Are on-scene blood transfusions by a helicopter emergency medical service useful and safe? A multicentre case–control study

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.

Prehospital Blood Transfusion in Helicopter Emergency Medical Services: An Italian Survey

OBJECTIVE

Hemorrhage remains the most common cause of preventable death after trauma. Prehospital blood product (PHBP) administration may improve outcomes. No data are available about PHBP use in Italian helicopter emergency medical services (HEMS). The primary aim of this survey was to establish the degree of PHBP used throughout Italy. The secondary aims were to evaluate the main indications for their use, the opinions about PHBPs, and users' experience.

METHODS

The study group performed a telephone/e-mail survey of all 56 Italian HEMS bases. The questions concerned whether PHBPs were used in their HEMS bases, the frequency of transfusions, the PHBP used, and the perceived benefits.

RESULTS

Four of 56 HEMS bases use PHBPs. Overall, 7% have prehospital access to packed red cells and only 1 to fresh plasma. In addition to blood product administration, 4 of 4 use tranexamic acid, and 3 of 4 also use fibrinogen. Seventy-five percent use PHBPs once a month and 25% once a week. The users' experience was that PHBPs are beneficial and lifesaving.

CONCLUSION

Only 4 of 56 HEMS in Italy use PHBPs. There is an absolute consensus among providers on the benefit of PHBPs despite the lack of evidence on PHBP use.

Prehospital Critical Care Blood Product Administration: Quantifying Clinical Benefit

BACKGROUND

Prehospital blood transfusion has been widely practiced in the military and is drawing renewed scrutiny after many years of civilian use.

OBJECTIVE

The objective of this article is to quantify the benefit derived from prehospital transfusion of blood products.

METHODS

Deidentified data were extracted retrospectively from the flight records of a critical care transportation program between April 2018 and January 2020. Patients who were transported before a prehospital blood transfusion protocol were compared with patients after initiation of the blood transfusion protocol. Demographic data, vital signs, laboratory analytics, and other outcome measures were analyzed.

RESULTS

Nine scene transport patients who met the transfusion criteria before a blood transfusion protocol were compared with 11 patients transported after initiation of the protocol. Identical outcome measures were analyzed. Patients who received prehospital blood transfusions had a statistically significantly longer hospital length of stay (16.5 vs 3.7 days, P = .03) and were more often taken directly to the operating room (80% vs 28%, P = .04). No statistically significant difference was identified when comparing mean arterial pressure, heart rate, respiratory rate, hemoglobin, hematocrit, or survival to hospital discharge.

CONCLUSIONS

Trauma patients who received prehospital blood transfusion had a longer hospital length of stay and were more often taken directly to the operating room, but without improvement in survival.

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.

Blood Product Supply for a Helicopter Emergency Medical Service

Background

Long patient transport times to trauma centers are a well-known problem in sparsely populated regions with a low hospital density. Transfusion of red blood cell concentrates (RBC) and plasma improves outcome of trauma patients with severe bleeding. Helicopter emergency services (HEMS) are frequently employed to provide early advanced medical care and to reduce time to hospital admission. Supplying HEMS with blood products allows prehospital transfusion and may help to prevent exsanguination or prolonged hemorrhagic shock. We have investigated the maintenance of blood product quality under air transport conditions and the logistical steps to introduce a HEMS blood depot into routine practice.

Methods

A risk analysis was performed and a validation plan developed. A special, commercially available transport container for blood products was identified. Maintenance of temperature conditions between 2 and 6°C in the box were monitored at ambient temperatures up to 35°C over 48 h. Quality of blood products before and after helicopter air transport were evaluated including (1) for RBCs: hemoglobin, hematocrit, hemolysis rate; (2) for thawed plasma: aPTT, INR, single clotting factor activities. The logistics for blood supply of the regional HEMS were developed by the transfusion service of the Greifswald University Hospital in collaboration with the in-hospital transport team, the HEMS team, and the HEMS operator.

Results

The transport container maintained a temperature below 6°C up to 36 h at 35°C ambient temperature. Vibration during helicopter operation did not impair quality of RBC and thawed plasma. To provide blood products for HEMS at least two transport containers and an additional set of cooling tiles is needed as the cooling tiles need a special temperature priming over 20 h. The two boxes were used at alternate days. To reduce wastage, RBCs and thawed plasmas were exchanged every fourth day and reintegrated into the blood bank inventory for further in-hospital use.

Conclusions

Supplying HEMS with RBCs and plasma is feasible. Helicopter transport has no negative impact on blood product quality. The logistic challenges require close collaboration between the HEMS team and the blood transfusion service.

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.

Prehospital administration of blood and plasma products

PURPOSE OF REVIEW

Posttraumatic bleeding following major trauma is life threatening for the patient and remains a major global health issue. Bleeding after major trauma is worsened by trauma-induced coagulopathy (TIC). TIC consists of acute trauma coagulopathy and resuscitation coagulopathy. The early diagnosis and management of prehospital TIC management are challenging.

RECENT FINDINGS

Concepts for early diagnosis and management of civilian prehospital TIC management are evolving. The feasibility of prehospital blood component as well as coagulation factor transfusion has been proven.

SUMMARY

Due to different national guidelines and regulations of blood component therapies there is a wide heterogeneity in concepts of prehospital damage control resuscitation. Tranexamic acid administration is widely accepted, whereas the transfusion of whole blood, blood components, or coagulations factors needs further examination in the civilian setting.

Evaluation of a Prehospital Rotation by Senior Residents: A Web-Based Survey

The added value of prehospital emergency medicine is usually assessed by measuring patient-centered outcomes. Prehospital rotations might however also help senior residents acquire specific skills and knowledge. To assess the perceived added value of the prehospital rotation in comparison with other rotations, we analyzed web-based questionnaires sent between September 2011 and August 2020 to senior residents who had just completed a prehospital rotation. The primary outcome was the perceived benefit of the prehospital rotation in comparison with other rotations regarding technical and non-technical skills. Secondary outcomes included resident satisfaction regarding the prehospital rotation and regarding supervision. A pre-specified subgroup analysis was performed to search for differences according to the participants’ service of origin (anesthesiology, emergency medicine, or internal medicine). The completion rate was of 71.5% (113/158), and 91 surveys were analyzed. Most senior residents found the prehospital rotation either more beneficial or much more beneficial than other rotations regarding the acquisition of technical and non-technical skills. Anesthesiology residents reported less benefits than other residents regarding pharmacological knowledge acquisition and confidence as to their ability to manage emergency situations. Simulation studies should now be carried out to confirm these findings.

Multiple trauma management in mountain environments - a scoping review : Evidence based guidelines of the International Commission for Mountain Emergency Medicine (ICAR MedCom). Intended for physicians and other advanced life support personnel

Background

Multiple trauma in mountain environments may be associated with increased morbidity and mortality compared to urban environments.

Objective

To provide evidence based guidance to assist rescuers in multiple trauma management in mountain environments.

Eligibility criteria

All articles published on or before September 30th 2019, in all languages, were included. Articles were searched with predefined search terms.

Sources of evidence

PubMed, Cochrane Database of Systematic Reviews and hand searching of relevant studies from the reference list of included articles.

Charting methods

Evidence was searched according to clinically relevant topics and PICO questions.

Results

Two-hundred forty-seven articles met the inclusion criteria. Recommendations were developed and graded according to the evidence-grading system of the American College of Chest Physicians. The manuscript was initially written and discussed by the coauthors. Then it was presented to ICAR MedCom in draft and again in final form for discussion and internal peer review. Finally, in a face-to-face discussion within ICAR MedCom consensus was reached on October 11th 2019, at the ICAR fall meeting in Zakopane, Poland.

Conclusions

Multiple trauma management in mountain environments can be demanding. Safety of the rescuers and the victim has priority. A crABCDE approach, with haemorrhage control first, is central, followed by basic first aid, splinting, immobilisation, analgesia, and insulation. Time for on-site medical treatment must be balanced against the need for rapid transfer to a trauma centre and should be as short as possible. Reduced on-scene times may be achieved with helicopter rescue. Advanced diagnostics (e.g. ultrasound) may be used and treatment continued during transport.

Civilian prehospital transfusion - experiences from a French region

BACKGROUND AND OBJECTIVES

Haemorrhagic shock is a leading cause of avoidable mortality in prehospital care. For several years, our centre has followed a procedure of transfusing two units of packed red blood cells outside the hospital. Our study's aim was twofold: describe the patient characteristics of those receiving prehospital blood transfusions and analyse risk factors for the 7-day mortality rate.

MATERIALS AND METHODS

We performed a monocentric retrospective observational study. Demographic and physiological data were recovered from medical records. The primary outcome was mortality at seven days for all causes. All patients receiving prehospital blood transfusions between 2013 and 2018 were included.

RESULTS

Out of 116 eligible patients, 56 patients received transfusions. Trauma patients (n = 18) were younger than medical patients (n = 38) (P = 0·012), had lower systolic blood pressure (P = 0·001) and had higher haemoglobin levels (P = 0·016). Mortality was higher in the trauma group than the medical group (P = 0·015). In-hospital trauma patients received more fresh-frozen plasma and platelet concentrate than medical patients (P < 0·05). Predictive factors of 7-day mortality included transfusion for trauma-related reasons, low Glasgow Coma Scale, low peripheral oxygen saturation, prehospital intensive resuscitation, existing coagulation disorders, acidosis and hyperlactataemia (P < 0·05).

CONCLUSION

Current guidelines recommend early transfusion in patients with haemorrhagic shock. Prehospital blood transfusions are safe. Coagulation disorders and acidosis remain a cause of premature death in patients with prehospital transfusions.

Prehospital administration of blood products: experiences from a Finnish physician-staffed helicopter emergency medical service

BACKGROUND

Massive infusions of crystalloids into bleeding hypotensive patients can worsen the outcome. Military experience suggests avoiding crystalloids using early damage control resuscitation with blood components in out of hospital setting. Civilian emergency medical services have since followed this idea. We describe our red blood cell protocol in helicopter emergency medical services (HEMS) and initial experience with prehospital blood products from the first 3 years after implementation.

METHODS

We performed an observational study of patients attended by the HEMS unit between 2015 and 2018 to whom packed red blood cells, freeze-dried plasma, or both were transfused. The Student's two-sided T-test was used to compare vitals in prehospital phase with those at the hospital's emergency department. A p-value < 0.05 was considered significant.

RESULTS

Altogether, 62 patients received prehospital transfusions. Of those, 48 (77%) were trauma patients and most (n = 39, 81%) suffered blunt trauma. The transfusion began at a median of 33 (IQR 21-47) minutes before hospital arrival. Median systolic blood pressure showed an increase from 90 mmHg (IQR 75-111 mmHg) to 107 mmHg (IQR 80-124 mmHg; P < 0.026) during the prehospital phase. Four units of red blood cells were handled incorrectly when unused red blood cells were returned and required disposal during a three-year period. There were no reported adverse effects from prehospital transfusions.

CONCLUSION

We treated two patients per month with prehospital blood products. A prehospital physician-staffed HEMS unit carrying blood products is a feasible and safe method to start transfusion roughly 30 min before arrival to the hospital.

TRIAL REGISTRATION

The study was retrospectively registered by the Tampere University Hospital's Medical Director (R19603) 5.11.2019.

Decision making in prehospital traumatic cardiac arrest; A qualitative study

BACKGROUND

Despite improving survival of patients in prehospital traumatic cardiac arrest (TCA), initiation and/or discontinuation of resuscitation of TCA patients remains a subject of debate among prehospital emergency medical service providers. The aim of this study was to identify factors that influence decision making by prehospital emergency medical service providers during resuscitation of patients with TCA.

METHODS

Twenty-five semi-structured interviews were conducted with experienced ambulance nurses, HEMS nurses and HEMS physicians individually, followed by a focus group discussion. Participants had to be currently active in prehospital medicine in the Netherlands. Interviews were encoded for analysis using ATLAS.ti. Using qualitative analysis, different themes around decision making in TCA were identified.

RESULTS

Eight themes were identified as being important factors for decision making during prehospital TCA. These themes were: (1) factual information (e.g., electrocardiography rhythm or trauma mechanism); (2) fear of providing futile care or major impairment if return of spontaneous circulation was obtained; (3) potential organ donation; (4) patient age; (5) suspicion of attempted suicide; (6) presence of bystanders or family; (7) opinions of other team members; and (8) training and education. Several ambulance nurses reported they do not feel adequately supported by the current official national ambulance guidelines on TCA, nor did they feel sufficiently trained to perform pre-hospital interventions such as endotracheal intubation or needle thoracocentesis on these patients.

CONCLUSION

Eight themes were identified as being important for decision making during prehospital TCA. While guidelines based on prognostic factors are important, it should be recognized that decision making in TCA is impacted by more than factual information alone. This should be reflected in educational programs and future guidelines.

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).

Red cell use in trauma

PURPOSE OF REVIEW

Red cell transfusions are commonly used in management of hemorrhage in trauma patients. The appropriate indications and criteria for transfusion are still debated. Here, we summarize the recent findings on the use of red cell transfusion in trauma setting.

RECENT FINDINGS

Recent evidence continues to support the long-established link between allogeneic transfusion and worse clinical outcomes, reinstating the importance of more judicious use of allogeneic blood and careful consideration of benefits versus risks when making transfusion decisions. Studies support restrictive transfusion strategies (often based on hemoglobin thresholds of 7-8 g/dl) in most patient populations, although some argue more caution in specific populations (e.g. patients with traumatic brain injury) and more studies are needed to determine if these patients benefit from less restrictive transfusion strategies. It should be remembered that anemia remains an independent risk factor for worse outcomes and red cell transfusion does not constitute a lasting treatment. Anemia should be properly assessed and managed based on the cause and using hematinic medications as indicated.

SUMMARY

Although the debate on hemoglobin thresholds for transfusion continues, clinicians should not overlook proper management of the underlying issue (anemia).

Association of Prehospital Plasma Transfusion With Survival in Trauma Patients With Hemorrhagic Shock When Transport Times Are Longer Than 20 Minutes: A Post Hoc Analysis of the PAMPer and COMBAT Clinical Trials

Importance

Both military and civilian clinical practice guidelines include early plasma transfusion to achieve a plasma to red cell ratio approaching 1:1 to 1:2. However, it was not known how early plasma should be given for optimal benefit. Two recent randomized clinical trials were published, with apparently contradictory results. The Prehospital Air Medical Plasma (PAMPer) clinical trial showed a nearly 30% reduction in mortality with plasma transfusion in the prehospital environment, while the Control of Major Bleeding After Trauma (COMBAT) clinical trial showed no survival improvement.

Objective

To facilitate a post hoc combined analysis of the COMBAT and PAMPer trials to examine questions that could not be answered by either clinical trial alone. We hypothesized that prehospital transport time influenced the effects of prehospital plasma on 28-day mortality.

Design, Setting, and Participants

A total of 626 patients in the 2 clinical trials were included. Patients with trauma and hemorrhagic shock were randomly assigned to receive either standard care or 2 U of thawed plasma followed by standard care in the prehospital environment. Data analysis was performed between September 2018 and January 2019.

Interventions

Prehospital transfusion of 2 U of plasma compared with crystalloid-based resuscitation.

Main Outcomes and Measures

The main outcome was 28-day mortality.

Results

In this post hoc analysis of 626 patients (467 men [74.6%] and 159 women [25.4%]; median [interquartile range] age, 42 [27-57] years) who had trauma with hemorrhagic shock, a Cox regression analysis showed a significant overall survival benefit for plasma (hazard ratio [HR], 0.65; 95% CI, 0.47-0.90; P = .01) after adjustment for injury severity, age, and clinical trial cohort (COMBAT or PAMPer). A significant association with prehospital transport time was detected (from arrival on scene to arrival at the trauma center). Increased mortality was observed in patients in the standard care group when prehospital transport was longer than 20 minutes (HR, 2.12; 95% CI, 1.05-4.30; P = .04), while increased mortality was not observed in patients in the prehospital plasma group (HR, 0.78; 95% CI, 0.40-1.51; P = .46). No serious adverse events were associated with prehospital plasma transfusion.

Conclusions and Relevance

These data suggest that prehospital plasma is associated with a survival benefit when transport times are longer than 20 minutes and that the benefit-risk ratio is favorable for use of prehospital plasma.

Trial Registration

ClinicalTrials.gov identifiers: NCT01838863 (COMBAT) and NCT01818427 (PAMPer).

Prehospital Blood Product Transfusion in Mountain Rescue Operations

Severely injured patients with hemorrhage present major challenges for emergency medical services, especially during mountain rescue missions in which harsh environmental conditions and long out-of-hospital times are frequent. Because uncontrolled hemorrhage is the leading cause of death within the first 48 hours after severe trauma, initiating damage control resuscitation (DCR) as early as possible after severe trauma and exporting the concept of DCR to the out-of-hospital arena is pivotal for patient survival. Appropriate bleeding control, management of coagulopathy, and transfusion of blood products are core aspects of DCR. This review summarizes the available evidence on out-of-hospital blood product transfusion and the management of coagulopathy with a special focus on mountain rescue missions. An overview of upcoming trials and possible future trends in the management of coagulopathy during rescue operations is provided.