Retrospective evaluation of anemia and transfusion in traumatic brain injury

Haemoglobin values, transfusion practices, and long-term outcomes in critically ill patients with traumatic brain injury: a secondary analysis of CENTER-TBI

Haemoglobin (Hb) thresholds and red blood cells (RBC) transfusion strategies in traumatic brain injury (TBI) are controversial. Our objective was to assess the association of Hb values with long-term outcomes in critically ill TBI patients. We conducted a secondary analysis of CENTER-TBI, a large multicentre, prospective, observational study of European TBI patients. All patients admitted to the Intensive Care Unit (ICU) with available haemoglobin data on admission and during the first week were included. During the first seven days, daily lowest haemoglobin values were considered either a continous variable or categorised as < 7.5 g/dL, between 7.5-9.5 and > 9.5 g/dL. Anaemia was defined as haemoglobin value < 9.5 g/dL. Transfusion practices were described as "restrictive" or "liberal" based on haemoglobin values before transfusion (e.g. < 7.5 g/dL or 7.5-9.5 g/dL). Our primary outcome was the Glasgow outcome scale extended (GOSE) at six months, defined as being unfavourable when < 5. Of 1590 included, 1231 had haemoglobin values available on admission. A mean Injury Severity Score (ISS) of 33 (SD 16), isolated TBI in 502 (40.7%) and a mean Hb value at ICU admission of 12.6 (SD 2.2) g/dL was observed. 121 (9.8%) patients had Hb < 9.5 g/dL, of whom 15 (1.2%) had Hb < 7.5 g/dL. 292 (18.4%) received at least one RBC transfusion with a median haemoglobin value before transfusion of 8.4 (IQR 7.7-8.5) g/dL. Considerable heterogeneity regarding threshold transfusion was observed among centres. In the multivariable logistic regression analysis, the increase of haemoglobin value was independently associated with the decrease in the occurrence of unfavourable neurological outcomes (OR 0.78; 95% CI 0.70-0.87). Congruous results were observed in patients with the lowest haemoglobin values within the first 7 days < 7.5 g/dL (OR 2.09; 95% CI 1.15-3.81) and those between 7.5 and 9.5 g/dL (OR 1.61; 95% CI 1.07-2.42) compared to haemoglobin values > 9.5 g/dL. Results were consistent when considering mortality at 6 months as an outcome. The increase of hemoglobin value was associated with the decrease of mortality (OR 0.88; 95% CI 0.76-1.00); haemoglobin values less than 7.5 g/dL was associated with an increase of mortality (OR 3.21; 95% CI 1.59-6.49). Anaemia was independently associated with long-term unfavourable neurological outcomes and mortality in critically ill TBI patients.Trial registration: CENTER-TBI is registered at ClinicalTrials.gov, NCT02210221, last update 2022-11-07.

Incidence and Associated Factors of Anemia in Patients with Acute Moderate and Severe Traumatic Brain Injury

Background

Anemia might contribute to the development of secondary injury in patients with acute traumatic brain injury (TBI). Potential determinants of anemia are still poorly acknowledged, and reported incidence of declined hemoglobin concentration varies widely between different studies. The aim of this study was to investigate the incidence of severe anemia among patients with moderate to severe TBI and to evaluate patient- and trauma-related factors that might be associated with the development of anemia.

Methods

This retrospective cohort study involved all adult patients admitted to Tampere University Hospital’s emergency department for moderate to severe TBI (August 2010 to July 2012). Detailed information on patient demographics and trauma characteristics were obtained, including data on posttraumatic care, data on neurosurgical procedures, and all measured in-hospital hemoglobin values. Severe anemia was defined as a hemoglobin level less than 100 g/L. Both univariate and multivariable analyses were performed, and hemoglobin trajectories were created.

Results

The study included 145 patients with moderate to severe TBI (male 83.4%, mean age 55.0 years). Severe anemia, with a hemoglobin level less than 100 g/L, was detected in 66 patients (45.5%) and developed during the first 48 h after the trauma. In the univariate analysis, anemia was more common among women (odds ratio [OR] 2.84; 95% confidence interval [CI] 1.13–7.15), patients with antithrombotic medication prior to trauma (OR 3.33; 95% CI 1.34–8.27), patients with cardiovascular comorbidities (OR 3.12; 95% CI 1.56–6.25), patients with diabetes (OR 4.56; 95% CI 1.69–12.32), patients with extracranial injuries (OR 3.14; 95% CI 1.69–12.32), and patients with midline shift on primary head computed tomography (OR 2.03; 95% CI 1.03–4.01). In the multivariable analysis, midline shift and extracranial traumas were associated with the development of severe anemia (OR 2.26 [95% CI 1.05–4.48] and OR 4.71 [95% CI 1.74–12.73], respectively).

Conclusions

Severe anemia is common after acute moderate to severe TBI, developing during the first 48 h after the trauma. Possible anemia-associated factors include extracranial traumas and midline shift on initial head computed tomography.

Potential of Hematologic Parameters in Predicting Mortality of Patients with Traumatic Brain Injury

Traumatic brain injury (TBI) occurs frequently, and acute TBI requiring surgical treatment is closely related to patient survival. Models for predicting the prognosis of patients with TBI do not consider various factors of patient status; therefore, it is difficult to predict the prognosis more accurately. In this study, we created a model that can predict the survival of patients with TBI by adding hematologic parameters along with existing non-hematologic parameters. The best-fitting model was created using the Akaike information criterion (AIC), and hematologic factors including preoperative hematocrit, preoperative C-reactive protein (CRP), postoperative white blood cell (WBC) count, and postoperative hemoglobin were selected to predict the prognosis. Among several prediction models, the model that included age, Glasgow Coma Scale, Injury Severity Score, preoperative hematocrit, preoperative CRP, postoperative WBC count, postoperative hemoglobin, and postoperative CRP showed the highest area under the curve and the lowest corrected AIC for a finite sample size. Our study showed a new prediction model for mortality in patients with TBI using non-hematologic and hematologic parameters. This prediction model could be useful for the management of patients with TBI.

Factors Associated With Brain Tissue Oxygenation Changes After RBC Transfusion in Acute Brain Injury Patients

OBJECTIVES

Anemia is common after acute brain injury and can be associated with brain tissue hypoxia. RBC transfusion (RBCT) can improve brain oxygenation; however, predictors of such improvement remain unknown. We aimed to identify the factors associated with PbtO2 increase (greater than 20% from baseline value) after RBCT, using a generalized mixed model.

DESIGN

This is a multicentric retrospective cohort study (2012-2020).

SETTING

This study was conducted in three European ICUs of University Hospitals located in Belgium, Switzerland, and Austria.

PATIENTS

All patients with acute brain injury who were monitored with brain tissue oxygenation (PbtO2) catheters and received at least one RBCT.

INTERVENTION

Patients received at least one RBCT. PbtO2 was recorded before, 1 hour, and 2 hours after RBCT.

MEASUREMENTS AND MAIN RESULTS

We included 69 patients receiving a total of 109 RBCTs after a median of 9 days (5-13 d) after injury. Baseline hemoglobin (Hb) and PbtO2 were 7.9 g/dL [7.3-8.7 g/dL] and 21 mm Hg (16-26 mm Hg), respectively; 2 hours after RBCT, the median absolute Hb and PbtO2 increases from baseline were 1.2 g/dL [0.8-1.8 g/dL] (p = 0.001) and 3 mm Hg (0-6 mm Hg) (p = 0.001). A 20% increase in PbtO2 after RBCT was observed in 45 transfusions (41%). High heart rate (HR) and low PbtO2 at baseline were independently associated with a 20% increase in PbtO2 after RBCT. Baseline PbtO2 had an area under receiver operator characteristic of 0.73 (95% CI, 0.64-0.83) to predict PbtO2 increase; a PbtO2 of 20 mm Hg had a sensitivity of 58% and a specificity of 73% to predict PbtO2 increase after RBCT.

CONCLUSIONS

Lower PbtO2 values and high HR at baseline could predict a significant increase in brain oxygenation after RBCT.

South African Society of Anaesthesiologists Perioperative Patient Blood Management Guidelines 2020

Anaesthesiologists regularly request and administer blood components to their patients, a potentially life-saving intervention. All anaesthesiologists must be familiar with the indications and appropriate use of blood and blood components and their alternatives, but close liaison with haematologists and their local haematology blood sciences laboratory is encouraged. In the last decade, there have been considerable changes in approaches to optimal use of blood components, together with the use of alternative products, with a need to update previous guidelines and adapt them for anaesthesiologists working throughout the hospital system.

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

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

Clinical role of low hemoglobin ratio in poor neurologic outcomes in infants with traumatic intracranial hemorrhage

Traumatic brain injury (TBI) is the leading cause of pediatric morbidity and mortality worldwide, and half of all fatalities occur in infants aged less than 1 year. We analyzed 129 infants diagnosed with TBI complicated with intracranial hemorrhage confirmed by brain computed tomography. We defined delta hemoglobin (ΔHB) as nadir HB - age specific mean HB, and the ratio of HB (%) as ΔHB/age specific mean HB x 100. Infants with poor neurologic outcomes had a lower admission HB and ΔHB (p < 0.05). The in-hospital mortality rate was 10.1% (13 infants), and the infants who died had a significantly lower ΔHB ratio compared to the survivors. The area under the receiving operating characteristic curve (AUC) of initial Glasgow Coma Score (GCS) in predicting neurologic outcomes was higher than that of ratio of ΔHB (0.881 v.s 0.859). In multivariate logistic regression analysis with the optimal cutoff ratio of ΔHB, it remained an independent predictor for in-hospital mortality and poor neurologic outcomes at discharge and at 6 months. AUC analysis for the ratio of ΔHB for poor neurologic outcomes in infants aged from 0–6 months was 0.85 and the optimal cutoff was −30.7% (sensitivity, 69%; specificity, 92%; positive likelihood ratio (LR⁺), 8.24; negative likelihood ratio (LR⁻), 0.34); the AUC was 0.88 in infants aged from 6–12 months and the optimal cutoff was −20.6% (sensitivity, 89%; specificity, 79%; LR⁺, 4.13; LR⁻, 0.15).

Clinical Significance of Nadir Hemoglobin in Predicting Neurologic Outcome in Infants With Abused Head Trauma

Traumatic brain injury (TBI) is a leading cause of pediatric morbidity and mortality and is categorized as abusive head trauma (AHT) and accidental head injury. A retrospective chart review of 124 children aged <1 year diagnosed with TBI were analyzed. Outcomes were evaluated at discharge and 6 months later by using the Pediatric Cerebral Performance Category (PCPC) Scale. The receiver operating characteristic (ROC) curve was applied to determine the cutoff values for hemoglobin (HB) levels. In the study, 50 infants (40.3%) achieved a favorable neurologic outcome (PCPC ≦ 2) and 74 (59.7%) had poor neurologic outcomes (PCPC ≧ 3). Infants with poor neurologic outcomes had lower HB on admission and nadir HB (p < 0.05). Based on multivariate logistic regression analysis, the nadir HB was a predictor of poor neurologic outcomes at discharge and 6 months later in both AHT and accidental head injury. Nadir HB had the largest area under the ROC curve for predicting poor neurologic outcomes. We determined the appropriate cutoff value of nadir HB as 9.35 g/dl for predicting neurologic outcomes in infants with TBI. Furthermore, the cutoff value of nadir HB in predicting poor neurologic outcomes in infants caused by AHT and accidental head injury were taken as 9.36 and 8.75 g/dl, respectively.

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.

Red blood cell transfusion in acute brain injury subtypes: An observational cohort study

PURPOSE

Optimal red blood cell (RBC) transfusion thresholds in acute brain injury (ABI) are poorly defined.

MATERIALS AND METHODS

We conducted a retrospective cohort study of adult patients with ABI and moderate anemia (Hb 7-10 g/dL) in a neurological intensive care unit (ICU) at an academic medical center between 2008 and 2015. Transfused and non-transfused patients were matched based on age, ABI subtype, pre-transfusion hemoglobin, and ICU length of stay (LOS) at the time of RBC transfusion. Multivariable regression analyses were performed to assess the relationship between RBC transfusion and hospital LOS, hospital mortality, ICU LOS, ICU mortality, and 24 h change in sequential organ failure assessment (SOFA) scores.

RESULTS

2638 patients met inclusion criteria, with 225 (8.5%) receiving RBC transfusion. Acute ischemic stroke was the most prevalent ABI diagnosis (43.3%) then intracranial hemorrhage (25.6%), subarachnoid hemorrhage (16.5%), and traumatic brain injury (TBI) (14.6%). In multivariable analyses, RBC transfusion was associated with longer hospital and ICU LOS, and higher SOFA scores. Each ABI subtype had similar results, except for TBI which showed no difference in hospital LOS. Mortality was not significantly different.

CONCLUSIONS

In moderately anemic patients with ABI, RBC transfusion was associated with longer hospital and ICU LOS. Prospective investigations are necessary to further assess these relationships.

Transfusion practices in traumatic brain injury

Purpose of review

The aim of this review is to summarize the recent studies looking at the effects of anemia and red blood cell transfusion in critically-ill patients with traumatic brain injury (TBI), describe the transfusion practice variations observed worldwide, and outline the ongoing trials evaluating restrictive versus liberal transfusion strategies for TBI.

Recent findings

Anemia is common among critically-ill patients with TBI, it is also thought to exacerbate secondary brain injury, and is associated with an increased risk of poor outcome. Conversely, allogenic red blood cell transfusion carries its own risks and complications, and has been associated with worse outcomes. Globally, there are large reported differences in the hemoglobin threshold used for transfusion after TBI. Observational studies have shown differential results for improvements in cerebral oxygenation and metabolism after red blood cell transfusion in TBI.

Summary

Currently, there is insufficient evidence to make strong recommendations regarding which hemoglobin threshold to use as a transfusion trigger in critically-ill patients with TBI. There is also uncertainty whether the restrictive transfusion strategy used in general critical care can be extrapolated to acutely brain injured patients. Ultimately, the consequences of anemia-induced cerebral injury need to be weighed up against the risks and complications associated with red blood cell transfusion.

Hemoglobin thresholds and red blood cell transfusion in adult patients with moderate or severe traumatic brain injuries: A retrospective cohort study

PURPOSE

We aimed to evaluate the association between transfusion practices and clinical outcomes in patients with traumatic brain injury.

MATERIAL AND METHODS

We conducted a retrospective cohort study of adult patients with moderate or severe traumatic brain injury admitted to the intensive care unit (ICU) of a level I trauma center between 2009 and 2013. The associations between hemoglobin (Hb) level, red blood cell (RBC) transfusion and clinical outcomes were estimated using robust Poisson models and proportional hazard models with time-dependent variables, adjusted for confounders.

RESULTS

We included 215 patients. Sixty-six patients (30.7%) were transfused during ICU stay. The median pre-transfusion Hb among transfused patients was 81g/L (IQR 67-100), while median nadir Hb among non-transfused patients was 110g/L (IQR 93-123). Poor outcomes were significantly more frequent in patients who were transfused (mortality risk ratio [RR]: 2.15 [95% CI 1.37-3.38] and hazard ratio: 3.06 [95% CI 1.57-5.97]; neurological complications RR: 3.40 [95% CI 1.35-8.56]; trauma complications RR: 1.65 [95% CI 1.31-2.08]; ICU length of stay geometric mean ratio: 1.42 [95% CI 1.06-1.92]).

CONCLUSIONS

During ICU stay, transfused patients tended to have lower Hb levels and worse outcomes than patients who did not receive RBCs, after adjustment for confounders.

Acute respiratory distress syndrome in traumatic brain injury: how do we manage it?

Traumatic brain injury (TBI) is an important cause of morbidity and mortality worldwide. TBI patients frequently suffer from lung complications and acute respiratory distress syndrome (ARDS), which is associated with poor clinical outcomes. Moreover, the association between TBI and ARDS in trauma patients is well recognized. Mechanical ventilation of patients with a concomitance of acute brain injury and lung injury can present significant challenges. Frequently, guidelines recommending management strategies for patients with traumatic brain injuries come into conflict with what is now considered best ventilator practice. In this review, we will explore the strategies of the best practice in the ventilatory management of patients with ARDS and TBI, concentrating on those areas in which a conflict exists. We will discuss the use of ventilator strategies such as protective ventilation, high positive end expiratory pressure (PEEP), prone position, recruitment maneuvers (RMs), as well as techniques which at present are used for 'rescue' in ARDS (including extracorporeal membrane oxygenation) in patients with TBI. Furthermore, general principles of fluid, haemodynamic and hemoglobin management will be discussed. Currently, there are inadequate data addressing the safety or efficacy of ventilator strategies used in ARDS in adult patients with TBI. At present, choice of ventilator rescue strategies is best decided on a case-by-case basis in conjunction with local expertise.

Restrictive transfusion threshold is safe in high-risk patients undergoing brain tumor surgery

OBJECTIVE

To assess the safety of a restrictive threshold for the transfusion of red blood cells (RBCs) compared to a liberal threshold in high-risk patients undergoing brain tumor surgery.

PATIENTS AND METHODS

We reviewed patients who were 50 years of age or older with a preoperative American Society of Anesthesiologists physical status class II to V who underwent open craniotomy for tumor resection and were transfused packed RBCs during or after surgery. We retrospectively assigned patients to a restrictive-threshold (a pretransfusion hemoglobin level <8g/dL) or a liberal-threshold group (a pretransfusion hemoglobin level of 8-10/dL). The primary outcome was in-hospital mortality rate. Secondary outcomes were in-hospital complication rates, length of stay, and discharge disposition.

RESULTS

Twenty-five patients were included in the study, of which 17 were assigned to a restrictive-threshold group and 8 patients to a liberal-threshold group. The in-hospital mortality rates were 12% for the restrictive-threshold group (odds ratio [OR] 0.93, 95% confidence interval [CI] 0.07-12.11) and 13% for the liberal-threshold group. The in-hospital complication rates were 52.9% for the restrictive-threshold group (OR 1.13, 95% CI 0.21-6.05) and 50% for the liberal-threshold group. The average number of days in the intensive care unit and hospital were 8.6 and 22.4 days in the restrictive-threshold group and 6 and 15 days in the liberal-threshold group, respectively (P=0.69 and P=0.20). The rates of non-routine discharge were 71% in the restrictive-threshold group (OR 2.40, 95% CI 0.42-13.60) and 50% in the liberal-threshold group.

CONCLUSIONS

A restrictive transfusion threshold did not significantly influence in-hospital mortality or complication rates, length of stay, or discharge disposition in patients at high operative risk.

Safety and cost efficiency of a restrictive transfusion protocol in patients with traumatic brain injury

OBJECTIVE Blood loss and moderate anemia are common in patients with traumatic brain injury (TBI). However, despite evidence of the ill effects and expense of the transfusion of packed red blood cells, restrictive transfusion practices have not been universally adopted for patients with TBI. At a Level I trauma center, the authors compared patients with TBI who were managed with a restrictive (target hemoglobin level > 7 g/dl) versus a liberal (target hemoglobin level > 10 g/dl) transfusion protocol. This study evaluated the safety and cost-efficiency of a hospital-wide change to a restrictive transfusion protocol. METHODS A retrospective analysis of patients with TBI who were admitted to the intensive care unit (ICU) between January 2011 and September 2015 was performed. Patients < 16 years of age and those who died within 24 hours of admission were excluded. Demographic data and injury characteristics were compared between groups. Multivariable regression analyses were used to assess hospital outcome measures and mortality rates. Estimates from an activity-based cost analysis model were used to detect changes in cost with transfusion protocol. RESULTS A total of 1565 patients with TBI admitted to the ICU were included in the study. Multivariable analysis showed that a restrictive transfusion strategy was associated with fewer days of fever (p = 0.01) and that patients who received a transfusion had a larger fever burden. ICU length of stay, ventilator days, incidence of lung injury, thromboembolic events, and mortality rates were not significantly different between transfusion protocol groups. A restrictive transfusion protocol saved approximately $115,000 annually in hospital direct and indirect costs. CONCLUSIONS To the authors' knowledge, this is the largest study to date to compare transfusion protocols in patients with TBI. The results demonstrate that a hospital-wide change to a restrictive transfusion protocol is safe and cost-effective in patients with TBI.

Complications following hospital admission for traumatic brain injury: A multicenter cohort study

PURPOSE

To evaluate the incidence, determinants and impact on outcome of in-hospital complications in adults with traumatic brain injury (TBI).

MATERIALS AND METHODS

We conducted a multicenter cohort study of TBI patients admitted between 2007 and 2012 in an inclusive Canadian trauma system. Risk ratios of complications, odds ratios of mortality and geometric mean ratios of length of stay (LOS) were calculated using generalized linear models with adjustment for prognostic indicators and hospital cluster effects.

RESULTS

Of 12,887 patients, 3.2% had at least one neurological complication and 22.6% a non-neurological complication. Mechanical ventilation, head injury severity, blood transfusion and neurosurgical intervention had the strongest correlation with neurological complications. Mechanical ventilation, the Glasgow Coma Scale, blood transfusion and concomitant injuries had the strongest correlation with non-neurological complications. Neurological and non-neurological complications were associated with a 85% and 53% increase in the odds of mortality, and a 60% and two-fold increases in LOS, respectively.

CONCLUSIONS

More than 20% of patients with TBI developed a complication. Many of these complications were associated with increased mortality and LOS. Results highlight the importance of prevention strategies adapted to treatment decisions and underline the need to improve knowledge on the underuse and overuse of clinical interventions.

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.

Risk associated with perioperative red blood cell transfusion in cranial surgery

We assessed the impact of intra- and postoperative RBC transfusion on postoperative morbidity and mortality in cranial surgery. A total of 8924 adult patients who underwent cranial surgery were identified in the 2006-2011 American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) database. Patients undergoing a biopsy, radiosurgery, or outpatient surgery were excluded. Propensity scores were calculated according to demographic variables, comorbidities, and preoperative laboratory values. Patients who had received RBC transfusion were matched to those who did not, by propensity score, preoperative hematocrit level, and by length of surgery, as an indirect measure of potential intraoperative blood loss. Logistic regression was used to predict adverse postoperative outcomes. A total of 625 (7%) patients were transfused with one or more units of packed RBCs. Upon matching, preoperative hematocrit, length of surgery, and emergency status were no longer different between transfused and non-transfused patients. RBC transfusion was associated with prolonged length of hospitalization (OR 1.6, 95% CI 1.2-2.2), postoperative complications (OR 2.8, 95% CI 2.0-3.8), 30-day return to operation room (OR 2.0, 95% CI 1.3-3.2), and 30-day mortality (OR 4.3, 95% CI 2.4-7.6). RBC transfusion is associated with substantive postoperative morbidity and mortality in patients undergoing both elective and emergency cranial surgery. These results suggest judicious use of transfusion in cranial surgery, consideration of alternative means of blood conservation, or pre-operative restorative strategies in patients undergoing elective surgery, when possible.

The effects of anaemia and transfusion on patients with traumatic brain injury: A review

BACKGROUND

Anaemia in traumatic brain injury (TBI) is frequently encountered. Neurosurgical texts continue to recommend transfusion for hematocrit below 30%, despite clear evidence to do so. Transfusion should increase oxygen delivery to the brain, but it may also increase morbidity and mortality.

METHODS

This study reviewed the relevant literature to better understand the risks of anaemia and benefits of correction of anaemia by transfusion.

RESULTS

Of the 21 studies reviewed, eight found that anaemia was harmful to patients with TBI; five found no significant outcome; seven found transfusion was associated with higher rates of morbidity and mortality; two found that transfusion lowered mortality and increased brain tissue oxygen levels; and ten found no correlation between transfusion and outcome. However, the levels of anaemia severity and the outcome measurements varied widely and the majority of outcomes focused on crude measurements rather than detailed functional assessments.

CONCLUSIONS

No division of response based on gender difference or impact of anaemia in the post-hospital treatment setting was observed. A randomized control trial is recommended to determine the impact of anaemia and transfusion on detailed outcome assessment in comparison of transfusion thresholds ranging from ≤ 7 g dL^-1 to ≤ 9 g dL^-1 in patients with moderate-to-severe TBI.

The Effect of Red Blood Cell Transfusion on Cerebral Autoregulation in Patients with Severe Traumatic Brain Injury

BACKGROUND

Red blood cell (RBC) transfusion is associated with inconsistent changes in brain tissue oxygenation (PbO2). Previous studies have failed to consider alterations in cerebral autoregulation. Our objective was to investigate the effect of RBC transfusion on cerebral autoregulation, as measured by pressure reactivity index (PRx).

METHODS

Retrospective analysis of 28 severe traumatic brain injury (TBI) patients from a prospective registry between 2007 and 2014. We recorded hemoglobin (Hb) concentration, intracranial pressure, PbO2, cerebral perfusion pressure, PRx, and cerebral lactate/pyruvate ratio for 6 h before and after RBC transfusion. We also recorded body temperature, PaO2, PCO2, pH, and fraction of inspired oxygen. Subgroups of normoxia (PbO2 >20 mmHg) and hypoxia (PbO2 <20 mmHg) prior to transfusion were defined a priori.

RESULTS

The median age was 36 years [interquartile range (IQR) 27-49], 32% were female. The median admission Glasgow Coma score was 5 (IQR 4-9) and injury severity score was 16 (IQR 9-21). Overall, mean Hb concentration [80 g/L (SD 7) to 89 g/L (SD 8), p < 0.001] and PbO2 increased [23.5 mmHg (SD 8) to 25.0 mmHg (SD 9), p = 0.033] following transfusion. PRx increased post-transfusion [0.028 (SD 0.29) to 0.11 (SD 0.24), p = 0.034], indicating worsening cerebrovascular pressure reactivity. In patients with mean PbO2 >20 mmHg pre-transfusion (n = 20), the PRx increased significantly [-0.052 (SD 0.24) to 0.079 (SD 0.22), p = 0.007] but did not change in patients with PbO2 <20 mmHg: PRx [0.22 (SD 0.34) to 0.18 (SD 0.30), p = 0.36].

CONCLUSION

RBC transfusion in severe TBI patients results in worsening PRx, indicating impaired cerebral autoregulation.

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.

Ratio-based Resuscitation in Trauma Patients with Traumatic Brain Injury: Is There a Similar Effect?

The use of 1:1:1 (packed red blood cells: fresh frozen plasma: platelets) transfusion ratio has been shown to improve survival in severely injured trauma patients. The aim of this study was to assess the outcomes in patients with traumatic brain injury (TBI) receiving 1:1:1 ratio-based blood product transfusion (RBT). We hypothesized that RBT improves survival in patients with TBI as only major injury. We performed a 3-year retrospective analysis of all patients with TBI as only major injury presenting to our Level I trauma center. Patients receiving blood transfusion were included. Patients were stratified into two groups: those who received RBT and those who did not receive RBT (No-RBT). The outcome measure was inhospital mortality. Multivariate logistic regression analysis was performed. A total of 189 patients were included of which 29 per cent (n = 55) received RBT. The mean age was 48 ± 24 years, median (range) Glasgow Coma Scale score was 12 (3–15), and median head abbreviated injury severity scale was 3 (3–5). The overall mortality rate was 28.5 per cent. Patients in the RBT group had a higher survival rate compared with the patients in the No-RBT group (83.6% vs 66.5%, P = 0.02). In conclusion, the survival benefit of RBT exists even in patients with TBI as major injury. Guidelines for the initial management of TBI patients should focus on the use of RBT. The beneficial effect of platelets in RBT among TBI patients requires further evaluation.

Restrictive Transfusion in Geriatric Trauma Patients

To determine whether a restrictive strategy of red cell transfusion was safe in elderly trauma patients, we compared those treated with a restrictive transfusion strategy versus those who were liberally transfused. We performed a retrospective study of elderly (age ≥ 70 years) trauma patients admitted to our Level I trauma center from 2005 to 2013. Patients with a hemoglobin (Hg) < 10 g/dL after 48 hours were included. We excluded patients with an Injury Severity Score > 25 or active cardiac ischemia. Patients who were transfused for an Hg < 10 g/dL (liberal group) were compared to those who were transfused for an Hg< 7 g/dL (restrictive group). There were 382 patients included, 229 and 153 in the liberal and restrictive transfusion groups, respectively. All patients in the liberal group and 20 per cent of patients in the restrictive group received a transfusion ( P < 0.0001). Patients in the liberal group had more overall complications (52 vs 32%, P = 0.0001). On multivariate analysis, receiving a transfusion was an independent risk factor to develop a complication [odds ratio = 2.3 (1.5–3.6), P < 0.0001]. For survivors, patients in the liberal group spent more days in the hospital (nine versus seven days, P = 0.007) and intensive care unit (two versus one day, P = 0.01). There was no difference in mortality (3 vs 4%, P = 0.82). In conclusion, restrictive transfusion appears to be safe in elderly trauma patients and may be associated with decreased complications and shortened length of stay.

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.

Low hemoglobin levels are associated with lower cerebral saturations and poor outcome after cardiac arrest

PURPOSE

Post-cardiac arrest (CA) patients have a large cerebral penumbra at risk for secondary ischemic damage in case of suboptimal brain oxygenation during ICU stay. The aims of this study were to investigate the association between hemoglobin, cerebral oxygenation (SctO2) and outcome in post-CA patients.

METHODS

Prospective observational study in 82 post-CA patients. Hemoglobin, a corresponding SctO2 measured by NIRS and SVO2 in patients with a pulmonary artery catheter (n=62) were determined hourly during hypothermia in the first 24h of ICU stay.

RESULTS

We found a strong linear relationship between hemoglobin and mean SctO2 (SctO2=0.70×hemoglobin+56 (R(2) 0.84, p=10(-6))). Hemoglobin levels below 10g/dl generally resulted in lower brain oxygenation. There was a significant association between good neurological outcome (43/82 patients in CPC 1-2 at 180 days post-CA) and admission hemoglobin above 13g/dl (OR 2.76, 95% CI 1.09:7.00, p=0.03) or mean hemoglobin above 12.3g/dl (OR 2.88, 95%CI 1.02:8.16, p=0.04). This association was entirely driven by results obtained in patients with a mean SVO2 below 70% (OR 6.25, 95%CI 1.33:29.43, p=0.01) and a mean SctO2 below 62.5% (OR 5.87, 95%CI 1.08:32.00, p=0.03).

CONCLUSION

Hemoglobin levels below 10g/dl generally resulted in lower cerebral oxygenation. Average hemoglobin levels below 12.3g/dl were associated with worse outcome in patients with suboptimal SVO2 or SctO2. The safety of a universal restrictive transfusion threshold of 7g/dl can be questioned in post-CA patients.

Red Blood Cell Transfusion in Patients With Traumatic Brain Injury: A Systematic Review and Meta-Analysis

Our objectives were to evaluate the frequency of red blood cell (RBC) transfusion in patients with traumatic brain injury (TBI) as well as potential determinants and outcomes associated with RBC transfusion in this population. We conducted a systematic review of cohort studies and randomized trials of patients with TBI. We searched Medline, Embase, the Cochrane Library, and BIOSIS databases from their inception up to April 2015. We selected studies of adult patients with acute TBI reporting data on RBC transfusions. Cumulative incidences of transfusion were pooled using random-effect models with a DerSimonian approach. To evaluate the association between RBC transfusion and potential determinants or clinical outcomes, we pooled risk ratios or mean differences with random-effect models and the Mantel-Haenszel method. We identified 24 eligible studies (17414 patients). After pooling data from 23 studies (7524 patients), approximately 36% (95% confidence interval [CI], 28-44; I(2) = 98%) of patients received RBC transfusion at some point during their hospital stay. Hemoglobin thresholds for transfusion were rarely available (reported in 9 studies) and varied from 6 to 10 g/dL. Glasgow Coma Scale scores at admission were lower in patients who were transfused than those who were not (3 cohort studies; 1371 patients; mean difference of 1.38 points [95% CI, 0.86-1.89]; I(2) = 12%). Mortality was not significantly different among transfused and nontransfused patients in univariate and multivariate meta-analyses. Hospital length of stay was longer among patients receiving RBC transfusion compared to those who did not (3 studies; n = 455; mean difference, 9.58 days [95% CI, 3.94-15.22]; I(2) = 74%). Results should be considered cautiously due to the high heterogeneity and high risk of confounding from the observational nature of included studies. Red blood cell transfusion is frequent in patients with TBI, and transfusion practices varied widely between studies. Current published data highlight the lack of clinical evidence guiding transfusion strategies in TBI.

Harnessing the master transcriptional repressor REST to reciprocally regulate neurogenesis

Neurogenesis begins in embryonic development and continues at a reduced rate into adulthood in vertebrate species, yet the signaling cascades regulating this process remain poorly understood. Plasma membrane-initiated signaling cascades regulate neurogenesis via downstream pathways including components of the transcriptional machinery. A nuclear factor that temporally regulates neurogenesis by repressing neuronal differentiation is the repressor element 1 (RE1) silencing transcription (REST) factor. We have recently discovered a regulatory site on REST that serves as a molecular switch for neuronal differentiation. Specifically, C-terminal domain small phosphatase 1, CTDSP1, present in non-neuronal cells, maintains REST activity by dephosphorylating this site. Reciprocally, extracellular signal-regulated kinase, ERK, activated by growth factor signaling in neural progenitors, and peptidylprolyl cis/trans isomerase Pin1, decrease REST activity through phosphorylation-dependent degradation. Our findings further resolve the mechanism for temporal regulation of REST and terminal neuronal differentiation. They also provide new potential therapeutic targets to enhance neuronal regeneration after injury.

Restrictive and liberal red cell transfusion strategies in adult patients: reconciling clinical data with best practice

Red blood cell (RBC) transfusion guidelines correctly promote a general restrictive transfusion approach for anemic hospitalized patients. Such recommendations have been derived from evaluation of specific patient populations, and it is important to recognize that engaging a strict guideline approach has the potential to incur harm if the clinician fails to provide a comprehensive review of the patient’s physiological status in determining the benefit and risks of transfusion. We reviewed the data in support of a restrictive or a more liberal RBC transfusion practice, and examined the quality of the datasets and manner of their interpretation to provide better context by which a physician can make a sound decision regarding RBC transfusion therapy. Reviewed studies included PubMed-cited (1974 to 2013) prospective randomized clinical trials, prospective subset analyses of randomized studies, nonrandomized controlled trials, observational case series, consecutive and nonconsecutive case series, and review articles. Prospective randomized clinical trials were acknowledged and emphasized as the best-quality evidence. The results of the analysis support that restrictive RBC transfusion practices appear safe in the hospitalized populations studied, although patients with acute coronary syndromes, traumatic brain injury and patients at risk for brain or spinal cord ischemia were not well represented in the reviewed studies. The lack of quality data regarding the purported adverse effects of RBC transfusion at best suggests that restrictive strategies are no worse than liberal strategies under the studied protocol conditions, and RBC transfusion therapy in the majority of instances represents a marker for greater severity of illness. The conclusion is that in the majority of clinical settings a restrictive RBC transfusion strategy is cost-effective, reduces the risk of adverse events specific to transfusion, and introduces no harm. In anemic patients with ongoing hemorrhage, with risk of significant bleeding, or with concurrent ischemic brain, spinal cord, or myocardium, the optimal hemoglobin transfusion trigger remains unknown. Broad-based adherence to guideline approaches of therapy must respect the individual patient condition as interpreted by comprehensive clinical review.

Blood component transfusion increases the risk of death in children with traumatic brain injury

BACKGROUND

Blood transfusion has been associated with worse outcomes in adult trauma patients with traumatic brain injury (TBI). However, the effects in injured children have not been evaluated. We hypothesize that blood transfusion is also associated with worse outcomes in children with TBI.

METHODS

A retrospective review of the trauma database at two Level I pediatric trauma centers was performed. We reviewed all patients 18 years and younger with TBI, who survived at least 24 hours, from 2002 to 2011. Exclusion criteria include those who underwent craniotomy, thoracotomy, exploratory laparotomy, and any orthopedic procedure.

RESULTS

A total of 1,607 children with TBI were included in the study population (mean age, 6.4 [5.7] years; 65% male), 178 of whom received a blood transfusion. Mean Injury Severity Score (ISS) was 16.5 (9.1). Patients who received a transfusion had a higher ISS than those who did not (26.7 vs. 15.3). After controlling for age, sex, ISS, Glasgow Coma Scale (GCS) score on presentation, and mechanism of injury, patients who received a blood transfusion were more likely to be admitted to the intensive care unit (p < 0.0001), less likely to survive to hospital discharge (p = 0.02), more likely to be discharged to a rehabilitation facility (p = 0.01) and be dependent on caretakers at follow-up (p < 0.0001), as well as more likely to develop urinary tract infection (p = 0.02) and bacteremia (p = 0.02) during their hospital stay. These differences in outcomes among those who did and did not receive a blood transfusion began to disappear in patients with a nadir hemoglobin of less than 8.0 g/dL.

CONCLUSION

Pediatric patients sustaining TBI who receive blood transfusion and do not require operative intervention have worse outcomes compared with patients who do not receive transfusion. This includes an increased risk of death. These data suggest that a transfusion trigger of hemoglobin level at 8.0 g/dL in injured children with TBI may be beneficial.

LEVEL OF EVIDENCE

Epidemiologic study, level III. Therapeutic study, level IV.

The impact of low hemoglobin levels and transfusion on critical care patients with severe ischemic stroke: STroke: RelevAnt Impact of HemoGlobin, Hematocrit and Transfusion (STRAIGHT)--an observational study

PURPOSE

Optimal management of hemoglobin (Hb) and red blood cell transfusion (RBCT) in neurologic intensive care unit (NICU) patients has not been determined yet. Here we aimed to investigate the impact of anemia and transfusion activity in patients who had acute ischemic stroke.

MATERIALS AND METHODS

A retrospective analysis of clinical, laboratory, and outcome data of patients with severe acute ischemic stroke treated on our NICU between 2004 and 2011 was performed.

RESULTS

Of 109 patients, 97.2% developed anemia and 33% received RBCT. Significant correlations were found between NICU length of stay (NICU LOS) and lowest (nadir) Hb (correlation coefficient, -0.42, P < .001), Hb decrease (0.52, P < .001), nadir hematocrit (Hct; -0.43, P < .001), and Hct decrease (0.51, P < .001). Duration of mechanical ventilation (MV) was strongly associated with both nadir Hb (-0.41, P < .001) and decrease (0.42, P < .001) and nadir Hct (-0.43, P < .001) and decrease (0.40, P < .001). Red blood cell transfusion correlated with NICU LOS (0.33, P < .001) and with duration of MV (0.40, P < .001). None of these hematologic parameters correlated with in-hospital mortality or 90-day outcome. The linear regression model showed number of RBCT (0.29, P = .008), nadir Hb (-0.18, P = .049), Hb decrease (0.33, P < .001), nadir Hct (-0.18, P = .03), and Hct decrease (0.29, P < .001) to be independent predictors of NICU LOS. Duration of MV was also independently predicted by number of RBC transfusions (0.29, P < .001), nadir Hb (-0.20, P = .02), Hb decrease (0.25, P = .002), nadir Hct (-0.21, P = .015), and Hct decrease (0.26, P < .001).

CONCLUSIONS

Low and further decreasing Hb and Hct levels as well as RBCT activity are associated with prolonged NICU stay and duration of MV but not with mortality or long-term outcome. Our findings do not justify using a more aggressive transfusion practice at present.

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.

Perioperative management of traumatic brain injury

Traumatic brain injury (TBI) is a major public health problem and the leading cause of death and disability worldwide. Despite the modern diagnosis and treatment, the prognosis for patients with TBI remains poor. While severity of primary injury is the major factor determining the outcomes, the secondary injury caused by physiological insults such as hypotension, hypoxemia, hypercarbia, hypocarbia, hyperglycemia and hypoglycemia, etc. that develop over time after the onset of the initial injury, causes further damage to brain tissue, worsening the outcome in TBI. Perioperative period may be particularly important in the course of TBI management. While surgery and anesthesia may predispose the patients to new onset secondary injuries which may contribute adversely to outcomes, the perioperative period is also an opportunity to detect and correct the undiagnosed pre-existing secondary insults, to prevent against new secondary insults and is a potential window to initiate interventions that may improve outcome of TBI. For this review, extensive Pubmed and Medline search on various aspects of perioperative management of TBI was performed, followed by review of research focusing on intraoperative and perioperative period. While the research focusing specifically on the intraoperative and immediate perioperative TBI management is limited, clinical management continues to be based largely on physiological optimization and recommendations of Brain Trauma Foundation guidelines. This review is focused on the perioperative management of TBI, with particular emphasis on recent developments.

The impact of anemia in moderate to severe traumatic brain injury

PURPOSE

The impact of anemia and restrictive transfusion strategies in traumatic brain injury (TBI) is unclear. The purpose of this study was to examine the outcome of varying degrees of anemia in patients who have sustained a TBI.

METHODS

We performed a retrospective study of all adult patients with isolated blunt TBI admitted between January 2003 and June 2010. The impact of increasing severity of anemia (Hb ≤8, ≤9, or ≤10 g/dl measured on three consecutive draws within the first 7 days of admission) and transfusions on complications, length of stay, and mortality was examined using univariate and multivariate analysis.

RESULTS

Of the 31,648 patients with blunt trauma admitted to the trauma service during the study period, 812 had an isolated TBI, among which 196 (24.1 %) met at least one of the anemia thresholds within the first 7 days [78 % male, mean age 47 ± 23 years, Injury Severity Score 16 ± 8, and head Abbreviated Injury Scale 3.3 ± 1.0]. Using a logistic regression model, anemia even as low as 8 g/dl was not associated with an increase in mortality [AOR8 = 0.8 (0.2, 3.2), p = 0.771; AOR9 = 0.8 (0.4, 1.6), p = 0.531; AOR10 = 0.6 (0.3, 1.3), p = 0.233] or complications. However, for all patients, the transfusion of packed red blood cells was associated with a significant increase in septic complications [AOR = 3.2 (1.5, 13.7), p = 0.030].

CONCLUSION

The presence of anemia in patients with TBI as low as 8 g/dl was not associated with increased mortality or complications, while the transfusion of red blood cells was associated with a significant increase in septic complications. Prospective evaluation of an optimal transfusion trigger in head-injured patients is warranted.

Effects of platelet and plasma transfusion on outcome in traumatic brain injury patients with moderate bleeding diatheses

Object

Coagulopathy and thrombocytopenia are common after traumatic brain injury (TBI), yet transfusion thresholds for mildly to moderately abnormal ranges of international normalized ratio and platelet count remain controversial. This study evaluates associations between fresh frozen plasma (FFP) and platelet transfusions with long-term functional outcome and survival in TBI patients with moderate hemostatic laboratory abnormalities.

Methods

This study is a retrospective review of prospectively collected data of patients with mild to severe TBI. Data include patient demographics, several initial injury severity metrics, daily laboratory values, Glasgow Outcome Score- Extended (GOSE) scores, Functional Status Examination (FSE) scores, and survival to 6 months. Correlations were evaluated between these variables and transfusion of FFP, platelets, packed red blood cells (RBCs), cryoprecipitate, recombinant factor VIIa, and albumin. Ordinal regression was performed to account for potential confounding variables to further define relationships between transfusion status and long-term outcome. By analyzing collected data, mild to moderate coagulopathy was defined as an international normalized ratio 1.4–2.0, moderate thrombocytopenia as platelet count 50 × 109/L to 107 × 109/L, and moderate anemia as 21%–30% hematocrit.

Results

In patients with mild to moderate laboratory hematological abnormalities, univariate analysis shows significant correlations between poor outcome scores and FFP, platelet, or packed RBC transfusion; the volume of FFP or packed RBCs transfused also correlated with poor outcome. Several measures of initial injury and laboratory abnormalities also correlated with poor outcome. Patient age, initial Glasgow Coma Scale score, and highest recorded serum sodium were included in the ordinal regression model using backward variable selection. In the moderate coagulopathy subgroup, patients transfused with FFP were more likely to have a lower GOSE score relative to those who did not receive a transfusion (OR 5.20 [95% CI 1.72–15.73]). Patients with moderate coagulopathy who received FFP and packed RBCs were even more likely to be have a lower GOSE score (OR 7.17 [95% CI 2.12–24.12]). Moderately anemic patients who received packed RBCs alone were more likely to have a worse long-term functional outcome as determined by GOSE and FSE scores (GOSE: OR 2.41 [95% CI 1.51–3.85]; and FSE: OR 3.27 [95% CI 2.00–5.35]). No transfusion types or combinations were noted to significantly correlate with the 6-month mortality in ordinal regression.

Conclusions

In TBI patients with moderate coagulopathy, FFP transfusions alone or a combination of FFP and packed RBCs were associated with poorer long-term functional outcomes as measured by the GOSE. Red blood cell transfusions were associated with poor long-term functional outcome in TBI patients with moderate anemia. Platelet transfusion in patients with moderate thrombocytopenia was not significantly associated with outcome. Although transfusion is beneficial to many patients with severe hematological abnormalities, it is not without risk, and the indications for transfusion should be carefully considered in patients with moderate hematological abnormalities.

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.

Hemoglobin levels and transfusions in neurocritically ill patients: a systematic review of comparative studies

Introduction

Accumulating evidence suggests that, in critically ill patients, a lower hemoglobin transfusion threshold is safe. However, the optimal hemoglobin level and associated transfusion threshold remain unknown in neurocritically ill patients.

Methods

We conducted a systematic review of comparative studies (randomized and nonrandomized) to evaluate the effect of hemoglobin levels on mortality, neurologic function, intensive care unit (ICU) and hospital length of stay, duration of mechanical ventilation, and multiple organ failure in adult and pediatric neurocritically ill patients. We searched MEDLINE, The Cochrane Central Register of Controlled Trials, Embase, Web of Knowledge, and Google Scholar. Studies focusing on any neurocritical care conditions were included. Data are presented by using odds ratios for dichotomous outcomes and mean differences for continuous outcomes.

Results

Among 4,310 retrieved records, six studies met inclusion criteria (n = 537). Four studies were conducted in traumatic brain injury (TBI), one in subarachnoid hemorrhage (SAH), and one in a mixed population of neurocritically ill patients. The minimal hemoglobin levels or transfusion thresholds ranged from 7 to 10 g/dl in the lower-Hb groups and from 9.3 to 11.5 g/dl in the higher-Hb groups. Three studies had a low risk of bias, and three had a high risk of bias. No effect was observed on mortality, duration of mechanical ventilation, or multiple organ failure. In studies reporting on length of stay (n = 4), one reported a significant shorter ICU stay (mean, -11.4 days (95% confidence interval, -16.1 to -6.7)), and one, a shorter hospital stay (mean, -5.7 days (-10.3 to -1.1)) in the lower-Hb groups, whereas the other two found no significant association.

Conclusions

We found insufficient evidence to confirm or refute a difference in effect between lower- and higher-Hb groups in neurocritically ill patients. Considering the lack of evidence regarding long-term neurologic functional outcomes and the high risk of bias of half the studies, no recommendation can be made regarding which hemoglobin level to target and which associated transfusion strategy (restrictive or liberal) to favor in neurocritically ill patients.

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.

Controversies in the management of adults with severe traumatic brain injury

Despite progress in the management of adults with severe traumatic brain injury, several controversies persist. Among the unresolved issues of greatest concern to neurocritical care clinicians and scientists are the following: (1) the best use of technological advances and the data obtained from multimodality monitoring; (2) the use of mannitol and hypertonic saline in the management of increased intracranial pressure; (3) the use of decompressive craniectomy and barbiturate coma in refractory increased intracranial pressure; (4) therapeutic hypothermia as a neuroprotectant; (5) anemia and the role of blood transfusion; and (6) venous thromboembolism prophylaxis in severe traumatic brain injury. Each of these strategies for managing severe traumatic brain injury, including the postulated mechanism(s) of action and beneficial effects of each intervention, adverse effects, the state of the science, and critical care nursing implications, is discussed.

The clinical significance of platelet counts in the first 24 hours after severe injury

BACKGROUND

Admission platelet (PLT) counts are known to be associated with all-cause mortality for seriously injured patients admitted to a trauma center. The course of subsequent PLT counts, their implications, and the effects of PLT therapy are less well known.

STUDY DESIGN AND METHODS

Trauma center patients who were directly admitted from the scene of injury, received 1 or more units of uncrossmatched red blood cells in the first hour of care, survived for at least 15 minutes, and had a PLT count measured in the first hour were analyzed for the association of their admission and subsequent PLT counts in the first 24 hours with injury severity and hemorrhagic and central nervous system (CNS) causes of in-hospital mortality.

RESULTS

Over an 8.25-year period, 1292 of 45,849 direct trauma admissions met entry criteria. Admission PLT counts averaged 228×10(9) ±90×10(9) /L and decreased by 104×10(9) /L by the second hour and 1×10(9) /L each hour thereafter. The admission count was not related to time to admission. Each 1-point increase in the injury severity score was associated with a 1×10(9) /L decrease in the PLT count at all times in the first 24 hours of care. Admission PLT counts were strongly associated with hemorrhagic and CNS injury mortality and subsequent PLT counts. Effects of PLT therapy could not be ascertained.

DISCUSSION

Admission PLT counts in critically injured trauma patients are usually normal, decreasing after admission. Low PLT counts at admission and during the course of trauma care are strongly associated with mortality.

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.