Helicopter emergency medical services (HEMS): impact on on-scene times

J Trauma. 2007 Aug;63(2):258-62. doi: 10.1097/01.ta.0000240449.23201.57.


Background: This study compared prehospital on-scene times (OSTs) for patients treated by nurse-staffed emergency medical services (EMS) with OST for patients treated by a combination of EMS and physician-staffed helicopter emergency medical services (HEMS). A secondary aim was to investigate the relationship between length of OST and mortality.

Methods: All trauma patients treated in the priority 1 emergency room of a Level I trauma center between January 2002 and 2004 were included in the study. To determine OST and outcome, hospital and prehospital data were entered into the trauma registry. OSTs for EMS and combined EMS/HEMS-treated patients were compared using linear regression analysis. Logistic regression analysis was used to compare mortality rates.

Results: The number of trauma patients included for analysis was 1,457. Of these, 1,197 received EMS assistance only, whereas 260 patients received additional care by an HEMS physician. HEMS patients had longer mean OSTs (35.4 vs. 24.6 minutes; p < 0.001) and higher Injury Severity Scores (24 vs. 9; p < 0.001). After correction for patient and trauma characteristics, like the Revised Trauma Score, age, Injury Severity Scores, daytime/night-time, and mechanism of trauma, the difference in OSTs between the groups was 9 minutes (p < 0.001). Logistic regression analyses showed a higher uncorrected chance of dying with increasing OST by 10 minutes (OR, 1.2; p < 0.001). This apparent effect of OST on mortality was explained by patient and trauma characteristics (adjusted OR, 1.0; p = 0.89).

Conclusions: Combined EMS/HEMS assistance at an injury scene is associated with longer OST. When corrected for severity of injury and patient characteristics, no influence of longer OST on mortality could be demonstrated.

MeSH terms

  • Acrylic Resins
  • Adolescent
  • Adult
  • Aged
  • Air Ambulances / statistics & numerical data*
  • Cohort Studies
  • Emergency Medical Services / standards*
  • Emergency Medical Services / statistics & numerical data
  • Emergency Medicine / standards
  • Emergency Medicine / statistics & numerical data
  • Female
  • Humans
  • Injury Severity Score*
  • Logistic Models
  • Male
  • Middle Aged
  • Netherlands
  • Odds Ratio
  • Probability
  • Quality of Health Care
  • Registries
  • Retrospective Studies
  • Risk Factors
  • Survival Analysis
  • Time Factors
  • Trauma Centers / statistics & numerical data
  • Wounds and Injuries / diagnosis
  • Wounds and Injuries / mortality*
  • Wounds and Injuries / therapy*


  • Acrylic Resins
  • Triad resin