Pre-hospital transfusion of red blood cells in civilian trauma patients

Current state of technical transfusion medicine practice for out-of-hospital blood transfusion in Canada

BACKGROUND AND OBJECTIVES

Canadian out-of-hospital blood transfusion programmes (OHBTPs) are emerging, to improve outcomes of trauma patients by providing pre-hospital transfusion from the scene of injury, given prolonged transport times. Literature is lacking to guide its implementation. Thus, we sought to gather technical transfusion medicine (TM)-specific practices across Canadian OHBTPs.

MATERIALS AND METHODS

A survey was sent to TM representatives of Canadian OHBTPs from November 2021 to March 2022. Data regarding transport, packaging, blood components and inventory management were included and reported descriptively. Only practices involving Blood on Board programme components for emergency use were included.

RESULTS

OHBTPs focus on helicopter emergency medical service programmes, with some supplying fixed-wing aircraft and ground ambulances. All provide 1-3 coolers with 2 units of O RhD/Kell-negative red blood cells (RBCs) per cooler, with British Columbia trialling coolers with 2 units of pre-thawed group A plasma. Inventory exchanges are scheduled and blood components are returned to TM inventory using visual inspection and internal temperature data logger readings. Coolers are validated to storage durations ranging from 72 to 124 h. All programmes audit to manage wastage, though there is no consensus on appropriate benchmarks. All programmes have a process for documenting units issued, reconciliation after transfusion and for transfusion reaction reporting; however, training programmes vary. Common considerations included storage during extreme temperature environments, O-negative RBC stewardship, recipient notification, traceability, clinical practice guidelines co-reviewed by TM and a common audit framework.

CONCLUSION

OHBTPs have many similarities throughout Canada, where harmonization may assist in further developing standards, leveraging best practice and national coordination.

Prehospital blood transfusion in Brazil: results of the first year of implementation in an emergency medical service

INTRODUCTION

Hemorrhagic shock is the main cause of death in the prehospital environment, which highlights the need to standardize measures aiming at bleeding control and volume replacement in this environment. In Brazil, the first prehospital packed red blood cell transfusion service started in September 2020, in Bragança Paulista, state of São Paulo.

OBJECTIVES

Describe the trends and characteristics of patients who received prehospital transfusions prior to hospital treatment during the first year of operation.

METHODS

A retrospective data review was made of all patients who received transfusions from the mobile intensive care unit in Bragança Paulista over one year.

RESULTS

In this period, 19 patients were transfused. Since activation, the average response time was 20 min. The mean shock indexes before and after blood transfusion were 2.16 and 1.1, respectively. During the course of the 1st year of prehospital transfusions, no blood was wasted and there were no adverse effects.

CONCLUSION

Introduction of the prehospital packed red blood cell transfusion service was successful, with significant improvement in hemodynamic parameters.

Pre-Hospital Blood Products for the Care of Bleeding Trauma Patients

BACKGROUND

Controversy surrounds the administration of blood products to severely traumatized patients before they arrive in the hospital in order to compensate for early blood loss and/or to correct coagulation disturbances that arise shortly after the traumatic event. A number of terrestrial and air rescue services have begun to provide this kind of treatment.

METHODS

This review is based on articles using the PICO framework, published from January 2001 to January 2021, that were retrieved by a selective search, with structured searching strategies and searching bundles in Medline (OVIDSP), the Cochrane Central Register of Controlled Trials (CENTRAL), and Epistemonikos. A demand analysis was carried out on the basis of data from the trauma registry of the German Society of Trauma Surgery (TR-DGU) and practical experience from program development and implementation was provided by the Bundeswehr Hospital Ulm.

RESULTS

The currently available evidence on the pre-hospital administration of blood products in the early treatment of severely injured patients is based largely on retrospective, single-center case series. Two randomized controlled trials (RCTs) concerning the early use of fresh frozen plasma concentrates have yielded partly conflicting results. Three further RCTs on the use of lyophilized plasma (lyplas), lyplas plus erythrocyte concentrate, or whole blood likewise revealed non-uniform effects on short-term and intermediate-term mortality. Our demand analysis based on data from the TR-DGU showed that 300 to 1800 patients per year in Germany could benefit from the pre-hospital administration of blood products. This might be indicated in patients who have systolic hypotension (<100 mmHg) in combination with a suspected or confirmed hemorrhage, as well as pathological shock parameters in the point-of-care diagnostic testing performed on the scene (serum base excess ≤ -2.5 mmol/L and/or serum lactate concentration >4 mmol/L).

CONCLUSION

The studies that have been published to date yield no clear evidence either for or against the early pre-hospital administration of blood products. Any treatment of this kind should be accompanied by scientific evaluation.

Air Medical Blood Transfusion as a Trigger of Massive Transfusion Protocol

Air medical services can improve access to blood products at the point of injury. Studies have shown that early activation of mass transfusion protocols (MTPs) can improve the survival of trauma patients by up to 25%. There are several scoring systems to guide early activation, but the use of a single criterion has been elusive. Our study sought to determine if air medical administration of blood products was a risk factor for massive transfusion activation and utilization of prehospital vital signs for calculation of the shock index. In our retrospective study, we evaluated adult trauma patients transfused by helicopter emergency medical services (HEMS) and as a control all patients in our institution receiving the MTP. Our study found HEMS blood transfusion was not a reliable trigger for MTP, although the sample size may have limited our findings. We found that HEMS care resulted in an overall reduction in the volume of transfusion and an improvement in hemodynamic parameters upon trauma center arrival. HEMS transfusion and a higher rate of tranexamic acid administration may have contributed to these findings. Of note, the assessment of blood consumption score and shock index were nonspecific in the study populations.

Advanced interventions in the pre-hospital resuscitation of patients with non-compressible haemorrhage after penetrating injuries

Abstract

Early haemorrhage control and minimizing the time to definitive care have long been the cornerstones of therapy for patients exsanguinating from non-compressible haemorrhage (NCH) after penetrating injuries, as only basic treatment could be provided on scene. However, more recently, advanced on-scene treatments such as the transfusion of blood products, resuscitative thoracotomy (RT) and resuscitative endovascular balloon occlusion of the aorta (REBOA) have become available in a small number of pre-hospital critical care teams. Although these advanced techniques are included in the current traumatic cardiac arrest algorithm of the European Resuscitation Council (ERC), published in 2021, clear guidance on the practical application of these techniques in the pre-hospital setting is scarce. This paper provides a scoping review on how these advanced techniques can be incorporated into practice for the resuscitation of patients exsanguinating from NCH after penetrating injuries, based on available literature and the collective experience of several helicopter emergency medical services (HEMS) across Europe who have introduced these advanced resuscitation interventions into routine practice.

Graphical Abstract

A Framework for Case-Based Learning in Prehospital Medicine: The London's Air Ambulance Experience

Clinical governance is the framework around which health care organizations can maintain a higher standard of safety and care. One of the central aspects of clinical governance is continuous professional education, including case-based review and case-based learning. In this article, we present the case-based education process in use at London's Air Ambulance, a mature advanced prehospital system in London, UK. The case review process begins with an on-scene hot debrief, an informal process often involving other emergency services. This is usually followed by internal team feedback and debrief and patient follow-up. All cases are then reviewed over the next 24 to 48 hours by the duty prehospital consultant (attending) in the rapid review process. After this, certain cases are volunteered or selected for discussion in the twice weekly death and disability (D&D) meeting or the monthly dispatch meeting. A small subset of cases is highlighted through this process for full formal audit and presentation at the monthly clinical governance meetings based on their educational value. Another subset of cases involving a fatality is also discussed at the monthly clinical pathology correlation meeting with the input of local forensic pathologists. Organization of the process, structure of the meetings, and educational value are described in detail.

Initial experiences of prehospital blood product transfusions between 2016 and 2020 in Päijät-Häme hospital district, Finland

Background

Treating hemorrhaging patients with prehospital blood product transfusions (PHBT) narrows transfusion delays and potentially benefits the patient. We describe our initial experiences of PHBT in a ground-based emergency medical service (EMS), where the transfusion protocol covers both traumatic and nontraumatic hemorrhaging patients.

Methods

A descriptive retrospective analysis was performed on the records of all the patients receiving red blood cells, freeze-dried plasma, or both during prehospital care from September 2016 to December 2020. The delays of PHBT and the effects on patients’ vital signs were analyzed and reported as the median and interquartile range (IQR) and analyzed using a Wilcoxon Signed rank test.

Results

65 patients received prehospital blood product transfusions (PHBT), 29 (45%) were non-traumatic, and 36 (55%) traumatic. The main two reasons for PHBT were blunt trauma (n = 30, 46%) and gastrointestinal hemorrhage (n = 20, 31%). The median time from the emergency call to the start of PHBT was 54 min (IQR 38), and the transfusion began on a median of 61 min (IQR 42) before arrival at the hospital. The median systolic blood pressure improved from a median 76.5 mmHg (IQR 36.5) before transfusion to a median of 116.60 mmHg (IQR 26.5) (p < 0.001) on arrival to the hospital. No transfusion-related severe adverse events were noted.

Conclusions

Starting PHBT in ground-based EMS is a feasible and viable option. The PHBT began significantly earlier than it would have started on arrival to the hospital, and it seems to be safe and improve patients’ physiology.

Study approval

D/2603/07.01.04.05/2019.

Multicentre observational study on practice of prehospital management of hypotensive trauma patients: the SPITFIRE study protocol

INTRODUCTION

Major haemorrhage after injury is the leading cause of preventable death for trauma patients. Recent advancements in trauma care suggest damage control resuscitation (DCR) should start in the prehospital phase following major trauma. In Italy, Helicopter Emergency Medical Services (HEMS) assist the most complex injuries and deliver the most advanced interventions including DCR. The effect size of DCR delivered prehospitally on survival remains however unclear.

METHODS AND ANALYSIS

This is an investigator-initiated, large, national, prospective, observational cohort study aiming to recruit >500 patients in haemorrhagic shock after major trauma. We aim at describing the current practice of hypotensive trauma management as well as propose the creation of a national registry of patients with haemorrhagic shock.

PRIMARY OBJECTIVE

the exploration of the effect size of the variation in clinical practice on the mortality of hypotensive trauma patients. The primary outcome measure will be 24 hours, 7-day and 30-day mortality. Secondary outcomes include: association of prehospital factors and survival from injury to hospital admission, hospital length of stay, prehospital and in-hospital complications, hospital outcomes; use of prehospital ultrasound; association of prehospital factors and volume of first 24-hours blood product administration and evaluation of the prevalence of use, appropriateness, haemodynamic, metabolic and effects on mortality of prehospital blood transfusions.

INCLUSION CRITERIA

age >18 years, traumatic injury attended by a HEMS team including a physician, a systolic blood pressure <90 mm Hg or weak/absent radial pulse and a confirmed or clinically likely diagnosis of major haemorrhage. Prehospital and in-hospital variables will be collected to include key times, clinical findings, examinations and interventions. Patients will be followed-up until day 30 from admission. The Glasgow Outcome Scale Extended will be collected at 30 days from admission.

ETHICS AND DISSEMINATION

The study has been approved by the Ethics committee 'Comitato Etico di Area Vasta Emilia Centro'. Data will be disseminated to the scientific community by abstracts submitted to international conferences and by original articles submitted to peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT04760977.

Effectiveness of massive transfusion protocol activation in pre-hospital setting for major trauma

INTRODUCTION

Hemorrhage in major trauma is life-threatening and the activation of the Massive Transfusion Protocol (MTP) was found to reduce the time to transfusion and mortality. The purpose was (i) to verify whether MTP activation identifies patients that require massive transfusions once admitted to the Emergency Department (ED), (ii) to establish whether pre-hospital MTP activation reduces the time to transfusion on arrival at the ED, (iii) to identify the variable that best predicts MTP activation.

MATERIALS AND METHODS

This is a retrospective, single-center study. The MTP was implemented at the end of 2012; it was activated for major trauma in pre-hospital setting on the basis on established criteria. Pre-hospital MTP activation aimed to make blood products available prior to the patients' arrival at the ED. The blood products are transfused when the patient arrives at the hospital.

RESULTS

The MTP was activated in pre-hospital setting in 219 patients. On arrival at the hospital, the Trauma Team Leader confirmed MTP activation in 146 (66.7%) patients. Patients with MTP criteria received a higher amount of blood products than the patients without MTP criteria, median 7 (IQR 2-13) units versus 2 (0-6) units, respectively (P < 0.001). At the same time, patients with a Shock Index ≥ 0.9 received more transfusions (5.5 [2-13] units) compared with patients characterized by a lower SI (2 [0-7.25] units, P = 0.009). 146 patients were transfused in the first hour of ED admission. Poisson's multiple regression shows that the SI is the variable that better predicted MTP activation compared to age, gender and the number of injured sites.

CONCLUSIONS

Pre-hospital MTP activation is useful to identify patients that require an urgent blood transfusion on arrival at the ED. Further analysis should be considered to evaluate the implementation of the Shock Index as a criterion to activate MTP.

Recovery of organ-specific tissue oxygen delivery at restrictive transfusion thresholds after fluid treatment in ovine haemorrhagic shock

Background

Fluid resuscitation is the standard treatment to restore circulating blood volume and pressure after massive haemorrhage and shock. Packed red blood cells (PRBC) are transfused to restore haemoglobin levels. Restoration of microcirculatory flow and tissue oxygen delivery is critical for organ and patient survival, but these parameters are infrequently measured. Patient Blood Management is a multidisciplinary approach to manage and conserve a patient’s own blood, directing treatment options based on broad clinical assessment beyond haemoglobin alone, for which tissue perfusion and oxygenation could be useful. Our aim was to assess utility of non-invasive tissue-specific measures to compare PRBC transfusion with novel crystalloid treatments for haemorrhagic shock.

Methods

A model of severe haemorrhagic shock was developed in an intensive care setting, with controlled haemorrhage in sheep according to pressure (mean arterial pressure 30–40 mmHg) and oxygen debt (lactate > 4 mM) targets. We compared PRBC transfusion to fluid resuscitation with either PlasmaLyte or a novel crystalloid. Efficacy was assessed according to recovery of haemodynamic parameters and non-invasive measures of sublingual microcirculatory flow, regional tissue oxygen saturation, repayment of oxygen debt (arterial lactate), and a panel of inflammatory and organ function markers. Invasive measurements of tissue perfusion, oxygen tension and lactate levels were performed in brain, kidney, liver, and skeletal muscle. Outcomes were assessed during 4 h treatment and post-mortem, and analysed by one- and two-way ANOVA.

Results

Each treatment restored haemodynamic and tissue oxygen delivery parameters equivalently (p > 0.05), despite haemodilution after crystalloid infusion to haemoglobin concentrations below 70 g/L (p < 0.001). Recovery of vital organ-specific perfusion and oxygen tension commenced shortly before non-invasive measures improved. Lactate declined in all tissues and correlated with arterial lactate levels (p < 0.0001). The novel crystalloid supported rapid peripheral vasodilation (p = 0.014) and tended to achieve tissue oxygen delivery targets earlier. PRBC supported earlier renal oxygen delivery (p = 0.012) but delayed peripheral perfusion (p = 0.034).

Conclusions

Crystalloids supported vital organ oxygen delivery after massive haemorrhage, despite haemodilution to < 70 g/L, confirming that restrictive transfusion thresholds are appropriate to support oxygen delivery. Non-invasive tissue perfusion and oximetry technologies merit further clinical appraisal to guide treatment for massive haemorrhage in the context of Patient Blood Management.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40635-022-00439-6.

Outcome measures used in clinical research evaluating prehospital blood component transfusion in traumatically injured bleeding patients: A systematic review

BACKGROUND

Trial outcomes should be relevant to all stakeholders and allow assessment of interventions' efficacy and safety at appropriate timeframes. There is no consensus regarding outcome measures in the growing field of prehospital trauma transfusion research. Harmonization of future clinical outcome reporting is key to facilitate interstudy comparisons and generate cohesive, robust evidence to guide practice. The objective of this study was to evaluate outcome measures reported in prehospital trauma transfusion trials.

METHODS

Data Sources, Eligibility Criteria, Participants, and InterventionsWe conducted a scoping systematic review to identify the type, number, and definitions of outcomes reported in randomized controlled trials, and prospective and retrospective observational cohort studies investigating prehospital blood component transfusion in adult and pediatric patients with traumatic hemorrhage. Electronic database searching of PubMed, Embase, Web of Science, Cochrane, OVID, clinical trials.gov, and the Transfusion Evidence Library was completed in accordance with Preferred Reporting Items for Meta-analyses guidelines.Study Appraisal and Synthesis MethodsTwo review authors independently extracted outcome data. Unique lists of salutogenic (patient-reported health and wellbeing outcomes) and nonsalutogenic focused outcomes were established.

RESULTS

A total of 3,471 records were identified. Thirty-four studies fulfilled the inclusion criteria: 4 military (n = 1,566 patients) and 30 civilian (n = 14,398 patients), all between 2000 and 2020. Two hundred twelve individual non-patient-reported outcomes were identified, which collapsed into 20 outcome domains with varied definitions and timings. All primary outcomes measured effectiveness, rather than safety or complications. Sixty-nine percent reported mortality, with 11 different definitions. No salutogenic outcomes were reported.

CONCLUSION

There is heterogeneity in outcome reporting and definitions, an absence of patient-reported outcome, and an emphasis on clinical effectiveness rather than safety or adverse events in prehospital trauma transfusion trials. We recommend stakeholder consultation and a Delphi process to develop a clearly defined minimum core outcome set for prehospital trauma transfusion trials.

LEVEL OF EVIDENCE

Scoping systematic review, level III.

Pre-hospital transfusion of post-traumatic hemorrhage: Medical and regulatory aspects

Data of good methodological quality have recently become available to support prehospital use of transfusion in the severe trauma setting. Consistent with recent guidelines for the implementation of damage control resuscitation in the hospital in this setting and in the wake of numerous cohort study data from wartime medicine, they are now guided by recent guidelines for the use of freeze-dried plasma. The main difficulties to overcome in order to implement a practice are of a regulatory and logistic nature.

Hypocalcemia in Military Casualties From Point of Injury to Surgical Teams in Afghanistan

INTRODUCTION

Hypocalcemia is a known sequela of citrated blood product transfusion. Civilian data suggest hypocalcemia on hospital admission is associated with worse outcomes. Initial calcium levels in military casualties have not previously been analyzed. The objective of this retrospective review aimed to assess the initial calcium levels in military trauma casualties at different Forward Surgical Teams (FST) locations in Afghanistan and describe the effects of prehospital blood product administration on arrival calcium levels.

MATERIALS AND METHODS

This is a retrospective cohort analysis of military casualties arriving from point of injury to one of two FSTs in Afghanistan from August 2018 to February 2019 split into four locations. The primary outcome was incidence of hypocalcemia (ionized calcium < 1.20 mmol/L).

RESULTS

There were 101 patients included; 55 (54.5%) experienced hypocalcemia on arrival to the FST with a mean calcium of 1.16 mmol/L (95% confidence interval [CI], 1.14 to 1.18). The predominant mechanism of injury consisted of blast patterns, 46 (45.5%), which conferred an increased risk of hypocalcemia compared to all other patterns of injury (odds ratio = 2.42, P = .042). Thirty-eight (37.6%) patients required blood product transfusion. Thirty-three (86.8%) of the patients requiring blood product transfusion were hypocalcemic on arrival. Mean initial calcium of patients receiving blood product was 1.13 mmol/L (95% CI, 1.08 to 1.18), which was significantly lower than those who did not require transfusion (P = .01). Eight (7.9%) of the patients received blood products before arrival, with 6/8 (75%) presenting with hypocalcemia.

CONCLUSIONS

Hypocalcemia develops rapidly in military casualties and is prevalent on admission even before transfusion of citrated blood products. Blast injuries may confer an increased risk of developing hypocalcemia. This data support earlier use of calcium supplementation during resuscitation.

Prehospital Whole Blood Resuscitation Reduces Fluid Requirement While Maintaining Critical Physiology in a Model of Penetrating Traumatic Brain Injury and Hemorrhage: Implications on Resource-Limited Combat Casualty Care

ABSTRACT

Prehospital resuscitation using whole blood (WB) is the standard of care for hemorrhagic shock (HS) but there is no consensus recommendation for resuscitation in the presence of traumatic brain injury (TBI) due to a lack of sufficient evidence. In order to evaluate the optimal resuscitation strategies for TBI+HS, Sprague-Dawley rats were randomized into four groups based on resuscitation fluid and prehospital mean arterial pressure (MAP) threshold (n = 9-10/group): Lactated Ringer's (LR)-60 mm Hg (LR60), LR-70 mm Hg (LR70), WB-60 mm Hg (WB60), WB-70 mm Hg (WB70). All groups received a frontal penetrating ballistic-like brain injury followed by a 35-min period of HS. During the prehospital phase, rats received an initial bolus of resuscitation fluid (WB or LR) followed by LR as needed to maintain MAP above the designated threshold for 90 min. During the in-hospital phase, rats received definitive resuscitation with shed WB. Physiological parameters were recorded continuously and cerebral edema was measured at 3 and 24 h postinjury. The WB60 group demonstrated a significantly lower prehospital fluid requirement compared WB70, LR60, and LR70 (P < 0.05). Compared to the respective LR groups, both the WB60 and WB70 groups also demonstrated improved MAP, cerebral perfusion pressure, brain tissue oxygen tension, and cerebral edema. The edema benefits were observed at 3 h, but not 24 h postinjury, and were localized to the injury site. Together, these results provide evidence that prehospital WB resuscitation and lower MAP resuscitation thresholds can reduce the prehospital fluid requirement while still maintaining critical cerebral physiology in a model of HS and concomitant TBI.

Comparison of massive and emergency transfusion prediction scoring systems after trauma with a new Bleeding Risk Index score applied in-flight

BACKGROUND

Assessment of blood consumption (ABC), shock index (SI), and Revised Trauma Score (RTS) are used to estimate the need for blood transfusion and triage. We compared Bleeding Risk Index (BRI) score calculated with trauma patient noninvasive vital signs and hypothesized that prehospital BRI has better performance compared with ABC, RTS, and SI for predicting the need for emergent and massive transfusion (MT).

METHODS

We analyzed 2-year in-flight data from adult trauma patients transported directly to a Level I trauma center via helicopter. The BRI scores 0 to 1 were derived from continuous features of photoplethymographic and electrocardiographic waveforms, oximetry values, blood pressure trends. The ABC, RTS, and SI were calculated using admission data. The area under the receiver operating characteristic curve (AUROC) with 95% confidence interval (CI) was calculated for predictions of critical administration threshold (CAT, ≥3 units of blood in the first hour) or MT (≥10 units of blood in the first 24 hours). DeLong's method was used to compare AUROCs for different scoring systems. p < 0.05 was considered statistically significant.

RESULTS

Among 1,396 patients, age was 46.5 ± 20.1 years (SD), 67.1% were male. The MT rate was 3.2% and CAT was 7.6%, most (92.8%) were blunt injury. Mortality was 6.6%. Scene arrival to hospital time was 35.3 ± (10.5) minutes. The BRI prediction of MT with AUROC 0.92 (95% CI, 0.89-0.95) was significantly better than ABC, SI, or RTS (AUROCs = 0.80, 0.83, 0.78, respectively; 95% CIs 0.73-0.87, 0.76-0.90, 0.71-0.85, respectively). The BRI prediction of CAT had an AUROC of 0.91 (95% CI, 0.86-0.94), which was significantly better than ABC (AUROC, 077; 95% CI, 0.73-0.82) or RTS (AUROC, 0.79; 95% CI, 0.74-0.83) and better than SI (AUROC, 0.85; 95% CI, 0.80-0.89). The BRI score threshold for optimal prediction of CAT was 0.25 and for MT was 0.28.

CONCLUSION

The autonomous continuous noninvasive patient vital signs-based BRI score performs better than ABC, RTS, and SI predictions of MT and CAT. Bleeding Risk Index does not require additional data entry or expert interpretation.

LEVEL OF EVIDENCE

Prognostic test, level III.

Pre-hospital transfusion of red blood cells. Part 1: A scoping review of current practice and transfusion triggers

OBJECTIVES

The primary aim of this scoping review is to describe the current use of pre-hospital transfusion of red blood cells (PHTRBC) and to evaluate criteria used to initiate PHTRBC. The effects on patients' outcomes will be reviewed in Part 2.

BACKGROUND

Haemorrhage is a preventable cause of death in trauma patients, and transfusion of red blood cells is increasingly used by Emergency Medical Services (EMS) for damage control resuscitation. However, there are no guidelines and little consensus on when to initiate PHTRBC.

METHODS

PubMed and Web of Science were searched through January 2019; 71 articles were included.

RESULTS

Transfusion triggers vary widely and involve vital signs, clinical signs of poor tissue perfusion, point of care measurements and pre-hospital ultrasound imaging. In particular, hypotension (most often defined as systolic blood pressure ≤ 90 mmHg), tachycardia (most often defined as heart rate ≥ 120/min), clinical signs of poor perfusion (eg, prolonged capillary refill time or changes in mental status) and injury type (ie, penetrating wounds) are common pre-hospital transfusion triggers.

CONCLUSIONS

PHTRBC is increasingly used by Emergency Medical Services, but guidelines on when to initiate transfusion are lacking. We identified the most commonly used transfusion criteria, and these findings may provide the basis for consensus-based pre-hospital transfusion protocols.

Pre-hospital transfusion of red blood cells. Part 2: A systematic review of treatment effects on outcomes

The primary aim of this systematic review is to describe the effects of prehospital transfusion of red blood cells (PHTRBC) on patient outcomes. Damage control resuscitation attempts to prevent death through haemorrhage in trauma patients. In this context, transfusion of red blood cells is increasingly used by emergency medical services (EMS). However, evidence on the effects on outcomes is scarce. PubMed and Web of Science were searched through January 2019; 55 articles were included. No randomised controlled studies were identified. While several observational studies suggest an increased survival after PHTRBC, consistent evidence for beneficial effects of PHTRBC on survival was not found. PHTRBC appears to improve haemodynamic parameters, but there is no evidence that shock on arrival to hospital is averted, nor of an association with trauma induced coagulopathy or with length of stay in hospitals or intensive care units. In conclusion, PHTRBC is increasingly used by EMS, but there is no strong evidence for effects of PHTRBC on mortality. Further research with study designs that allow causal inferences is required for more conclusive evidence. The combination of PHTRBC with plasma, as well as the use of individualised transfusion criteria, may potentially show more benefits and should be thoroughly investigated in the future. The review was registered at Prospero (CRD42018084658).

What is the impact of prehospital blood product administration for patients with catastrophic haemorrhage: an integrative review

INTRODUCTION

Catastrophic haemorrhage is recognised as the leading cause of preventable death in trauma and is also prevalent in medical and other surgical aetiology. Prehospital blood product transfusion is increasingly available for both military and civilian emergency teams. Hospitals have well-established massive transfusion protocols for the resuscitation of this patient group, however the use and impact in the prehospital field is less understood.

AIM

To identify and evaluate the current knowledge surrounding prehospital blood product administration for patients with catastrophic haemorrhage.

METHODS

The integrative review method included systematic searching of online databases Medline, EMBASE, SCOPUS and CINAHL alongside hand-searching for primary research articles published prior to 19 November 2018. Papers were included if the population studied patients with catastrophic haemorrhage who received prehospital transfusion of blood products. The level of evidence and quality was evaluated using the NHMRC hierarchy of evidence. All identified full text articles were reviewed by all authors.

RESULTS

Twenty-two papers were included in the final analysis, including both civilian (16) and military (6) practice. The earliest publication for prehospital transfusion was 1999, with increasing prevalence in recent years. Findings were extracted and into two main categories; (1) transfusion processes included team staffing, product selection, and criteria for transfusion and (2) transfusion outcomes; transfusion safety, haemoglobin, hospital intervention and mortality.

DISCUSSION

The level of evidence specific to prehospital blood product transfusion is low, with predominantly retrospective methods and rarely sufficient sample sizes to reach statistical significance. Prehospital research is challenged by clinical and logistical variability preventing accurate cohort matching, sample sizes and inconsistent data collection. Evaluation of prehospital transfusion in isolation is also particularly problematic as multiple factors and developments in clinical practice affect patient outcomes and all samples were subject to survival bias. Conclusion The volume and strength of the available evidence prevents accurate evaluation of the intervention and definitive practice recommendations however prehospital transfusion is shown to be logistically achievable and without serious incident. The reviewed evidence broadly supports the translation of recent in-hospital studies, such as PROMTT and PROPPR. Further research specific to prehospital practice is required to guide the development of evidence-based protocols.