Plasma coadministration improves resuscitation with tranexamic acid or prothrombin complex in a porcine hemorrhagic shock model

Prehospital Freeze-Dried Plasma in Trauma: A Critical Review

Major traumatic hemorrhage is now frequently treated by early hemostatic resuscitation on hospital arrival. Prehospital hemostatic resuscitation could therefore improve outcomes for bleeding trauma patients, but there are logistical challenges. Freeze-dried plasma (FDP) offers indisputable logistical advantages over conventional blood products, such as long shelf life, stability at ambient temperature, and rapid reconstitution without specialized equipment. We sought high level, randomized, controlled evidence of FDP clinical efficacy in trauma. A structured systematic search of MEDLINE/PubMed was carried out and identified 52 relevant English language publications. Three studies involving 607 patients met our criteria: Resuscitation with Blood Products in Patients with Trauma-related Hemorrhagic Shock receiving Prehospital Care (RePHILL, n = 501); Prehospital Lyophilized Plasma Transfusion for Trauma-Induced Coagulopathy in Patients at Risk for Hemorrhagic Shock (PREHO-PLYO, n = 150); and a pilot Australian trial (n = 25). RePHILL found no effect of FDP plus packed red blood cells (PRBC) concentrate transfusion versus saline on mortality. PREHO-PLYO found no effect of FDP versus saline on International Normalized Ratio (INR) at hospital arrival. The pilot trial found that study of PRBC versus PRBC plus FDP was feasible during long air transport times to an Australian trauma centre. Further research is required to determine under what conditions FDP might provide prehospital benefit to trauma patients.

The Use of Large Animal Models in Trauma and Bleeding Studies

BACKGROUND

 Major trauma often results in significant bleeding and coagulopathy, posing a substantial clinical burden. To understand the underlying pathophysiology and to refine clinical strategies to overcome coagulopathy, preclinical large animal models are often used. This review scrutinizes the clinical relevance of large animal models in hemostasis research, emphasizing challenges in translating findings into clinical therapies.

METHODS

 We conducted a thorough search of PubMed and EMBASE databases from January 1, 2010, to December 31, 2022. We used specific keywords and inclusion/exclusion criteria centered on large animal models.

RESULTS

 Our review analyzed 84 pertinent articles, including four animal species: pigs, sheep, dogs, and nonhuman primates (NHPs). Eighty-five percent of the studies predominantly utilized porcine models. Meanwhile, sheep and dogs were less represented, making up only 2.5% of the total studies. Models with NHP were 10%. The most frequently used trauma models involved a combination of liver injury and femur fractures (eight studies), arterial hemorrhage (seven studies), and a combination of hemodilution and liver injury (seven studies). A wide array of coagulation parameters were employed to assess the efficacy of interventions in hemostasis and bleeding control.

CONCLUSIONS

 Recognizing the diverse strengths and weaknesses of large animal models is critical for trauma and hemorrhage research. Each model is unique and should be chosen based on how well it aligns with the specific scientific objectives of the study. By strategically considering each model's advantages and limitations, we can enhance our understanding of trauma and hemorrhage pathophysiology and further advance the development of effective treatments.

Resuscitation with whole blood or blood components improves survival and lessens the pathophysiological burden of trauma and haemorrhagic shock in a pre-clinical porcine model

PURPOSE

In military trauma, disaster medicine, and casualties injured in remote locations, times to advanced medical and surgical treatment are often prolonged, potentially reducing survival and increasing morbidity. Since resuscitation with blood/blood components improves survival over short pre-surgical times, this study aimed to evaluate the quality of resuscitation afforded by blood/blood products or crystalloid resuscitation over extended 'pre-hospital' timelines in a porcine model of militarily relevant traumatic haemorrhagic shock.

METHODS

This study underwent local ethical review and was done under the authority of Animals (Scientific Procedures) Act 1986. Forty-five terminally anaesthetised pigs received a soft tissue injury to the right thigh, haemorrhage (30% blood volume and a Grade IV liver injury) and fluid resuscitation initiated 30 min later [Group 1 (no fluid); 2 (0.9% saline); 3 (1:1 packed red blood cells:plasma); 4 (fresh whole blood); or 5 (plasma)]. Fluid (3 ml/kg bolus) was administered during the resuscitation period (maximum duration 450 min) when the systolic blood pressure fell below 80 mmHg. Surviving animals were culled with an overdose of anaesthetic.

RESULTS

Survival time was significantly shorter for Group 1 compared to the other groups (P < 0.05). Despite the same triggers for resuscitation when compared to blood/blood components, saline was associated with a shorter survival time (P = 0.145), greater pathophysiological burden and significantly greater resuscitation fluid volume (P < 0.0001).

CONCLUSION

When times to advanced medical care are prolonged, resuscitation with blood/blood components is recommended over saline due to the superior quality and stability of resuscitation achieved, which are likely to lead to improved patient outcomes.

Reversing direct factor Xa or thrombin inhibitors: Factor V addition to prothrombin complex concentrate is beneficial in vitro

Background

Prothrombin complex concentrate (PCC) is a human plasma‐derived mixture of partially purified vitamin K‐dependent coagulation factors (VKCF). Current therapeutic indication is treatment and perioperative prophylaxis of bleeding in acquired VKCF deficiency. Off‐label uses include treatment of direct factor Xa‐ or thrombin inhibitor‐associated bleeds, treatment of trauma‐induced coagulopathy, and hemorrhagic complications in patients with liver disease.

Objective

Considering PCC as a general prohemostatic drug, we argued that its clinical efficacy can benefit from supplementation with coagulation factors that are absent in the current PCC formulation. In this study, we focused on factor V.

Methods

We mimicked a coagulopathy in vitro by spiking whole blood or derived plasma with the direct oral anticoagulants (DOAC) rivaroxaban or dabigatran. We studied DOAC reversal by PCC and factor V concentrate (FVC) using a thrombin generation assay, thromboelastography, fibrin generation clot lysis test, and microfluidic thrombus formation under flow.

Results

In DOAC‐treated plasma, PCC increased the amount of thrombin generated. The addition of FVC alone or in combination with PCC caused a partial correction of the thrombin generation lag time and clotting time. In DOAC‐treated whole blood, the combination of PCC and FVC synergistically improved clotting time under static conditions, whereas complete correction of fibrin formation was observed under flow. Clot strength and clot resistance toward tissue plasminogen activator‐induced lysis were both increased with PCC and further enhanced by additional FVC.

Conclusion

Our in vitro study demonstrates a beneficial effect of the combined use of PCC and FVC in DOAC reversal.

Hemodynamic Effects of Cardiovascular Medications in a Normovolemic and Hemorrhaged Yorkshire-cross Swine Model

The Yorkshire-cross swine model is a valuable translational model commonly used to study cardiovascular physiologyand response to insult. Although the effects of vasoactive medications have been well described in healthy swine, the effects of these medications during hemorrhagic shock are less studied. In this study, we sought to expand the utility of the swine model by characterizing the hemodynamic changes that occurred after the administration of commonly available vasoactive medications during euvolemic and hypovolemic states. To this end, we anesthetized and established femoral arterial,central venous, and pulmonary arterial access in 15 juvenile Yorkshire-cross pigs. The pigs then received a series of rapidlymetabolized but highly vasoactive medications in a standard dosing sequence. After completion of this sequence, each pigunderwent a 30-mL/kg hemorrhage over 10 min, and the standard dosing sequence was repeated. We then used standard statisticaltechniques to compare the effects of these vasoactive medications on a variety of hemodynamic parameters betweenthe euvolemic and hemorrhagic states. All subjects completed the study protocol. The responses in the hemorrhagic state wereoften attenuated or even opposite of those in the euvolemic state. For example, phenylephrine decreased the mean arterialblood pressure during the euvolemic state but increased it in the hemorrhagic state. These results clarify previously poorlydefined responses to commonly used vasoactive agents during the hemorrhagic state in swine. Our findings also demonstratethe need to consider the complex and dynamic physiologic state of hemorrhage when anticipating the effects of vasoactivedrugs and planning study protocols.

Prothrombin Complex Concentrate for Trauma Induced Coagulopathy: A Systematic Review and Meta-Analysis

Background

Optimal management for trauma-induced coagulopathy (TIC) is a clinical conundrum. In conjunction with the transfusion of fresh-frozen plasma (FFP), additional administration of prothrombin complex concentrate (PCC) was proposed to bring about further coagulative benefit. However, investigations evaluating the efficacy as well as corresponding side effects were scarce and inconsistent. The aim of this study was to systematically review current literature and to perform a meta-analysis comparing FFP+PCC with FFP alone.

Methods

Web search followed by manual interrogation was performed to identify relevant literatures fulfilling the following criteria, subjects as TIC patients taking no baseline anticoagulants, without underlying coagulative disorders, and reported clinical consequences. Those comparing FFP alone with PCC alone were excluded. Comprehensive Meta-analysis software was utilized, and statistical results were delineated with odd ratio (OR), mean difference (MD), and 95% confidence interval (CI). I² was calculated to determine heterogeneity. The primary endpoint was set as all-cause mortality, while the secondary endpoint consisted of international normalized ratio (INR) correction, transfusion of blood product, and thrombosis rate.

Results

One hundred and sixty-four articles were included for preliminary evaluation, 3 of which were qualified for meta-analysis. A total of 840 subjects were pooled for assessment. Minimal heterogeneity was present in the comparisons (I² < 25%). In the PCC + FFP cohort, reduced mortality rate was observed (OR: 0.631; 95% CI: 0.450-0.884, p = 0.007) after pooling. Meanwhile, INR correction time was shorter under PCC + FFP (MD: -608.300 mins, p < 0.001), whilst the rate showed no difference (p = 0.230). The PCC + FFP group is less likely to mandate transfusion of packed red blood cells (p < 0.001) and plasma (p < 0.001), but not platelet (p = 0.615). The incidence of deep vein thrombosis was comparable in the two groups (p = 0.460).

Conclusions

Compared with FFP only, PCC + FFP demonstrated better survival rate, favorable clinical recovery and no elevation of thromboembolism events after TIC.

Physiology of Human Hemorrhage and Compensation

Hemorrhage is a leading cause of death following traumatic injuries in the United States. Much of the previous work in assessing the physiology and pathophysiology underlying blood loss has focused on descriptive measures of hemodynamic responses such as blood pressure, cardiac output, stroke volume, heart rate, and vascular resistance as indicators of changes in organ perfusion. More recent work has shifted the focus toward understanding mechanisms of compensation for reduced systemic delivery and cellular utilization of oxygen as a more comprehensive approach to understanding the complex physiologic changes that occur following and during blood loss. In this article, we begin with applying dimensional analysis for comparison of animal models, and progress to descriptions of various physiological consequences of hemorrhage. We then introduce the complementary side of compensation by detailing the complexity and integration of various compensatory mechanisms that are activated from the initiation of hemorrhage and serve to maintain adequate vital organ perfusion and hemodynamic stability in the scenario of reduced systemic delivery of oxygen until the onset of hemodynamic decompensation. New data are introduced that challenge legacy concepts related to mechanisms that underlie baroreflex functions and provide novel insights into the measurement of the integrated response of compensation to central hypovolemia known as the compensatory reserve. The impact of demographic and environmental factors on tolerance to hemorrhage is also reviewed. Finally, we describe how understanding the physiology of compensation can be translated to applications for early assessment of the clinical status and accurate triage of hypovolemic and hypotensive patients. © 2021 American Physiological Society. Compr Physiol 11:1531-1574, 2021.

Early outcomes following trauma related to sex: A matched analysis of military service members in the department of defense trauma registry

BACKGROUND

Several studies have identified sex as a factor influencing early outcomes after trauma. With the increased representation of women in combat roles, there is a need for improved understanding of the pathophysiology of traumatic injury in women. The purpose of this study was to define sex-based differences in early combat trauma outcomes amongst military service members.

METHODS

A retrospective review of the Department of Defense Trauma Registry between 2008 and 2016 was performed. A 2:1 case control match was performed to match for Injury Severity Score, mechanism of injury, and age. The primary outcome of the study was mortality.

RESULTS

A total of 4,625 patients were included in the study, 2.2% of whom were women. Women were less significantly injured than men (Injury Severity Score, 7.7 vs. 11, p = 0.003) and more likely to sustain blunt trauma (81% vs. 62.5%, p = 0.01). After case-control matching, 202 men and 101 women were evaluated. There was no statistical difference in the primary outcome of mortality. There was no statistical difference in Glasgow Coma Scale score, crystalloid or colloid administration, Packed Red Blood Cells (PRBC), platelet, cryoprecipitate, or plasma usage between men and women.

CONCLUSION

Contrary to the civilian trauma literature, our study demonstrated no significant difference in early mortality between male and female combat casualties in a matched cohort. This finding may represent a difference in injury patterns, resuscitation practices, or lifesaving interventions in a deployed setting as compared with civilian setting. As the proportion of women involved in combat operations continues to increase, prospective studies should be performed to better define injury patterns, as well as early and late outcomes related to military trauma in the female population.

LEVEL OF EVIDENCE

Retrospective, Level IV.

Four-Factor Prothrombin Complex Concentrate: An Indispensable Adjunct in Coagulopathy of Trauma Management - A Comparative Review of the Literature over 2 Decades

BACKGROUND

Damage control resuscitation forms the cornerstone of management in trauma surgery. Several blood products have been widely used for preoperative transfusions prior to emergency surgeries and for hemorrhage control in trauma. Prothrombin complex concentrate (PCC) is now being introduced as an essential component of damage control resuscitation.

SUMMARY

We did a comparative descriptive analysis of several single and multi-institutional clinical trials and retrospective cohort studies. The primary focus of these studies was a comparison between PCC and other transfusion modalities including recombinant factor VIIa, fresh-frozen plasma, and fibrinogen based on several vital parameters. The parameters included rapid international normalized ratio reversal, hospital length of stay, cost-effectiveness, mortality rate, and rate of thromboembolic complications.

KEY POINTS

Although still awaiting its approval from the FDA for use in traumatic coagulopathy, 4-factor PCC has shown far more convincing results in contrast to former transfusion modalities, even 3-factor PCC. However, more prospective extensive clinical trials on national levels are needed to compare its effectiveness to 3-factor PCC and gather promising recognition in the trauma care fraternity.

Efficacy of intermittent versus standard resuscitative endovascular balloon occlusion of the aorta in a lethal solid organ injury model

BACKGROUND

High-grade solid organ injury is a major cause of mortality in trauma. Use of resuscitative endovascular balloon occlusion of the aorta (REBOA) can be effective but is limited by ischemia-reperfusion injury. Intermittent balloon inflation/deflation has been proposed as an alternative, but the safety and efficacy prior to operative hemorrhage control is unknown.

METHODS

Twenty male swine underwent standardized high-grade liver injury, then randomization to controls (N = 5), 60-min continuous REBOA (cR, n = 5), and either a time-based (10-minute inflation/3-minute deflation, iRT = 5) or pressure-based (mean arterial pressure<40 during deflation, iRP = 5) intermittent schedule. Experiments were concluded after 120 minutes or death.

RESULTS

Improved overall survival was seen in the iRT group when compared to cR (p < 0.01). Bleeding rate in iRT (5.9 mL/min) was significantly lower versus cR and iRP (p = 0.02). Both iR groups had higher final hematocrit (26% vs. 21%) compared to cR (p = 0.03). Although overall survival was lower in the iRP group, animals surviving to 120 minutes with iRP had decreased end organ injury (Alanine aminotransferase [ALT] 33 vs. 40 in the iRT group, p = 0.03) and lower lactate levels (13 vs. 17) compared with the iRT group (p = 0.03). No differences were seen between groups in terms of coagulopathy based on rotational thromboelastometry.

CONCLUSION

Intermittent REBOA is a potential viable adjunct to improve survival in lethal solid organ injury while minimizing the ischemia-reperfusion seen with full REBOA. The time-based intermittent schedule had the best survival and prolonged duration of tolerable zone 1 placement. Although the pressure-based schedule was less reliable in terms of survival, when effective, it was associated with decreased acidosis and end-organ injury.

Thromboelastometry assessment of the effects of fibrinogen, activated prothrombin complex concentrate, and tranexamic acid on clot formation and fibrinolysis in a model of trauma-induced coagulopathy

PURPOSE

Coagulation abnormalities are common following major trauma. The aim of this study was to assess the improvement of trauma-induced coagulopathy (TIC) in an in vitro model.

METHODS

TIC was created on blood taken from healthy individuals by inducing hemodilution, acidosis, hypothermia and fibrinolysis. Next, blood samples were subjected to rotational thromboelastometry to assess the effect of hemostasis modulators on blood coagulation and fibrinolysis.

RESULTS

Introducing to blood fibrinogen at 0.75 mg/mL, prothrombin complex concentrate at 0.66 IU/mL or tranexamic acid at 95 µg/mL increased clot strength. Higher effect was observed by combination of fibrinogen with tranexamic acid and prothrombin complex with tranexamic acid, whereas the maximal effect was achieved using all agents together. Fibrinolysis was inhibited by tranexamic acid and stronger by triple combination of the agents. Selective treating the TIC blood with fibrinogen, prothrombin complex or tranexamic acid at two time lower concentrations did not affect clot strength. Combining fibrinogen with prothrombin complex or with tranexamic acid stimulated clot strength but at lower extent compared to higher concentrations. Lysis onset time was prolonged by tranexamic acid. Maximal effect on both clot formation and fibrinolysis was achieved using all three agents together.

CONCLUSIONS

Blood clotting stimulation and fibrinolysis inhibition in the TIC model was enough combining subthreshold concentrations of fibrinogen, prothrombin complex and tranexamic acid. Further experiments are warranted in both in vitro and in vivo conditions with minimally effective concentrations of both pro-coagulant and anti-fibrinolytic drugs assuming that this combinatorial approach may not only improve coagulopathy but also minimize the risk of thrombotic complications.

Damage control orthopaedics: State of the art

Damage control orthopaedics (DCO) originally consisted of the provisional immobilisation of long bone - mainly femur - fractures in order to achieve the advantages of early treatment and to minimise the risk of complications, such as major pain, fat embolism, clotting, pathological inflammatory response, severe haemorrhage triggering the lethal triad, and the traumatic effects of major surgery on a patient who is already traumatised (the “second hit” effect). In recent years, new locations have been added to the DCO concept, such as injuries to the pelvis, spine and upper limbs. Nonetheless, this concept has not yet been validated in well-designed prospective studies, and much controversy remains. Indeed, some researchers believe the indiscriminate application of DCO might be harmful and produce substantial and unnecessary expense. In this respect, too, normalised parameters associated with the acid-base system have been proposed, under a concept termed early appropriate care, in the view that this would enable patients to receive major surgical procedures in an approach offering the advantages of early total care together with the apparent safety of DCO. This paper discusses the diagnosis and treatment of severely traumatised patients managed in accordance with DCO and highlights the possible drawbacks of this treatment principle.