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The Restrictive Red Blood Cell Transfusion Strategy for Critically Injured Patients (RESTRIC) trial: a cluster-randomized, crossover, non-inferiority multicenter trial of restrictive transfusion in trauma
Hayakawa, M., Tagami, T., Kudo, D., Ono, K., Aoki, M., Endo, A., Yumoto, T., Matsumura, Y., Irino, S., Sekine, K., et al
Journal of intensive care. 2023;11(1):34
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Editor's Choice
Abstract
BACKGROUND The efficacies of fresh frozen plasma and coagulation factor transfusion have been widely evaluated in trauma-induced coagulopathy management during the acute post-injury phase. However, the efficacy of red blood cell transfusion has not been adequately investigated in patients with severe trauma, and the optimal hemoglobin target level during the acute post-injury and resuscitation phases remains unclear. Therefore, this study aimed to examine whether a restrictive transfusion strategy was clinically non-inferior to a liberal transfusion strategy during the acute post-injury phase. METHODS This cluster-randomized, crossover, non-inferiority multicenter trial was conducted at 22 tertiary emergency medical institutions in Japan and included adult patients with severe trauma at risk of major bleeding. The institutions were allocated a restrictive or liberal transfusion strategy (target hemoglobin levels: 7-9 or 10-12 g/dL, respectively). The strategies were applied to patients immediately after arrival at the emergency department. The primary outcome was 28-day survival after arrival at the emergency department. Secondary outcomes included transfusion volume, complication rates, and event-free days. The non-inferiority margin was set at 3%. RESULTS The 28-day survival rates of patients in the restrictive (n = 216) and liberal (n = 195) strategy groups were 92.1% and 91.3%, respectively. The adjusted odds ratio for 28-day survival in the restrictive versus liberal strategy group was 1.02 (95% confidence interval: 0.49-2.13). Significant non-inferiority was not observed. Transfusion volumes and hemoglobin levels were lower in the restrictive strategy group than in the liberal strategy group. No between-group differences were noted in complication rates or event-free days. CONCLUSIONS Although non-inferiority of the restrictive versus liberal transfusion strategy for 28-day survival was not statistically significant, the mortality and complication rates were similar between the groups. The restrictive transfusion strategy results in a lower transfusion volume. TRIAL REGISTRATION NUMBER umin.ac.jp/ctr: UMIN000034405, registration date: 8 October 2018.
PICO Summary
Population
Adult patients with severe trauma at risk of major bleeding, enrolled in the RESTRIC cluster-randomized, crossover trial at 22 tertiary emergency medical institutions in Japan (n= 422).
Intervention
Restrictive transfusion strategy (n= 222).
Comparison
Liberal transfusion strategy (n= 200).
Outcome
The restrictive and liberal red blood cell strategy groups included 216 and 195 patients in the intention-to-treat analysis, respectively. The primary outcome was 28-day survival after arrival at the emergency department. Secondary outcomes included transfusion volume, complication rates, and event-free days. The non-inferiority margin was set at 3%. The 28-day survival rates of patients in the restrictive (n= 216) and liberal (n= 195) strategy groups were 92.1% and 91.3%, respectively. The adjusted odds ratio for 28-day survival in the restrictive versus liberal strategy group was 1.02; 95% confidence interval [0.49, 2.13]. Significant non-inferiority was not observed. Transfusion volumes and haemoglobin levels were lower in the restrictive strategy group than in the liberal strategy group. No between-group differences were noted in complication rates or event-free days.
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Resuscitation with blood products in patients with trauma-related haemorrhagic shock receiving prehospital care (RePHILL): a multicentre, open-label, randomised, controlled, phase 3 trial
Crombie N, Doughty HA, Bishop JRB, Desai A, Dixon EF, Hancox JM, Herbert MJ, Leech C, Lewis SJ, Nash MR, et al
The Lancet. Haematology. 2022
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Editor's Choice
Abstract
BACKGROUND Time to treatment matters in traumatic haemorrhage but the optimal prehospital use of blood in major trauma remains uncertain. We investigated whether use of packed red blood cells (PRBC) and lyophilised plasma (LyoPlas) was superior to use of 0·9% sodium chloride for improving tissue perfusion and reducing mortality in trauma-related haemorrhagic shock. METHODS Resuscitation with pre-hospital blood products (RePHILL) is a multicentre, allocation concealed, open-label, parallel group, randomised, controlled, phase 3 trial done in four civilian prehospital critical care services in the UK. Adults (age ≥16 years) with trauma-related haemorrhagic shock and hypotension (defined as systolic blood pressure <90 mm Hg or absence of palpable radial pulse) were assessed for eligibility by prehospital critial care teams. Eligible participants were randomly assigned to receive either up to two units each of PRBC and LyoPlas or up to 1 L of 0·9% sodium chloride administered through the intravenous or intraosseous route. Sealed treatment packs which were identical in external appearance, containing PRBC-LyoPlas or 0·9% sodium chloride were prepared by blood banks and issued to participating sites according to a randomisation schedule prepared by the co-ordinating centre (1:1 ratio, stratified by site). The primary outcome was a composite of episode mortality or impaired lactate clearance, or both, measured in the intention-to-treat population. This study is completed and registered with ISRCTN.com, ISRCTN62326938. FINDINGS From Nov 29, 2016 to Jan 2, 2021, prehospital critical care teams randomly assigned 432 participants to PRBC-LyoPlas (n=209) or to 0·9% sodium chloride (n=223). Trial recruitment was stopped before it achieved the intended sample size of 490 participants due to disruption caused by the COVID-19 pandemic. The median follow-up was 9 days (IQR 1 to 34) for participants in the PRBC-LyoPlas group and 7 days (0 to 31) for people in the 0·9% sodium chloride group. Participants were mostly white (62%) and male (82%), had a median age of 38 years (IQR 26 to 58), and were mostly involved in a road traffic collision (62%) with severe injuries (median injury severity score 36, IQR 25 to 50). Before randomisation, participants had received on average 430 mL crystalloid fluids and tranexamic acid (90%). The composite primary outcome occurred in 128 (64%) of 199 participants randomly assigned to PRBC-LyoPlas and 136 (65%) of 210 randomly assigned to 0·9% sodium chloride (adjusted risk difference -0·025% [95% CI -9·0 to 9·0], p=0·996). The rates of transfusion-related complications in the first 24 h after ED arrival were similar across treatment groups (PRBC-LyoPlas 11 [7%] of 148 compared with 0·9% sodium chloride nine [7%] of 137, adjusted relative risk 1·05 [95% CI 0·46-2·42]). Serious adverse events included acute respiratory distress syndrome in nine (6%) of 142 patients in the PRBC-LyoPlas group and three (2%) of 130 in 0·9% sodium chloride group, and two other unexpected serious adverse events, one in the PRBC-LyoPlas (cerebral infarct) and one in the 0·9% sodium chloride group (abnormal liver function test). There were no treatment-related deaths. INTERPRETATION The trial did not show that prehospital PRBC-LyoPlas resuscitation was superior to 0·9% sodium chloride for adult patients with trauma related haemorrhagic shock. Further research is required to identify the characteristics of patients who might benefit from prehospital transfusion and to identify the optimal outcomes for transfusion trials in major trauma. The decision to commit to routine prehospital transfusion will require careful consideration by all stakeholders. FUNDING National Institute for Health Research Efficacy and Mechanism Evaluation.
PICO Summary
Population
Patients aged 16 years old or older with trauma-related haemorrhagic shock enrolled in the resuscitation with pre-hospital blood products (RePHILL) trial, based across four UK prehospital critical care services (n= 432).
Intervention
Packed red blood cells and lyophilised plasma (PRBC-LyoPlas, n= 209).
Comparison
Sodium chloride (n= 223).
Outcome
The primary outcome was a composite of episode mortality or impaired lactate clearance, or both, measured in the intention-to-treat population. The composite primary outcome occurred in 128 (64%) of 199 patients receiving PRBC-LyoPlas and 136 (65%) of 210 receiving sodium chloride. The rates of transfusion-related complications in the first 24 hours after emergency department arrival were similar (PRBC-LyoPlas eleven (7%) of 148 compared with sodium chloride nine (7%) of 137). Serious adverse events included acute respiratory distress syndrome in nine (6%) of 142 patients in the PRBC-LyoPlas group and three (2%) of 130 in the sodium chloride group, and two other unexpected serious adverse events, one in the PRBC-LyoPlas (cerebral infarct) and one in the sodium chloride group (abnormal liver function test). There were no treatment-related deaths.
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Dose-dependent association between blood transfusion and nosocomial infections in trauma patients: A secondary analysis of patients from the PAMPer trial
Ladhani, H. A., Ho, V. P., Charbonnet, C. C., Sperry, J. L., Guyette, F. X., Brown, J. B., Daley, B. J., Miller, R. S., Harbrecht, B. G., Phelan, H. A., et al
The Journal of Trauma and Acute Care Surgery. 2021;91(2):272-278
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Abstract
BACKGROUND The Prehospital Air Medical Plasma (PAMPer) trial demonstrated a survival benefit to trauma patients who received thawed plasma as part of early resuscitation. The objective of our study was to examine the association between blood transfusion and nosocomial infections among trauma patients who participated in the PAMPer trial. We hypothesized that transfusion of blood products will be associated with the development of nosocomial infections in a dose-dependent fashion. METHODS We performed a secondary analysis of prospectively collected data of patients in the PAMPer trial with hospital length of stay of at least 3 days. Demographics, injury characteristics, and number of blood products transfused were obtained to evaluate outcomes. Bivariate analysis was performed to identify differences between patients with and without nosocomial infections. Two logistic regression models were created to evaluate the association between nosocomial infections and (1) any transfusion of blood products, and (2) quantity of blood products. Both models were adjusted for age, sex, and Injury Severity Score. RESULTS A total of 399 patients were included: age, 46 years (interquartile range, 29-59 years); Injury Severity Score, 22 (interquartile range, 12-29); 73% male; 80% blunt mechanism; and 40 (10%) deaths. Ninety-three (27%) developed nosocomial infections, including pneumonia (n = 67), bloodstream infections (n = 14), catheter-associated urinary tract infection (n = 10), skin and soft tissue infection (n = 8), Clostridium difficile colitis (n = 7), empyema (n = 6), and complicated intra-abdominal infections (n = 3). Nearly 80% (n = 307) of patients received packed red blood cells (PRBCs); 12% received cryoprecipitate, 69% received plasma, and 27% received platelets. Patients who received any PRBCs had more than a twofold increase in nosocomial infections (odds ratio, 2.15; 95% confidence interval, 1.01-4.58; p = 0.047). The number of PRBCs given was also associated with the development of nosocomial infection (odds ratio, 1.10; 95% confidence interval, 1.05-1.16; p < 0.001). CONCLUSION Trauma patients in the PAMPer trial who received a transfusion of at least 1 U of PRBCs incurred a twofold increased risk of nosocomial infection, and the risk of infection was dose dependent. LEVEL OF EVIDENCE Therapeutic/care management, level IV.
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Dynamic Impact of Transfusion Ratios on Outcomes in Severely Injured Patients: Targeted Machine Learning Analysis of the PROPPR Randomized Clinical Trial
Nguyen M, Pirracchio R, Kornblith LZ, Callcut R, Fox EE, Wade CE, Schreiber M, Holcomb JB, Coyle J, Cohen M, et al
J Trauma Acute Care Surg. 2020
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BACKGROUND Massive transfusion protocols to treat post-injury hemorrhage are based on pre-defined blood product transfusion ratios followed by goal-directed transfusion based on patient's clinical evolution. However, it remains unclear how these transfusion ratios impact patient outcomes over time from injury. METHODS The Pragmatic, Randomized Optimal Platelet and Plasma Ratios (PROPPR) is a phase 3, randomized controlled trial, across 12 level-I trauma centers in North America. From 2012 to 2013, 680 severely injured patients required massive transfusion. We used semi-parametric machine learning techniques and causal inference methods to augment the intent-to-treat analysis of PROPPR, estimating the dynamic relationship between transfusion ratios and outcomes: mortality and hemostasis at different time-points during the first 24 hours after admission. RESULTS In the intention-to-treat analysis, the 1:1:1 group tended to have decreased mortality, but with no statistical significance. For patients in whom hemostasis took longer than 2 hours, the 1:1:1 ratio was associated with a higher probability of hemostasis, statistically significant from the 4 hour on. In the per-protocol, actual-transfusion-ratios-received analysis, during four successive time intervals, no significant association was found between the actual ratios and mortality. When comparing patient groups who received both high plasma:PRBC and high platelet:PRBC ratios to the group of low ratios in both, the relative risk of achieving hemostasis was 2.49 (95% CI = 1.19-5.22) during the 3 hour after admission, suggesting a significant beneficial impact of higher transfusion ratios of plasma and platelets on hemostasis. CONCLUSIONS Our results suggest that the impact of transfusion ratios on hemostasis is dynamic. Overall, the transfusion ratios had no significant impact on mortality over time. However, receiving higher ratios of platelets and plasma relative to red blood cells hastens hemostasis in subjects who have yet to achieve hemostasis within 3 hours after hospital admission. LEVEL OF EVIDENCE Prognostic, level III.
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Sex-based differences in transfusion need after severe injury: Findings of the PROPPR study
McCrum ML, Leroux B, Fang T, Bulger E, Arbabi S, Wade CE, Fox E, Holcomb JB, Robinson B
Surgery. 2019
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BACKGROUND Women are underrepresented in trauma research, and aggregated results of clinical trials may mask effects that differ by sex. It is unclear whether women respond differently to severe hemorrhage compared with men. We sought to evaluate sex-based differences in outcomes after severe trauma with hemorrhage. METHODS We performed a secondary analysis of the Pragmatic Randomized Optimal Platelet and Plasma Ratios trial. Trauma patients predicted to require massive transfusion were randomized to a 1:1:1 vs 1:1:2 plasma to platelet to red blood cell transfusion ratio. Analysis was performed according to sex, controlling for clinical characteristics and transfusion arm. RESULTS A total of 134 women and 546 men were analyzed. In multivariable analysis, there was no difference in mortality at 24 hours (hazard ratio for women 0.64, 95% confidence interval 0.34-1.23, P = .18) or in time to hemostasis (hazard ratio 1.10, 95% confidence interval 0.84-1.42, P = .49) by sex. We observed no difference between sexes in volume of blood products transfused during active hemorrhage. However, after anatomic hemostasis, women received lower volumes of all products, with a 38% reduction in fresh frozen plasma (mean ratio 0.62 (95% confidence interval 0.43-0.89, P = .01), 49% reduction in platelets (mean ratio 0.51, 95% confidence interval 0.33-0.79, P < .01) and 49% reduction in volume of red blood cells (mean ratio 0.51, 95% confidence interval 0.33-0.79, P < .01). CONCLUSION Mortality and time to hemostasis of trauma patients with hemorrhage did not differ by sex. Although there was no difference in transfusion requirement during active hemorrhage, once hemostasis was achieved, women received fewer units of all blood products than men. Further research is required to determine whether women exhibit differences in coagulation during and after severe traumatic hemorrhage.
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The hyperfibrinolytic phenotype is the most lethal and resource intense presentation of fibrinolysis in massive transfusion patients
Taylor, J. R., 3rd, Fox, E. E., Holcomb, J. B., Rizoli, S., Inaba, K., Schreiber, M. A., Brasel, K., Scalea, T. M., Wade, C. E., Bulger, E., et al
The Journal of Trauma and Acute Care Surgery. 2018;84(1):25-30
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BACKGROUND Among bleeding patients, we hypothesized that the hyperfibrinolytic (HF) phenotype would be associated with the highest mortality, whereas shutdown (SD) patients would have the greatest complication burden. METHODS Severely injured patients predicted to receive a massive transfusion at 12 Level I trauma centers were randomized to one of two transfusion ratios as described in the Pragmatic, Randomized, Optimal Platelet and Plasma Ratio trial. Fibrinolysis phenotypes were determined based on admission clot lysis at 30 minutes (LY30): SD ≤0.8%, physiologic (PHYS) 0.9-2.9%, and HF ≥3%. Univariate and multivariate analysis was performed. Logistic regression was used to adjust for age, gender, arrival physiology, shock, injury severity, center effect, and treatment arm. RESULTS Among the 680 patients randomized, 547(80%) had admission thrombelastography (TEG) values available to determine fibrinolytic phenotypes. Compared to SD and PHYS, HF patients had higher Injury Severity Score (25 vs. 25 vs. 34), greater base deficit (-8 vs. -6 vs. -12) and were more uniformly hypocoagulable on admission by PT, PTT, and TEG values; all p <0.001. HF patients also received more red blood cells, plasma, and platelets (at 3, 6, and 24 hours); had fewer ICU-, ventilator-, and hospital-free days; and had higher 24-hour and 30-day mortality. There were no differences in complications between the three phenotypes. Multivariate logistic regression demonstrated that HF on admission was associated with a threefold higher mortality (OR 3.06, 95% CI 1.57-5.95, p = 0.001). CONCLUSIONS Previous data have shown that both the SD and HF phenotypes are associated with increased mortality and complications in the general trauma population. However, in a large cohort of bleeding patients, HF was confirmed to be a much more lethal and resource-intense phenotype. These data suggest that further research into the understanding of SD and HF is warranted to improve outcomes in this patient population. LEVEL OF EVIDENCE Prognostic, level II.
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A comparison of resuscitation intensity (RI) and critical administration threshold (CAT) in predicting early mortality among bleeding patients: a multicenter validation in 680 major transfusion patients
Meyer DE, Cotton BA, Fox EE, Stein D, Holcomb JB, Cohen M, Inaba K, Rahbar E
The Journal of Trauma and Acute Care Surgery. 2018;85((4):):691-696
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BACKGROUND To address deficiencies associated with the classic definition of massive transfusion, Critical Administration Threshold and Resuscitation Intensity were developed to better quantify the overall severity of illness and predict the need for transfusions and early mortality. We sought to evaluate these as more appropriate replacements for MT in defining mortality risk in patients undergoing major transfusions. METHODS Patients predicted to receive MT at 12 Level-1 trauma centers were randomized in the PROPPR trial. MT: ≥10U RBC in 24 hours; CAT+: ≥3U RBC in the first hour; and RI: total products in the first 30 minutes (1U RBC, 1U plasma, 1000mL crystalloid, 500mL colloid each valued at 1U). RI was evaluated as a continuous variable and dichotomized as RI4+, where RI≥4 U. Each metric was evaluated for its ability to predict mortality at 3, 6, and 24 hours, and at 30 days. RESULTS Of the 680 patients, 301 patients met MT definition, 521 were CAT+, and 445 were RI4+. Of those that died, 23% never reached MT threshold, but all were captured by CAT+ and RI4+. The 3-hr (9 vs. 9%), 6-hr (14 vs. 14%), 24-hr (17 vs. 18%), and 30-day mortality rates (28 vs. 29%) were similar between CAT+ and RI4+ patients. When RI was evaluated as a continuous variable, each unit increase was associated with a 20% increase in hemorrhage-related mortality (OR 1.20, 95% CI [1.15-1.29], p<0.05).CONCLUSIONBoth RI and CAT are valid surrogates for early mortality in patients undergoing major transfusion, capturing patients omitted by the MT definition. CAT+ showed the best sensitivity; RI4+ demonstrated better specificity and good PPV and NPV. While CAT+ may be suited for patients receiving a RBC-dominant resuscitation, RI4+ is more comprehensive. RI can also be used as a continuous variable to provide quantitative as well qualitative risk of death.LEVEL OF EVIDENCELevel III, Prognostic.
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Every minute counts: time to delivery of initial massive transfusion cooler and its impact on mortality
Meyer DE, Vincent LA, Fox EE, O'Keeffe T, Inaba K, Bulger E, Holcomb JB, Cotton BA
The Journal of Trauma and Acute Care Surgery. 2017;83((1):):19-24
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BACKGROUND ACS-TQIP Best Practices recommends initial massive transfusion (MT) cooler delivery within 15 minutes of protocol activation, with a goal of 10 minutes. The current study sought to examine the impact of timing of first cooler delivery on patient outcomes. METHODS Patients predicted to receive MT at 12 level-1 trauma centers were randomized to two separate transfusion ratios as described in the PROPPR trial. ABC score or clinician gestalt prediction of MT was used to randomize patients and call for initial study cooler. In this planned sub-analysis, the time to MT protocol activation and time to delivery of the initial cooler were evaluated. The impact of these times on mortality and time to hemostasis were examined using both Wilcoxon rank sum and linear and logistic regression. RESULTS Among 680 patients, the median time from patient arrival to MT protocol activation was 9 minutes with a median time from MT activation call to delivery of first cooler of 8 minutes. An increase in both time to MT activation and time to arrival of first cooler were associated with prolonged time to achieving hemostasis (coef 1.09, p=0.001 and coef. 1.16, p < 0.001, respectively). Increased time to MT activation and time to arrival of first cooler were associated with increased mortality (OR 1.02, p=0.009 and OR 1.02, p = 0.012, respectively). Controlling for injury severity, physiology, resuscitation intensity, and treatment arm (1:1:1 vs. 1:1:2), increased time to arrival of first cooler was associated with an increased mortality at 24-hours (OR 1.05, p = 0.035) and 30-days (OR 1.05, p = 0.016). CONCLUSIONS Delays in MT protocol activation and delays in initial cooler arrival were associated with prolonged time to achieve hemostasis and an increase in mortality. Independent of products ratios, every minute from time of MT protocol activation to time of initial cooler arrival increases odds of mortality by 5%. LEVEL OF EVIDENCE Level II, Prognostic.
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Transfusion strategies in patients with traumatic brain injury: which is the optimal hemoglobin target?
Lelubre C, Taccone FS
Minerva Anestesiologica. 2016;82((1)):112-6.
Abstract
Robertson et al. (JAMA 2014; 312:36-47) investigated the effects of two different thresholds of hemoglobin (Hb) to guide red blood cells transfusions (RBCT; 7 g/dL vs. 10 g/dL) in patients suffering from traumatic brain injury (TBI). In a two-center, controlled, open-label trial (from May 2006 and August 2012), comatose patients with a closed TBI were randomized within 6 hours since initial resuscitation to one of the two RBCT strategies and, in a factorial design (2x2), to receive erythropoietin (EPO) or placebo. Patients were excluded if they had a Glasgow Coma Scale (GCS) score of 3 with fixed and dilated pupils, penetrating trauma, pregnancy, life-threatening systemic injuries and severe preexisting diseases. A total of 200 patients (7 g/dL with [N.=49] or without EPO [N. =50]; 10 g/dL with [N.=53] or without EPO [N.=48]) were enrolled among 598 who were screened. There was no interaction between EPO and Hb thresholds on the primary outcome, which was the occurrence of favorable neurological outcome, assessed using the Glasgow Outcome Scale (GOS) at 6 months after the injury (favorable=GOS 4-5). Favorable outcome was similar between patients included in the 7 g/dL (37/87-43%) and the 10 g/dL group (31/94-33%) as if receiving EPO or placebo, even after adjustment for several covariates. Thromboembolic events were significantly more frequent in the group transfused at 10 g/dL (22/101 [22%] vs. 8/99 [8%]; P=0.009). We discussed how theses results might influence the management of such patients as well as the methodological limitations that underline the need for further investigations.
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Progressive hemorrhagic injury after severe traumatic brain injury: effect of hemoglobin transfusion thresholds
Vedantam A, Yamal JM, Rubin ML, Robertson CS, Gopinath SP
Journal of Neurosurgery. 2016;:1-6.
Abstract
OBJECT There is limited literature available to guide transfusion practices for patients with severe traumatic brain injury (TBI). Recent studies have shown that maintaining a higher hemoglobin threshold after severe TBI offers no clinical benefit. The present study aimed to determine if a higher transfusion threshold was independently associated with an increased risk of progressive hemorrhagic injury (PHI), thereby contributing to higher rates of morbidity and mortality. METHODS The authors performed a secondary analysis of data obtained from a recently performed randomized clinical trial studying the effects of erythropoietin and blood transfusions on neurological recovery after severe TBI. Assigned hemoglobin thresholds (10 g/dl vs 7 g/dl) were maintained with packed red blood cell transfusions during the acute phase after injury. PHI was defined as the presence of new or enlarging intracranial hematomas on CT as long as 10 days after injury. A severe PHI was defined as an event that required an escalation of medical management or surgical intervention. Clinical and imaging parameters and transfusion thresholds were used in a multivariate Cox regression analysis to identify independent risk factors for PHI. RESULTS Among 200 patients enrolled in the trial, PHI was detected in 61 patients (30.5%). The majority of patients with PHI had a new, delayed contusion (n = 29) or an increase in contusion size (n = 15). The mean time interval between injury and identification of PHI was 17.2 +/- 15.8 hours. The adjusted risk of severe PHI was 2.3 times higher for patients with a transfusion threshold of 10 g/dl (95% confidence interval 1.1-4.7; p = 0.02). Diffuse brain injury was associated with a lower risk of PHI events, whereas higher initial intracranial pressure increased the risk of PHI (p < 0.001). PHI was associated with a longer median length of stay in the intensive care unit (18.3 vs 14.4 days, respectively; p = 0.04) and poorer Glasgow Outcome Scale scores (42.9% vs 25.5%, respectively; p = 0.02) at 6 months. CONCLUSIONS A higher transfusion threshold of 10 g/dl after severe TBI increased the risk of severe PHI events. These results indicate the potential adverse effect of using a higher hemoglobin transfusion threshold after severe TBI.