Systematic review of the effectiveness of prehospital critical care following out-of-hospital cardiac arrest

The forgotten cohort-lessons learned from prehospital trauma death: a retrospective cohort study

BACKGROUND

Trauma related deaths remain a relevant public health problem, in particular in the younger male population. A significant number of these deaths occur prehospitally without transfer to a hospital. These patients, sometimes termed "the forgotten cohort", are usually not included in clinical registries, resulting in a lack of information about prehospitally trauma deaths. The aim of the present study was to compare patients who died prehospital with those who sustained life-threatening injuries in order to analyze and potentially improve prehospital strategies.

METHODS

This cohort study included all primary operations carried out by Switzerland's largest helicopter emergency medical service (HEMS) between January 1, 2011, and December 31, 2021. We included all adult trauma patients with life-threatening or fatal conditions. The outcome of this study is the vital status of the patient at the end of mission, i.e. fatal or life-threatening. Injury, rescue characteristics, and interventions of the forgotten trauma cohort, defined as patients with a fatal injury (NACA score of VII), were compared with life-threatening injuries (NACA score V and VI).

RESULTS

Of 110,331 HEMS missions, 5534 primary operations were finally analyzed, including 5191 (93.8%) life-threatening and 343 (6.2%) fatal injuries. More than two-thirds of patients (n = 3772, 68.2%) had a traumatic brain injury without a significant difference between the two groups (p > 0.05). Thoracic trauma (44.6% vs. 28.7%, p < 0.001) and abdominal trauma (22.2% vs. 16.1%, p = 0.004) were more frequent in fatal missions whereas pelvic trauma was similar between the two groups (13.4% vs. 12.9%, p = 0.788). Pneumothorax decompression rate (17.2% vs. 3.7%, p < 0.001) was higher in the forgotten cohort group and measures for bleeding control (15.2% vs. 42.7%, p < 0.001) and pelvic belt application (2.9% vs. 13.1% p < 0.001) were more common in the life-threating injury group.

CONCLUSION

Chest decompression rates and measures for early hemorrhage control are areas for potential improvement in prehospital care.

Nine golden codes: improving the accuracy of Helicopter Emergency Medical Services (HEMS) dispatch-a retrospective, multi-organisational study in the East of England

BACKGROUND

Helicopter Emergency Medical Services (HEMS) are a limited and expensive resource, and should be intelligently tasked. HEMS dispatch was identified as a key research priority in 2011, with a call to identify a 'general set of criteria with the highest discriminating potential'. However, there have been no published data analyses in the past decade that specifically address this priority, and this priority has been reaffirmed in 2023. The objective of this study was to define the dispatch criteria available at the time of the initial emergency call with the greatest HEMS utility using a large, regional, multi-organizational dataset in the UK.

METHODS

This retrospective observational study utilized dispatch data from a regional emergency medical service (EMS) and three HEMS organisations in the East of England, 2016-2019. In a logistic regression model, Advanced Medical Priority Dispatch System (AMPDS) codes with ≥ 50 HEMS dispatches in the study period were compared with the remainder to identify codes with high-levels of HEMS patient contact and HEMS-level intervention/drug/diagnostic (HLIDD). The primary outcome was to identify AMPDS codes with a > 10% HEMS dispatch rate of all EMS taskings that would result in 10-20 high-utility HEMS dispatches per 24-h period in the East of England. Data were analysed in R, and are reported as number (percentage); significance was p < 0.05.

RESULTS

There were n = 25,491 HEMS dispatches (6400 per year), of which n = 23,030 (90.3%) had an associated AMPDS code. n = 13,778 (59.8%) of HEMS dispatches resulted in patient contact, and n = 8437 (36.6%) had an HLIDD. 43 AMPDS codes had significantly greater rates of patient contact and/or HLIDD compared to the reference group. In an exploratory analysis, a cut-off of ≥ 70% patient contact rate and/or ≥ 70% HLIDD (with a > 10% HEMS dispatch of all EMS taskings) resulted in 17 taskings per 24-h period. This definition derived nine AMPDS codes with high HEMS utility.

CONCLUSION

We have identified nine 'golden' AMPDS codes, available at the time of initial emergency call, that are associated with high-levels of whole-system and HEMS utility in the East of England. We propose that UK EMS should consider immediate HEMS dispatch to these codes.

Cost-effectiveness of catheter ablation versus medical therapy for the treatment of atrial fibrillation in the United Kingdom

Introduction

Research evidence has shown that catheter ablation is a safe and superior treatment for atrial fibrillation (AF) compared to medical therapy, but real‐world practice has been slow to adopt an early interventional approach. This study aims to determine the cost effectiveness of catheter ablation compared to medical therapy from the perspective of the United Kingdom.

Methods

A patient‐level Markov health‐state transition model was used to conduct a cost‐utility analysis. The population included patients previously treated for AF with medical therapy, including those with heart failure (HF), simulated over a lifetime horizon. Data sources included published literature on utilization and cardiovascular event rates in real world patients, a systematic literature review and meta‐analysis of randomized controlled trials for AF recurrence, and publicly available government data/reports on costs.

Results

Catheter ablation resulted in a favorable incremental cost‐effectiveness ratio (ICER) of £8614 per additional quality adjusted life years (QALY) gained when compared to medical therapy. More patients in the medical therapy group failed rhythm control at any point compared to catheter ablation (72% vs. 24%) and at a faster rate (median time to treatment failure: 3.8 vs. 10 years). Additionally, catheter ablation was estimated to be more cost‐effective in patients with AF and HF (ICER = £6438) and remained cost‐effective over all tested time horizons (10, 15, and 20 years), with the ICER ranging from £9047–£15 737 per QALY gained.

Conclusion

Catheter ablation is a cost‐effective treatment for atrial fibrillation, compared to medical therapy, from the perspective of the UK National Health Service.

Hypertonic versus isotonic crystalloid infusion for cerebral perfusion pressure in a porcine experimental cardiac arrest model

BACKGROUND

The effect of intravenous (IV) fluid administration type on cerebral perfusion pressure (CePP) during cardiopulmonary resuscitation (CPR) is controversial. The purpose of this study was to evaluate the association between IV fluid type and CePP in a porcine cardiac arrest model.

METHODS

We randomly assigned 12 pigs to the hypertonic crystalloid, isotonic crystalloid and no-fluid groups. After 4 min of untreated ventricular fibrillation (VF), chest compression was conducted for 2 cycles (CC only). Chest compression with IV fluid infusion (CC + IV) was followed for 2 cycles. Advanced life support, including defibrillation and epinephrine, was added for 8 cycles (ALS phase). Mean arterial pressure (MAP), intracranial pressure (ICP) and CePP were measured. A paired t-test was used to measure the mean difference in CePP.

RESULTS

Twelve pigs underwent the experiment. The hypertonic crystalloid group showed higher CePP values than those demonstrated by the isotonic crystalloid group from ALS cycles 2 to 8. The MAP values in the hypertonic group were higher than those in the isotonic group starting at ALS cycle 2. The ICP values in the hypertonic group were lower than those in the isotonic group starting at ALS cycle 4. From ALS cycles 2 to 8, the reduction in the mean difference in the isotonic group was larger than that in the other groups.

CONCLUSION

In a VF cardiac arrest porcine study, the hypertonic crystalloid group showed higher CePP values by maintaining higher MAP values and lower ICP values than those of the isotonic crystalloid group.

Does experience in prehospital post-resuscitation critical care affect outcomes? A retrospective cohort study

AIMS OF THE STUDY

Helicopter Emergency Medical Services (HEMS) often provide post-resuscitation care. Our aims were to investigate whether physicians' frequent exposure to prehospital post-resuscitation care is associated with differences in (1) medical management, (2) achieving treatment targets recommended by resuscitation guidelines, (3) survival.

METHODS

We conducted a retrospective cohort study using data from a national HEMS quality register. We included patients between January 1st, 2012 and September 9th, 2019 who received post-resuscitation care by a HEMS physician. We excluded patients <16 years old. For each patient we determined the number of post-resuscitation cases the physician had attended in the previous 12 months. Patients were divided in to three groups: low (0-5), intermediate (6-11) and high exposure (≥12 cases). Medical management and proportions within treatment targets were compared. Survival at 30-days and 1-year was analysed by multivariate logistic regression analysis, controlling for known prognostic factors.

RESULTS

2272 patients were analysed. Patients in the high exposure group had mechanical ventilation and vasoactive medications initiated more often (P < 0.001 and P = 0.008, respectively) and on-scene times were longer (P < 0.001). The target for blood pressure was achieved more often in this group (P = 0.026), but targets for oxygenation and ventilation were not. We did not see an association between survival and physicians' exposure to post-resuscitation care (odds ratio 0.96, 95% confidence interval 0.70-1.33 for low and 0.78, 0.56-1.08 for intermediate, compared to high exposure).

CONCLUSIONS

Physicians with more, frequent exposure take a more active approach to post-resuscitation care, but this does not seem to improve survival.

European Resuscitation Council Guidelines 2021: Epidemiology of cardiac arrest in Europe

In this section of the European Resuscitation Council Guidelines 2021, key information on the epidemiology and outcome of in and out of hospital cardiac arrest are presented. Key contributions from the European Registry of Cardiac Arrest (EuReCa) collaboration are highlighted. Recommendations are presented to enable health systems to develop registries as a platform for quality improvement and to inform health system planning and responses to cardiac arrest.

Can We Predict Good Survival Outcomes by Classifying Initial and Re-Arrest Rhythm Change Patterns in Out-of-Hospital Cardiac Arrest Settings?

Objective

The purpose of this study was to investigate whether a change in prehospital arrest rhythms could allow medical personnel to predict survival outcomes in patients who achieved a return of spontaneous circulation (ROSC) in the setting of out-of-hospital cardiac arrest (OHCA).

Methods

The design of this study was retrospective, multi-regional, observational, and cross-sectional with a determining period between August 2015 and July 2016. Cardiac arrest rhythms were defined as a shockable rhythm (S), which refers to ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT), and non-shockable rhythm (NS), which refers to pulseless electrical activity or asystole. Survival to admission, survival to discharge, and good cerebral performance category (CPC) (CPC 1 or 2) were defined as good survival outcomes.

Results

A total of 163 subjects were classified into four groups according to the rhythm change pattern: NS→NS (98), S→S (27), S→NS (23), and NS→S (15). NS→NS pattern was used as the reference in logistic regression analysis. In the case of survival to hospital admission, the odds ratio (OR) (95% CI) of the S→S pattern was the highest [12.63 (3.56-44.85), p: <0.001 by no correction] and [7.29 (1.96-27.10), p = 0.003 with adjusting]. In the case of survival to hospital discharge, the OR (95% CI) of the S→S pattern was the highest [37.14 (11.71-117.78), p: <0.001 by no correction] and [13.85 (3.69-51.97), p: <0.001 with adjusting]. In the case of good CPC (CPC 1 or 2) at discharge, the OR (95% CI) of the S→S pattern was the highest [96 (19.14-481.60), p: <0.001 by no correction] and [149.69 (19.51-1148.48), p: <0.001 with adjusting].

Conclusions

The S→S group showed the highest correlation with survival to hospital admission, survival to hospital discharge, and good CPC (CPC 1 or 2) at discharge compared to the NS→NS group. Verifying changes in initial cardiac arrest rhythm and prehospital re-arrest (RA) rhythm patterns after prehospital ROSC can help us predict good survival outcomes in the OHCA setting.

The first seven years of nationally organized helicopter emergency medical services in Finland - the data from quality registry

Background

Helicopter Emergency Medical Services (HEMS) play an important role in prehospital care of the critically ill. Differences in funding, crew composition, dispatch criteria and mission profile make comparison between systems challenging. Several systems incorporate databases for quality control, performance evaluation and scientific purposes. FinnHEMS database was incorporated for such purposes following the national organization of HEMS in Finland 2012. The aims of this study are to describe information recorded in the database, data collection, and operational characteristics of Finnish HEMS during 2012–2018.

Methods

All dispatches of the six Finnish HEMS units recorded in the national database from 2012 to 2018 were included in this observational registry study. Five of the units are physician staffed, and all are on call 24/7. The database follows a template for uniform reporting in physician staffed pre-hospital services, exceeding the recommended variables of relevant guidelines.

Results

The study included 100,482 dispatches, resulting in 33,844 (34%) patient contacts. Variables were recorded with little or no missing data. A total of 16,045 patients (16%) were escorted by HEMS to hospital, of which 2239 (2%) by helicopter. Of encountered patients 4195 (4%) were declared deceased on scene. The number of denied or cancelled dispatches was 66,638 (66%). The majority of patients were male (21,185, 63%), and the median age was 57.7 years. The median American Society of Anesthesiologists Physical Scale classification was 2 and Eastern Cooperative Oncology Group performance class 0. The most common reason for response was trauma representing 26% (8897) of the patients, followed by out-of-hospital cardiac arrest 20% (6900), acute neurological reason excluding stroke 13% (4366) and intoxication and related psychiatric conditions 10% (3318). Blunt trauma (86%, 7653) predominated in the trauma classification.

Conclusions

Gathering detailed and comprehensive data nationally on all HEMS missions is feasible. A national database provides valuable insights into where the operation of HEMS could be improved. We observed a high number of cancelled or denied missions and a low percentage of patients transported by helicopter. The medical problem of encountered patients also differs from comparable systems.

Does second EMS unit response time affect outcomes of OHCA in multi-tiered system? A nationwide observational study

OBJECTIVES

The time dependence of a multi-tier response for out-of-hospital cardiac arrest (OHCA) is unclear. The aim of this study was to evaluate the time-dependent effect of EMS response type in a multi-tiered system on the clinical outcomes of OHCA.

METHODS

Adult EMS-treated OHCA of presumed cardiac etiology who were not witnessed by EMS between January 2015 and December 2017 were included. The main exposure was EMS response type: single-tier response, early multi-tier response (0-18 min from call to second EMS arrival), and late multi-tier response (19 min from call to second EMS arrival). The primary outcome was good neurologic recovery at the time of discharge from the hospital. Multivariate logistic regression analysis was performed, adjusting for patient-community and prehospital variables.

RESULTS

Among 54,436 patients, 29,995 patients (55.1%), 21,552 patients (39.6%), and 2889 patients (5.3%) were treated by single-tiered EMS, early multi-tiered EMS, and late multi-tiered EMS, respectively. Good neurological recovery and survival to discharge were more frequent in the early multi-tiered response group (6.4% and 9.7%) than in the single-tiered response group (4.8% and 7.5%) or late multi-tiered response group (3.1% and 5.8%). Compared to the single-tiered response group, the early multi-tiered response group was more likely to have good neurological recovery (adjusted OR, 95% CI: 1.15 [1.06-1.26]), but the late multi-tiered response group was less likely to have good neurological recovery (adjusted OR, 95% CI: 0.76 [0.61-0.96]).

CONCLUSION

In our basic to intermediate-tiered EMS system, early multi-tier response was associated with improved survival and good neurological recovery.

The effect of prehospital critical care on survival following out-of-hospital cardiac arrest: A prospective observational study

AIM

To examine the effect of prehospital critical care on survival following OHCA, compared to routine advanced life support (ALS) care.

METHODS

We undertook a prospective multi-centre cohort study including two ambulance services and six prehospital critical care services in the United Kingdom (UK), between September 2016 and October 2017. Inclusion criteria were adult patients with non-traumatic OHCA treated by either prehospital critical care teams or ALS paramedics. Patients who received prehospital critical care were matched to those receiving ALS using propensity score matching. Primary outcome was survival to hospital discharge; secondary outcome was survival to hospital admission.

RESULTS

The primary analysis included 658 patients with OHCA receiving prehospital critical care and 1847 patients receiving ALS care. Rates of survival to hospital discharge (primary outcome) were 11.9% in both groups; rates of survival to hospital admission (secondary outcome) were 34.4% and 27.7% in the prehospital critical care and ALS group, respectively. The corresponding odds ratios for survival to hospital discharge and survival to hospital admission with prehospital critical care were 1.06 (95% confidence interval 0.75-1.49) and 1.39 (95% confidence interval 1.10-1.75), respectively. Results were consistent across subgroups and sensitivity analyses.

CONCLUSIONS

Despite a positive association with the secondary outcome of survival to hospital admission, prehospital critical care was not associated with increased rates of survival to hospital discharge following OHCA.

Cost-effectiveness of advanced life support and prehospital critical care for out-of-hospital cardiac arrest in England: a decision analysis model

OBJECTIVES

This research aimed to answer the following questions: What are the costs of prehospital advanced life support (ALS) and prehospital critical care for out-of-hospital cardiac arrest (OHCA)? What is the cost-effectiveness of prehospital ALS? What improvement in survival rates from OHCA would prehospital critical care need to achieve in order to be cost-effective?

SETTING

A single National Health Service ambulance service and a charity-funded prehospital critical care service in England.

PARTICIPANTS

The patient population is adult, non-traumatic OHCA.

METHODS

We combined data from previously published research with data provided by a regional ambulance service and air ambulance charity to create a decision tree model, coupled with a Markov model, of costs and outcomes following OHCA. We compared no treatment for OHCA to the current standard of care of prehospital ALS, and prehospital ALS to prehospital critical care. To reflect the uncertainty in the underlying data, we used probabilistic and two-way sensitivity analyses.

RESULTS

Costs of prehospital ALS and prehospital critical care were £347 and £1711 per patient, respectively. When costs and outcomes of prehospital, in-hospital and postdischarge phase of OHCA care were combined, prehospital ALS was estimated to be cost-effective at £11 407/quality-adjusted life year. In order to be cost-effective in addition to ALS, prehospital critical care for OHCA would need to achieve a minimally economically important difference (MEID) in survival to hospital discharge of 3%-5%.

CONCLUSION

This is the first economic analysis to address the question of cost-effectiveness of prehospital critical care following OHCA. While costs of either prehospital ALS and/or critical care per patient with OHCA are relatively low, significant costs are incurred during hospital treatment and after discharge in patients who survive. Knowledge of the MEID for prehospital critical care can guide future research in this field.

TRIAL REGISTRATION NUMBER

ISRCTN18375201.

Prehospital determinants of successful resuscitation after traumatic and non-traumatic out-of-hospital cardiac arrest

Background

Out-of-hospital cardiac arrest (OHCA) is prevalent in the UK. Reported survival is lower than in countries with comparable healthcare systems; a better understanding of outcome determinants may identify areas for improvement.

Methods

An analysis of 9109 OHCA attended in East of England between 1 January 2015 and 31 July 2017. Univariate descriptives and multivariable analysis were used to understand the determinants of survival for non-traumatic cardiac arrest (NTCA) and traumatic cardiac arrest (TCA). Two Utstein outcome variables were used: survival to hospital admission and hospital discharge.

Results

The incidence of OHCA was 55.1 per 100 000 population/year. The overall survival to hospital admission was 27.6% (95% CI 26.7% to 28.6%) and the overall survival to discharge was 7.9% (95% CI 7.3% to 8.5%). Survival to hospital admission and survival to hospital discharge were both greater in the NTCA group compared with the TCA group: 27.9% vs 19.3% p=0.001, and 8.0% vs 3.8% p=0.012 respectively.

Determinants of NTCA and TCA survival were different, and varied according to the outcome examined. In NTCA, bystander cardiopulmonary resuscitation (CPR) was associated with survival at discharge but not at admission, and the likelihood of bystander CPR was dependent on geographical socioeconomic status. An air ambulance was associated with increased survival to both hospital admission and discharge in NTCA, but only with survival to admission in TCA.

Conclusion

NTCA and TCA are clinically distinct entities with different predictors for outcome—future OHCA reports should aim to separate arrest aetiologies. Determinants of survival to hospital admission and discharge differ in a way that likely reflects the determinants of neurological injury. Bystander CPR public engagement may be best focused in more deprived areas.

Do RATs save lives? A service evaluation of an out-of-hospital cardiac arrest team in an English ambulance service

INTRODUCTION

Out-of-hospital cardiac arrest (OHCA) is a major public health problem, leading to a substantial number of deaths in the UK. In response to this, the Yorkshire Ambulance Service NHS Trust (YAS) has introduced red arrest teams (RATs). RAT members attend a three-day training course, focusing on the technical and non-technical skills that are required to effectively team lead an OHCA and provide high quality post-resuscitation care. This evaluation aims to determine the impact of the RATs on survival to 30 days and return of spontaneous circulation (ROSC) at hospital.

METHODS

All adult (≥ 18 years) OHCAs entered onto the YAS computer aided dispatch (CAD) system between 1 October 2015 and 30 September 2017 were included if the patient was resuscitated and the cause of the arrest was considered to be medical in origin. Multi-variable logistic regression models were created to enable adjustment for common predictors of survival and ROSC.

RESULTS

During the 2-year data collection period, YAS attended 15,151 cardiac arrests. After removing ineligible cases, 5868 cardiac arrests remained. RATs attended 2000/5868 (34.1%) incidents, with each RAT attending a median of 13 cardiac arrests (IQR 7-23, min. 1, max. 78).The adjusted odds ratios suggest that a RAT on scene is associated with a slight increase in the odds of survival to 30 days (OR 1.01, 95% CI 0.74-1.38) and odds of ROSC on arrival at hospital (OR 1.13, 95% CI 0.99-1.29), compared to the odds of not having a RAT present, although neither result is statistically significant.

CONCLUSION

The presence of a RAT paramedic was associated with a small increase in survival to 30 days and ROSC on arrival at hospital, although neither were statistically significant. Larger prospective studies are required to determine the effect of roles such as RAT on outcomes from OHCA.

Impact of prehospital physician-led cardiopulmonary resuscitation on neurologically intact survival after out-of-hospital cardiac arrest: A nationwide population-based observational study

AIM

The impact of prehospital physician care for out-of-hospital cardiac arrest (OHCA) on long-term neurological outcome is unclear. We aimed to determine the association between emergency medical services (EMS) physician-led cardiopulmonary resuscitation (CPR) versus paramedic-led CPR and neurologically intact survival after OHCA.

METHODS

We assessed 613,251 patients using All-Japan Utstein Registry data from 2011 to 2015 retrospectively. The main outcome measure was 1-month neurologically intact survival after OHCA, defined as Cerebral Performance Category 1 or 2 (CPC 1-2).

RESULTS

Before propensity score matching, the 1-month CPC 1-2 rate was significantly higher in EMS physician-led CPR than in paramedic-led CPR [5.7% (1114/19,551) vs. 2.5% (14,859/593,700), P < 0.001; adjusted odds ratio (aOR), 1.50; 95% confidence interval (CI), 1.40-1.61]. After propensity score matching, EMS physician-led CPR showed more favourable neurological outcomes than paramedic-led CPR [6.0% (996/16,612) vs. 4.6% (766/16,612), P < 0.001; aOR, 1.44; 95% CI, 1.29-1.60]. In most subgroup analyses after matching, physician-led CPR had higher 1-month CPC 1-2 rates than paramedic-led CPR did; however, 1-month CPC 1-2 rates were similar between the two CPR configurations for patients aged <18 years (5.6% vs. 8.2%, P = 0.10; aOR, 0.82; 95% CI, 0.46-1.47) and those who received bystander defibrillation (26.3% vs. 21.5%; P = 0.10; aOR, 1.07; 95% CI, 0.74-1.53).

CONCLUSION

Within the limitations of this retrospective observational research, EMS physician-led CPR for OHCA was associated with improved 1-month neurologically intact survival compared with paramedic-led CPR. However, neurologically intact survival was similar for patients aged <18 years and those receiving bystander defibrillation.

Variations in stakeholders' priorities and views on randomisation and funding decisions in out-of-hospital cardiac arrest: An exploratory study

BACKGROUND AND AIMS

Prehospital critical care for out-of-hospital cardiac arrest (OHCA) is a complex and largely unproven intervention. During research to examine this intervention, we noted significant differences in stakeholders' views about research, randomisation, and the funding of prehospital critical care for OHCA. We aimed to answer the following questions: What are stakeholders' priorities for prehospital research? What are stakeholders' views on randomisation of prehospital critical care? How do stakeholders consider allocation of resources in prehospital care?

METHODS

We undertook an explanatory qualitative framework analysis of interviews and focus group with 5 key stakeholder groups: patients and public, air ambulance charities, ambulance service commissioners, prehospital researchers, and prehospital critical care providers.

RESULTS

We undertook 3 focus group discussions with a total of 23 participants and 8 interviews with a total of 9 participants. Despite sharing a common appreciation of the concepts of scientific enquiry, fairness, and beneficence, the 5 relevant stakeholder groups displayed divergent views of research and funding strategies regarding the intervention of prehospital critical care for the condition of OHCA. The reasons for this divergence could largely be explained through the different personal experiences and situational contexts of each stakeholder group. Many aspects of the strategies suggested by the stakeholder groups only partially aligned with principles of traditional evidence-based medicine, but were held with strong conviction.

DISCUSSION

Analysis of the views of 5 stakeholder groups regarding research and the funding of prehospital critical care for OHCA revealed shared values but a variety of different strategies to achieve these. This knowledge can help researchers in similar fields in the planning and presentation of their research, to maximise impact on decision making.

Effects of advanced life support versus basic life support on the mortality rates of patients with trauma in prehospital settings: a study protocol for a systematic review and meta-analysis

INTRODUCTION

Advanced life support (ALS) is thought to be associated with improved survival in prehospital trauma care when compared with basic life support (BLS). However, evidence on the benefits of prehospital ALS for patients with trauma is controversial. Therefore, we aim to clarify if ALS improves mortality in patients with trauma when compared with BLS by conducting a systematic review and meta-analysis of the recent literature.

METHODS AND ANALYSIS

We will perform searches in PubMed, Embase and the Cochrane Central Register of Controlled Trials for published observational studies, controlled before-and-after studies, randomised controlled trials and other controlled trials conducted in humans and published until March 2017. We will screen search results, assess study selection, extract data and assess the risk of bias in duplicate; disagreements will be resolved through discussions. Data from clinically homogeneous studies will be pooled using a random-effects meta-analysis, heterogeneity of effects will be assessed using the χ² test of homogeneity, and any observed heterogeneity will be quantified using the I² statistic. Last, the Grading of Recommendations Assessment, Development and Evaluation approach will be used to rate the quality of the evidence.

ETHICS AND DISSEMINATION

Our study does not require ethical approval as it is based on findings of previously published articles. Results will be disseminated through publication in a peer-reviewed journal, presentations at relevant conferences and publications for patient information.

TRIAL REGISTRATION NUMBER

PROSPERO (International Prospective Register of Systematic Reviews) registration number CRD42017054389.