Logistics of air medical transport: When and where does helicopter transport reduce prehospital time for trauma?

The Role of Integrated Air Transport System in Managing Patients with Abdominal Aortic Aneurysm Rupture

OBJECTIVE

Ruptured abdominal aortic aneurysms (rAAAs) are highly morbid emergencies. Not all hospitals are equipped to repair them, and an air ambulance network may aid in regionalising specialty care to quaternary referral centres. The association between travel distance by air ambulance and rAAA mortality in patients transferred as an emergency for repair was examined.

METHODS

A retrospective review of institutional data. Adults with rAAA (2002 - 2019) transferred from an outside hospital (OSH) to a single quaternary referral centre for repair via air ambulance were identified. Patients who arrived via ground transport or post-repair at an OSH for continued critical care were excluded. Patients were divided into near and far groups based on the 75th percentile of the straight line travel distance (> 72 miles) between hospitals. The primary outcome was 30 day mortality. Multivariable logistic regression was used to assess the association between distance and mortality after adjusting for age, sex, race, cardiovascular comorbidities, and repair type.

RESULTS

A total of 290 patients with rAAA were transported a median distance of 40.4 miles (interquartile range 25.5, 72.7) with 215 (74.1%) near and 75 (25.9%) far patients. Both the near and far groups had similar ages, sex, and race. There was no difference in pre-operative loss of consciousness, intubation, or cardiac arrest between groups. Endovascular aneurysm repair utilisation and intra-operative aortic occlusion balloon use were also similar. Neither the observed (26.8% vs. 23.9%, p = .61) nor the adjusted odds ratio (0.70, 95% confidence interval 0.36 - 1.39, p = .32) 30 day mortality rate differed significantly between the near and far groups.

CONCLUSION

Increasing distance travelled during transfer by air ambulance was not associated with worse outcomes in patients with rAAA. The findings support the regionalisation of rAAA repair to large quaternary centres via an integrated and robust air ambulance network.

Impact of patient, system, and environmental factors on utilization of air medical transport after trauma

BACKGROUND

Air medical transport (AMT) improves outcomes for severely injured patients. The decision to fly patients is complex and must consider multiple factors. Our objective was to evaluate the interaction between geography, patient and environmental factors, and emergency medical services (EMS) system resources on AMT after trauma. We hypothesize that significant geographic variation in AMT utilization will be associated with varying levels of patient, environmental, and EMS resources.

METHODS

Patients transported by EMS in the Pennsylvania state trauma registry 2000 to 2017 were included. We used our previously developed Air Medical Prehospital Triage (AMPT; ≥2 points triage to AMT) score and Geographic Emergency Medical Services Index (GEMSI; higher indicates more system resources) as measures for patient factors and EMS resources, respectively. A mixed-effects logistic regression model determined the association of AMT utilization with patient, system, and environmental variables.

RESULTS

There were 195,354 patients included. Fifty-five percent of variation in AMT utilization was attributed to geographic differences. Triage to AMT by the AMPT score was associated with nearly twice the odds of AMT utilization (adjusted odds ratio, 1.894; 95% confidence interval, 1.765-2.032; p < 0.001). Each 1-point increase in GEMSI was associated with a 6.1% reduction in odds of AMT (0.939; 0.922-0.957; p < 0.001). Younger age, rural location, and more severe injuries were also associated with increased odds of AMT ( p < 0.05). When categorized by GEMSI level, the AMPT score and patient factors were more important for predicting AMT utilization in the middle tercile (moderate EMS resources) compared with the lower (low EMS resources) and higher tercile (high EMS resources). Weather, season, time-of-day, and traffic were all associated with AMT utilization ( p < 0.05).

CONCLUSION

Patient, system, and environmental factors are associated with AMT utilization, which varies geographically and by EMS/trauma system resource availability. A more comprehensive approach to AMT triage could reduce variation and allow more tailored efforts toward optimizing resource allocation and outcomes.

LEVEL OF EVIDENCE

Prognostic and Epidemiological; Level III.

The association between geospatial and temporal factors and pre-hospital response to major trauma: a retrospective cohort study in the North of England

BACKGROUND

Major trauma is a leading cause of premature death and disability worldwide, and many healthcare systems seek to improve outcomes following severe injury with provision of pre-hospital critical care. Much research has focussed on the efficacy of pre-hospital critical care and advanced pre-hospital interventions, but less is known about how the structure of pre-hospital critical care services may influence response to major trauma. This study assessed the association between likelihood of pre-hospital critical care response in major trauma and factors important in the planning and development of those services: geographic isolation, time of day, and tasking mechanism.

METHODS

A local trauma registry, supported with data from the Trauma Audit and Research Network alongside additional information regarding pre-hospital management, identified patients sustaining major trauma admitted to Major Trauma Centres in the North of England. Data was extracted on location and time of incident, mechanism of injury, on-scene times, and presence or absence of pre-hospital critical care team. An isochrone map was constructed for 30-minute intervals to regional Major Trauma Centres, defining geographic isolation. Univariate logistic regression compared likelihood of pre-hospital critical care response to that of conventional ambulance response for varying degrees of geographic isolation, day or night period, and mechanism of injury, and multiple linear regression assessed the association between geographic isolation, service response and on-scene time.

RESULTS

2619 incidents were included, with 23.3% attended by pre-hospital critical care teams. Compared to conventional ambulance services, pre-hospital critical care teams were more likely to respond major trauma in areas of greater geographic isolation (OR 1.42, 95% CI 1.30-1.55, p < 0.005). There were significant differences in the mechanism of injury attended and no significant difference in response by day or night period. Pre-hospital critical care team response and increasing geographic isolation was associated with longer on-scene times (p < 0.005).

CONCLUSION

Pre-hospital critical care teams are more likely to respond to major trauma in areas of greater geographic isolation. Enhanced pre-hospital care may mitigate geographic inequalities when providing advanced interventions and transport of severely injured patients. There may be an unmet need for pre-hospital critical care response in areas close to major hospitals.

Trauma patient transport to hospital using helicopter emergency medical services or road ambulance in Sweden: a comparison of survival and prehospital time intervals

BACKGROUND

The benefits of helicopter emergency medical services (HEMS) transport of adults following major trauma have been examined with mixed results, with some studies reporting a survival benefit compared to regular emergency medical services (EMS). The benefit of HEMS in the context of the Swedish trauma system remains unclear.

AIM

To investigate differences in survival and prehospital time intervals for trauma patients in Sweden transported by HEMS compared to road ambulance EMS.

METHODS

A total of 74,032 trauma patients treated during 2012-2022 were identified through the Swedish Trauma Registry (SweTrau). The primary outcome was 30-day mortality and Glasgow Outcome Score at discharge from hospital (to home or rehab); secondary outcomes were the proportion of severely injured patients who triggered a trauma team activation (TTA) on arrival to hospital and the proportion of severely injured patients with GCS ≤ 8 who were subject to prehospital endotracheal intubation.

RESULTS

4529 out of 74,032 patients were transported by HEMS during the study period. HEMS patients had significantly lower mortality compared to patients transported by EMS at 1.9% vs 4.3% (ISS 9-15), 5.4% vs 9.4% (ISS 16-24) and 31% vs 42% (ISS ≥ 25) (p < 0.001). Transport by HEMS was also associated with worse neurological outcome at discharge from hospital, as well as a higher rate of in-hospital TTA for severely injured patients and higher rate of prehospital intubation for severely injured patients with GCS ≤ 8. Prehospital time intervals were significantly longer for HEMS patients compared to EMS across all injury severity groups.

CONCLUSION

Trauma patients transported to hospital by HEMS had significantly lower mortality compared to those transported by EMS, despite longer prehospital time intervals and greater injury severity. However, this survival benefit may have been at the expense of a higher degree of adverse neurological outcome. Increasing the availability of HEMS to include all regions should be considered as it may be the preferrable option for transport of severely injured trauma patients in Sweden.

Locating helicopter ambulance bases in Iceland: efficient and fair solutions

BACKGROUND

Fixed-wing air ambulances play an important role in healthcare in rural Iceland. More frequent use of helicopter ambulances has been suggested to shorten response times and increase equity in access to advanced emergency care. In finding optimal base locations, the objective is often efficiency-maximizing the number of individuals who can be reached within a given time. This approach benefits people in densely populated areas more than people living in remote areas and the solution is not necessarily fair. This study aimed to find efficient and fair helicopter ambulance base locations in Iceland.

METHODS

We used high-resolution population and incident location data to estimate the service demand for helicopter ambulances, with possible base locations limited to twenty-one airports and landing strips around the country. Base locations were estimated using both the maximal covering location problem (MCLP) optimization model, which aimed for maximal coverage of demand, and the fringe sensitive location problem (FSLP) model, which also considered uncovered demand (i.e., beyond the response time threshold). We explored the percentage of the population and incidents covered by one to three helicopter bases within 45-, 60-, and 75-min response time thresholds, conditioned or not, on the single existing base located at Reykjavík Airport. This resulted in a total of eighteen combinations of conditions for each model. The models were implemented in R and solved using Gurobi.

RESULTS

Model solutions for base locations differed between the demand datasets for two out of eighteen combinations, both with the lowest service standard. Base locations differed between the MCLP and FSLP models for one combination involving a single base, and for two combinations involving two bases. Three bases covered all or almost all demand with longer response time thresholds, and the models differed in four of six combinations. The two helicopter ambulance bases can possibly obtain 97% coverage within 60 min, with bases in Húsafell and Grímsstaðir. Bases at Reykjavík Airport and Akureyri would cover 94.2%, whereas bases at Reykjavík Airport and Egilsstaðir would cover 88.5% of demand.

CONCLUSION

An efficient and fair solution would be to locate bases at Reykjavík Airport and in Akureyri or Egilsstaðir.

Direct Trauma Center Access by Helicopter Emergency Medical Services is Associated With Improved Survival After Severe Injury

OBJECTIVE

Evaluate the association of survival with helicopter transport directly to a trauma center compared with ground transport to a non-trauma center (NTC) and subsequent transfer.

SUMMARY BACKGROUND DATA

Helicopter transport improves survival after injury. One potential mechanism is direct transport to a trauma center when the patient would otherwise be transported to an NTC for subsequent transfer.

METHODS

Scene patients 16 years and above with positive physiological or anatomic triage criteria within PTOS 2000-2017 were included. Patients transported directly to level I/II trauma centers by helicopter were compared with patients initially transported to an NTC by ground with a subsequent helicopter transfer to a level I/II trauma center. Propensity score matching was used to evaluate the association between direct helicopter transport and survival. Individual triage criteria were evaluated to identify patients most likely to benefit from direct helicopter transport.

RESULTS

In all, 36,830 patients were included. Direct helicopter transport was associated with a nearly 2-fold increase in odds of survival compared with NTC ground transport and subsequent transfer by helicopter (aOR 2.78; 95% CI 2.24-3.44, P <0.01). Triage criteria identifying patients with a survival benefit from direct helicopter transport included GCS≤13 (1.71; 1.22-2.41, P <0.01), hypotension (2.56; 1.39-4.71, P <0.01), abnormal respiratory rate (2.30; 1.36-3.89, P <0.01), paralysis (8.01; 2.03-31.69, P <0.01), hemothorax/pneumothorax (2.34; 1.36-4.05, P <0.01), and multisystem trauma (2.29; 1.08-4.84, P =0.03).

CONCLUSIONS

Direct trauma center access is a mechanism driving the survival benefit of helicopter transport. First responders should consider helicopter transport for patients meeting these criteria who would otherwise be transported to an NTC.

Assessing the Impact of Transport Modality on Prehospital Times for Victims of Motorcycle Road Traffic Collisions in the Scottish Highlands

OBJECTIVE

Dispersed population, mountainous topography, and extreme weather present logistical challenges for the emergency services providing care to the resident population and tourists visiting the Scottish Highlands. Debate over the value of air ambulances has left uncertainty over when they benefit patients and when their use may inadvertently prolong transfer times in rural settings. The primary objective of this study was to find a provisional threshold at which air ambulances are likely to improve time from injury to arrival at the emergency department for this rural patient cohort using motorcycle road traffic collisions as a single trauma etiology.

METHODS

A retrospective search of Scottish Trauma Audit Group data was undertaken within the time frame of January 1, 2019, to September 30, 2020, inclusive to identify adult motorcyclists who had sustained traumatic injuries on highland roads resulting in a transfer to the single trauma unit located within the territorial health board of NHS Highland. For inclusion to the Scottish Trauma Audit Group audit, injuries sustained had resulted in a hospital stay of 3 or more days or death with an Injury Severity Score calculated post-computed tomography/operating room diagnosis. The method of arrival to the hospital was categorized as 1 of the following: road ambulance only, road ambulance (+ prehospital doctor), any involvement of air resources, or self-presentation to hospital.

RESULTS

Forty-two cases were identified. The mean on-scene times were longer for patients who were transported by air by 43 minutes. Within an isochrone of 77 minutes (road transfer time) around Raigmore Hospital in Inverness, transfer by land ambulance was faster than air. The majority of patients received definitive care at Raigmore Hospital and did not require further onward transfer.

CONCLUSION

For adult motorcyclists with traumatic injuries in the Highlands, helicopter transfer appears to reduce transport times when the estimated journey to the trauma unit by land is greater than 77 minutes or approximately 49 miles. Patients injured closer to the hospital should be transferred by land to achieve an earlier arrival time. On-scene times were shorter for patients conveyed by land rather than helicopter, and the presence of a physician during the prehospital phase did not prolong on-scene time.

International Perspectives of Prehospital and Hospital Trauma Services: A Literature Review

Background: Evidence suggests that reductions in the incidence in trauma observed in some countries are related to interventions including legislation around road and vehicle safety measures, public behaviour change campaigns, and changes in trauma response systems. This study aims to briefly review recent refereed and grey literature about prehospital and hospital trauma care services in different regions around the world and describe similarities and differences in identified systems to demonstrate the diversity of characteristics present. Methods: Articles published between 2000 and 2020 were retrieved from MEDLINE and EMBASE. Since detailed comparable information was lacking in the published literature, prehospital emergency service providers’ annual performance reports from selected example countries or regions were reviewed to obtain additional information about the performance of prehospital care. Results: The review retained 34 studies from refereed literature related to trauma systems in different regions. In the U.S. and Canada, the trauma care facilities consisted of five different levels of trauma centres ranging from Level I to Level IV and Level I to Level V, respectively. Hospital care and organisation in Japan is different from the U.S. model, with no dedicated trauma centres; however, patients with severe injury are transported to university hospitals’ emergency departments. Other similarities and differences in regional examples were observed. Conclusions: The refereed literature was dominated by research from developed countries such as Australia, Canada, and the U.S., which all have organised trauma systems. Many European countries have implemented trauma systems between the 1990s and 2000s; however, some countries, such as France and Greece, are still forming an integrated system. This review aims to encourage countries with immature trauma systems to consider the similarities and differences in approaches of other countries to implementing a trauma system.

Effects of mode and time of EMS transport on the rate and distribution of dead on arrival among trauma population transported to ACSCOT-verified trauma centers in the United States

BACKGROUND

Unintentional injury remains the leading cause of death for adults worldwide. We aimed to investigate the rates and distribution of dead on arrival (DOA) patients according to emergency medical services (EMS) mode of transport (MoT), EMS transport time (TT), injury severity score (ISS), and type of injury.

METHODS

This retrospective study utilized de-identified incident-based data from the American College of Surgeons Trauma Quality Improvement Program Participant Use File (ACS-TQIP PUF) dataset (2013-2018) to study Adult DOA patients. DOA was defined according to the data point, "arrived with no signs of life and did not recover". Patients with unknown vitals and patients with no EMS vitals at the scene (HR = 0, RR = 0, and SBP = 0) were excluded to identify DOAs who died during transport. The DOAs included for analysis were sorted into three groups based on injury severity score [low (ISS < 15), intermediate (ISS = 15-24), and severe (ISS ≥ 25)] and subdivided according to injury type (blunt vs. penetrating), EMS Mode of transport and transport times. Statistical significance was defined as p < 0.05.

RESULTS

The majority of the evaluated 6030 adult DOA patients were male (73.3%) and 18-64 years of age (79.6%). Most patients sustained blunt injuries (58.2%), and the most common mechanism of injury was motor vehicle collisions (MVCs). Patients who traveled by helicopter EMS (HEMS) experienced less deaths than those traveling by ground EMS (GEMS) despite transporting more severely injured patients over longer time intervals. Median HEMS TTs were greater than their GEMS counterparts for blunt and penetrating injuries across all ISS groups but were associated with fewer deaths.

CONCLUSION

Helicopter emergency medical service use with intermediate and severely injured patients with penetrating injuries is associated with a reduced number of DOAs. Future studies should prospectively investigate EMS performance to confirm the findings identified in this retrospective analysis. Additionally, other factors affecting pre-hospital EMS performance (e.g., geographic variations, weather-related characteristics, in-flight interventions/procedures) should be investigated. Finally, the results of this study highlight the need for standardized HEMS utilization triage criteria.

Factors associated with non-optimal resource utilization of air ambulance for interfacility transfer of injured patients

OBJECTIVE

Timely access to definitive care is associated with improved outcomes in trauma patients. The goal of this study is to identify patient, institutional and paramedic risk factors for non-optimal resource utilization for interfacility transfers of injured adult patients transported by air ambulance to a LTC.

METHODS

This is a retrospective cohort study of adult emergent interfacility transports via Ornge with data collected on patient demographics, clinical status, sending facilities, transport details and paramedic qualifications. A logistic regression model was used to analyze data.

RESULTS

1777 injured patients undergoing transport with Ornge were analyzed with 805 of these undergoing non-optimal transport. Patients who had an optimal resource use were found to be older and mechanically ventilated. Risk factors increasing odds of non-optimal transport included patients transported from a nursing station (OR 1.94), transport with primary or advanced care paramedics (OR 6.57 and 1.44, respectively) and transport between both 0800-1700 and 1700-0000 (OR 1.40 and 1.54, respectively). The median delay to arrival to receiving facility if a patient had a non-optimal resource use was 40 minutes.

CONCLUSIONS

Three main risk factors were identified in this study. We believe that nursing stations as a sending facility and type of paramedics crew transporting patients resulted in non-optimal resource utilization primarily due to triage of lower acuity patients. However the timing of day is more likely to be a resource availability issue and something that can be further studied and potentially improved moving forward.

Time-saving effects using helicopter transportation: comparison to a ground transportation time predicted using a social navigation software

Previous comparison studies regarding 2 types of transportation, helicopter (HEMS) versus ground emergency medical services (GEMS), have shown underlying heterogeneity as these options have completely different routes and consequent times with reference to one patient. To compare the 2 types of transportation on a case-by-case basis, we analyzed the retrospectively reviewed HEMS and predicted GEMS data using an open-source navigation software.Patients transferred by military HEMS from 2016 to 2019 were retrospectively enrolled. The HEMS records on the time of notification, injury point and destination address, and time required were reviewed. The GEMS data on distance and the predicted time required were acquired using open-source social navigation systems. Comparison analyses between the two types of transportation were conducted. Furthermore, linear logistic regression analyses were performed on the distance and time of the two options.A total of 183 patients were enrolled. There was no statistical difference (P = .3021) in the distance between the 2 types of transportation, and the HEMS time was significantly shorter than that of GEMS (61.31 vs 116.92 minutes, P < .001). The simple linear curves for HEMS and GEMS were separately secured, and two graphs presented the statistical significance (P) as well as reasonable goodness-of-fit (R2). In general, the HEMS graph demonstrates a more gradual slope and narrow distribution compared to that of GEMS.Ideally, HEMS is identified as a better transportation modality because it has a shorter transportation time (56 minutes saved) and a low possibility of potential time delays (larger R2). With a strict patient selection, HEMS can rescue injured or emergent patients who are "out of the golden hour."

Geospatial assessment of helicopter emergency medical service overtriage

BACKGROUND

Despite evidence of benefit after injury, helicopter emergency medical services (HEMS) overtriage remains high. Scene and transfer overtriage are distinct processes. Our objectives were to identify geographic variation in overtriage and patient-level predictors, and determine if overtriage impacts population-level outcomes.

METHODS

Patients 16 years or older undergoing scene or interfacility HEMS in the Pennsylvania Trauma Outcomes Study were included. Overtriage was defined as discharge within 24 hours of arrival. Patients were mapped to zip code, and rates of overtriage were calculated. Hot spot analysis identified regions of high and low overtriage. Mixed-effects logistic regression determined patient predictors of overtriage. High and low overtriage regions were compared for population-level injury fatality rates. Analyses were performed for scene and transfer patients separately.

RESULTS

A total of 85,572 patients were included (37.4% transfers). Overtriage was 5.5% among scene and 11.8% among transfer HEMS (p < 0.01). Hot spot analysis demonstrated geographic variation in high and low overtriage for scene and transfer patients. For scene patients, overtriage was associated with distance (odds ratio [OR], 1.03; 95% confidence interval [CI], 1.01-1.06 per 10 miles; p = 0.04), neck injury (OR, 1.27; 95% CI, 1.01-1.60; p = 0.04), and single-system injury (OR, 1.37; 95% CI, 1.15-1.64; p < 0.01). For transfer patients, overtriage was associated with rurality (OR, 1.64; 95% CI, 1.22-2.21; p < 0.01), facial injury (OR, 1.22; 95% CI, 1.03-1.44; p = 0.02), and single-system injury (OR, 1.35; 95% CI, 1.18-2.19; p < 0.01). For scene patients, high overtriage was associated with higher injury fatality rate (coefficient, 1.72; 95% CI, 1.68-1.76; p < 0.01); low overtriage was associated with lower injury fatality rate (coefficient, -0.73; 95% CI, -0.78 to -0.68; p < 0.01). For transfer patients, high overtriage was not associated with injury fatality rate (p = 0.53); low overtriage was associated with lower injury fatality rate (coefficient, -2.87; 95% CI, -4.59 to -1.16; p < 0.01).

CONCLUSION

Geographic overtriage rates vary significantly for scene and transfer HEMS, and are associated with population-level outcomes. These findings can help guide targeted performance improvement initiatives to reduce HEMS overtriage.

LEVEL OF EVIDENCE

Therapeutic, level IV.

Association Between Mode of Transportation and Outcomes in Penetrating Trauma Across Different Prehospital Time Intervals: A Matched Cohort Study

BACKGROUND

National guidelines do not provide recommendations concerning optimal dispatch time for helicopter emergency medical services (HEMS) in the United States.

OBJECTIVES

This study describes the association between mode of transport (ground vs. helicopter) and survival of patients with penetrating injury across different prehospital time intervals and proposes evidence-based time-related dispatch criteria for HEMS.

METHODS

A retrospective matched cohort study was conducted using the 2015 National Trauma Data Bank. Adult patients (age ≥ 16 years) with penetrating injuries were included. Patients transported via HEMS were selected and matched (1 to 1) for 17 variables to patients transported by ground ambulance (GEMS). Bivariate analyses were conducted to compare characteristics and outcomes (survival to hospital discharge) of patients across different prehospital time intervals.

RESULTS

Each group consisted of 949 patients. Overall survival rate was similar in both groups (90.6% for HEMS vs. 87.9% for GEMS, p = 0.054). Patients transported by HEMS had significantly higher survival compared with those transported by GEMS (92.5% for HEMS vs. 87.0% for GEMS, p = 0.002) in the 0-60-min time interval from dispatch to arrival to hospital, and more specifically, in the 31-60-min interval (92.2% vs. 85.2%, p = 0.001). No difference in survival between the two groups was observed in the shortest (0-30 min) or in the extended prehospital time intervals (>60 min).

CONCLUSION

In adult patients with penetrating trauma, HEMS transport was associated with improved survival in a specific total prehospital time interval (31 to 60 min). This finding can help emergency medicine service administrators develop evidence-based HEMS dispatch criteria.

Predictors of Inappropriate Helicopter Transport

Background

Helicopter transport (HT) is an efficient, but costly, means for injured patients to receive life-saving, definitive trauma care. Identifying the characteristics of inappropriate HT presents an opportunity to improve the utilization of this finite medical resource.

Methods

Trauma registry records of all HT for a 3-year period (2016-2018) to an urban Level I trauma center were reviewed. HT was defined as inappropriate for patients who were discharged home from the emergency department or had a hospital length of stay <1 day, and who were discharged alive. Chi-square analysis and Student’s t-test were used for univariate analysis. Predictors with a P value of less than .15 were subject to binary logistic regression analysis. A P value ≤.05 was considered significant.

Results

There were 713 patients who received HT during the study period. One-hundred and forty-eight (20.8%) patients met the criteria as an inappropriate HT. In univariate analysis, Glasgow Coma Scale >8, Shock Index <0.9, and fall mechanism were found to be significantly associated with inappropriate HT. Age >55 was found to be associated with an appropriate HT. The average Injury Severity Score of the inappropriate HT group was 3.86 (±3.85) compared with 16.80 (±11.23) ( P = .0001, Student’s t-test).

Discussion

Our findings suggest that there are evidence-based predictors of patients receiving inappropriate HT. Triage of HT using these predictors has the potential to decrease unnecessary deployments and reduce health care costs.

Can Resuscitative Endovascular Balloon Occlusion of the Aorta Fly? Assessing Aortic Balloon Performance for Aeromedical Evacuation

BACKGROUND

Noncompressible torso hemorrhage remains a leading cause of death. Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) placement may occur before transport; however, its efficacy has not been demonstrated at altitude. We hypothesized that changes in altitude would not result in blood pressure changes proximal to a deployed REBOA.

METHODS

A simulation model for 7Fr guidewireless REBOA was used at altitudes up to 22,000 feet. Female pigs then underwent hemorrhagic shock to a mean arterial pressure (MAP) of 40 mm Hg. After hemorrhage, a REBOA catheter was deployed in the REBOA group and positioned but not inflated in the no-REBOA group. Animals underwent simulated aeromedical evacuation at 8000 ft or were left at ground level. After altitude exposure, the balloon was deflated, and the animals were observed.

RESULTS

Taking the REBOA catheter to 22,000 ft in the simulation model resulted in a lower systolic blood pressure but a preserved MAP. In the porcine model, REBOA increased both systolic blood pressure and MAP compared with no-REBOA (P < 0.05) and was unaffected by altitude. No differences in postflight blood pressure, acidosis, or systemic inflammatory response were observed between ground and altitude REBOA groups.

CONCLUSIONS

REBOA maintained MAP up to 22,000 feet in an inanimate model. In the porcine model, REBOA deployment improved MAP, and the balloon remained effective at altitude.

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.

Identifying patients with time-sensitive injuries: Association of mortality with increasing prehospital time

BACKGROUND

Trauma is a time-sensitive disease. However, recognizing which patients have time-critical injuries in the field is challenging. Many studies failed to identify an association between increasing prehospital time (PHT) and mortality due to evaluation of heterogenous trauma patients, as well as inherent survival bias from missed deaths in patients with long PHT. Our objective was to determine if a subset of existing trauma triage criteria can identify patients in whom mortality is associated with PHT.

METHODS

Trauma patients 16 years or older transported from the scene in the National Trauma Databank 2007 to 2015 were included. Cubic spline analysis used to identify an inflection where mortality increases to identify a marginal population in which PHT is more likely associated with mortality and exclude biased patients with long PHT. Logistic regression determined the association between mortality and PHT, adjusting for demographics, transport mode, vital signs, operative interventions, and complications. Interaction terms between existing trauma triage criteria and PHT were tested, with model stratification across triage criteria with a significant interaction to determine which criteria identify patients that have increased risk of mortality associated with increasing PHT.

RESULTS

Mortality risk increased in patients with total PHT of 30 minutes or less, comprising a study population of 517,863 patients. Median total PHT was 26 minutes (interquartile range, 22-28 minutes) with median Injury Severity Score of 9 (interquartile range, 4-14) and 7.4% mortality. Overall, PHT was not associated with mortality (adjusted odd ratio [AOR], 0.984 per 5-minute increase; 95% confidence interval [CI], 0.960-1.009; p = 0.20). Interaction analysis demonstrated increased mortality associated with increasing PHT for patients with systolic blood pressure less than 90 mm Hg (AOR, 1.039; 95% CI, 1.003-1.078, p = 0.04), Glasgow Coma Scale score of 8 or less (AOR, 1.047; 95% CI, 1.018-1.076; p < 0.01), or nonextremity firearm injury (AOR, 1.049; 95% CI, 1.010-1.089; p < 0.01).

CONCLUSION

Patients with prehospital hypotension, Glasgow Coma Scale score of 8 or less, and nonextremity firearm injury have higher mortality with increasing PHT. These patients may have time-sensitive injuries and benefit from rapid transport to definitive care.

LEVEL OF EVIDENCE

Prognostic/Epidemiologic III; Therapeutic/Care Management IV.

Defining geographic emergency medical services coverage in trauma systems

BACKGROUND

Geographic distribution of trauma system resources including trauma centers and helicopter bases correlate with outcomes. However, ground emergency medical services (EMS) coverage is dynamic and more difficult to quantify. Our objective was to evaluate measures that describe ground EMS coverage in trauma systems and correlate with outcome.

METHODS

Trauma system resources in Pennsylvania were mapped. Primary outcome was county age-adjusted transportation injury fatality rate. Measures of county EMS coverage included average distance to the nearest trauma center, number of basic life support and advanced life support units/100 square miles, distance differential between the nearest trauma center and nearest helicopter base, and nearest neighbor ratio (dispersed or clustered geographic pattern of agencies). Spatial-lag regression determined association between fatality rates and these measures, adjusted for prehospital time, Injury Severity Score, and socioeconomic factors. Relative importance of these measures was determined by assessing the loss in R value from the full model by removing each measure. A Geographic Emergency Medical Services Index (GEMSI) was created based on these measures for each county.

RESULTS

Median fatality rate was higher in counties with fewer trauma system resources. Decreasing distance to nearest trauma center, increasing advanced life support units/100 square miles, greater distance reduction due to helicopter bases, and dispersed geographic pattern of county EMS agencies were associated with lower fatality rates. The GEMSI ranged from -6.6 to 16.4 and accounted for 49% of variation in fatality rates. Adding an EMS agency to a single county that produced a dispersed pattern of EMS coverage reduced predicted fatality rate by 6%, while moving a helicopter base into the same county reduced predicted fatality rate by 22%.

CONCLUSION

The GEMSI uses several measures of ground EMS coverage and correlates with outcome. This tool may be used to describe and compare ground EMS coverage across trauma system geographies, as well as help optimize the geographic distribution of trauma system resources.

LEVEL OF EVIDENCE

Ecological study, level IV.

Helicopter air ambulance services

PURPOSE OF REVIEW

Helicopter air ambulances are an integral component of modern trauma care, and are able to transport patients to facilities with greater capabilities, extract injured patients from hostile terrain, and speed transport to a trauma center.

RECENT FINDINGS

HAA transport does not reduce the total time required to transport a patient, but it does reduce the time that the patient is between healthcare facilities. Factors that have been suggested to improve outcomes for trauma patients include the availability of advanced interventions, skilled personnel, speed, and trauma center access. Despite their potential benefits to the patient, HAA operations carry significant risks. HAA operations are among the most dangerous professions for both pilot and crew with a mortality rate greater than commercial fishing, loggers, and steelworkers. The US Federal Aviation Administration (FAA) has identified that the four most common causes of HAA accidents as inadvertent flight into instrument meteorological conditions, loss of control, controlled flight into terrain, and night conditions.

SUMMARY

HAA operations are safe and can improve patient care, but additional research is needed to improve our understanding of HAA operations and their effect on outcomes.