Written by Sam Parnell
Ambulance use of lights and sirens is associated with increased risk of crashes, especially from scene to medical care. Transport-phase crashes more than doubled when ambulances used lights and sirens.
Why does this matter?
Ambulances utilize lights and sirens during emergencies to warn other drivers and request the right-of-way in traffic to reduce travel time and hopefully improve patient outcomes. Unfortunately, this only saves approximately 1-3 minutes of travel time, and 91% of ambulance crashes occur during travel with lights and sirens. Whether lights and sirens use specifically increases the risk of collision and injury was unknown prior to this study.
We’re runnin’ emergency traffic…but should we be?
This was a retrospective, national, cross-sectional study from 2016 of more than 19 million EMS activations in the U.S., comparing crash rates for ambulances traveling with or without lights and sirens. Investigators looked at delays caused by crashes reported to the NEMSIS database for ambulance responses to the scene (response phase) and transports of patients to medical care (transport phase).
The response phase crash rate was 5.4/100,000 runs with lights and sirens (AOR 1.5; 95% CI 1.2 to 1.9) and 4.6/100,000 runs without lights and sirens. For the transport phase, the crash rate was 17.1/100,000 runs with lights and sirens (AOR 2.9; 95% CI 2.2 to 3.9) and 7.0/100,000 runs without lights and sirens. Of note, lights and sirens were used far more frequently in scene responses compared to patient transports (77% of responses vs only 23% of transports). However, the use of lights and sirens during patient transport was associated with significantly higher odds of crash compared to scene response (AOR 2.9 vs 1.5).
Given these findings and the fact that lights and sirens use only saves a few minutes of travel time, lights and sirens use should likely be limited to only a few truly time sensitive clinical scenarios such as stroke, STEMI, cardiac arrest, airway obstruction or compromise, respiratory insufficiency, severe trauma, uncontrolled hemorrhage, and obstetric emergencies.
Addendum: We have received feedback from EMS Medical Directors after posting this that deciding when and if to use lights and sirens for ambulance transportation is a complicated and nuanced subject. The risk of using lights and sirens may not outweigh the benefits of saving a few minutes of transport time even for critical diagnoses such as stroke and STEMI. EMS agencies and medical directors should carefully evaluate their lights and sirens policies to maximize patient benefit while minimizing medical personnel and patient risk during ambulance transport. ~ Sam Parnell
Is Use of Warning Lights and Sirens Associated With Increased Risk of Ambulance Crashes? A Contemporary Analysis Using National EMS Information System (NEMSIS) Data. Ann Emerg Med. 2019 Jul;74(1):101-109. doi: 10.1016/j.annemergmed.2018.09.032. Epub 2019 Jan 12.
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Reviewed by Thomas Davis
2 thoughts on “Lights and Sirens – Worth the Risk?”
Readers keep in mind that in some areas lights/sirens can make the difference between 40 minutes to the nearest stroke/STEMI/trauma center or 15 minutes. Not because we’re speeding, but rather because we weave around gridlocked traffic at low speed. Any collisions that did happen would usually be fender benders / scrapes.
The study included urban areas, but I wonder if it included ultra-densely populated areas.
Working in London, I can speak from experience (hardly empirical data I know) and say that some conveyance times have been cut significantly with the use of lights and sirens. It is definitely nuanced and requires the balance of driver experience, familiarity with road conditions and driver behaviour. But used correctly, IS a life saving tool