Physician staffed helicopter emergency medical service dispatch via centralised control or directly by crew - case identification rates and effect on the Sydney paediatric trauma system

Improving ambulance dispatch triage to trauma: A scoping review using the framework of development and evaluation of clinical prediction rules

OBJECTIVE

Ambulance dispatch algorithms should function as clinical prediction rules, identifying high acuity patients for advanced life support, and low acuity patients for non-urgent transport. Systematic reviews of dispatch algorithms are rare and focus on study types specific to the final phases of rule development, such as impact studies, and may miss the complete value-added evidence chain. We sought to summarise the literature for studies seeking to improve dispatch in trauma by performing a scoping review according to standard frameworks for developing and evaluating clinical prediction rules.

METHODS

We performed a scoping review searching MEDLINE, EMBASE, CINAHL, the CENTRAL trials registry, and grey literature from January 2005 to October 2021. We included all study types investigating dispatch triage to injured patients in the English language. We reported the clinical prediction rule phase (derivation, validation, impact analysis, or user acceptance) and the performance and outcomes measured for high and low acuity trauma patients.

RESULTS

Of 2067 papers screened, we identified 12 low and 30 high acuity studies. Derivation studies were most common (52%) and rule-based computer-aided dispatch was the most frequently investigated (23 studies). Impact studies rarely reported a prior validation phase, and few validation studies had their impact investigated. Common outcome measures in each phase were infrequent (0 to 27%), making a comparison between protocols difficult. A series of papers for low acuity patients and another for pediatric trauma followed clinical prediction rule development. Some low acuity Medical Priority Dispatch System codes are associated with the infrequent requirement for advanced life support and clinician review of computer-aided dispatch may enhance dispatch triage accuracy in studies of helicopter emergency medical services.

CONCLUSIONS

Few derivation and validation studies were followed by an impact study, indicating important gaps in the value-added evidence chain. While impact studies suggest clinician oversight may enhance dispatch, the opportunity exists to standardize outcomes, identify trauma-specific low acuity codes, and develop intelligent dispatch systems.

Characteristics of Children Cared for by a Physician-Staffed Helicopter Emergency Medical Service

OBJECTIVES

The effectiveness of Japanese helicopter emergency medical services (HEMS) and interventions at the scene is not clear as regard children. For effective use of HEMS at the clinical scene, we need to clarify the characteristics of pediatric patients cared for by HEMS. Therefore, the objective of this study was to describe the characteristics of pediatric scene flights and to describe the procedures performed on the patients.

METHODS

This was a retrospective cohort study based on the database for children aged younger than 18 years who were cared for by physician-staffed HEMS of Ibaraki prefecture, in Japan. We reviewed the database for air medical transports conducted at our institution from July 2010 to December 2016.

RESULTS

During the 6.5-year period, the Ibaraki HEMS attended to 288 children. The median age of the children was 11 (interquartile range, 5-14) years. Of the total, 196 (68.1%) of the children had trauma-related injuries. The head was the most common site of significant injuries (12.4%). The most common cause of nontrauma incidents was seizure (9.0%). In 65.9% of the patients, the injury or illness was of mild or moderate severity at the scene. An intervention was applied at the scene in 76.0% of the cases: 75.1%, intravenous route; 6.9%, intubation; and 13.4%, drug administration. Of those patients, 29.1% were discharged from the emergency department. In-hospital mortality accounted for 1.5% (n = 2) of the cases.

CONCLUSIONS

Although the condition at the scene of most of the pediatric patients transported by the physician-staffed HEMS was not severe, an intervention was frequently applied from the scene. Improving the dispatch criteria and monitoring compliance are needed for appropriate use of HEMS.

Physician-staffed helicopter emergency medical services augment ground ambulance paediatric airway management in urban areas: a retrospective cohort study

Objectives

Paediatric intubation is a high-risk procedure for ground emergency medical services (GEMS). Physician-staffed helicopter EMS (PS-HEMS) may bring additional skills, drugs and equipment to the scene including advanced airway management beyond the scope of GEMS even in urban areas with short transport times. This study aimed to evaluate prehospital paediatric intubation performed by a PS-HEMS when dispatched to assist GEMS in a large urban area and examine how often PS-HEMS provided airway intervention that was not or could not be provided by GEMS.

Methods

We performed a retrospective observational study from July 2011 to December 2016 of a PS-HEMS in a large urban area (Sydney, Australia), which responds in parallel to GEMS. GEMS intubate without adjuvant neuromuscular blockade, whereas the PS-HEMS use neuromuscular blockade and anaesthetic agents. We examined endotracheal intubation success rate, first-look success rate and complications for the PS-HEMS and contrasted this with the advanced airway interventions provided by GEMS prior to PS-HEMS arrival.

Results

Overall intubation success rate was 62/62 (100%) and first-look success was 59/62 (95%) in the PS-HEMS-treated group, whereas the overall success rate was 2/7 (29%) for the GEMS group. Peri-intubation hypoxia was documented in 5/65 (8%) of the PS-HEMS intubation attempts but no other complications were reported. However, 3/7 (43%) of the attempted intubations by GEMS were oesophageal intubations, two of which were unrecognised.

Conclusions

PS-HEMS have high success with low complication rates in paediatric prehospital intubation. Even in urban areas with rapid GEMS response, PS-HEMS activated in parallel can provide safe and timely advanced prehospital airway management for seriously ill and injured children beyond the scope of GEMS practice. Review of GEMS airway management protocols and the PS-HEMS case identification and dispatch system in Sydney is warranted.

Impact of Trauma System Structure on Injury Outcomes: A Systematic Review and Meta-Analysis

BACKGROUND

The effectiveness of trauma systems in decreasing injury mortality and morbidity has been well demonstrated. However, little is known about which components contribute to their effectiveness. We aimed to systematically review the evidence of the impact of trauma system components on clinically important injury outcomes.

METHODS

We searched MEDLINE, EMBASE, Cochrane CENTRAL, and BIOSIS/Web of Knowledge, gray literature and trauma association Web sites to identify studies evaluating the association between at least one trauma system component and injury outcome. We calculated pooled effect estimates using inverse-variance random-effects models. We evaluated quality of evidence using GRADE criteria.

RESULTS

We screened 15,974 records, retaining 41 studies for qualitative synthesis and 19 for meta-analysis. Two recommended trauma system components were associated with reduced odds of mortality: inclusive design (odds ratio [OR] = 0.72 [0.65-0.80]) and helicopter transport (OR = 0.70 [0.55-0.88]). Pre-Hospital Advanced Trauma Life Support was associated with a significant reduction in hospital days (mean difference [MD] = 5.7 [4.4-7.0]) but a nonsignificant reduction in mortality (OR = 0.78 [0.44-1.39]). Population density of surgeons was associated with a nonsignificant decrease in mortality (MD = 0.58 [-0.22 to 1.39]). Trauma system maturity was associated with a significant reduction in mortality (OR = 0.76 [0.68-0.85]). Quality of evidence was low or very low for mortality and healthcare utilization.

CONCLUSIONS

This review offers low-quality evidence for the effectiveness of an inclusive design and trauma system maturity and very-low-quality evidence for helicopter transport in reducing injury mortality. Further research should evaluate other recommended components of trauma systems and non-fatal outcomes and explore the impact of system component interactions.

Clinician tasking in ambulance control improves the identification of major trauma patients and pre-hospital critical care team tasking

INTRODUCTION

Trauma remains the fourth leading cause of death in western countries and is the leading cause of death in the first four decades of life. NICE guidance in 2016 advocated the attendance of pre-hospital critical care trauma team (PHCCT) in the pre-hospital stage of the care of patients with major trauma. Previous publications support dispatch by clinicians who are also actively involved in the delivery of the PHCCT service; however there is a lack of objective outcome measures across the current reviewed evidence base. In this study, we aimed to assess the accuracy of PHCCT clinician led dispatch, when measured by Injury Severity Score (ISS).

METHODS

A retrospective cohort study over a 2 year period pre and post implementation of a PHCCT clinician led dispatch of PHCCT for potential major trauma patients, using national ambulance data combined with national trauma registry data.

RESULTS

A total of 99,702 trauma related calls were made to SAS including 495 major trauma patients with an ISS >15, and a total of 454 dispatches of a PHCCT. Following the introduction of a PHCCT clinician staffed trauma desk, the sensitivity for major trauma was increased from 11.3% to 25.9%. The difference in sensitivity between the pre and post trauma desk group was significant at 14.6% (95% CI 7.4%-21.4%, p < .001).

DISCUSSION

The results from the study support the results from other studies recommending that a PHCCT clinician should be located in ambulance control to identify major trauma patients as early as possible and co-ordinate the response.

Outcomes after cancelled helicopter emergency medical service missions due to concurrencies: a retrospective cohort study

BACKGROUND

Appropriate dispatch criteria and helicopter emergency medical service (HEMS) crew decisions are crucial for avoiding over-triage and reducing the number of concurrencies. The aim of the present study was to compare patient outcomes after completed HEMS missions and missions cancelled by the HEMS due to concurrencies.

METHODS

Missions cancelled due to concurrencies (AMB group) and completed HEMS missions (HEMS group) in Western Norway from 2004 to 2013 were assessed. Outcomes were survival to hospital discharge, physiology score in the emergency department, emergency interventions in the hospital, type of department for patient admittance, and length of hospital stay.

RESULTS

Survival to discharge was similar in the two groups. One-third of the primary missions in the HEMS group and 13% in the AMB group were patients with pre-hospital conditions posing an acute threat to life. In a sub group analysis of these patients, HEMS patients were younger, more often admitted to an intensive care unit, and had an increased survival to discharge. In addition, the HEMS group had a greater proportion of patients with deranged physiology in the emergency department according to an early warning score.

CONCLUSION

Patients in the HEMS group seemed to be critically ill more often and received more emergency interventions, but the two groups had similar in-hospital mortality. Patients with pre-hospital signs of acute threat to life were younger and presented increased survival in the HEMS group.

Are severely injured trauma victims in Norway offered advanced pre-hospital care? National, retrospective, observational cohort

Background

Studies of severely injured patients suggest that advanced pre‐hospital care and/or rapid transportation provides a survival benefit. This benefit depends on the disposition of resources to patients with the greatest need. Norway has 19 Emergency Helicopters (HEMS) staffed by anaesthesiologists on duty 24/7/365. National regulations describe indications for their use, and the use of the national emergency medical dispatch guideline is recommended. We assessed whether severely injured patients had been treated or transported by advanced resources on a national scale.

Methods

A national survey was conducted collecting data for 2013 from local trauma registries at all hospitals caring for severely injured patients. Patients were analysed according to hospital level; trauma centres or acute care hospitals with trauma functions. Patients with an Injury Severity Score (ISS) > 15 were considered severely injured.

Results

Three trauma centres (75%) and 17 acute care hospitals (53%) had data for trauma patients from 2013, a total of 3535 trauma registry entries (primary admissions only), including 604 victims with an ISS > 15. Of these 604 victims, advanced resources were treating and/or transporting 51%. Sixty percent of the severely injured admitted directly to trauma centres received advanced services, while only 37% of the severely injured admitted primarily to acute care hospitals received these services.

Conclusion

A highly developed and widely distributed HEMS system reached only half of severely injured trauma victims in Norway in 2013.

HEMS dispatch: A systematic review

Introduction

Helicopter emergency medical services dispatch is a contentious issue in modern prehospital services. Whilst the link between helicopter emergency medical services and improved patient outcome is well evidenced, allocation to the most appropriate incidents remains problematic. It is unclear which model of deployment is the most efficient at targeting major trauma and whether this can be improved with a change in dispatch process. The objective of this study was to have an overview of the evidence for dispatch models of helicopter emergency medical services to critically ill or injured patients.

Methods

This systematic review was conducted in accordance with a protocol developed from the PRISMA guidelines. MEDLINE, Embase, CINAHL and the Cochrane library were searched focusing on keywords involving dispatch of helicopter emergency medical services resources.

Results

Ninety-seven articles were screened and 14 articles were eligible for inclusion. Most were of low quality, with three of moderate quality. Heterogeneity in the methodology of included articles precluded meta-analysis, so a narrative review was performed.

Conclusions

This review demonstrates the lack of evidence surrounding helicopter emergency medical services dispatch models. Whilst it is not possible to identify a method of dispatch that will optimize helicopter emergency medical services allocation, common themes within the literature indicate that helicopter emergency medical services use is region specific and dispatch criteria should be designed to match specific systems. Additionally, mechanism of injury as well as physiological data from scene was shown to be the most accurate indicator for helicopter emergency medical services attendance.

Outcomes of Physician-Staffed Versus Non-Physician-Staffed Helicopter Transport for ST-Elevation Myocardial Infarction

Background

The effect of physician‐staffed helicopter emergency medical service (HEMS) on ST‐elevation myocardial infarction (STEMI) patient transfer is unknown. The purpose of this study was to evaluate the characteristics and outcomes of physician‐staffed HEMS (Physician‐HEMS) versus non‐physician‐staffed (Standard‐HEMS) in patients with STEMI.

Methods and Results

We studied 398 STEMI patients transferred by either Physician‐HEMS (n=327) or Standard‐HEMS (n=71) for primary or rescue percutaneous coronary intervention at 2 hospitals between 2006 and 2014. Data were collected from electronic medical records and each institution's contribution to the National Cardiovascular Data Registry. Baseline characteristics were similar between groups. Median electrocardiogram‐to‐balloon time was longer for the Standard‐HEMS group than for the Physician‐HEMS group (118 vs 107 minutes; P=0.002). The Standard‐HEMS group was more likely than the Physician‐HEMS group to receive nitroglycerin (37% vs 15%; P<0.001) and opioid analgesics (42.3% vs 21.7%; P<0.001) during transport. In‐hospital adverse outcomes, including cardiac arrest, cardiogenic shock, and serious arrhythmias, were more common in the Standard‐HEMS group (25.4% vs 11.3%; P=0.002). After adjusting for age, sex, Killip class, and transport time, patients transferred by Standard‐HEMS had increased risk of any serious in‐hospital adverse event (odds ratio=2.91; 95% CI=1.39–6.06; P=0.004). In‐hospital mortality was not statistically different between the 2 groups (9.9% in the Standard‐HEMS group vs 4.9% in the Physician‐HEMS group; P=0.104).

Conclusions

Patients with STEMI transported by Standard‐HEMS had longer transport times, higher rates of nitroglycerin and opioid administration, and higher rates of adjusted in‐hospital events. Efforts to better understand optimal transport strategies in STEMI patients are needed.

Physician staffed helicopter emergency medical service case identification - a before and after study in children

BACKGROUND

Severely injured children may have better outcomes when transported directly to a Paediatric Trauma Centre (PTC). A case identification system using the crew of a physician staffed helicopter emergency medical service (P-HEMS) that identified severely injured children for P-HEMS dispatch was previously associated with high rates of direct transfer. It was theorised that discontinuation of this system may have resulted in deterioration of system performance.

METHODS

Severe paediatric trauma cases were identified from a state based trauma registry over two time periods. In Period A the P-HEMS case identification system operated in parallel with a paramedic dispatcher (Rapid Launch Trauma Co-ordinator-RLTC) operating from a central control room (n = 71). In Period B the paramedic dispatcher operated in isolation (n = 126). Case identification and direct transfer rates were compared as was time to arrival at the PTC.

RESULTS

After cessation of the P-HEMS system the rate of case identification fell from 62 to 31 % (P < 0.001), identification of fatal cases fell from 100 to 47 % (P < 0.001), the rate of direct transfer to a PTC fell from 66 to 53 % (P = 0.076) and the time to arrival in a PTC increased from a median 69 (interquartile range 52 - 104) mins to 97 (interquartile range 56 - 305) mins (P = 0.003). When analysing the rate of direct transfer to a PTC as a function of team composition, after adjusting for age and injury severity scores, there was no change in the rate between the physician and paramedic groups across the two time periods (relative risk 0.92, 95 % CI: 0.44 to 1.41).

DISCUSSION

The parallel identification system improves case identification rates and decreases time to arrival at the PTC, whilst requiring RLTC authorisation preserves the safety and efficiency benefits of centralised dispatch. The model could be extended to adult patients with similar benefits.

CONCLUSIONS

A case identification system relying solely on RLTC paramedics resulted in a significantly lower case identification rate and increased prehospital time with a non-significant fall in direct transfer rate to the PTC. The elimination of the P-HEMS input from the tasking system resulted in worse performance indicators and has the potential for poorer outcomes.

Paediatric trauma systems and their impact on the health outcomes of severely injured children: An integrative review

BACKGROUND

Injury is a leading cause of death and disability for children. Regionalised trauma systems have improved outcomes for severely injured adults, however the impact of adult orientated trauma systems on the outcomes of severely injured children remains unclear.

AIMS

This research aims to identify the impact of trauma systems on the health outcomes of children following severe injury.

METHODS

Integrative review with data sourced from Medline, Embase, CINAHL, Scopus and hand searched references. Abstracts were screened for inclusion/exclusion criteria with fifty nine articles appraised for quality, analysed and synthesised into 3 main categories.

RESULTS

The key findings from this review include: (1) a lack of consistency of prehospital and inhospital triage criteria for severely injured children leading to missed injuries, secondary transfer and poor utilisation of finite resources; (2) severely injured children treated at paediatric trauma centres had improved outcomes when compared to those treated at adult trauma centres, particularly younger children; (3) major causes of delays to secondary transfer are unnecessary imaging and failure to recognise the need for transfer; (4) a lack of functional or long term outcomes measurements identified in the literature.

CONCLUSIONS

Research designed to identify the best processes of care and describe the impacts of trauma systems on the long term health outcomes of severely injured children is required. Ideally all phases of care including prehospital, paediatric triage trauma criteria, hospital type and interfacility transfer should be included, focusing on timeliness and appropriateness of care. Outcome measures should include long term functional outcomes in addition to mortality.

Retrospective evaluation of prehospital triage, presentation, interventions and outcome in paediatric drowning managed by a physician staffed helicopter emergency medical service

Background

Drowning patients may benefit from the advanced airway management capabilities that can be provided by physician staffed helicopter emergency medical services. The aim of this study is to describe paediatric drowning patients treated by such a service examining tasking systems, initial physiology at the incident scene, survival and neurological outcome.

Methods

Retrospective analysis of paediatric drowning victims over a 5- year period. Case identification system, patient age, site of drowning, presence or absence of cardiac output, first Glasgow Coma Scale (GCS) score and interventions were collected from prehospital notes, and survival and neurological outcomes from hospital and rehabilitation notes.

Results

The P-HEMS direct case identification system operating in parallel with a central control system identified all severe drowning cases but 3 of 7 cases (43 %) were missed when the central control system operated in isolation. All severe drowning cases (22) identified for P-HEMS response were intubated and transported directly to a paediatric specialist centre. Intubation required adjuvant anaesthesia in 10 (45 %) cases. All children with GCS greater than eight on arrival of the P-HEMS survived neurologically intact. Seven of eight children with a GCS between four and seven survived without neurological impairment and all children with a GCS greater than three survived. Four of twelve asystolic children survived including one child who at 18 months post drowning is neurologically normal. All children who survived had return of spontaneous circulation prior to arrival in the emergency department.

Conclusions

P-HEMS played a significant role in the management of severe paediatric drowning in this case series. Requirement for P-HEMS only interventions were high and all identified cases were transferred directly to a paediatric specialist centre. Discontinuation of the P-HEMS direct case identication system that operated during the majority of the study period resulted in deterioration in system performance with some paediatric drowning cases subsequently not identified for P-HEMS response being transported to adult hospitals.

Does the use of dedicated dispatch criteria by Emergency Medical Services optimise appropriate allocation of advanced care resources in cases of high severity trauma? A systematic review

BACKGROUND AND OBJECTIVES

The deployment of Enhanced Care Teams (ECTs) capable of delivering advanced clinical interventions for patients at the scene of incidents is commonplace by Emergency Medical Services in most developed countries. It is unclear whether primary dispatch models for ECT resources are more efficient at targeting deployment to patients with severe trauma than secondary dispatch, following requests from EMS personnel at scene. The objective of this study was to review the evidence for primary and secondary models in the targeted dispatch of ECT resources to patients with severe traumatic injury.

METHODS

This review was completed in accordance with a protocol developed using the PRISMA guidelines. We conducted a search of the MEDLINE, EmBase, Web of Knowledge/Science databases and the Cochrane library, focussed on subject headings and keywords involving the dispatch of ECT resources by Emergency Medical Services. Design and results of each study were described. Heterogeneity in the design of the included studies precluded the completion of a meta-analysis. A narrative synthesis of the results therefore was performed.

RESULTS

Five hundred and forty-eight articles were screened, and 16 were included. Only one study compared the performance of the different models of dispatch. A non-statistically significant reduction in the length of time for HEMS resources to reach incident scenes of 4min was found when primary dispatch protocols were utilised compared to requests from EMS personnel at scene. No effect on mortality; severity of injury or proportion of patients admitted to intensive care was observed. The remaining studies examined the processes utilised within current primary dispatch models but did not perform any comparative analysis with existing secondary dispatch models.

CONCLUSIONS

This review identifies a lack of evidence supporting the role of primary dispatch models in targeting the deployment of Enhanced Care Teams to patients with severe injuries. It is therefore not possible to identify a model for ECT dispatch within pre-hospital systems that optimises resource utilisation. Further studies are required to assess the efficiency of systems utilised at each stage of the process used to dispatch Enhanced Care Team resources to incidents within regionalised pre-hospital trauma systems.

Prehospital response model and time to CT scan in blunt trauma patients; an exploratory analysis of data from the head injury retrieval trial

Background

It has been suggested that prehospital care teams that can provide advanced prehospital interventions may decrease the transit time through the ED to CT scan and subsequent surgery. This study is an exploratory analysis of data from the Head Injury Retrieval Trial (HIRT) examining the relationship between prehospital team type and time intervals during the prehospital and ED phases of management.

Methods

Three prehospital care models were compared; road paramedics, and two physician staffed Helicopter Emergency Medical Services (HEMS) - HIRT HEMS and the Greater Sydney Area (GSA) HEMS. Data on prehospital and ED time intervals for patients who were randomised into the HIRT were extracted from the trial database. Additionally, data on interventions at the scene and in the ED, plus prehospital entrapment rate was also extracted. Subgroups of patients that were not trapped or who were intubated at the scene were also specifically examined.

Results

A total of 3125 incidents were randomised in the trial yielding 505 cases with significant injury that were treated by road paramedics, 302 patients treated by the HIRT HEMS and 45 patients treated by GSA HEMS. The total time from emergency call to CT scan was non-significantly faster in the HIRT HEMS group compared with road paramedics (medians of 1.9 hours vs. 2.1 hours P = 0.43) but the rate of prehospital intubation was 41% higher in the HIRT HEMS group (46.4% vs. 5.3% P < 0.001). Most time intervals for the GSA HEMS were significantly longer with a regression analysis indicating that GSA HEMS scene times were 13 (95% CI, 7–18) minutes longer than the HIRT HEMS independent of injury severity, entrapment or interventions performed on scene.

Conclusion

This study suggests that well-rehearsed and efficient interventions carried out on-scene, by a highly trained physician and paramedic team can allow earlier critical care treatment of severely injured patients without increasing the time elapsed between injury and hospital-based intervention. There is also indication that role specialisation improves time intervals in physician staffed HEMS which should be confirmed with purpose designed trials.

The study protocol for the Head Injury Retrieval Trial (HIRT): a single centre randomised controlled trial of physician prehospital management of severe blunt head injury compared with management by paramedics

BACKGROUND

The utility of advanced prehospital interventions for severe blunt traumatic brain injury (BTI) remains controversial. Of all trauma patient subgroups it has been anticipated that this patient group would most benefit from advanced prehospital interventions as hypoxia and hypotension have been demonstrated to be associated with poor outcomes and these factors may be amenable to prehospital intervention. Supporting evidence is largely lacking however. In particular the efficacy of early anaesthesia/muscle relaxant assisted intubation has proved difficult to substantiate.

METHODS

This article describes the design and protocol of the Head Injury Retrieval Trial (HIRT) which is a randomised controlled single centre trial of physician prehospital care (delivering advanced interventions such as rapid sequence intubation and blood transfusion) in addition to paramedic care for severe blunt TBI compared with paramedic care alone.

RESULTS

Primary endpoint is Glasgow Outcome Scale score at six months post injury. Issues with trial integrity resulting from drop ins from standard care to the treatment arm as the result of policy changes by the local ambulance system are discussed.

CONCLUSION

This randomised controlled trial will contribute to the evaluation of the efficacy of advance prehospital interventions in severe blunt TBI.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00112398.