The conundrum of the definition of haemorrhagic shock: a pragmatic exploration based on a scoping review, experts' survey and a cohort analysis

The critical care literature 2023

The number of critically ill patients that present to emergency departments across the world continues to rise. In fact, the proportion of critically ill patients in emergency departments is now higher than pre-COVID-19 pandemic levels. [1] The emergency physician (EP) is typically the first physician to evaluate and resuscitate the critically ill patient. Given the continued shortage of intensive care unit (ICU) beds, persistent staff shortages, and overall inefficient hospital throughput, EPs are often tasked with providing intensive care to these patients long beyond the initial resuscitation phase. Prolonged boarding of critically ill patients in the ED is associated with increased ICU and hospital length of stay, increased adverse events, ED staff burnout, decreased patient and family satisfaction, and, most importantly, increased mortality. [2-5]. As such, it is imperative for the EP to be knowledgeable about recent literature in resuscitation and critical care medicine, so that critically ill ED patients can continue to receive the best, most up-to-date evidence-based care. This review summarizes important articles published in 2023 that pertain to the resuscitation and management of select critically ill ED patients. Topics included in this article include cardiac arrest, post-cardiac arrest care, septic shock, rapid sequence intubation, severe pneumonia, transfusions, trauma, and critical procedures.

Massive transfusion in trauma

PURPOSE OF REVIEW

The purpose of this review is to provide an overview of currently recommended treatment approaches for traumatic hemorrhage shock, with a special focus on massive transfusion.

RECENT FINDINGS

Severe trauma patients require massive transfusion, but consensual international definitions for traumatic hemorrhage shock and massive transfusion are missing. Current literature defines a massive transfusion as transfusion of a minimum of 3-4 packed red blood cells within 1 h. Using standard laboratory and/or viscoelastic tests, earliest diagnosis and treatment should focus on trauma-induced coagulopathy and substitution of substantiated deficiencies.

SUMMARY

To initiate therapy immediately massive transfusion protocols are helpful focusing on early hemorrhage control using hemostatic dressing and tourniquets, correction of metabolic derangements to decrease coagulopathy and substitution according to viscoelastic assays and blood gases analysis with tranexamic acid, fibrinogen concentrate, red blood cells, plasma and platelets are recommended. Alternatively, the use of whole blood is possible. If needed, further support using prothrombin complex, factor XIII or desmopressin is suggested.

Heterogeneity in defining multiple trauma: a systematic review of randomized controlled trials

INTRODUCTION

While numerous randomized controlled trials (RCTs) have been conducted in the field of trauma, a substantial portion of them are yielding negative results. One potential contributing factor to this trend could be the lack of agreement regarding the chosen definitions across different trials. The primary objective was to identify the terminology and definitions utilized for the characterization of multiple trauma patients within randomized controlled trials (RCTs).

METHODS

A systematic review of the literature was performed in MEDLINE, EMBASE and clinicaltrials.gov between January 1, 2002, and July 31, 2022. RCTs or RTCs protocols were eligible if they included multiple trauma patients. The terms employed to characterize patient populations were identified, and the corresponding definitions for these terms were extracted. The subsequent impact on the population recruited was then documented to expose clinical heterogeneity.

RESULTS

Fifty RCTs were included, and 12 different terms identified. Among these terms, the most frequently used were "multiple trauma" (n = 21, 42%), "severe trauma" (n = 8, 16%), "major trauma" (n = 4, 8%), and trauma with hemorrhagic shock" (n = 4, 8%). Only 62% of RCTs (n = 31) provided a definition for the terms used, resulting a total of 21 different definitions. These definitions primarily relied on the injury severity score (ISS) (n = 15, 30%), displaying an important underlying heterogeneity. The choice of the terms had an impact on the study population, affecting both the ISS and in-hospital mortality. Eleven protocols were included, featuring five different terms, with "severe trauma" being the most frequent, occurring six times (55%).

CONCLUSION

This systematic review uncovers an important heterogeneity both in the terms and in the definitions employed to recruit trauma patients within RCTs. These findings underscore the imperative of promoting the use of a unique and consistent definition.

CD44+ and CD31+ extracellular vesicles (EVs) are significantly reduced in polytraumatized patients with hemorrhagic shock - evaluation of their diagnostic and prognostic potential

Background

Hemorrhagic shock (HS) is responsible for approximately 2 million deaths per year worldwide and is caused in 80% by polytrauma. These patients need a precise and quick diagnostic, which should be based on a combination of laboratory markers and radiological data. Extracellular vesicles (EVs) were described as potential new markers and mediators in trauma. The aim of the present study was to analyze, whether the surface epitopes of plasma-EVs reflect HS in polytraumatized patients and whether cell-specific EV subpopulations are useful diagnostic tools.

Material and methods

Plasma samples from polytraumatized patients (ISS ≥16) with HS (n=10) and without (n=15), were collected at emergency room (ER) and 24h after trauma. Plasma-EVs were isolated via size exclusion chromatography and EV-concentrations were detected by Coomassie Plus (Bradford) Assay. The EVs subpopulations were investigated by a bead-based multiplex flow cytometry measurement of surface epitopes and were compared with healthy controls (n=10). To investigate the diagnostic and prognostic potential of EVs subpopulations, results were correlated with clinical outcome parameters documented in the electronical patients' record.

Results

We observed a significant reduction of the total amount of plasma EVs in polytrauma patients with HS, as compared to polytrauma patients without HS and healthy controls. We found significant reduction of CD42a+ and CD41b+ (platelet-derived) EVs in all polytrauma patients, as well as a reduction of CD29+ EVs compared to healthy volunteers (*p<0.05). CD44+ and CD31+ EVs were specifically altered in patients with HS (*p<0.05). Both EV populations showed a moderate correlation (r² = 0.42) with the transfusion of erythrocyte concentrate, were associated with non-survival and the need for catecholamines (*p<0.05).

Conclusion

Our data reveal that polytrauma patients with a hemorrhagic shock are characterized by a reduction of CD44+ and CD31+ plasma-EVs. Both EV populations showed a moderate correlation with the need of erythrocyte transfusion, were associated with non-survival and the need for catecholamines.

Efficacy and Safety of Early Administration of 4-Factor Prothrombin Complex Concentrate in Patients With Trauma at Risk of Massive Transfusion: The PROCOAG Randomized Clinical Trial

Importance

Optimal transfusion strategies in traumatic hemorrhage are unknown. Reports suggest a beneficial effect of 4-factor prothrombin complex concentrate (4F-PCC) on blood product consumption.

Objective

To investigate the efficacy and safety of 4F-PCC administration in patients at risk of massive transfusion.

Design, Setting, and Participants

Double-blind, randomized, placebo-controlled superiority trial in 12 French designated level I trauma centers from December 29, 2017, to August 31, 2021, involving consecutive patients with trauma at risk of massive transfusion. Follow-up was completed on August 31, 2021.

Interventions

Intravenous administration of 1 mL/kg of 4F-PCC (25 IU of factor IX/kg) vs 1 mL/kg of saline solution (placebo). Patients, investigators, and data analysts were blinded to treatment assignment. All patients received early ratio-based transfusion (packed red blood cells:fresh frozen plasma ratio of 1:1 to 2:1) and were treated according to European traumatic hemorrhage guidelines.

Main Outcomes and Measures

The primary outcome was 24-hour all blood product consumption (efficacy); arterial or venous thromboembolic events were a secondary outcome (safety).

Results

Of 4313 patients with the highest trauma level activation, 350 were eligible for emergency inclusion, 327 were randomized, and 324 were analyzed (164 in the 4F-PCC group and 160 in the placebo group). The median (IQR) age of participants was 39 (27-56) years, Injury Severity Score was 36 (26-50 [major trauma]), and admission blood lactate level was 4.6 (2.8-7.4) mmol/L; prehospital arterial systolic blood pressure was less than 90 mm Hg in 179 of 324 patients (59%), 233 patients (73%) were men, and 226 (69%) required expedient hemorrhage control. There was no statistically or clinically significant between-group difference in median (IQR) total 24-hour blood product consumption (12 [5-19] U in the 4F-PCC group vs 11 [6-19] U in the placebo group; absolute difference, 0.2 U [95% CI, -2.99 to 3.33]; P = .72). In the 4F-PCC group, 56 patients (35%) presented with at least 1 thromboembolic event vs 37 patients (24%) in the placebo group (absolute difference, 11% [95% CI, 1%-21%]; relative risk, 1.48 [95% CI, 1.04-2.10]; P = .03).

Conclusions and Relevance

Among patients with trauma at risk of massive transfusion, there was no significant reduction of 24-hour blood product consumption after administration of 4F-PCC, but thromboembolic events were more common. These findings do not support systematic use of 4F-PCC in patients at risk of massive transfusion.

Trial Registration

ClinicalTrials.gov Identifier: NCT03218722.

Shock Index for Early Detection of Low Plasma Fibrinogen in Trauma: A Prospective Observational Cohort Pilot Study

Shock index (a ratio between heart rate and systolic blood pressure) predicts transfusion requirements and the need for haemostatic resuscitation in severe trauma patients. In the present study, we aimed to determine whether prehospital and on-admission shock index values can be used to predict low plasma fibrinogen in trauma patients. Between January 2016 and February 2017, trauma patients admitted from the helicopter emergency medical service into two large trauma centres in the Czech Republic were prospectively assessed for demographic, laboratory and trauma-associated variables and shock index at scene, during transport and at admission to the emergency department. Hypofibrinogenemia defined as fibrinogen plasma level of 1.5 g·L^-l was deemed as a cut-off for further analysis. Three hundred and twenty-two patients were screened for eligibility. Of these, 264 (83%) were included for further analysis. The hypofibrinogenemia was predicted by the worst prehospital shock index with the area under the receiver operating characteristics curve (AUROC) of 0.79 (95% CI 0.64-0.91) and by the admission shock index with AUROC of 0.79 (95% CI 0.66-0.91). For predicting hypofibrinogenemia, the prehospital shock index ≥ 1 has 0.5 sensitivity (95% CI 0.19-0.81), 0.88 specificity (95% CI 0.83-0.92) and a negative predictive value of 0.98 (0.96-0.99). The shock index may help to identify trauma patients at risk of hypofibrinogenemia early in the prehospital course.