Helicopter scene response: regional variation in compliance with air medical triage guidelines

Our state has consensus guides for helicopter emergency medical services (HEMS) scene dispatch, based on physiologic, anatomic, and special criteria (e.g., ejection from a vehicle, age < 10 or > 55 years). There has been much attention paid to improving HEMS triage criteria, but less focus on whether current HEMS uses meet existing criteria.

To assess a HEMS program's compliance with regional air medical dispatch guidelines and to identify factors associated with noncompliant flights.

Using chart review and discussion with referring agencies, we conducted a consecutive case review of a HEMS program's initial 100 flights in one year (2005), collecting data pertinent to triage, prehospital times, and hospital course. Analysis (p = 0.05) of the outcome "met triage criteria" (MTC) used Kruskal-Wallis and Fisher's exact tests. Logistic regression, reporting odds ratios (ORs) with 95% confidence intervals (CIs), was used to adjust for covariates while assessing predictors of the dichotomous outcome MTC. The predictors assessed included demographics, advanced life support (ALS) scene presence, and whether transports occurred during rush hours (0700-1000 and 1600-1900).

The 100 patients (98 blunt trauma; 73% male) from four Massachusetts emergency medical services (EMS) regions (n = 94) and New Hampshire (n = 6) were classified as MTC in 73% of cases. Physiologic criteria were met in 19% of cases (they were the sole criterion met in one case), anatomic criteria in 49% (sole criterion n = 24), and special criteria in 67% (sole criterion n = 15). There was no association between MTC status and age (p = 0.98), gender (p = 0.39), rush-hour transport (p = 0.81), or ALS-trained ground EMS presence on scene (p = 0.98). Analysis adjusting for transport distance and injury mechanism identified an association between EMS region and MTC transport status (p = 0.006); regions' likelihoods of MTC proportions ranged from 50% to 94%.

Despite promulgation of consensus guidelines, nearly a fourth of HEMS transports were non-MTC. Wide interregional variation in the likelihood of MTC HEMS use provides a focus for further research/education. Regional systems should strive not only for the refinement of, but also the compliance with, HEMS triage guidelines.