Comparing the Air Medical Prehospital Triage Score With Current Practice for Triage of Injured Patients to Helicopter Emergency Medical Services: A Cost-effectiveness Analysis

Aeromedical Transport for Critically Ill Patients

Aeromedical transport (AMT) is an integral part of healthcare systems worldwide. In this article, the personnel and equipment required, associated safety considerations, and evidence supporting the use of AMT is reviewed, with an emphasis on helicopter emergency medical services (HEMS). Indications for HEMS as guideded by the Air Medical Prehospital Triage Score are presented. Lastly, physiologic considerations, which are important to both AMT crews and receiving clinicians, are reviewed.

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.

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.

Evaluating the Cost-effectiveness of Prehospital Plasma Transfusion in Unstable Trauma Patients: A Secondary Analysis of the PAMPer Trial

Importance

Prehospital plasma transfusion is lifesaving for trauma patients in hemorrhagic shock but is not commonly used owing to cost and feasibility concerns.

Objective

To evaluate the cost-effectiveness of prehospital thawed plasma transfusion in trauma patients with hemorrhagic shock during air medical transport.

Design, Setting, and Participants

A decision tree and Markov model were created to compare standard care and prehospital thawed plasma transfusion using published and unpublished patient-level data from the Prehospital Plasma in Air Medical Transport in Trauma Patients at Risk for Hemorrhagic Shock (PAMPer) trial conducted from May 2014 to October 2017, health care and trauma-specific databases, and the published literature. Prehospital transfusion, short-term inpatient care, and lifetime health care costs and quality of life outcomes were included. One-way, 2-way, and Monte Carlo probabilistic sensitivity analyses were performed across clinically plausible ranges. Data were analyzed in December 2019.

Main Outcomes and Measures

Relative costs and health-related quality of life were evaluated by an incremental cost-effectiveness ratio at a standard willingness-to-pay threshold of $100 000 per quality-adjusted life-year (QALY).

Results

The trial included 501 patients in the modified intention-to-treat cohort. Median (interquartile range) age for patients in the thawed plasma and standard care cohorts were 44 (31-59) and 46 (28-60) years, respectively. Overall, 364 patients (72.7%) were male. Thawed plasma transfusion was cost-effective with an incremental cost-effectiveness ratio of $50 467.44 per QALY compared with standard care. The preference for thawed plasma was robust across all 1- and 2-way sensitivity analyses. When considering only patients injured by a blunt mechanism, the incremental cost-effectiveness ratio decreased to $37 735.19 per QALY. Thawed plasma was preferred in 8140 of 10 000 iterations (81.4%) on probabilistic sensitivity analysis. A detailed analysis of incremental costs between strategies revealed most were attributable to the in-hospital and postdischarge lifetime care of critically ill patients surviving severe trauma.

Conclusions and Relevance

In this study, prehospital thawed plasma transfusion during air medical transport for trauma patients in hemorrhagic shock was lifesaving and cost-effective compared with standard care and should become commonplace.

Risk factors for cancellation after dispatch of rapid response cars for prehospital emergency care: a single-center, case-control study

Aim

The objective of this study is to identify the risk factors for cancellation after dispatch of rapid response cars (RRC) for prehospital emergency care.

Methods

We retrospectively extracted data from all RRC cases dispatched from our hospital between April 2017 and March 2019. A total of 1,440 cases were included in our study and divided into either the “cancelled” group (n = 723) or the “treated” group (n = 717), based on the occurrence of cancellation. The variables obtained from the request calls for RRC included patient characteristics, distance from the hospital to the scene, and reasons for RRC request. The variables were compared between the two groups and logistic regression analysis was carried out to identify the risk factors for RRC cancellation.

Results

Multivariable analysis showed that distance from the hospital to the scene (odds ratio [OR] 1.25; 95% confidence interval (CI), 1.21–1.28), suspicion of cardiopulmonary arrest with no witness information (OR 7.61; 95% CI, 4.13–14.00), dyspnea (OR 2.22; 95% CI, 1.19–4.11), and suicide by hanging (OR 3.49; 95% CI, 1.37–8.89) were independent risk factors for cancellation.

Conclusions

In our study, a greater distance from the hospital to the scene, suspicion of cardiopulmonary arrest with no witness information, dyspnea, and suicide by hanging were identified as independent risk factors for cancellation after dispatch of RRC. Evaluating the risk factors for cancellation at individual facilities could help hospitals adjust their dispatch criteria to allocate limited medical resources more effectively.

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.

Field-Triage, Hospital-Triage and Triage-Assessment: A Literature Review of the Current Phases of Adult Trauma Triage

ABSTRACT

Despite major improvements in the United States trauma system over the past two decades, prehospital trauma triage is a significant challenge. Undertriage is associated with increased mortality, and overtriage results in significant resource overuse. The American College of Surgeons Committee on Trauma benchmarks for undertriage and overtriage are not being met. Many barriers to appropriate field triage exist, including lack of a formal definition for major trauma, absence of a simple and widely applicable triage mode, and emergency medical service adherence to triage protocols. Modern trauma triage systems should ideally be based on the need for intervention rather than injury severity. Future studies should focus on identifying the ideal definition for major trauma and creating triage models that can be easily deployed. This narrative review article presents challenges and potential solutions for prehospital trauma triage.

Non-Invasive Venous waveform Analysis (NIVA) for monitoring blood loss in human blood donors and validation in a porcine hemorrhage model

STUDY OBJECTIVE

There is an unmet need for a non-invasive approach to diagnose hemorrhage early, before changes in vital signs occur. Non-Invasive Venous waveform Analysis (NIVA) uses a unique physiological signal (the peripheral venous waveform) to assess intravascular volume. We hypothesized changes in the venous waveform would be observed with blood loss in healthy adult blood donors and characterized hemorrhage using invasive monitoring in a porcine model.

DESIGN

Prospective observational study.

SETTING

American Red Cross donation center.

PATIENTS

50 human blood donors and 12 non-donating controls; 7 Yorkshire pigs.

INTERVENTIONS

A venous waveform capturing prototype (NIVA device) was secured to the volar aspect of the wrist in human subjects. A central venous catheter was used to obtain hemodynamic indices and venous waveforms were obtained using the prototype NIVA device over the saphenous vein during 400 mL of graded hemorrhage in a porcine model.

MEASUREMENTS

Venous waveforms were transformed from the time to the frequency domain. The ratiometric power contributions of the cardiac frequencies were used to calculate a NIVA value representative of volume status.

MAIN RESULTS

A significant decrease in NIVA value was observed after 500 mL of whole blood donation (p < .05). A ROC curve for the ability of the NIVA to detect 500 mL of blood loss demonstrated an area under the curve (AUC) of 0.94. In the porcine model, change in NIVA value correlated linearly with blood loss and with changes in hemodynamic indices.

CONCLUSIONS

This study provides proof-of-concept for a potential application of NIVA in detection of blood loss. NIVA represents a novel physiologic signal for detection of early blood loss that may be useful in early triage and perioperative management.

Thoracic trauma in military settings: a review of current practices and recommendations

PURPOSE OF REVIEW

To examine current literature on thoracic trauma related to military combat and to explore its relevance to the civilian population.

RECENT FINDINGS

Damage control resuscitation (DCR) has improved the management of hemorrhaging trauma patients. Permissive hypotension below 110 mmHg and antifibrinolytic use during DCR is widely accepted, whereas the use of freeze-dried plasma and whole blood is gaining popularity. The Modified Physiologic Triaging Tool can be used for primary triage and it may have applications in civilian trauma systems. Although Tactical Combat Casualty Care protocol recommends the Cric-Key device for surgical cricothyroidotomies, other devices may offer comparable performance. Recommendations for regional anesthesia after blunt trauma are not well defined. Increasing amounts of evidence favor the use of extracorporeal membrane oxygenation for refractory hypoxemia and resuscitative endovascular balloon occlusion of the aorta (REBOA) for severe hemorrhage. REBOA outcomes are potentially improved by partial occlusion and small 7 Fr catheters.

SUMMARY

The Global War on Terror has provided opportunities to better understand and treat thoracic trauma in military settings. Trauma registries and other data sources have contributed to significant advancements in the management of thoracic trauma in military and civilian populations.

Analysis of Transport to an American College of Surgeons Level I Trauma Center

INTRODUCTION

Efficient patient transportation by ground emergency medical services (GEMS) or helicopter emergency medical services (HEMS) to a trauma center is vital for optimal care. We investigated differences between the modes of transport in terms of demographics, injury, scene location, and outcome.

SETTING

Morristown Medical Center (MMC), Morristown, NJ METHODS: All 903 trauma admissions in 2016 by advanced life support (ALS) to MMC, a Level I Trauma Center, were retrospectively analyzed.

RESULTS

22% of admissions were HEMS and 78% were GEMS. HEMS patients had higher Injury Severity Scores (ISS) (p<0.001); however, mortality and length of stay were not statistically different. The percentage of pediatric patients transported by HEMS that were discharged home after emergency department evaluation was greater than the older populations (p<0.001). Older age and higher ISS had the largest impact on mortality (p<0.001).

CONCLUSION

We believe our current use of HEMS is adequate since patient outcomes between HEMS and GEMS was similar, even though HEMS patients have higher ISS. However, helicopter use in the pediatric population was over-utilized, possibly due to the scarcity of hospitals capable of managing pediatric traumas. Implementation of the Air Medical Prehospital Triage scoring system may also help correct for these unnecessary HEMS transports.