Implementation of a prehospital air medical thawed plasma program: Is it even feasible?

Dried Plasma for Major Trauma: Past, Present, and Future

Uncontrollable bleeding is recognized as the leading cause of preventable death among trauma patients. Early transfusion of blood products, especially plasma replacing crystalloid and colloid solutions, has been shown to increase survival of severely injured patients. However, the requirements for cold storage and thawing processes prior to transfusion present significant logistical challenges in prehospital and remote areas, resulting in a considerable delay in receiving thawed or liquid plasma, even in hospitals. In contrast, freeze- or spray-dried plasma, which can be massively produced, stockpiled, and stored at room temperature, is easily carried and can be reconstituted for transfusion in minutes, provides a promising alternative. Drawn from history, this paper provides a review of different forms of dried plasma with a focus on in vitro characterization of hemostatic properties, to assess the effects of the drying process, storage conditions in dry form and after reconstitution, their distinct safety and/or efficacy profiles currently in different phases of development, and to discuss the current expectations of these products in the context of recent preclinical and clinical trials. Future research directions are presented as well.

Prehospital transfusion of allogeneic blood products

PURPOSE OF REVIEW

The purpose of this article is to provide a structural and practical analysis of the currently available data concerning prehospital transfusion of allogeneic blood products in cases of trauma and severe bleeding.

RECENT FINDINGS

Prehospital transfusion of allogeneic blood products is a very early intervention, which may offer the potential to improve outcome, but that also comes with challenges including resource allocation, blood product storage, logistics, patient selection, legal and ethical considerations, adverse effects, and costs. Potential benefits including improved stability and reduction in coagulopathy and blood loss have not yet been clearly demonstrated.

SUMMARY

The questionable efficacy and challenges in clinical practice may outweigh the potential benefits of prehospital allogeneic transfusion.

Management of Hemorrhagic Shock: Physiology Approach, Timing and Strategies

Hemorrhagic shock (HS) management is based on a timely, rapid, definitive source control of bleeding/s and on blood loss replacement. Stopping the hemorrhage from progressing from any named and visible vessel is the main stem fundamental praxis of efficacy and effectiveness and an essential, obligatory, life-saving step. Blood loss replacement serves the purpose of preventing ischemia/reperfusion toxemia and optimizing tissue oxygenation and microcirculation dynamics. The "physiological classification of HS" dictates the timely management and suits the 'titrated hypotensive resuscitation' tactics and the 'damage control surgery' strategy. In any hypotensive but not yet critical shock, the body's response to a fluid load test determines the cut-off point between compensation and progression between the time for adopting conservative treatment and preparing for surgery or rushing to the theater for rapid bleeding source control. Up to 20% of the total blood volume is given to refill the unstressed venous return volume. In any critical level of shock where, ab initio, the patient manifests signs indicating critical physiology and impending cardiac arrest or cardiovascular accident, the balance between the life-saving reflexes stretched to the maximum and the insufficient distal perfusion (blood, oxygen, and substrates) remains in a liable and delicate equilibrium, susceptible to any minimal change or interfering variable. In a cardiac arrest by exsanguination, the core of the physiological issue remains the rapid restoration of a sufficient venous return, allowing the heart to pump it back into systemic circulation either by open massage via sternotomy or anterolateral thoracotomy or spontaneously after aorta clamping in the chest or in the abdomen at the epigastrium under extracorporeal resuscitation and induced hypothermia. This is the only way to prevent ischemic damage to the brain and the heart. This is accomplishable rapidly and efficiently only by a direct approach, which is a crush laparotomy if the bleeding is coming from an abdominal +/- lower limb site or rapid sternotomy/anterolateral thoracotomy if the bleeding is coming from a chest +/- upper limbs site. Without first stopping the bleeding and refilling the heart, any further exercise is doomed to failure. Direct source control via laparotomy/thoracotomy, with the concomitant or soon following venous refilling, are the two essential, initial life-saving steps.

Frozen and freeze-dried solvent/detergent treated plasma: Two different pharmaceutical formulations with comparable quality

BACKGROUND

OctaplasLG is a frozen solvent/detergent-treated plasma product used for treating complex coagulation factor deficiencies or as substitution therapy in emergency situations where specific factor concentrates are not available. A new freeze-dried (also known as lyophilized) form of OctaplasLG, referred as OctaplasLG Lyo (Octapharma AG, Switzerland) offers rapid reconstitution and more flexible storage conditions, improving logistics and utilization. This study compared the biochemical quality of OctaplasLG Lyo with OctaplasLG and single-donor fresh frozen plasma units.

STUDY DESIGN AND METHODS

Three batches of OctaplasLG Lyo, manufactured for production process qualification, and 12 batches of OctaplasLG were provided by Octapharma AB (Sweden). Twelve units of fresh frozen plasma were collected by the local FDA-licensed blood provider. All plasma samples were assessed for global coagulation parameters, coagulation factors and protease inhibitors, activation markers of coagulation and fibrinolysis, and important plasma proteins. Quality control assays were conducted in accordance with European Pharmacopeia requirements.

RESULTS

Frozen and freeze-dried OctaplasLG demonstrated comparable quality profiles upon thawing or reconstitution. All coagulation factor and protease inhibitor activity parameters were in line with levels mandated by the European Pharmacopeia. Fresh frozen plasma units showed comparable coagulation factor activities, with higher protein S and plasmin inhibitor levels than the OctaplasLG products. Fresh frozen plasma parameters showed high lot-to-lot variations.

DISCUSSION

The two pharmaceutical forms of OctaplasLG (frozen and freeze-dried) have comparable biochemical quality. Key features of OctaplasLG Lyo are rapid reconstitution time and storage flexibility, which may improve logistics and utilization, and have particular advantages in emergency situations and pre-hospital settings.

Use of Dried Plasma in Prehospital and Austere Environments

More than 1,000,000 units of lyophilized plasma have been used in France, Germany, and South Africa. Recently, numerous other countries have adopted lyophilized plasma for patients with severe bleeding in prehospital and austere settings.

Evaluating the Cost-effectiveness of Prehospital Plasma Transfusion in Unstable Trauma Patients: A Secondary Analysis of the PAMPer Trial

Importance

Prehospital plasma transfusion is lifesaving for trauma patients in hemorrhagic shock but is not commonly used owing to cost and feasibility concerns.

Objective

To evaluate the cost-effectiveness of prehospital thawed plasma transfusion in trauma patients with hemorrhagic shock during air medical transport.

Design, Setting, and Participants

A decision tree and Markov model were created to compare standard care and prehospital thawed plasma transfusion using published and unpublished patient-level data from the Prehospital Plasma in Air Medical Transport in Trauma Patients at Risk for Hemorrhagic Shock (PAMPer) trial conducted from May 2014 to October 2017, health care and trauma-specific databases, and the published literature. Prehospital transfusion, short-term inpatient care, and lifetime health care costs and quality of life outcomes were included. One-way, 2-way, and Monte Carlo probabilistic sensitivity analyses were performed across clinically plausible ranges. Data were analyzed in December 2019.

Main Outcomes and Measures

Relative costs and health-related quality of life were evaluated by an incremental cost-effectiveness ratio at a standard willingness-to-pay threshold of $100 000 per quality-adjusted life-year (QALY).

Results

The trial included 501 patients in the modified intention-to-treat cohort. Median (interquartile range) age for patients in the thawed plasma and standard care cohorts were 44 (31-59) and 46 (28-60) years, respectively. Overall, 364 patients (72.7%) were male. Thawed plasma transfusion was cost-effective with an incremental cost-effectiveness ratio of $50 467.44 per QALY compared with standard care. The preference for thawed plasma was robust across all 1- and 2-way sensitivity analyses. When considering only patients injured by a blunt mechanism, the incremental cost-effectiveness ratio decreased to $37 735.19 per QALY. Thawed plasma was preferred in 8140 of 10 000 iterations (81.4%) on probabilistic sensitivity analysis. A detailed analysis of incremental costs between strategies revealed most were attributable to the in-hospital and postdischarge lifetime care of critically ill patients surviving severe trauma.

Conclusions and Relevance

In this study, prehospital thawed plasma transfusion during air medical transport for trauma patients in hemorrhagic shock was lifesaving and cost-effective compared with standard care and should become commonplace.

Lactate as a mediator of prehospital plasma mortality reduction in hemorrhagic shock

BACKGROUND

Prehospital plasma transfusion in trauma reduces mortality. However, the underlying mechanism remains unclear. Reduction in shock severity may play a role. Lactate correlates with physiologic shock severity and mortality after injury. Our objective was to determine if prehospital plasma reduces lactate and if this contributes to the mortality benefit of plasma.

METHODS

Patients in the Prehospital Air Medical Plasma trial in the upper quartile of injury severity (Injury Severity Score, >30) were included to capture severe shock. Trial patients were randomized to prehospital plasma or standard care resuscitation (crystalloid ± packed red blood cells). Regression determined the associations between admission lactate, 30-day mortality, and plasma while adjusting for demographics, prehospital crystalloid, time, mechanism, and injury characteristics. Causal mediation analysis determined what proportion of the effect of plasma on mortality is mediated by lactate reduction.

RESULTS

A total of 125 patients were included. The plasma group had a lower adjusted admission lactate than standard of care group (coefficient, -1.64; 95% confidence interval [CI], -2.96 to -0.31; p = 0.02). Plasma was associated with lower odds of 30-day mortality (odds ratio [OR], 0.27; 95% CI, 0.08-0.90; p = 0.03). When adding lactate to this model, the effect of plasma on 30-day mortality was no longer significant (OR, 0.36; 95% CI, 0.07-1.88; p = 0.23), while lactate was associated with mortality (OR, 1.74 per 1 mmol/L increase; 95% CI, 1.10-2.73; p = 0.01). Causal mediation demonstrated 35.1% of the total effect of plasma on 30-day mortality was mediated by the reduction in lactate among plasma patients.

CONCLUSION

Prehospital plasma is associated with reduced 30-day mortality and lactate in severely injured patients. More than one third of the effect of plasma on mortality is mediated by a reduction in lactate. Thus, reducing the severity of hemorrhagic shock appears to be one mechanism of prehospital plasma benefit. Further study should elucidate other mechanisms and if a dose response exists.

LEVEL OF EVIDENCE

Therapeutic, level II.

Use of fibrinogen concentrate for trauma-related bleeding: A systematic-review and meta-analysis

BACKGROUND

Trauma-induced coagulopathy contributes to significant morbidity and mortality in patients who experience trauma-related bleeding. This study aimed to synthesize the evidence supporting the efficacy and safety of preemptive and goal-directed fibrinogen concentrate (FC) in the management of trauma-related hemorrhage.

METHODS

PubMed, Medline, EMBASE, Web of Science, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, and the WHO International Clinical Trials Registry Platform were systematically searched. All trial designs, except individual case reports, which evaluated the preemptive or goal-directed use of FC for trauma-related bleeding/coagulopathy, in patients older than 16 years, were included in the systematic review. For the included randomized controlled trials comparing FC with control, meta-analysis was performed and a risk-of bias-assessment was completed using the Cochrane Methodology and Preferred Reporting Items Systematic Reviews and Meta-analysis guidelines.

RESULTS

A total of 2,743 studies were identified; 26 were included in the systematic review, and 5 randomized controlled trials (n = 238) were included in the meta-analysis. For the primary outcome of mortality, there was no statistically significant difference between the groups, with 22% and 23.4% in the FC and comparator arms, respectively (risk ratio, 1.00 [95% confidence interval, 0.39 to 2.56]; p = 0.99). In addition, there was no statistical difference between FC and control in packed red blood cell, fresh frozen plasma, or platelet transfusion requirements, and thromboembolic events. Overall, the quality of evidence was graded as low to moderate because of concerns with risk of bias, imprecision, and inconsistency.

CONCLUSION

Further high-quality, adequately powered studies are needed to assess the impact of FC in trauma, with a focus on administration as early as possible from the point of entry into the trauma system of care.

LEVEL OF EVIDENCE

Systematic review and Meta-analysis, level II.

Economical provision of blood components for critical patient transport across a large geographic area

BACKGROUND

Rapid air transport of critically injured patients to sites of appropriate care can save lives. The provision of blood products on critical care transport flights may save additional lives by starting resuscitation earlier.

METHODS

Our regional trauma center transfusion service provided 2 units of O-negative red blood cells and 2 units of A low-titer anti-B liquid plasma in an internally monitored and sealed eutectic box weighing 10.4 pounds to eight air bases once weekly. Flight crews were instructed to transfuse plasma units first. Unused blood was returned to the transfusion service. Total blood use and wastage were recorded.

RESULTS

Over a 6-year period, ≈ 7400 blood components were provided, and >1000 were used by the air transport service in patient care. Plasma units were 57% of all units given. Unused units were returned to the providing transfusion service and used in hospital patient care with <3% loss. Estimated cost of providing blood per mission was $63 and per patient transfused was $1940.

CONCLUSIONS

With appropriate attention to detail, it is possible to provide life-saving blood components to aeromedical transport services across a large geographic area with efficient blood component usage, minimal blood wastage, and low cost.

Age of thawed plasma does not affect clinical outcomes or biomarker expression in patients receiving prehospital thawed plasma: a PAMPer secondary analysis

Background

Prehospital plasma administration during air medical transport reduces the endotheliopathy of trauma, circulating pro-inflammatory cytokines, and 30-day mortality among traumatically injured patients at risk of hemorrhagic shock. No clinical data currently exists evaluating the age of thawed plasma and its association with clinical outcomes and biomarker expression post-injury.

Methods

We performed a secondary analysis from the prehospital plasma administration randomized controlled trial, PAMPer. We dichotomized the age of thawed plasma creating three groups: standard-care, YOUNG (day 0-1) plasma, and OLD (day 2-5) plasma. We generated HRs and 95% CIs for mortality. Among all patients randomized to plasma, we compared predicted biomarker values at hospital admission (T0) and 24 hours later (T24) controlling for key difference between groups with a multivariable linear regression. Analyses were repeated in a severely injured subgroup.

Results

Two hundred and seventy-one patients were randomized to standard-care and 230 to plasma (40% YOUNG, 60% OLD). There were no clinically or statistically significant differences in demographics, injury, admission vital signs, or laboratory values including thromboelastography between YOUNG and OLD. Compared with standard-care, YOUNG (HR 0.66 (95% CI 0.41 to 1.07), p=0.09) and OLD (HR 0.64 (95% CI 0.42 to 0.96), p=0.03) plasma demonstrated reduced 30-day mortality. Among those randomized to plasma, plasma age did not affect mortality (HR 1.04 (95% CI 0.60 to 1.82), p=0.90) and/or adjusted serum markers by plasma age at T0 or T24 (p>0.05). However, among the severely injured subgroup, OLD plasma was significantly associated with increased adjusted inflammatory and decreased adjusted endothelial biomarkers at T0.

Discussion

Age of thawed plasma does not result in clinical outcome or biomarker expression differences in the overall PAMPer study cohort. There were biomarker expression differences in those patients with severe injury. Definitive investigation is needed to determine if the age of thawed plasma is associated with biomarker expression and outcome differences following traumatic injury.

Level of evidence

II.