A review of red cell transfusion in the neurological intensive care unit

Predictive indicators for determining red blood cell transfusion strategies in the emergency department

BACKGROUND AND IMPORTANCE

Appropriate decision-making is critical for transfusions to prevent unnecessary adverse outcomes; however, transfusion in the emergency department (ED) can only be decided based on sparse evidence in a limited time window.

OBJECTIVES

This study aimed to identify factors associated with appropriate red blood cell (RBC) transfusion in the ED by analyzing retrospective data of patients who received transfusions at a single center.

OUTCOME MEASURES AND ANALYSIS

This study analyzed associations between transfusion appropriateness and sex, age, initial vital signs, an ED triage score [the Korean Triage and Acuity Scale (KTAS)], the length of stay, and the hemoglobin (Hb) concentration.

MAIN RESULTS

Of 10 490 transfusions, 10 109 were deemed appropriate, and 381 were considered inappropriate. A younger age ( P  < 0.001) and a KTAS level of 3-5 ( P  = 0.028) were associated with inappropriate transfusions, after adjusting for O 2 saturation and the Hb level.

CONCLUSIONS

In this single-center retrospective study, younger age and higher ED triage scores were associated with the appropriateness of RBC transfusions.

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.

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.

Blood Products

Perioperative hemorrhage, anemia, thrombocytopenia, and coagulopathy are common in the surgical intensive care unit. As a result, blood product transfusion occurs frequently. While red blood cell, plasma, and platelet transfusions have a lifesaving role in the resuscitation of patients with trauma and hemorrhagic shock, their application in other settings is under scrutiny. Current data would suggest a conservative approach be taken, thus avoiding unnecessary transfusion and associated potential adverse events. New and developmental products such as prothrombin complex concentrates offer appealing alternatives to traditional transfusion practice—potentially with fewer risks—however, further investigation into their safety and efficacy is required before practice change can take place.

Effect of Hemoglobin Transfusion Threshold on Cerebral Hemodynamics and Oxygenation

Cerebral dysfunction caused by traumatic brain injury may adversely affect cerebral hemodynamics and oxygenation leading to worse outcomes if oxygen capacity is decreased due to anemia. In a randomized clinical trial of 200 patients comparing transfusion thresholds <7 g/dl versus 10 g/dl, where transfusion of leukoreduced packed red blood cells was used to maintain the assigned hemoglobin threshold, no long-term neurological difference was detected. The current study examines secondary outcome measures of intracranial pressure (ICP), cerebral perfusion pressure (CPP), and brain tissue oxygenation (PbtO2) in patients enrolled in this randomized clinical trial. We observed a lower hazard for death (hazard ratio [HR]=0.12, 95% confidence interval [CI]=0.02-0.99) during the first 3 days post-injury, and a higher hazard for death after three days (HR=2.55, 95% CI=1.00-6.53) in the 10 g/dl threshold group as compared to the 7 g/dL threshold group. No significant differences were observed for ICP and CPP but MAP was slightly lower in the 7 g/dL group, although the decreased MAP did not result in increased hypotension. Overall brain tissue hypoxia events were not significantly different in the two transfusion threshold groups. When the PbtO2 catheter was placed in normal brain, however, tissue hypoxia occurred in 25% of patients in the 7 g/dL threshold group, compared to 10.2% of patients in the 10 g/dL threshold group (p=0.04). Although we observed a few differences in hemodynamic outcomes between the transfusion threshold groups, none were of major clinical significance and did not affect long-term neurological outcome and mortality.

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.

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.

Perioperative management of adult traumatic brain injury

This article presents an overview of the management of traumatic brain injury (TBI) as relevant to the practicing anesthesiologist. Key concepts surrounding the pathophysiology and anesthetic principles are used to describe potential ways to reduce secondary insults and improve outcomes after TBI.

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.

The impact of beta-blocker therapy on anemia after traumatic brain injury

BACKGROUND

An increase in endogenous catecholamine levels after traumatic brain injury (TBI) is well described. Animal studies suggest that postinjury anemia is exacerbated by a persistent hyperadrenergic state. This study aims to determine if beta-blocker (BB) exposure affects anemia after TBI.

STUDY DESIGN AND METHODS

We reviewed a Level I trauma registry for patients with TBI, examining markers of anemia between patients who received BB with those who did not.

RESULTS

A total of 174 patients were exposed to BB (BB+) and 245 were not exposed (BB-). The mean age in the BB+ group was 50 years (vs. 36 years in BB- group, p < 0.001). The mean injury severity score was 33.6 for the BB+ group (vs. 30.8 for BB- group, p = 0.01). While BB+ patients were more likely to receive a transfusion (60.9% vs. 35.1%, p < 0.001), BB+ patients reached their nadir hemoglobin (Hb) at a later day of hospitalization and their rate of decrease in Hb was significantly slower (both p < 0.001). Choosing Hb cutoffs for anemia of both 7 and 10 g/dL, Kaplan-Meier demonstrated a significant delay in time to anemia.

CONCLUSION

This study suggests beta-blockade delays anemia after TBI. Elaboration of this effect may demonstrate an additional benefit of beta-blockade after head injury.

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.

The effect of red blood cell transfusion on cerebral oxygenation and metabolism after severe traumatic brain injury

OBJECTIVE

There is evidence to suggest that anemia after severe traumatic brain injury (sTBI) is detrimental. However, there is a paucity of evidence supporting the use of transfusion of packed red blood cells in patients with sTBI. To understand the acute effect of packed red blood cell transfusion on cerebral oxygenation and metabolism in patients with sTBI.

DESIGN

Prospective clinical study.

SETTING

Addenbrooke's Neurosciences Critical Care Unit, a 21-bed tertiary academic unit.

PATIENTS

Thirty patients with sTBI.

INTERVENTIONS

Patients were randomized by computer random number generator to one of three transfusion thresholds: 8, 9, or 10 g/dL. When the patients' hemoglobin concentration fell below their assigned threshold, two units of packed red blood cells were transfused over 2 hours. A 1-hour period of stabilization was observed before final data collection.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was change in brain tissue oxygen (Pbto2). Secondary outcomes included dependence of baseline hemoglobin concentration and baseline Pbto2 on the relationship of transfusion and Pbto2, and the effect of transfusion on lactate pyruvate ratio (LPR) and brain pH as markers of cerebral metabolic state. Fifty-seven percent of patients experienced an increase in Pbto2 during the course of the study, whereas in 43% of patients, Pbto2 either did not change or decreased. Multivariable generalized estimating equation analysis revealed change in hemoglobin concentration to significantly and positively associated with change in Pbto2 [0.10 kPa/(g/dL) 95% confidence interval 0.03-0.17, p = 0.003]. Improvement in Pbto2 was not associated with baseline hemoglobin concentration or low Pbto2 (<1 kPa). Fifty-six percent of patients experienced an increase in LPR. No significant relationship between change in LPR or transfusion on pHbt and change in hemoglobin could be demonstrated.

CONCLUSIONS

Transfusion of packed red blood cells acutely results in improved brain tissue oxygen without appreciable effect on cerebral metabolism.

TRIAL REGISTRATION

ISRCTN89085577.

[Transfusion in neurosurgery]

In neurosurgery, the question of the optimal transfusion "trigger" remains a controversial matter. Regarding the brain, the current data are still incomplete, justifying the continuation of experimental and clinical studies. The existing expert advices are based on these rather poor data and would probably evolve after the completion of clinical studies in progress. In spine surgery, the situation is simpler and the transfusional stakes are quite similar to those of orthopedics and traumatology. With regard to hemostasis, standardized recommendations exist depending on the laboratory test results or the anticoagulant treatments of the patient.

Optimal hemoglobin concentration in patients with subarachnoid hemorrhage, acute ischemic stroke and traumatic brain injury

PURPOSE OF REVIEW

The review outlines recent clinical and experimental studies regarding the effects of red blood-cell transfusion on clinical outcome in neurocritical patients, including patients with subarachnoid hemorrhage, acute ischemic stroke and traumatic brain injury. Optimal hemoglobin transfusion trigger and the role of other transfusion indicators for neurocritical patients are discussed.

RECENT FINDINGS

Acute anemia (hemoglobin levels near 7 g/dl) is well tolerated by healthy subjects, but extreme anemia might negatively affect clinical outcome of neurocritical patients. Conversely, high hemoglobin levels, attained by means other than red blood-cell transfusion, improve clinical outcome, whereas red blood-cell transfusion is associated with poorer clinical outcome (mortality, length of stay and disability) in patients presenting subarachnoid hemorrhage, acute ischemic stroke and traumatic brain injury. Studies defining the optimal hemoglobin concentration in neurocritical patients are lacking, but a restrictive transfusion policy seems to be safe and is often recommended. In the near future, signals coming from the brain, such as brain tissue oxygen tension and regional cerebral oxygen saturation, might potentially be developed into transfusion triggers.

SUMMARY

Both severe anemia and red blood-cell transfusion may negatively influence clinical outcome in neurocritical patients. Acceptance of low hemoglobin concentrations may be justified by avoiding negative transfusion effects. No evidence-based transfusion trigger in neurocritical patients can be recommended.

Transfusion of erythrocyte concentrates produces a variable increment on cerebral oxygenation in patients with severe traumatic brain injury: a preliminary study

OBJECTIVE

To investigate the long-term influence of erythrocyte transfusion on cerebral oxygenation in patients with severe traumatic brain injury.

DESIGN

Prospective and observational study.

SETTING

Neurotrauma intensive care unit of trauma center level I.

PATIENTS

Sixty consecutive, hemodynamically stable patients with severe traumatic brain injury, pretransfusion hemoglobin<100g/l, non-bleeding and monitored through intracranial pressure and brain tissue partial pressure of oxygen (PtiO(2)) catheters were included.

INTERVENTIONS

Transfusion of 1-2 units of red blood cells.

MEASUREMENTS AND RESULTS

Ten sets of variables (pretransfusion, end of transfusion, and 1, 2, 3, 4, 5, 6, 12 and 24h after transfusion) were recorded, including: PtiO(2), cerebral perfusion pressure (CPP), end-tidal CO(2), peripheral saturation of oxygen, temperature, hemoglobin, lactate and PaO(2)/FiO(2) ratio. Transfusion was associated with an increase in PtiO(2) during a 6-h period, with a peak at 3h (26.2%; p=0.0001) in 78.3% of the patients. No relationship was observed between PtiO(2), CPP and hemoglobin increments. The relative increment in PtiO(2) at hour 3 was only correlated with baseline PtiO(2) (r(2) 0.166; p=0.001). All of the patients with basal PtiO(2)<15mmHg showed an increment in PtiO(2) versus 74.5% of patients with basal PtiO(2)>or=15mmHg (p<0.01, hour 3).

CONCLUSIONS

Erythrocyte transfusion is associated with a variable and prolonged increment of cerebral tissue oxygenation in anemic patients with severe traumatic brain injury. Low baseline PtiO(2) levels (<15mmHg) could define those patients who benefit the most from erythrocyte transfusion.