The effectiveness of lights and siren use during ambulance transport by paramedics

To determine whether lights and siren (L&S) use during transport in the authors' EMS system results in reduced transport time to the hospital. Second, to determine whether L&S use results in any emergency department critical interventions in the time saved.

A convenience sample of transport times were measured for 75 ambulances traveling to the hospital with L&S and compared with measured simultaneous transport times for a personal observer vehicle traveling the same route as the ambulance. Upon hospital arrival, the driver of the observer vehicle proceeded to the patients' locations and noted the medical interventions accomplished at the hospital prior to his arrival. Interventions were reviewed to identify time-critical interventions that would have been delayed without L&S use.

The mean ambulance transit time was 666 seconds and the mean observer transit time was 896 seconds. The mean difference in ambulance (L&S) transit time and the observer (no L&S) transit time was 230 seconds (3 min, 50 sec). There was a statistically significant correlation between transit time difference and number of stoplights encountered, traffic intensity, and distance traveled. Of the 75 patients transported, four patients were felt to have benefited clinically by the time saved.

Use of L&S significantly shortens transport time. In this series of patients transported under the care of a paramedic, the time saved by the use of L&S was not usually associated with immediately apparent clinical significance.