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Many developed countries have adopted helicopter emergency medical services (HEMS) for trauma patients over the past 2–3 decades. The experiences gained by them can guide appropriate adoption of HEMS in the other countries. There is, however, a lot of heterogeneity in data reporting among various nations and this impedes the process of evidence generation through meta-analysis. A Cochrane database systematic review attempted in 2015 included data from 282,258 adults with major trauma from 28 studies in the primary analysis.[1] They tried finding the elements of HEMS that are beneficial for adult trauma patients but because of low quality of evidence from the published studies, they could not reach meaningful conclusions and recommended the ongoing need for diligent reporting of research methods, treatment effects, cost, and safety of HEMS.[1] Some of the studies included showed benefits with the use of HEMS, whereas others did not.[1] Interestingly, none of the studies reported morbidity as assessed by quality-adjusted life years and disability-adjusted life years with the use of HEMS.[1]
Outcomes of HEMS in pediatric trauma have been reported by a nationwide study from Japan and have not been found to be lowered by the use of physician-based HEMS when compared with ground-based emergency service (GEMS).[2] A similar analysis for 21286 adult trauma patients having Injury Severity Score ≥16 has, however, reported significantly lower mortality with HEMS compared to GEMS in Japan between 2004 and 2014.[3]
Jitsuiki et al. have reported the usefulness of physician-staffed HEMS in the management of severe abdominal trauma when compared to the GEMS.[4] Specific patient factors reported in another Japan registry to have better outcomes in patients transported using HEMS includes patients with falls, compression injuries, severe chest injuries, extremity (including pelvic) injuries, and traumatic arrest on arrival to the emergency department (ED).[3]
Other notable patient characteristics reported to have a survival advantage when transported using HEMS include abnormal respiratory rate, Glasgow Coma Scale of ≤8, and hemo/pneumothorax.[5] The advantage for these injuries was found even when total prehospital time with HEMS was 13 min longer than GEMS for these patients.[5] This shows that specific injuries benefit from HEMS care (advanced airway and chest trauma management) rather than the time advantage of HEMS.[5]
Researchers have tried to stratify HEMS versus GEMS by transport times and investigated whether there is still any survival advantage for the patients who took similar time by HEMS or GEMS.[6] There were 155,691 HEMS/GEMS pairs that showed a survival advantage with HEMS when transport times were between 6 min and 30 min.[6] Since the time advantage was eliminated by time-based stratified pairing, the survival advantage was solely attributed to the care provided by HEMS.[6]
Another issue with physician-staffed HEMS is the dispatch accuracy, in the absence of which, the whole service may become counterproductive. An analysis of 2506 physician-staffed HEMS dispatches in Norway showed that there were an overtriage in 75%–80% cases and undertriage in 20%–32% cases.[7] The dispatch criteria were vague and prehospital data were inconsistent and inaccurate to be used in scientific research.[7] This tells us that HEMS is a costly mistake if not utilized for properly selected patients and further research is needed to identify the patient subsets, clinical characteristics, and dispatch criteria for HEMS to be most beneficial and cost-effective for most nations.
There are also reports of strict dispatch criteria that are biased and thus leading to delay in dispatch of HEMS in elderly patients. The prevalent dispatch criteria are mainly based on the mechanism of trauma and ignore the age and physiological factors while making the decision. This results in delay in HEMS dispatch in cases of older trauma patients who sustain minor injuries with seemingly innocuous mechanisms, not fulfilling criteria for immediate HEMS dispatch but ultimately require advanced clinical interventions such has prehospital emergency anesthesia and subsequent care in major trauma centers.[8] Therefore, it needs to be studied whether the addition of age-related and physiological parameters will enhance the quality of triage and dispatch for HEMS to the patient advantage.
Overall, HEMS is more effective than GEMS because of the immediate advanced trauma care possible in the helicopter with a physician-on-board. This holds true for survival advantage even when the time taken to transport was more than that for the GEMS. For most developing nations who are looking forward to establish HEMS in near future, it is important not to repeat the mistakes done by the other nations, establish proper dispatch criteria based on their patient population, geography, and level of medical care. HEMS is an important offshoot of ED that when properly utilized can be life-saving in specific trauma subsets. Uniformity in the documentation and reporting of patients catered by HEMS and GEMS is needed to generate high-quality evidence from all over the world.
References 
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/jets.jets_29_22
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