How are forward helicopter emergency medical services dispatches decided in civil and military settings?

Position du problème et objectif(s) de l’étude

The decision-making process within dispatching or commanding headquarters, on airborne primary MEDEVAC, combines technical and human complexity, a high level of interdependence, high risk, a plurality of actors and time constraints. Even if the literature describes the positive impact that Helicopter Emergency Medical Services (HEMS) have compared to Ground Emergency Medical Services (GEMS) (Ringburg, 2009) alongside indications, counter-indications and non-indications of civilian (Noizet, 2023) and military (Frassini, 2021) transport, since guidelines are rarely precise, the decision-making process strongly influence helicopter usage. To improve and support HEMS dispatching, it is thus important to better understand decision strategies. In this study, we wanted to test if the decision to use an artial vector for primary medical evacuation in a civilian setting could be modeled mathematically based on the expected utility theory (Von Neumann, 1944), which could be then optimized.

Matériel et méthodes

We analysed the characteristics of trauma patients (as Vittel scale) primarily transported by HEMS and GEMS to Sainte-Anne Military Hospital in 2023 as present in the TRAUMABASE® registry. This represented 398 trauma patients primarily transported by HEMS (125) or GEMS (273), primarily after road accidents or falls. Missing data ranging from 0% (age) to 45% (transport time to trauma centre) were not replaced. We used t-test for significance analysis, converting non numerical data to values. Figure 1: Flowchart of patient inclusion in our analysis

Résultats & Discussion

This analysis of the Sainte-Anne military hospital transportation data did not find statistically significant decision predictors of HEMS vs GEMS but highlighted significant (p < 0.05) differences in age, mechanism of injury, transport time and day/night usage. Figure 2: Statistical analysis of HEMS vs GEMS dispatch Multivariateregression on 11 variablesfound a 0.06 R2 corrected coefficient with no data significantly explaining the variation in HEMS versus GEMS decision making. Although some criteria thus appear to be taken into account when making a decision, they are not articulated in a mathematical model as could be expected if adhering to the utility paradigm. Further research is needed integrating non-clinical data (weather, distance, etc.), multi-centric information, interviews and consensus to better assess decision-making patterns/bias with a larger population that could compensate missing information.

Conclusion

This cohort study’s findings suggest that in a given French region, the use of HEMS was not associated with statistically significant predictors matching an expected utility model. However, our results found that among patients transported with HEMS or GEMS some variables were statistically different suggesting that bias, thresholds or patterns may exist throughout the decision-making process. This study warrants a larger and more robust evaluation of triage criteria. Testing of various scoring systems described in the literature to assess under- or over-triage of real decisions, including logistical and operational factors would enable the improvement of protocols for utilization of HEMS in the civilian and military setting. This work should be considered in conjunction with clinical assessments of HEMS utility.

Auteurs

Mathieu CYNOBER (1) , Jerome CLECH (2), Mickael CARDINALE (3) - (1)Conservatoire National Des Arts Et Métiers, Paris, France, (2)Centre D'études Stratégiques Aérospatiales, Paris, France, (3)Hôpital D'instruction Des Armées Sainte-Anne, Toulon, France

Orateur(s)

Mathieu CYNOBER (Paris)