Background: The effective treatment of airway compromise in trauma and non-trauma patients is important.
Hypoxia and hypotension are predictors of negative patient outcomes and increased mortality, and may be
important quality indicators of care provided by emergency medical services. Excluding cardiac arrests, critical
trauma and non-trauma patients remain the two major groups to which helicopter emergency medical services
(HEMS) are dispatched. Several studies describe the impact of pre-hospital hypoxia or hypotension on trauma
patients, but few studies compare this in trauma and non-trauma patients. The primary aim was to describe the
incidence of pre-hospital hypoxia and hypotension in the two groups receiving pre-hospital tracheal intubation
(TI) by physician-staffed HEMS.
Methods: Data were collected prospectively over a 12-month period, using a uniform Utstein-style airway
template. Twenty-one physician-staffed HEMS in Europe and Australia participated. We compared peripheral
oxygen saturation and systolic blood pressure before and after definitive airway management. Data were
analysed using Cochran?Mantel?Haenszel methods and mixed-effects models.
Results: Eight hundred forty three trauma patients and 422 non-trauma patients receiving pre-hospital TI
were included. Non-trauma patients had significantly lower predicted mean pre-intervention SpO2 compared
to trauma patients. Post-intervention and admission SpO2 for the two groups were comparable. However, 3% in
both groups were still hypoxic at admission. For hypotension, the differences between the groups were less
prominent. However, 9% of trauma and 10% of non-trauma patients were still hypotensive at admission. There
was no difference in short-term survival between trauma (97%) and non-trauma patients (95%). Decreased level
of consciousness was the most frequent indication for TI, and was associated with increased survival to hospital
(cOR 2.8; 95% CI: 1.4?5.4).Conclusions: Our results showed that non-trauma patients had a higher incidence of hypoxia before TI than
trauma patients, but few were hypoxic at admission. The difference for hypotension was less prominent, but
one in ten patients were still hypotensive at admission. Further investigations are needed to identify reversible
causes that may be corrected to improve haemodynamics in the pre-hospital setting. We found high survival
rates to hospital in both groups, suggesting that physician-staffed HEMS provide high-quality emergency airway
m

Objective

This study sought to assess the impact of a helicopter emergency medical service (HEMS) capable of night operations.

Methods

This is a retrospective case review of all night HEMS missions attended by a charity air ambulance service in South East England over a 2-year period (October 1, 2013, to October 1, 2015).

Results

During the 2-year trial period, the HEMS service undertook a total of 5,004 missions and attended to 3,728 patients. Of these, 1,373 missions, or 27.4% of the total HEMS activity, were night missions. Night missions increased from year 1 (n = 617) to year 2 (n = 756). A mean of 1.9 missions per night were conducted, resulting in the treatment of 1.3 patients per night. A higher proportion of patients were transported to a major trauma center at night (64% vs. 51%, Ç2 = 41.8, P

Conclusion

A 2-year trial period of a night HEMS service in South East England showed the predicted activation rate, with a mean of 1.3 patients attended to per night. Patients transported to a major trauma center had a mean Injury Severity Score of 23. Further research is warranted to determine if the night HEMS service conveys a patient outcome benefit.

Major trauma is a leading cause of serious morbidity and mortality.1,2 Advanced prehospital care can improve the outcome for major trauma patients.3,4 Kent, Surrey & Sussex Air Ambulance Trust (KSSAAT) delivers advanced prehospital care by deploying 2 doctor/paramedic teams by aircraft or response car. The 2 teams respond from 2 separate bases in South East England, 1 based in Surrey and 1 based in Kent. Historically, KSSAAT was operational between 0700 and 1900 hours 7 days per week. However, major trauma frequently occurs overnight, and the lack of a night helicopter emergency medical service (HEMS) was felt to be detrimental to enhanced patient care because no enhanced prehospital medical care was available overnight.

Before any night HEMS service was available, KSSAAT undertook a prospective study in 2010 to explore the possible impact that a night HEMS service may have.5 This study showed the likely need of a night HEMS team being tasked 1.7 times per night during the hours of 1900 to 0700. The incidence of these predicted cases continued throughout the entire night period but with gradually decreasing frequency. Most nights of the week were predicted to have similar levels of activity with the exception of Saturday, which appeared to be the busiest night of the week. A high number of the cases identified resulted in the patient being transported to a major trauma center (MTC), indicating that HEMS activation may well have been warranted.

Based on this study, KSSAAT made the decision to commit itself to exploring the options for night HEMS operations. This commitment was the start of a 3-year research, development, and training process, which culminated with the launch of a 2-year night HEMS operational trial on the night of September 26, 2013. At this point, KSSAAT became the first 24/7 helicopter-based HEMS in the United Kingdom. The purpose of this study is to review the activity, case mix, and demographics of the 2-year night HEMS trial period. We sought to compare the actual activity of the night HEMS service with the previously estimated need.

Introduction

Major trauma can result in both life-threatening haemorrhage and traumatic brain injury (TBI). The pre-hospital management of these conditions, particularly in relation to the cardiovascular system, is very different. TBI can result in cardiovascular instability but the exact incidence remains poorly described. This study explores the incidence of cardiovascular instability in patients undergoing pre-hospital anaesthesia for suspected TBI.

Methods

Retrospective case series of all pre-hospital trauma patients attended by Kent, Surrey & Sussex Air Ambulance Trust (United Kingdom) trauma team during the period 1 January 2015?31 December 2016. Patients were included if they showed clinical signs of TBI, underwent pre-hospital anaesthesia and hospital computed tomography scanning subsequently confirmed an isolated TBI.

Results

Out of 121 patients with confirmed isolated TBI, 68 were cardiovascularly stable throughout the pre-anaesthesia phase, whilst 53 (44%) showed signs of instability (HR/Ã/100bpm and/or SBP/Â/100/mmHg pre-anaesthesia). Hypotension (SBP/Â/100) with or without tachycardia was present in 14 (12%) patients. 10 (8%) patients with isolated TBI received pre-hospital blood product transfusion.

Conclusion

Increased awareness that traumatic brain injury can cause significant derangement to heart rate and blood pressure, even in the absence of major haemorrhage, would allow the pre-hospital clinician to treat cardiovascular instability with the most appropriate means, such as crystalloid and vasopressors, to limit secondary brain injury.

Background

Poor communication during patient handover is recognised internationally as a root cause of a significant proportion of preventable deaths. Improving the accuracy and quality of handover may reduce associated mortality and morbidity. Although the practice of handover between Ambulance and Emergency Department clinicians has received some attention over recent years there is little evidence to support handover best practice within the prehospital domain. Further research is therefore urgently required to understand the most appropriate way to deliver clinical information exchange in the pre-hospital environment. We aimed to investigate current clinical information exchange practices, perceived challenges and the preferred handover mnemonic for use during transfer of high acuity patients between ambulance clinicians and specialist prehospital teams.

Methods

A national, cross-sectional questionnaire study. Participants were road based ambulance clinicians (RBAC) or active members of specialist prehospital teams (SPHT) based in Scotland.

Results

Over a three month study period there were 247 prehospital incidents involving specialist teams. 190 individuals completed the questionnaire; 61% [n=116] RBAC and 39% [n=74] SPHT. Median length of prehospital experience was 10 years (IQR 5-18). Overall current prehospital handover practices were perceived as being effective (Mdn 4.00; IQR 3-4 [1= very ineffective - 5 = very effective]) although SPHT clinicians rated handover effectiveness slightly lower than RBAC's (Mdn 3.00 vs 4.00, U = 1842.5, p = .03). 'ATMIST' (Age, Time of onset, Medical complaint/injury, Investigation, Signs and Treatment) was deemed the mnemonic of choice. The clinical variables perceived as essential for handover are not explicitly identified within the SBAR mnemonic. The most frequently reported method of recording and transferring information during handover was via memory (n=112 and n=120 respectively) and ?interruptions? were perceived as the most significant barrier to effective handover.

Conclusion

While, overall, current prehospital handover practice is perceived as effective this study has identified a number of areas for handover improvement. These include the development of a shared mental model through system standardisation, innovations to support information recording and delivery, and the clear identification at incidents of a handover lead. Mnemonics must be carefully selected to ensure they explicitly contain the perceived essential clinical variables required for prehospital handover; the mnemonic ATMIST meets these requirements. New theoretically informed, evidence-based interventions, must be developed and tested within existing systems of care to minimise information loss and risk to patients.

Background:

Poor communication during patient handover is recognised internationally as a root cause of a
significant proportion of preventable deaths. Improving the accuracy and quality of handover may reduce
associated mortality and morbidity. Although the practice of handover between Ambulance and Emergency
Department clinicians has received some attention over recent years there is little evidence to support handover
best practice within the prehospital domain. Further research is therefore urgently required to understand the most
appropriate way to deliver clinical information exchange in the pre-hospital environment. We aimed to investigate
current clinical information exchange practices, perceived challenges and the preferred handover mnemonic for
use during transfer of high acuity patients between ambulance clinicians and specialist prehospital teams.

Methods:

A national, cross-sectional questionnaire study. Participants were road based ambulance clinicians (RBAC)
or active members of specialist prehospital teams (SPHT) based in Scotland.

Results:

Over a three month study period there were 247 prehospital incidents involving specialist teams. One
hundred ninety individuals completed the questionnaire; 61% [n = 116] RBAC and 39% [n = 74] SPHT. Median
length of prehospital experience was 10 years (IQR 5?18). Overall current prehospital handover practices were
perceived as being effective (Mdn 4.00; IQR 3?4 [1 = very ineffective - 5 = very effective]) although SPHT clinicians
rated handover effectiveness slightly lower than RBAC?s (Mdn 3.00 vs 4.00, U = 1842.5, p = .03). ?ATMIST? (Age, Time
of onset, Medical complaint/injury, Investigation, Signs and Treatment) was deemed the mnemonic of choice. The
clinical variables perceived as essential for handover are not explicitly identified within the SBAR mnemonic. The
most frequently reported method of recording and transferring information during handover was via memory (n = 112
and n = 120 respectively) and ?interruptions? were perceived as the most significant barrier to effective handover.

Conclusion:

While, overall, current prehospital handover practice is perceived as effective this study has identified a
number of areas for improvement. These include the development of a shared mental model through system
standardisation, innovations to support information recording and delivery, and the clear identification at incidents of a
handover lead. Mnemonics must be carefully selected to ensure they explicitly contain the perceived essential clinical
variables required for prehospital handover; the mnemonic ATMIST meets these requirements. New theoretically
informed, evidence-based interventions, must be developed and tested within existing systems of care to minimise
information loss and risk to patients.

Background:

Poor communication during patient handover is recognised internationally as a root cause of a
significant proportion of preventable deaths. Improving the accuracy and quality of handover may reduce
associated mortality and morbidity. Although the practice of handover between Ambulance and Emergency
Department clinicians has received some attention over recent years there is little evidence to support handover
best practice within the prehospital domain. Further research is therefore urgently required to understand the most
appropriate way to deliver clinical information exchange in the pre-hospital environment. We aimed to investigate
current clinical information exchange practices, perceived challenges and the preferred handover mnemonic for
use during transfer of high acuity patients between ambulance clinicians and specialist prehospital teams.

Methods:

A national, cross-sectional questionnaire study. Participants were road based ambulance clinicians (RBAC)
or active members of specialist prehospital teams (SPHT) based in Scotland.

Results:

Over a three month study period there were 247 prehospital incidents involving specialist teams. One
hundred ninety individuals completed the questionnaire; 61% [n = 116] RBAC and 39% [n = 74] SPHT. Median
length of prehospital experience was 10 years (IQR 5?18). Overall current prehospital handover practices were
perceived as being effective (Mdn 4.00; IQR 3?4 [1 = very ineffective - 5 = very effective]) although SPHT clinicians
rated handover effectiveness slightly lower than RBAC?s (Mdn 3.00 vs 4.00, U = 1842.5, p = .03). ?ATMIST? (Age, Time
of onset, Medical complaint/injury, Investigation, Signs and Treatment) was deemed the mnemonic of choice. The
clinical variables perceived as essential for handover are not explicitly identified within the SBAR mnemonic. The
most frequently reported method of recording and transferring information during handover was via memory (n = 112
and n = 120 respectively) and ?interruptions? were perceived as the most significant barrier to effective handover.

Conclusion:

While, overall, current prehospital handover practice is perceived as effective this study has identified a
number of areas for improvement. These include the development of a shared mental model through system
standardisation, innovations to support information recording and delivery, and the clear identification at incidents of a
handover lead. Mnemonics must be carefully selected to ensure they explicitly contain the perceived essential clinical
variables required for prehospital handover; the mnemonic ATMIST meets these requirements. New theoretically
informed, evidence-based interventions, must be developed and tested within existing systems of care to minimise
information loss and risk to patients.

Objectives The aim of this study is to describe the demographics of reported traumatic cardiac arrest (TCA) victims, prehospital resuscitation and survival to hospital rate.

Setting Helicopter Emergency Medical Service (HEMS) in south-east England, covering a resident population of 4.5 million and a transient population of up to 8 million people.

Participants Patients reported on the initial 999 call to be in suspected traumatic cardiac arrest between 1 July 2016 and 31 December 2016 within the trust?s geographical region were identified. The inclusion criteria were all cases of reported TCA on receipt of the initial emergency call. Patients were subsequently excluded if a medical cause of cardiac arrest was suspected.

Outcome measures Patient records were analysed for actual presence of cardiac arrest, prehospital resuscitation procedures undertaken and for survival to hospital rates.

Results 112 patients were reported to be in TCA on receipt of the 999/112 call. 51 (46%) were found not to be in TCA on arrival of emergency medical services. Of the ?not in TCA cohort?, 34 (67%) received at least one advanced prehospital medical intervention (defined as emergency anaesthesia, thoracostomy, blood product transfusion or resuscitative thoracotomy). Of the 61 patients in actual TCA, 10 (16%) achieved return-of-spontaneous circulation. In 45 (88%) patients, the HEMS team escorted the patient to hospital.

Conclusion A significant proportion of patients reported to be in TCA on receipt of the emergency call are not in actual cardiac arrest but are critically unwell requiring advanced prehospital medical intervention. Early activation of an enhanced care team to a reported TCA call allows appropriate advanced resuscitation. Further research is warranted to determine which interventions contribute to improved TCA survival.

Background



Helicopter Emergency Medical Services (HEMS) are a scarce resource that can provide advanced emergency medical care to unwell or injured patients. Accurate tasking of HEMS is required to incidents where advanced pre-hospital clinical care is needed. We sought to evaluate any association between non-clinically trained dispatchers, following a bespoke algorithm, compared with HEMS paramedic dispatchers with respect to incidents requiring a critical HEMS intervention.



Methods



Retrospective analysis of prospectively collected data from two 12-month periods was performed (Period one: 1st April 2014 ? 1st April 2015; Period two: 1st April 2016 ? 1st April 2017). Period 1 was a Paramedic-led dispatch process. Period 2 was a non-clinical HEMS dispatcher assisted by a bespoke algorithm. Kent, Surrey & Sussex HEMS (KSS HEMS) is tasked to approximately 2500 cases annually and operates 24/7 across south-east England. The primary outcome measure was incidence of a HEMS intervention.



Results



A total of 4703 incidents were included; 2510 in period one and 2184 in period two. Variation in tasking was reduced by introducing non-clinical dispatchers. There was no difference in median time from 999 call to HEMS activation between period one and two (period one; median 7 min (IQR 4?17) vs period two; median 7 min (IQR 4?18). Non-clinical dispatch improved accuracy of HEMS tasking to a mission where a critical care intervention was required (OR 1.25, 95% CI 1.04?1.51, p = 0.02).



Conclusion



The introduction of non-clinical, HEMS-specific dispatch, aided by a bespoke algorithm improved accuracy of HEMS tasking. Further research is warranted to explore where this model could be effective in other HEMS services.

Background

Major haemorrhage is a leading cause of mortality following major trauma. Increasingly, Helicopter Emergency Medical Services (HEMS) in the United Kingdom provide pre-hospital transfusion with blood products, although the evidence to support this is equivocal. This study compares mortality for patients with suspected traumatic haemorrhage transfused with pre-hospital packed red blood cells (PRBC) compared to crystalloid.

Methods

A single centre retrospective observational cohort study between 1 January 2010 and 1 February 2015. Patients triggering a pre-hospital Code Red activation were eligible. The primary outcome measure was all-cause mortality at 6 hours and 28 days, including a sub-analysis of patients receiving a major and massive transfusion. Multivariable regression models predicted mortality. Multiple Imputation (MI) was employed, and logistic regression models were constructed for all imputed datasets.

Results

The crystalloid (n= 103) and PRBC (n= 92) group were comparable for demographics, Injury Severity Score (p= 0.67) and mechanism of injury (p= 0.74). Observed 6 hour mortality was smaller in the PRBC group (n= 10, 10%) compared to crystalloid group (n= 19, 18%). Adjusted OR was not statistically significant (OR 0.48, CI 0.19-1.19, p= 0.11). Observed mortality at 28 days was smaller in the PRBC group (n= 21, 27%) compared to crystalloid group (n= 31, 40%), p= 0.09. Adjusted OR was not statistically significant (OR 0.66, CI 0.32-1.35, p= 0.26). A statistically significant greater proportion of the crystalloid group required a major transfusion (n= 62, 63%) compared to the PRBC group (n= 41, 46%), p= 0.02. For patients requiring a massive transfusion observed mortality was smaller in the PRBC group at 28 days (p= 0.07).

Conclusion

In a single centre UK HEMS study, in patients with suspected traumatic haemorrhage who received a PRBC transfusion there was an observed, but non-significant, reduction in mortality at 6 hours and 28 days, also reflected in a massive transfusion subgroup. Patients receiving pre-hospital PRBC were significantly less likely to require an in-hospital major transfusion. Further adequately powered multi-centre prospective research is required to establish the optimum strategy for pre-hospital volume replacement in patients with traumatic haemorrhage.

Objectives:

The aim of this study was to establish if in patients who die at scene as a result of a traumatic cardiac arrest (TCA), their cause of death could be determined through coroners reports, and to ascertain the quality of the feedback provided.

Methods:

This is a retrospective study of all patients presenting in TCA who were attended by the Kent, Surrey and Sussex Air Ambulance trust between 1 January 2015 and 30 June 2016.

Results:

In total, 159 patients were attended during the study period. PM reports could not be obtained for 37 patients, mainly due to unestablished identities at scene. Forty of the 122 reports obtained were full PM reports, 3 were inquest reports and for 79 patients only their (presumed) cause of death was provided. A specific cause of death was provided for 68 patients, whereas in the remaining 54 patients the cause of death was given as ?multiple injuries?. In 32% of the patients with a full PM report, injuries were identified during the post mortem examination that had not been noted on scene.

Conclusion:

Feedback from coroners to pre-hospital teams after patients die as a result of a TCA is important, but currently suboptimal.

Introduction

Helicopter emergency medical services (HEMS) are often dispatched to patients in traumatic cardiac arrest (TCA) as they can provide treatments and advanced interventions in the pre-hospital environment that have the potential to contribute to an increased survival. This study, aimed to investigate the added value of HEMS in the treatment of TCA.

Methods

We performed a retrospective cohort study of all patients with a pre-hospital TCA who were attended by a non-urban HEMS (Kent, Surrey and Sussex Air Ambulance trust) between July 1st 2013 and May 1st 2018. We investigated how many patients got return of spontaneous circulation (ROSC) at scene, which HEMS specific advanced interventions were performed in these patients, and how these interventions were related to ROSC.

Results

During the study period 263 patients with a TCA were attended by HEMS with an average response time of 30/min [range 13?109]. 51 patients (20%) regained ROSC at scene (28 before- and 23 after arrival of HEMS). The HEMS specific interventions of blood product administration (OR 8.54 [2.84?25.72]), and RSI (2.95 [1.32?6.58]) were positively associated with ROSC. Most patients who had a ROSC had one or more HEMS specific interventions being performed ? RSI (n/=/19, 37%), blood product administration (n/=/32, 62%), thoracostomies (n/=/36, 71%) and thoracotomy (n/=/1, 2%). HEMS also delivered other important interventions to these patients as IV/IO access (n/=/20, 39.2%) and endotracheal intubation without drugs (n/=/9, 17.6%).

Conclusion

HEMS teams should be involved in the treatment of patients with a TCA, even in non-urban areas with prolonged response times, as they provide knowledge and skills that contribute to regaining and maintaining a sustained ROSC in this critically ill and injured cohort of patients.

Objectives Patients who sustain a head injury but maintain a Glasgow Coma Scale (GCS) of 13?15 may still be suffering from a significant brain injury. We aimed to assess the appropriateness of triage and decision to perform prehospital rapid sequence induction (RSI) in patients attended by a UK Helicopter Emergency Medical Service (HEMS) following head injury.

Design A retrospective cohort study of patients attended by Kent Surrey & Sussex Air Ambulance Trust (KSSAAT) HEMS.

Setting A mixed urban and rural area of 4.5 million people in South East England.

Participants GCS score of 13, 14 or 15 on arrival of the HEMS team and clinical findings suggesting head injury. Patients accompanied by the HEMS team to hospital (?Escorted?), and those that were ?Assisted? but conveyed by the ambulance service were reviewed. No age restrictions to inclusion were set.

Primary outcome measure Significant brain injury.

Secondary outcome measure Recognition of patients requiring prehospital anaesthesia for head injury.

Results Of 517 patients, 321 had adequate follow-up, 69% of these were Escorted, 31% Assisted. There was evidence of intracranial injury in 13.7% of patients and clinically important brain injury in 7.8%. There was no difference in the rate of clinically important brain injury between Escorted and Assisted patients (p=0.46). Nineteen patients required an RSI by the HEMS team and this patient group was significantly more likely to have clinically important brain injury (p=0.04).

Conclusion In patients attended by a UK HEMS service with a head injury and a GCS of 13?15, a small but significant proportion had a clinically important brain injury and a proportion were appropriately recognised as requiring prehospital RSI. For patients deemed not to need a HEMS intervention, differentiating between those with and without clinically important brain injury appears challenging.

Background

Early transfusion of patients with major traumatic haemorrhage may improve survival. This study aims to establish the feasibility of freeze-dried plasma transfusion in a Helicopter Emergency Medical Service in the United Kingdom.

Method

A retrospective observational study of major trauma patients attended by Kent, Surrey and Sussex Helicopter Emergency Medical Service and transfused freeze-dried plasma since it was introduced in April 2014.

Results

Of the 1873 patients attended over a 12-month period before its introduction, 79 patients received packed red blood cells (4.2%) with a total of 193 units transfused. Of 1881 patients after the introduction of freeze-dried plasma, 10 patients received packed red blood cells only and 66 received both packed red blood cells and freeze-dried plasma, with a total of 158 units of packed red blood cells transfused, representing an 18% reduction between the two 12-month periods. In the 20 months since its introduction, of 216 patients transfused with at least 1 unit of freeze-dried plasma, 116 (54.0%) patients received both freeze-dried plasma and packed red blood cells in a 1:1 ratio. Earlier transfusion was feasible, transferring the patient to hospital prior to transfusion would have incurred a delay of 71 minutes (IQR 59-90).

Conclusion

Pre-hospital freeze-dried plasma and packed red blood cell transfusion is feasible in a 1:1 ratio in patients with suspected traumatic haemorrhage. The use of freeze-dried plasma as a first line fluid bolus reduced the number of pre-hospital packed red blood cell units required and reduced the time to transfusion.

Background

Obtaining accurate information from a 112 caller is key to correct tasking of Helicopter Emergency Medical Services (HEMS). Being able to view the incident scene via video from a mobile phone may assist HEMS dispatch by providing more accurate information such as mechanism of injury and/or injuries sustained. The objective of this study is to describe the acceptability and feasibility of using live video footage from the mobile phone of a 112 caller as an HEMS dispatch aid.

Methods

Live footage is obtained via the 112 caller?s mobile phone camera through the secure GoodSAM app?s Instant-on-scene" platform. Video footage is streamed directly to the dispatcher, and not stored. During the feasibility trial period, dispatchers noted the purpose for which they used the footage and rated ease of use and any technical- and operational issues they encountered. A subjective assessment of caller acceptance to use video was conducted.

Results

Video footage from scene was attempted for 21 emergency calls. The leading reasons listed by the dispatchers to use live footage were to directly assess the patient (18/21) and to obtain information about the mechanism of injury and the scene (11/21). HEMS dispatchers rated the ease of use with a 4.95 on a 5-point scale (range 4?5). All callers gave permission to stream from their telephone camera. Video footage from scene was successfully obtained in 19 calls, and was used by the dispatcher as an aid to send (5) or stand down (14) a Helicopter Emergency Medical Services team.

Conclusion

Live video footage from a 112 caller can be used to provide dispatchers with more information from the scene of an incident and the clinical condition of the patient(s). The use of mobile phone video was readily accepted by the 112 caller and the technology robust. Further research is warranted to assess the impact video from scene could have on HEMS dispatching.

Most trauma and out of hospital cardiac arrest (OHCA) deaths occur prior to arrival at hospital, with increased risk for rural compared to urban patients. Essex and Hertfordshire Air Ambulance Trust (EHAAT) and Kent Surrey Sussex Air Ambulance Trust (KSS) provide a physician-paramedic Helicopter Emergency Medical Service (HEMS) in two regions of the United Kingdom. We investigated whether an association exists between prehospital mortality and distance from care in HEMS patients. We performed a retrospective study using spatial statistics to investigate the geographic distribution of scene outcome (alive versus deceased). We also performed multiple logistic regression of outcome against quartiles of distance from base to scene and a relative risk (RR) estimation over the operational areas. Organisations were analysed separately to assess consistency of spatial relationships. 2680 EHAAT and 4213 KSS patients met the inclusion criteria. Ripley?s K and Cross K functions indicated that outcomes (death and leaving the scene alive) cluster together. For KSS distance was not associated with outcome, for EHAAT distance was a significant predictor of mortality at furthest distance (41 to 95 km; OR 5.82, 95%CI 1.63 to 37.18, p = 0.019). Only one area of KSS and no areas of EHAAT had an increased RR of mortality. In contrast to previous research of pre-hospital patients, we found little evidence of geographic difference in scene outcome for trauma patients attended by the two HEMS services. Increased mortality risk for OHCA at the furthest distance from helicopter base was found in one organisation; a single area of increased RR of mortality was found for the other organisation.