Contemporary resuscitation of hemorrhagic shock: What will the future hold?

Red blood cell transfusion in neurocritical patients: a systematic review and meta-analysis

BACKGROUND

Anemia can lead to secondary brain damage by reducing arterial oxygen content and brain oxygen supply. Patients with acute brain injury have impaired self-regulation. Brain hypoxia may also occur even in mild anemia. Red blood cell (RBC) transfusion is associated with increased postoperative complications, poor neurological recovery, and mortality in critically ill neurologic patients. Balancing the risks of anemia and red blood cell transfusion-associated adverse effects is challenging in neurocritical settings.

METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), Embase, and MEDLINE (PubMed) from inception to January 31, 2024. We included all randomized controlled trials (RCTs) assessing liberal versus restrictive RBC transfusion strategies in neurocritical patients. We included all relevant studies published in English. The primary outcome was mortality at intensive care unit (ICU), discharge, and six months.

RESULTS

Of 5195 records retrieved, 84 full-text articles were reviewed, and five eligible studies were included. There was no significant difference between the restrictive and liberal transfusion groups in ICU mortality (RR: 2.53, 95% CI: 0.53 to 12.13), in-hospital mortality (RR: 2.34, 95% CI: 0.50 to 11.00), mortality at six months (RR: 1.42, 95% CI: 0.42 to 4.78) and long-term mortality (RR: 1.22, 95% CI: 0.64 to 2.33). The occurrence of neurological adverse events and most major non-neurological complications was similar in the two groups. The incidence of deep venous thrombosis was lower in the restrictive strategy group (RR: 0.41, 95% CI: 0.18 to 0.91).

CONCLUSIONS

Due to the small sample size of current studies, the evidence is insufficiently robust to confirm definitive conclusions for neurocritical patients. Therefore, further investigation is encouraged to define appropriate RBC transfusion thresholds in the neurocritical setting.

Use of whole blood deployment programs for mass casualty incidents: South Texas experience in regional response and preparedness

INTRODUCTION

Firearm-related deaths have become the leading cause of death in adolescents and children. Since the Sutherland Springs, TX mass casualty incident (MCI), the Southwest Texas Regional Advisory Council for trauma instituted a prehospital whole blood (WB) program and blood deployment program for MCIs.

METHODS

The program was adopted statewide by the Texas Emergency Medical Task Force, of which Southwest Texas Regional Advisory Council is the lead for Emergency Medical Task Force 8. The recent active shooter MCI in Uvalde, TX was the first time the MCI blood deployment program had been used. To our knowledge, no other similar programs exist in this or any other country.

RESULTS

On May 24, 2022, 19 children and 2 adults were killed at an MCI in Uvalde, TX. The MCI WB deployment protocol was initiated, and South Texas Blood and Tissue Center prepared 15 U of low-titer O-positive whole blood and 10 U of leukoreduced O packed cells. The deployed blood arrived at Uvalde Memorial Hospital within 67 minutes. One of the pediatric patients sustained multiple gunshots to the chest and extremities. The child was hypotensive and received 2 U of leukoreduced O packed cells, one at the initial hospital and another during transport. On arrival, the patient required 2 U of low-titer O-positive whole blood and underwent a successful hemorrhage control operation. The remaining blood was returned to South Texas Blood and Tissue Center for distribution.

CONCLUSION

Multiple studies have shown the association of early blood product resuscitation and improved mortality, with WB being the ideal resuscitative product for many. The ongoing efforts in South Texas serve as a model for development of similar programs throughout the country to reduce preventable deaths. This event represents the first ever successful deployment of WB to the site of an MCI related to a school shooting in the modern era.

LEVEL OF EVIDENCE

Therapeutic/Care Management; Level V.

The Choice between Plasma-Based Common Coagulation Tests and Cell-Based Viscoelastic Tests in Monitoring Hemostatic Competence: Not an either-or Proposition

There has been a significant interest in the last decade in the use of viscoelastic tests (VETs) to determine the hemostatic competence of bleeding patients. Previously, common coagulation tests (CCTs) such as the prothrombin time (PT) and partial thromboplastin time (PTT) were used to assist in the guidance of blood component and hemostatic adjunctive therapy for these patients. However, the experience of decades of VET use in liver failure with transplantation, cardiac surgery, and trauma has now spread to obstetrical hemorrhage and congenital and acquired coagulopathies. Since CCTs measure only 5 to 10% of the lifespan of a clot, these assays have been found to be of limited use for acute surgical and medical conditions, whereby rapid results are required. However, there are medical indications for the PT/PTT that cannot be supplanted by VETs. Therefore, the choice of whether to use a CCT or a VET to guide blood component therapy or hemostatic adjunctive therapy may often require consideration of both methodologies. In this review, we provide examples of the relative indications for CCTs and VETs in monitoring hemostatic competence of bleeding patients.

Effects of Different Types of Early Restrictive Fluid Resuscitation on Immune Function and Multiorgan Damage on Hemorrhagic Shock Rat Model in a Hypothermic Environment

Objective

This study was aimed at investigating the effects of different types of fluid restriction fluid resuscitation on the immune dysfunction and organ injury of hemorrhagic shock rats under a hypothermic environment.

Methods

SD rats were divided into sham operation group (SHAM), hemorrhagic shock model group (HS), crystal liquid limited resuscitation group (CRLLR), colloidal liquid limited resuscitation group (COLLR), and nonlimited resuscitation group (NLR); rats in each group were placed in a low-temperature environment of 0-5°C for 30 min, and then, a hemorrhagic shock rat model was prepared. Sodium lactate Ringer's restricted resuscitation solution, hydroxyethyl starch restricted resuscitation solution, and hydroxyethyl starch were used for resuscitation, and hemodynamic examination was performed. The mortality rate, inflammatory factors, oxidative stress factors, and immune function were detected by ELISA. The dysfunction and injury of the intestinal, lung, liver, and kidney were examined by histological methods.

Results

Hemorrhagic shock resulted in decreased immune function and activation of inflammation. Unrestricted fluid infusion further activated the inflammatory response. The crystalloid-restricted fluid infusion performed effectively to regulate inflammatory response, promote antioxidative activity, and reduce the immunosuppressive reaction. Rehydration could regulate the coagulation. The hydroxyethyl starch reduced the expression of platelet glycoproteins Ib and IIb/IIIa and blocked the binding of fibrinogen to activated platelets, thereby inhibiting intrinsic coagulation and platelet adhesion and aggregation. Rats in the CRLLR group showed to relieve the injury of the lung, liver, kidney, and intestine from hemorrhagic shock in low-temperature environment.

Conclusion

The early application of restrictive crystalloid resuscitation in hemorrhagic shock rats in hypothermic environment showed the best therapy results. Early LR-restrictive fluid replacement promotes the balance of inflammatory response and the recovery of immunosuppressive state, resists oxidative stress, stabilizes the balance of coagulation and fibrinolysis, improves coagulation function, and relieves organ injury.

Role of Fibrinogen in Trauma-Induced Coagulopathy

BACKGROUND

Fibrinogen is the first coagulation factor to decrease after massive hemorrhage. European massive transfusion guidelines recommend early repletion of fibrinogen; however, this practice has not been widely adopted in the US. We hypothesize that hypofibrinogenemia is common at hospital arrival and is an integral component of trauma-induced coagulopathy.

STUDY DESIGN

This study entailed review of a prospective observational database of adults meeting the highest-level activation criteria at an urban level 1 trauma center from 2014 through 2020. Resuscitation was initiated with 2:1 red blood cell (RBC) to fresh frozen plasma (FFP) ratios and continued subsequently with goal-directed thrombelastography. Hypofibrinogenemia was defined as fibrinogen below 150 mg/dL. Massive transfusion (MT) was defined as more than 10 units RBC or death after receiving at least 1 unit RBC over the first 6 hours of admission.

RESULTS

Of 476 trauma activation patients, 70 (15%) were hypofibrinogenemic on admission, median age was 34 years, 78% were male, median New Injury Severity Score (NISS) was 25, and 72 patients died (15%). Admission fibrinogen level was an independent risk factor for MT (odds ratio [OR] 0.991, 95% CI 0.987-0.996]. After controlling for confounders, NISS (OR 1.034, 95% CI 1.017-1.052), systolic blood pressure (OR 0.991, 95% CI 0.983-0.998), thrombelastography angle (OR 0.925, 95% CI 0.896-0.954), and hyperfibrinolysis (OR 2.530, 95% CI 1.160-5.517) were associated with hypofibrinogenemia. Early cryoprecipitate administration resulted in the fastest correction of hypofibrinogenemia.

CONCLUSION

Hypofibrinogenemia is common after severe injury and predicts MT. Cryoprecipitate transfusion results in the most expeditious correction. Earlier administration of cryoprecipitate should be considered in MT protocols.

Protective Effect of Moderate Hypotonic Fluid on Organ Dysfunction via Alleviating Lethal Triad Following Seawater Immersion With Hemorrhagic Shock in Rats

Previous studies found that seawater immersion combined with hemorrhagic shock (SIHS) induced serious organ function disorder, and lethal triad was a critical sign. There were no effective treatments of SIHS. Fluid resuscitation was the initial measurement for early aid following hemorrhagic shock, while the proper fluid for SIHS is not clear. Effects of different osmotic pressures [lactated Ringer’s (LR) solution, 0.3% saline, 0.6% saline, and 0.9% normal saline] on the lethal triad, mitochondrial function, vital organ functions, and survival were observed following SIHS in rats. The results showed that SIHS led to an obvious lethal triad, which presented the decrease of the body temperature, acidosis, and coagulation functions disorder in rats. Fluid resuscitation with different osmotic pressures recovered the body temperature and corrected acidosis with different levels; effects of 0.6% normal saline were the best; especially for the coagulation function, 0.6% normal saline alleviated the lethal triad significantly. Further studies showed that SIHS resulted in the damage of the mitochondrial function of vital organs, the increase of the vascular permeability, and, at the same time, the organ function including cardiac, liver, and kidney was disordered. Conventional fluid such as LR or 0.9% normal saline could not improve the mitochondrial function and vascular leakage and alleviate the damage of the organ function. While moderate hypotonic fluid, the 0.6% normal saline, could lighten organ function damage via protecting mitochondrial function. The 0.6% normal saline increased the left ventricular fractional shortening and the left ventricular ejection fraction, and decreased the levels of aspartate transaminase, alanine transferase, blood urea nitrogen, and creatinine in the blood. The effects of fluids with different osmotic pressures on the mean arterial pressure (MAP) had a similar trend as above parameters. The survival results showed that the 0.6% normal saline group improved the survival rate and prolonged the survival time, the 72 h survival rate was 7/16, as compared with the LR group (3/16). The results indicate that appropriate hypotonic fluid is suitable after SIHS, which alleviates the lethal triad, protects the mitochondrial function and organ functions, and prolongs the survival time.

Whole Blood, Fixed Ratio, or Goal-Directed Blood Component Therapy for the Initial Resuscitation of Severely Hemorrhaging Trauma Patients: A Narrative Review

This narrative review explores the pathophysiology, geographic variation, and historical developments underlying the selection of fixed ratio versus whole blood resuscitation for hemorrhaging trauma patients. We also detail a physiologically driven and goal-directed alternative to fixed ratio and whole blood, whereby viscoelastic testing guides the administration of blood components and factor concentrates to the severely bleeding trauma patient. The major studies of each resuscitation method are highlighted, and upcoming comparative trials are detailed.