Ambulance staging for potentially dangerous scenes: another hidden component of response time

Prehosp Emerg Care. 2010 Jul-Sep;14(3):340-4. doi: 10.3109/10903121003760176.


Background: Emergency medical services (EMS) responses to some scenes are potentially more dangerous than others, requiring EMS systems to develop policies that stage medical responders away from the scene until law enforcement has the area secured.

Objectives: We sought to characterize the calls that are staged and to demonstrate the effect of staging on the response time interval and differences in red lights and sirens (RLS) transport to the hospital between staged calls (SC) and nonstaged calls (NSC).

Methods: This was a retrospective cohort study of all 9-1-1 calls received during calendar year 2006 in a midwestern, high-performance system. Descriptive statistics, Mann-Whitney U test, and chi-square analysis were used as appropriate; p < 0.05 was considered significant.

Results: There were 62,157 emergency calls for which responders arrived on scene during the study period; 4,414 (7.1%) were SC and 57,743 (92.9%) were NSC. By protocol, dispatchers ordered EMS to stage on five categories: 924 for assault/rape (20.9%), 393 for unknown problem/man down (8.9%), 918 for overdose (20.8%), 734 for psychiatric/suicide attempt (16.6%), and 413 for stab/gunshot wound (9.4%). Dispatchers ordered staging using their own discretion for 1,032 (23.4%) calls. The median response time interval (call received until ambulance arrived at the scene) was 10 minutes 55 seconds (i.e., 10:55 minutes) (interquartile range [IQR]: 8:00-14:27) for SC and 6:16 minutes (IQR: 4:42-8:28) for NSC (p < 0.0001). Patients were transported to the hospital for 3,104 (70.3%) of SC, 223 (7.2%) with RLS; patients were transported to the hospital for 41,716 (72.2%) of NSC, 2,802 (6.7%) with RLS. There was no difference in the rate of RLS return between SC and NSC (p = 0.314).

Conclusion: The practice of staging ambulances while police secure potentially dangerous scenes added approximately 4.5 minutes to the response time. We were unable to demonstrate a difference in RLS return to the hospital (our proxy for patient acuity) between SC and NSC.

MeSH terms

  • Ambulances / organization & administration*
  • Cohort Studies
  • Efficiency, Organizational*
  • Emergency Medical Services
  • Humans
  • Missouri
  • Occupational Health
  • Organizational Policy
  • Retrospective Studies
  • Time Factors