Simulation of survivorship bias in observational studies on plasma to red blood cell ratios in massive transfusion for trauma

Delayed TBI-Induced Neuronal Death in the Ipsilateral Hippocampus and Behavioral Deficits in Rats: Influence of Corticosterone-Dependent Survivorship Bias?

Acute and chronic corticosterone (CS) elevations after traumatic brain injury (TBI) may be involved in distant hippocampal damage and the development of late posttraumatic behavioral pathology. CS-dependent behavioral and morphological changes were studied 3 months after TBI induced by lateral fluid percussion in 51 male Sprague-Dawley rats. CS was measured in the background 3 and 7 days and 1, 2 and 3 months after TBI. Tests including open field, elevated plus maze, object location, new object recognition tests (NORT) and Barnes maze with reversal learning were used to assess behavioral changes in acute and late TBI periods. The elevation of CS on day 3 after TBI was accompanied by early CS-dependent objective memory impairments detected in NORT. Blood CS levels > 860 nmol/L predicted delayed mortality with an accuracy of 0.947. Ipsilateral neuronal loss in the hippocampal dentate gyrus, microgliosis in the contralateral dentate gyrus and bilateral thinning of hippocampal cell layers as well as delayed spatial memory deficits in the Barnes maze were revealed 3 months after TBI. Because only animals with moderate but not severe posttraumatic CS elevation survived, we suggest that moderate late posttraumatic morphological and behavioral deficits may be at least partially masked by CS-dependent survivorship bias.

Early identification of the need for major intervention in patients with traumatic hemorrhage: development and internal validation of a simple bleeding score

BACKGROUND

Failure to rapidly identify bleeding in trauma patients leads to substantial morbidity and mortality. We aimed to develop and validate a simple bedside score for identifying bleeding patients requiring escalation of care beyond initial resuscitation.

METHODS

We included patients with major blunt or penetrating trauma, defined as those with an Injury Severity Score greater than 12 or requiring trauma team activation, at The Ottawa Hospital from September 2014 to September 2017. We used logistic regression for derivation. The primary outcome was a composite of the need for massive transfusion, embolization or surgery for hemostasis. We prespecified clinical, laboratory and imaging predictors using findings from our prior systematic review and survey of Canadian traumatologists. We used an AIC-based stepdown procedure based on the Akaike information criterion and regression coefficients to create a 5-variable score for bedside application. We used bootstrap internal validation to assess optimism-corrected performance.

RESULTS

We included 890 patients, of whom 133 required a major intervention. The main model comprised systolic blood pressure, clinical examination findings suggestive of hemorrhage, lactate level, focused assessment with sonography in trauma (FAST) and computed tomographic imaging. The C statistic was 0.95, optimism-corrected to 0.94. A simplified Canadian Bleeding (CAN-BLEED) score was devised. A score cut-off of 2 points yielded sensitivity of 97.7% (95% confidence interval [CI] 93.6 to 99.5) and specificity 73.2% (95% CI 69.9 to 76.3). An alternative version that included mechanism of injury rather than CT had lower discriminative ability (C statistic = 0.89).

CONCLUSION

A simple yet promising bleeding score is proposed to identify highrisk patients in need of major intervention for traumatic bleeding and determine the appropriateness of early transfer to specialized trauma centres. Further research is needed to evaluate the performance of the score in other settings, define interrater reliability and evaluate the potential for reduction of time to intervention.

A retrospective register study comparing fibrinogen treated trauma patients with an injury severity score matched control group

BACKGROUND

Fibrinogen concentrate (FC) is frequently used to treat bleeding trauma patients, although the clinical effects are not well known. In this study we describe demographic and clinical outcome data in a cohort of trauma patients receiving FC, compared to a matched control group, who did not receive FC.

METHODS

This retrospective, single-center, observational study included adult trauma patients admitted to a level 1-trauma center in Sweden between January 2013 and June 2015. The study population consisted of patients to whom FC was administrated within 24 h (n = 138, "Fib+"). Patients with Injury Severity Score (ISS) > 49 and/or deceased within 1 h from arrival were excluded (n = 30). Controls (n = 108) were matched for age, gender and ISS ("Fib-"). Primary outcome was mortality (24 h-/30 days-/1 year-), and secondary outcomes were blood transfusions, thromboembolic events and organ failure.

RESULTS

The Fib+ group, despite having similar ISS as Fib-, had higher prevalence of penetrating trauma and lower Glasgow Coma Scale (GCS), indicating more severe injuries. Patients receiving FC had a higher mortality after 24 h/ 30 days/ 1 year compared to controls (Fib-). However, in a propensity score matched model, the differences in mortality between Fib+ and Fib- were no longer significant. Blood transfusions were more common in the Fib+ group, but no difference was observed in thromboembolic events or organ failure. In both groups, low as well as high P-fibrinogen levels at arrival were associated with increased mortality, with the lowest mortality observed at P-fibrinogen values of 2-3 g/l.

CONCLUSIONS

Despite equal ISS, patients receiving FC had a higher mortality compared to the control group, presumably associated to the fact that these patients were bleeding and physiologically deranged on arrival. When applying a propensity score matching approach, the difference in mortality between the groups was no longer significant. No differences were observed between the groups regarding thromboembolic events or organ failure, despite higher transfusion volumes in patients receiving FC.

Fresh Frozen Plasma-to-Packed Red Blood Cell Ratio and Mortality in Traumatic Hemorrhage: Nationwide Analysis of 4,427 Patients

BACKGROUND

Despite the presence of highly reliable data, studies on packed red blood cells (pRBC):fresh frozen plasma (FFP) ratio suffer from limited sample size and the presence of survivor bias. We sought to study the association between FFP:pRBC and early mortality in the hemorrhaging trauma patient.

STUDY DESIGN

This was a retrospective nationwide cohort that included all TQIP participating hospitals (2013 to 2016). We included all trauma patients who were transfused ≥10 pRBCs and ≥1 FFP within 24 hours. We excluded transferred patients and those who died in the emergency department or had missing/inaccurate transfusion data. Patients were assigned to 7 FFP:pRBC cohorts (range 1:1 to 1:6, and 1:6+) only if the ratio was similar at 4 and 24 hours and, to avoid survival bias, were excluded otherwise. Multivariable analyses correcting for all available confounders (age, demographics, comorbidities, vital signs, Injury Severity Score [ISS] and mechanism, procedures performed) were derived to study the independent relationship between FFP:pRBC and 24-hour mortality.

RESULTS

Of 1,002,595 patients, 4,427 patients were included. Mean age was 41 years, 79% were males, 61% had blunt trauma, and median ISS was 29. Most patients were transfused in a 1:1, 1:2, or 1:3 ratio (31%, 41%, and 11%, respectively); mortality ranged between 28% for 1:1 and 62% for 1:4. In multivariable analyses, the odds of mortality independently and incrementally increased to 1.23 (95% CI 1.02 to 1.48) for a 1:2 ratio, 2.11 (95% CI 1.42 to 3.13) for 1:4, and as high as 4.11 (95% CI 2.31 to 7.31) for 1:5 (all p < 0.05).

CONCLUSIONS

A 1:1 FFP:pRBC ratio is associated with the lowest mortality in the hemorrhaging trauma patient, and mortality increases with decreasing ratios.

Accuracy of massive transfusion as a surrogate for significant traumatic bleeding in health administrative datasets

BACKGROUND

Due to the challenge of identifying need for intervention in bleeding patients, there is a growing interest in prediction modeling. Massive transfusion (MT; 10 or more packed red cells in 24 h) is the most commonly studied dependent variable, serving as a surrogate for severe bleeding and its prediction guides the need for intervention. The critical administration threshold (CAT; 3 packed red cells in 1 h) has been proposed as an alternative. In this study, we aim to compare the classification accuracy of these two surrogates for hemorrhage-related outcomes in health administrative datasets.

METHODS

We performed a secondary analysis of major trauma patients from the prospectively collected Ottawa Trauma Registry, from September 2014 to September 2017. We conducted a logistic regression analysis utilizing need for hemostasis or hemorrhagic death as dependent variables. We compared classification accuracy in terms of sensitivity, specificity, positive predictive value, negative predictive value and AUC. CAT + and MT + status is not mutually exclusive.

RESULTS

We studied 890 major trauma patients, including 145 CAT + and 48 MT + patients. CAT + demonstrated a superior association for the composite outcome of 24-hour hemorrhage-related mortality and need for hemostasis (AUC 0.815 vs. 0.644, p < 0.0001). This performance was driven by a substantial difference in sensitivity, noted to be 70.0% (95% CI 62.1-77.9%) for CAT + but only 30.0% (95% CI 22.1-37.9%) for MT+. CAT + and MT + demonstrated specificities of 92.9% (95% CI 91.1-94.7%) and 98.9% (98.1-99.6%) respectively.

CONCLUSION

This study illustrates the concepts of survivorship and competing risk bias for massive transfusion. Utilizing a composite outcome of need for hemostasis and early hemorrhagic death, we demonstrate that CAT + is more accurate for identifying significantly bleeding patients.

Issues and challenges for research in major trauma

The starting point for evidence-based guidelines is the systematic review and critical appraisal of the relevant literature. This review highlights the risk of bias identified while critically appraising the evidence to inform the National Institute of Health and Care Excellence guideline on the assessment and initial management of major trauma.

Long-term use of oral nucleos(t)ide analogues for chronic hepatitis B does not increase cancer risk - a cohort study of 44 494 subjects

BACKGROUND

Patients with chronic hepatitis B (CHB) need long-term antiviral treatment with nucleos(t)ide analogues (NA). Animal studies suggest that some NA may increase cancer risk, but human data are lacking.

AIM

To investigate cancer risks in patients with or without NA treatment.

METHODS

We conducted a territory-wide cohort study using the database from Hospital Authority in Hong Kong. The diagnosis of CHB and various malignancies was based on the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis codes between 2000 and 2012. Patients exposed to any of the oral NA for CHB were included. The primary outcome was incident cancers. A 3-year landmark analysis, with follow-up up to 7 years, was used to evaluate the relative risk of cancers in treated and untreated patients.

RESULTS

A total of 44 494 patients (39 712 untreated and 4782 treated) were included in the analysis. During 194 890 patient-years of follow-up, hepatocellular carcinoma developed in 402 (1.0%) untreated patients and 179 (3.7%) treated patients, while other cancers developed in 528 (1.3%) and 128 (2.7%) patients respectively. After propensity score weighting, treated patients had similar risks of all malignancies [weighted hazard ratio (wHR): 1.01, 95% CI: 0.82-1.25, P = 0.899], lung/pleural cancers (wHR: 0.82, 95% CI: 0.52-1.31, P = 0.409) and urinary/renal malignancies (wHR: 1.04, 95% CI: 0.38-2.81, P = 0.944) when compared with untreated patients.

CONCLUSIONS

Oral nucleos(t)ide analogue treatment does not appear to increase cancer risk in patients with chronic hepatitis B. Given the beneficial effect on liver outcomes, our data support the current practice of long-term anti-viral therapy.

Early identification of patients requiring massive transfusion, embolization, or hemostatic surgery for traumatic hemorrhage: a systematic review protocol

BACKGROUND

Hemorrhage is a major cause of early mortality following a traumatic injury. The progression and consequences of significant blood loss occur quickly as death from hemorrhagic shock or exsanguination often occurs within the first few hours. The mainstay of treatment therefore involves early identification of patients at risk for hemorrhagic shock in order to provide blood products and control of the bleeding source if necessary. The intended scope of this review is to identify and assess combinations of predictors informing therapeutic decision-making for clinicians during the initial trauma assessment. The primary objective of this systematic review is to identify and critically assess any existing multivariable models predicting significant traumatic hemorrhage that requires intervention, defined as a composite outcome comprising massive transfusion, surgery for hemostasis, or angiography with embolization for the purpose of external validation or updating in other study populations. If no suitable existing multivariable models are identified, the secondary objective is to identify candidate predictors to inform the development of a new prediction rule.

METHODS

We will search the EMBASE and MEDLINE databases for all randomized controlled trials and prospective and retrospective cohort studies developing or validating predictors of intervention for traumatic hemorrhage in adult patients 16 years of age or older. Eligible predictors must be available to the clinician during the first hour of trauma resuscitation and may be clinical, lab-based, or imaging-based. Outcomes of interest include the need for surgical intervention, angiographic embolization, or massive transfusion within the first 24 h. Data extraction will be performed independently by two reviewers. Items for extraction will be based on the CHARMS checklist. We will evaluate any existing models for relevance, quality, and the potential for external validation and updating in other populations. Relevance will be described in terms of appropriateness of outcomes and predictors. Quality criteria will include variable selection strategies, adequacy of sample size, handling of missing data, validation techniques, and measures of model performance.

DISCUSSION

This systematic review will describe the availability of multivariable prediction models and summarize evidence regarding predictors that can be used to identify the need for intervention in patients with traumatic hemorrhage.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42017054589.

Comparison of Statistical Approaches for Dealing With Immortal Time Bias in Drug Effectiveness Studies

In time-to-event analyses of observational studies of drug effectiveness, incorrect handling of the period between cohort entry and first treatment exposure during follow-up may result in immortal time bias. This bias can be eliminated by acknowledging a change in treatment exposure status with time-dependent analyses, such as fitting a time-dependent Cox model. The prescription time-distribution matching (PTDM) method has been proposed as a simpler approach for controlling immortal time bias. Using simulation studies and theoretical quantification of bias, we compared the performance of the PTDM approach with that of the time-dependent Cox model in the presence of immortal time. Both assessments revealed that the PTDM approach did not adequately address immortal time bias. Based on our simulation results, another recently proposed observational data analysis technique, the sequential Cox approach, was found to be more useful than the PTDM approach (Cox: bias = -0.002, mean squared error = 0.025; PTDM: bias = -1.411, mean squared error = 2.011). We applied these approaches to investigate the association of β-interferon treatment with delaying disability progression in a multiple sclerosis cohort in British Columbia, Canada (Long-Term Benefits and Adverse Effects of Beta-Interferon for Multiple Sclerosis (BeAMS) Study, 1995-2008).

Interventional Algorithms for the Control of Coagulopathic Bleeding in Surgical, Trauma, and Postpartum Settings: Recommendations From the Share Network Group

Several clinical settings are associated with specific coagulopathies that predispose to uncontrolled bleeding. With the growing concern about the need for optimizing transfusion practices and improving treatment of the bleeding patient, a group of 9 Portuguese specialists (Share Network Group) was created to discuss and develop algorithms for the clinical evaluation and control of coagulopathic bleeding in the following perioperative clinical settings: surgery, trauma, and postpartum hemorrhage. The 3 algorithms developed by the group were presented at the VIII National Congress of the Associação Portuguesa de Imuno-hemoterapia in October 2013. They aim to provide a structured approach for clinicians to rapidly diagnose the status of coagulopathy in order to achieve an earlier and more effective bleeding control, reduce transfusion requirements, and improve patient outcomes. The group highlights the importance of communication between different specialties involved in the care of bleeding patients in order to achieve better results.

Patterns of early resuscitation associated with mortality after penetrating injuries

BACKGROUND

Penetrating injuries are rare in European populations so their management represents a particular challenge. The aim was to assess early therapeutic aspects that are associated with favourable outcomes in patients with penetrating trauma.

METHODS

Patients with penetrating injuries documented from 2009 to 2013 in the TraumaRegister DGU® were analysed. Patients with a primary admission and an Injury Severity Score (ISS) of at least 9 were included. The Revised Injury Severity Classification (RISC) II score was used for mortality prediction, and a standardized mortality ratio (SMR) calculated per hospital. Hospitals with favourable outcome (SMR below 1) were compared with those with poor outcome (SMR 1 or more).

RESULTS

A total of 50 centres had favourable outcome (1242 patients; observed mortality rate 15.7 per cent) and 34 centres had poor outcome (918 patients; observed mortality rate 24.4 per cent). Predicted mortality rates according to RISC-II were 20.4 and 20.5 per cent respectively. Mean(s.d.) ISS values were 22(14) versus 21(14) (P = 0.121). Patients in the favourable outcome group had a significantly shorter time before admission to hospital and a lower intubation rate. They received smaller quantities of intravenous fluids on admission to the emergency room, but larger amounts of fresh frozen plasma, and were more likely to receive haemostatic agents. A higher proportion of patients in the favourable outcome group were treated in a level I trauma centre. Independent risk factors for hospital death following penetrating trauma identified by multivariable analysis included gunshot injury mechanism and treatment in non-level I centres.

CONCLUSION

Among penetrating traumas, gunshot injuries pose an independent risk of death. Treatment of penetrating trauma in a level I trauma centre was significantly and independently associated with lower hospital mortality.

The Effect of Evolving Fluid Resuscitation on the Outcome of Severely Injured Patients: An 8-year Experience at a Tertiary Trauma Center

BACKGROUND AND AIMS

Fluid resuscitation of severely injured patients has shifted over the last decade toward less crystalloids and more blood products. Helsinki University trauma center implemented the massive transfusion protocol in the end of 2009. The aim of the study was to review the changes in fluid resuscitation and its influence on outcome of severely injured patients with hemodynamic compromise treated at the single tertiary trauma center.

MATERIAL AND METHODS

Data on severely injured patients (New Injury Severity Score > 15) from Helsinki University Hospital trauma center's trauma registry was reviewed over 2006-2013. The isolated head-injury patients, patients without hemodynamic compromise on admission (systolic blood pressure > 90 or base excess > -5.0), and those transferred in from another hospital were excluded. The primary outcome measure was 30-day in-hospital mortality. The study period was divided into three phases: 2006-2008 (pre-protocol, 146 patients), 2009-2010 (the implementation of massive transfusion protocol, 85 patients), and 2011-2013 (post massive transfusion protocol, 121 patients). Expected mortality was calculated using the Revised Injury Severity Classification score II. The Standardized Mortality Ratio, as well as the amounts of crystalloids, colloids, and blood products (red blood cells, fresh frozen plasma, platelets) administered prehospital and in the emergency room were compared.

RESULTS

Of the 354 patients that were included, Standardized Mortality Ratio values decreased (indicating better survival) during the study period from 0.97 (pre-protocol), 0.87 (the implementation of massive transfusion protocol), to 0.79 (post massive transfusion protocol). The amount of crystalloids used in the emergency room decreased from 3870 mL (pre-protocol), 2390 mL (the implementation of massive transfusion protocol), to 2340 mL (post massive transfusion protocol). In these patients, the blood products' (red blood cells, fresh frozen plasma, and platelets together) relation to crystalloids increased from 0.36, 0.70, to 0.74, respectively, in three phases.

CONCLUSION

During the study period, no other major changes in the protocols on treatment of severely injured patients were implemented. The overall awareness of damage control fluid resuscitation and introduction of massive transfusion protocol in a trauma center has a significant positive effect on the outcome of severely injured patients.

Collider bias in trauma comparative effectiveness research: the stratification blues for systematic reviews

BACKGROUND

Collider bias, or stratifying data by a covariate consequence rather than cause (confounder) of treatment and outcome, plagues randomised and observational trauma research. Of the seven trials of prehospital hypertonic saline in dextran (HSD) that have been evaluated in systematic reviews, none found an overall between-group difference in survival, but four reported significant subgroup effects. We hypothesised that an avoidable type of collider bias often introduced inadvertently into trauma comparative effectiveness research could explain the incongruous findings.

METHODS

The two most recent HSD trials, a single-site pilot and a multi-site pivotal study, provided data for a secondary analysis to more closely examine the potential for collider bias. The two trials had followed the a priori statistical analysis plan to subgroup patients by a post-randomisation covariate and well-established surrogate for bleeding severity, massive transfusion (MT), ≥ 10 unit of red blood cells within 24h of admission. Despite favourable HSD effects in the MT subgroup, opposite effects in the non-transfused subgroup halted the pivotal trial early. In addition to analyzing the data from the two trials, we constructed causal diagrams and performed a meta-analysis of the results from all seven trials to assess the extent to which collider bias could explain null overall effects with subgroup heterogeneity.

RESULTS

As in previous trials, HSD induced significantly greater increases in systolic blood pressure (SBP) from prehospital to admission than control crystalloid (p=0.003). Proportionately more HSD than control decedents accrued in the non-transfused subgroup, but with paradoxically longer survival. Despite different study populations and a span of over 20 years across the seven trials, the reported mortality effects were consistently null, summary RR=0.99 (p=0.864, homogeneity p=0.709).

CONCLUSIONS

HSD delayed blood transfusion by modifying standard triggers like SBP with no detectable effect on survival. The reported heterogeneous HSD effects in subgroups can be explained by collider bias that trauma researchers can avoid by improved covariate selection and data capture strategies.

In vitro combinations of red blood cell, plasma and platelet components evaluated by thromboelastography

BACKGROUND

Thromboelastography is increasingly used to evaluate coagulation in massively bleeding patients. The aim of this study was to investigate how different combinations of blood components affect in vitro whole blood clotting measured by thromboelastography.

MATERIALS AND METHODS

Packed red blood cells, plasma and platelets from fresh and old blood components were mixed in vitro, in proportions of 4:4:1, 5:5:2, 8:4:1 and 2:1:0, and analysed with thromboelastography. For the ratio 4:4:1 the experiment was done at both 37 °C and 32 °C.

RESULTS

Thromboelastography curves were within normal reference values for the blood component proportions of 4:4:1 and 5:5:2. For 8:4:1, the angle and maximal amplitude were reduced below normal values, indicating low levels of fibrinogen and/or platelets. For the 2:1:0 proportion, all parameters were affected resulting in severely impaired in vitro clot formation. The reaction-time, reflecting the coagulation factor-dependent, initial clot formation, was slightly increased at a low temperature. Prolonged storage of the components did not affect the curve.

DISCUSSION

With the introduction of guidelines on the management of massive bleeding it is important to have tools for the assessment of the new protocols. In vitro evaluation of mixtures of packed red blood cells, plasma and platelets by thromboelastography may be relevant in the prediction of in vivo clot formation and haemostasis.

Coagulopathy after severe pediatric trauma

Trauma remains the leading cause of morbidity and mortality in the United States among children aged 1 to 21 years. The most common cause of lethality in pediatric trauma is traumatic brain injury. Early coagulopathy has been commonly observed after severe trauma and is usually associated with severe hemorrhage and/or traumatic brain injury. In contrast to adult patients, massive bleeding is less common after pediatric trauma. The classical drivers of trauma-induced coagulopathy include hypothermia, acidosis, hemodilution, and consumption of coagulation factors secondary to local activation of the coagulation system after severe traumatic injury. Furthermore, there is also recent evidence for a distinct mechanism of trauma-induced coagulopathy that involves the activation of the anticoagulant protein C pathway. Whether this new mechanism of posttraumatic coagulopathy plays a role in children is still unknown. The goal of this review is to summarize the current knowledge on the incidence and potential mechanisms of coagulopathy after pediatric trauma and the role of rapid diagnostic tests for early identification of coagulopathy. Finally, we discuss different options for treating coagulopathy after severe pediatric trauma.

Cause and timing of death in massively transfused trauma patients

BACKGROUND

The purpose of this study was to characterize the cause of death in severely injured trauma patients to define potential responses to resuscitation.

METHODS

Prospective analysis of 190 critically injured patients who underwent massive transfusion protocol (MTP) activation or received massive transfusion (>10 U of packed red blood cells [RBC] per 24 hours). Cause of death was adjudicated into one of four categories as follows: (1) exsanguination, (2) early physiologic collapse, (3) late physiologic collapse, and (4) nonsurvivable injury.

RESULTS

A total 190 patients underwent massive transfusion or MTP with 76 deaths (40% mortality), of whom 72 deaths were adjudicated to one of four categories: 33.3% died of exsanguination, 16.6% died of early physiologic collapse, 11.1% died of late physiologic collapse, while 38.8% died of nonsurvivable injuries. Patients who died of exsanguination were younger and had the highest RBC/fresh frozen plasma ratio (2.97 [2.24]), although the early physiologic collapse group survived long enough to use the most blood products (p < 0.001). The late physiologic collapse group had significantly fewer penetrating injuries, was older, and had significantly more crystalloid use but received a lower RBC/fresh frozen plasma ratio (1.50 [0.42]). Those who were determined to have a nonsurvivable injury had a lower presenting Glasgow Coma Scale (GCS) score, fewer penetrating injuries, and higher initial blood pressure reflecting a preponderance of nonsurvivable traumatic brain injury. The average survival time for patients with potentially survivable injuries was 2.4 hours versus 18.4 hours for nonsurvivable injuries (p < 0.001).

CONCLUSION

Severely injured patients requiring MTP have a high mortality rate. However, no studies to date have addressed the cause of death after MTP. Characterization of cause of death will allow targeting of surgical and resuscitative conduct to allow extension of the physiologic reserve time, therefore rendering previously nonsurvivable injury potentially survivable.

Resuscitate early with plasma and platelets or balance blood products gradually: findings from the PROMMTT study

BACKGROUND

The trauma transfusion literature has yet to resolve which is more important for hemorrhaging patients, transfusing plasma and platelets along with red blood cells (RBCs) early in resuscitation or gradually balancing blood product ratios. In a previous report of PROMMTT results, we found (1) plasma and platelet:RBC ratios increased gradually during the 6 hours following admission, and (2) patients achieving ratios more than 1:2 (relative to ratios <1:2) had significantly decreased 6-hour to 24-hour mortality adjusting for baseline and time-varying covariates. To differentiate the association of in-hospital mortality with early plasma or platelet transfusion from that with delayed but gradually balanced ratios, we developed a separate analytic approach.

METHODS

Using PROMMTT data and multilevel logistic regression to adjust for center effects, we related in-hospital mortality to the early receipt of plasma or platelets within the first three to six transfusion units (including RBCs) and 2.5 hours of admission. We adjusted for the same covariates as in our previous report: Injury Severity Score (ISS), age, time and total number of blood product transfusions upon entry to the analysis cohort, and bleeding from the head, chest, or limb.

RESULTS

Of 1,245 PROMMTT patients, 619 were eligible for this analysis. Early plasma was associated with decreased 24-hour and 30-day mortality (adjusted odds ratios of 0.47 [p = 0.009] and 0.44 [p = 0.002], respectively). Too few patients (24) received platelets early for meaningful assessment. In the subgroup of 222 patients receiving no early plasma but continuing transfusions beyond Hour 2.5, achieving gradually balanced plasma and platelet:RBC ratios of 1:2 or greater by Hour 4 was not associated with 30-day mortality (adjusted odds ratios of 0.9 and 1.1, respectively). There were no significant center effects.

CONCLUSION

Plasma transfusion early in resuscitation had a protective association with mortality, whereas delayed but gradually balanced transfusion ratios did not. Further research will require considerably larger numbers of patients receiving platelets early.

The concept of damage control: extending the paradigm in the prehospital setting

OBJECTIVE

The purpose of this review is to present the progressive extension of the concept of damage control resuscitation, focusing on the prehospital phase.

ARTICLE TYPE

Review of the literature in Medline database over the past 10 years.

DATA SOURCE

Medline database looking for articles published in English or in French between April 2002 and March 2013. Keywords used were: damage control resuscitation, trauma damage control, prehospital trauma, damage control surgery. Original articles were firstly selected. Editorials and reviews were secondly studied.

DATA SYNTHESIS

The importance of early management of life-threatening injuries and rapid transport to trauma centers has been widely promulgated. Technical progress appears for external methods of hemostasis, with the development of handy tourniquets and hemostatic dressings, making the crucial control of external bleeding more simple, rapid and effective. Hypothermia is independently associated with increased risk of mortality, and appeared accessible to improvement of prehospital care. The impact of excessive fluid resuscitation appears negative. The interest of hypertonic saline is denied. The place of vasopressor such as norepinephrine in the early resuscitation is still under debate. The early use of tranexamic acid is promoted. Specific transfusion strategies are developed in the prehospital setting.

CONCLUSION

It is critical that both civilian and military practitioners involved in trauma continue to share experiences and constructive feedback. And it is mandatory now to perform well-designed prospective clinical trials in order to advance the topic.

Low hemorrhage-related mortality in trauma patients in a Level I trauma center employing transfusion packages and early thromboelastography-directed hemostatic resuscitation with plasma and platelets

BACKGROUND

Hemorrhage accounts for most preventable trauma deaths, but still the optimal strategy for hemostatic resuscitation remains debated.

STUDY DESIGN AND METHODS

This was a prospective study of adult trauma patients admitted to a Level I trauma center. Demography, Injury Severity Score (ISS), transfusion therapy, and mortality were registered. Hemostatic resuscitation was based on a massive transfusion protocol encompassing transfusion packages and thromboelastography (TEG)-guided therapy.

RESULTS

A total of 182 patients were included (75% males, median age 43 years, ISS of 17, 92% with blunt trauma). Overall 28-day mortality was 12% with causes of death being exsanguinations (14%), traumatic brain injury (72%, two-thirds expiring within 24 hr), and other (14%). One-fourth, 16 and 15% of the patients, received red blood cells (RBCs), plasma, or platelets (PLTs) within 2 hours from admission and 68, 71, and 75%, respectively, of patients transfused within 24 hours received the respective blood products within the first 2 hours. In patients transfused within 24 hours, the median number of blood products at 2 hours was 5 units of RBCs, 5 units of plasma, and 2 units of PLT concentrates. Nonsurvivors had lower clot strength by kaolin-activated TEG and TEG functional fibrinogen and lower kaolin-tissue factor-activated TEG α-angle and lysis after 30 minutes compared to survivors. None of the TEG variables were independent predictors of massive transfusion or mortality.

CONCLUSION

Three-fourths of the patients transfused with plasma or PLTs within 24 hours received these in the first 2 hours. Hemorrhage caused 14% of the deaths. We introduced transfusion packages and early TEG-directed hemostatic resuscitation at our hospital 10 years ago and this may have contributed to reducing hemorrhagic trauma deaths.

Current management of massive hemorrhage in trauma

Hemorrhage remains a major cause of potentially preventable deaths. Trauma and massive transfusion are associated with coagulopathy secondary to tissue injury, hypoperfusion, dilution, and consumption of clotting factors and platelets. Concepts of damage control surgery have evolved prioritizing early control of the cause of bleeding by non-definitive means, while hemostatic control resuscitation seeks early control of coagulopathy.Hemostatic resuscitation provides transfusions with plasma and platelets in addition to red blood cells in an immediate and sustained manner as part of the transfusion protocol for massively bleeding patients. Although early and effective reversal of coagulopathy is documented, the most effective means of preventing coagulopathy of massive transfusion remains debated and randomized controlled studies are lacking. Viscoelastical whole blood assays, like TEG and ROTEM however appear advantageous for identifying coagulopathy in patients with severe hemorrhage as opposed the conventional coagulation assays.In our view, patients with uncontrolled bleeding, regardless of it's cause, should be treated with hemostatic control resuscitation involving early administration of plasma and platelets and earliest possible goal-directed, based on the results of TEG/ROTEM analysis. The aim of the goal-directed therapy should be to maintain a normal hemostatic competence until surgical hemostasis is achieved, as this appears to be associated with reduced mortality.