, but it also may increase complications, most notably deep venous thrombosis. Erythropoietin is currently of great interest as a potential neuroprotective agent, but until it is adequately evaluated in randomized controlled trials, it should not be used routinely for this purpose. HBBSs are also of interest, but existing preparations have not been shown to be beneficial-or even safe-in the context of TBI.

Anemia and transfusion after subarachnoid hemorrhage

Delayed cerebral ischemia after subarachnoid hemorrhage (SAH) may be affected by a number of factors, including cerebral blood flow and oxygen delivery. Anemia affects about half of patients with SAH and is associated with worse outcome. Anemia also may contribute to the development of or exacerbate delayed cerebral ischemia. This review was designed to examine the prevalence and impact of anemia in patients with SAH and to evaluate the effects of transfusion. A literature search was made to identify original research on anemia and transfusion in SAH patients. A total of 27 articles were identified that addressed the effects of red blood cell transfusion (RBCT) on brain physiology, anemia in SAH, and clinical management with RBCT or erythropoietin. Most studies provided retrospectively analyzed data of very low-quality according to the GRADE criteria. While RBCT can have beneficial effects on brain physiology, RBCT may be associated with medical complications, infection, vasospasm, and poor outcome after SAH. The effects may vary with disease severity or the presence of vasospasm, but it remains unclear whether RBCTs are a marker of disease severity or a cause of worse outcome. Erythropoietin data are limited. The literature review further suggests that the results of the Transfusion Requirements in Critical Care Trial and subsequent observational studies on RBCT in general critical care do not apply to SAH patients and that randomized trials to address the role of RBCT in SAH are required.

Red blood cell transfusion in the neurological ICU

Red blood cell transfusion (RBCT) is a common therapy used in the intensive care unit to treat anemia. However, due to deleterious side effects and questionable efficacy, the clinical benefit of RBCT in patients who are not actively bleeding is unclear. The results of randomized controlled trials suggest there is no benefit to a liberal transfusion practice in general critical care populations. Whether the results of these trials are applicable to brain injured patients is unknown, as patients with primary neurological injury were excluded. This article reviews the efficacy and complications of RBCT, as well as the relationship between RBCT and its outcome in both the general intensive care unit and neurologically critically ill populations.

Red blood cell transfusion in patients with subarachnoid hemorrhage: a multidisciplinary North American survey

INTRODUCTION

Anemia is associated with poor outcomes in patients with aneurysmal subarachnoid hemorrhage (SAH). It remains unclear whether this association can be modified with more aggressive use of red blood cell (RBC) transfusions. The degree to which restrictive thresholds have been adopted in neurocritical care patients remains unknown.

METHODS

We performed a survey of North American academic neurointensivists, vascular neurosurgeons and multidisciplinary intensivists who regularly care for patients with SAH to determine hemoglobin (Hb) concentrations which commonly trigger a decision to initiate transfusion. We also assessed minimum and maximum acceptable Hb goals in the context of a clinical trial and how decision-making is influenced by advanced neurological monitoring, clinician characteristics and patient-specific factors.

RESULTS

The survey was sent to 531 clinicians, of whom 282 (53%) responded. In a hypothetical patient with high-grade SAH (WFNS 4), the mean Hb concentration at which clinicians administered RBCs was 8.19 g/dL (95% CI, 8.07 to 8.30 g/dL). Transfusion practices were comparatively more restrictive in patients with low-grade SAH (mean Hb 7.85 g/dL (95% CI, 7.73 to 7.97 g/dL)) (P < 0.0001) and more liberal in patients with delayed cerebral ischemia (DCI) (mean Hb 8.58 g/dL (95% CI, 8.45 to 8.72 g/dL)) (P < 0.0001). In each setting, there was a broad range of opinions. The majority of respondents expressed a willingness to study a restrictive threshold of ≤8 g/dL (92%) and a liberal goal of ≥10 g/dl (75%); in both cases, the preferred transfusion thresholds were significantly higher for patients with DCI (P < 0.0001). Neurosurgeons expressed higher minimum Hb goals than intensivists, especially for patients with high-grade SAH (β = 0.46, P = 0.003), and were more likely to administer two rather than one unit of RBCs (56% vs. 19%; P < 0.0001). Institutional use of transfusion protocols was associated with more restrictive practices. More senior clinicians preferred higher Hb goals in the context of a clinical trial. Respondents were more likely to transfuse patients with brain tissue oxygen tension values <15 mmHg and lactate-to-pyruvate ratios >40.

CONCLUSIONS

There is widespread variation in the use of RBC transfusions in SAH patients. Practices are heavily influenced by the specific dynamic clinical characteristics of patients and may be further modified by clinician specialty and seniority, the use of protocols and advanced neurological monitoring.

Anemia in the setting of traumatic brain injury: the arguments for and against liberal transfusion

Anemia is recognized as a possible cause of secondary injury following traumatic brain injury (TBI). Cogent arguments can be made for both liberal and restrictive blood transfusion practices in this setting. In this narrative review, we summarize available knowledge regarding the risks of anemia and transfusion in patients with TBI. Laboratory studies using animal models and healthy human subjects suggest that anemia below a hemoglobin (Hb) concentration of 7 g/dL results in impaired brain function and below 10 g/dL may be detrimental to recovery from TBI. Clinical studies that have evaluated the association of anemia with clinical outcomes have not consistently demonstrated harm, but they generally have important methodological weaknesses. Alternatively, studies that have analyzed transfusion as a predictor of worse outcome have consistently identified such an association, but these studies may involve residual confounding. What little information exists from randomized trials that have included patients with TBI and evaluated liberal versus restrictive transfusion strategies is inconclusive. Since anemia in the setting of TBI is relatively common and there is considerable variation in transfusion preferences, greater study of this topic - preferably with one or more rigorous, adequately powered, non-inferiority randomized trials - is desirable.

Transfusions and long-term functional outcomes in traumatic brain injury

OBJECT

In this paper, the authors' goal was to examine the relationship between transfusion and long-term functional outcomes in moderately anemic patients (lowest hematocrit [HCT] level 21-30%) with traumatic brain injury (TBI). While evidence suggests that transfusions are associated with poor hospital outcomes, no study has examined transfusions and long-term functional outcomes in this population. The preferred transfusion threshold remains controversial.

METHODS

The authors performed a retrospective review of patients who were admitted with TBI between September 2005 and November 2007, extracting data such as HCT level, status of red blood cell transfusion, admission Glasgow Coma Scale (GCS) score, serum glucose, and length of hospital stay. Outcome measures assessed at 6 months were Glasgow Outcome Scale-Extended score, Functional Status Examination score, and patient death. A multivariate generalized linear model controlling for confounding variables was used to assess the association between transfusion and outcome.

RESULTS

During the study period, 292 patients were identified, and 139 (47.6%) met the criteria for moderate anemia. Roughly half (54.7%) underwent transfusions. Univariate analyses showed significant correlations between outcome score and patient age, admission GCS score, head Abbreviated Injury Scale score, number of days with an HCT level < 30%, highest glucose level, number of days with a glucose level > 200 mg/dl, length of hospital stay, number of patients receiving a transfusion, and transfusion volume. In multivariate analysis, admission GCS score, receiving a transfusion, and transfusion volume were the only variables associated with outcome (F = 2.458, p = 0.007; F = 11.694, p = 0.001; and F = 1.991, p = 0.020, respectively). There was no association between transfusion and death.

CONCLUSIONS

Transfusions may contribute to poor long-term functional outcomes in anemic patients with TBI. Transfusion strategies should be aimed at patients with symptomatic anemia or physiological compromise, and transfusion volume should be minimized.

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

OBJECTIVE

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

DESIGN

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

SETTING

University-affiliated pediatric hospital.

PATIENTS

Children with severe traumatic brain injury and blood transfusion.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

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

CONCLUSIONS

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

Anemia and red blood cell transfusion in neurocritical care

INTRODUCTION

Anemia is one of the most common medical complications to be encountered in critically ill patients. Based on the results of clinical trials, transfusion practices across the world have generally become more restrictive. However, because reduced oxygen delivery contributes to 'secondary' cerebral injury, anemia may not be as well tolerated among neurocritical care patients.

METHODS

The first portion of this paper is a narrative review of the physiologic implications of anemia, hemodilution, and transfusion in the setting of brain-injury and stroke. The second portion is a systematic review to identify studies assessing the association between anemia or the use of red blood cell transfusions and relevant clinical outcomes in various neurocritical care populations.

RESULTS

There have been no randomized controlled trials that have adequately assessed optimal transfusion thresholds specifically among brain-injured patients. The importance of ischemia and the implications of anemia are not necessarily the same for all neurocritical care conditions. Nevertheless, there exists an extensive body of experimental work, as well as human observational and physiologic studies, which have advanced knowledge in this area and provide some guidance to clinicians. Lower hemoglobin concentrations are consistently associated with worse physiologic parameters and clinical outcomes; however, this relationship may not be altered by more aggressive use of red blood cell transfusions.

CONCLUSIONS

Although hemoglobin concentrations as low as 7 g/dl are well tolerated in most critical care patients, such a severe degree of anemia could be harmful in brain-injured patients. Randomized controlled trials of different transfusion thresholds, specifically in neurocritical care settings, are required. The impact of the duration of blood storage on the neurologic implications of transfusion also requires further investigation.