Wailing for Risk Reduction: The Quantifiable Risks of Using Lights and Sirens


“Competence is more often shown by quiet deliberateness than by noisy bravado.” – E. Marie Wilson



Wantabe et al. (2018) “Is Use of Warning Lights and Sirens Associated With Increased Risk of Ambulance Crashes?” was the first to definitively link L&S use with ambulance crashes.


Data extrapolated from
Wantabe et al. (2018)

Response Crash Rate:

4.6 / 100,000 without L&S

5.4 / 100,000 with L/S

Transport Crash Rate:

7 / 100,000 without L&S

17.1 / 100,000 with L&S

The authors theorize a driving reason behind their observations as such: “During response two providers are in the front and share the cognitive load required to operate an ambulance”.

NHTSA – Proposed L&S Response Benchmark:

  • Reduce L/S use to less than 50% during response.
  • Less than 5% during transport.

Common arguments for the use of L/S:

  • Saves time
  • Time is brain/muscle
  • Public expectation

History

The general attitude may stem from the genesis of EMS, where First Aid attendants were not trusted to discern if a patient was stable or not. Ergo, the strategy of the time was to rapidly transport all patients with the underlying presumption that all patients “would” deteriorate unless proven otherwise AFTER arrival at a hospital.

With current advances in prehospital care, the vast majority of injury/illnesses can be effectively managed during the out-of-hospital phase of patient care.

Increased vehicle safety should be championed along with the need to decrease the use of L&S.

  • Lime Green colors decreases rate of overall crashes
  • Lime Green: 28.2 crashes per 1 million miles travelled
  • Red/White: 62.1 crashes per 1 million miles travelled

The average rate of car crashers per 1 million miles is 2.6 / 1 million miles of travel. (Solomon, 1995)


Does it save lives?

(Anderson, 2014)
Study in Denmark looked for morbidity by studying 94,488 patients transported without L&S and found only 152 patients (0.16%) that died the same day as their ambulance transport. A panel of prehospital anesthesiologists reviewed the patient care reports and found 13 (0.02%) with potentially preventable deaths. If every one of these deaths could have been prevented with L&S transport, the “number needed to treat” would have been 5000 extra L&S transports. (Anderson 2014)

(Kupas 1994)
Protocol is used to identify patients that may benefit by the time saved with L&S transport. When using this protocol on 1625 patients, only 130 (8%) were transported using L&S. A review of the 92% of cases where L&S was not used, the receiving physicians did not identify any cases of possible morbidity due to a slower transport.

(Merlin 2012)
Merlin developed an even simpler medical protocol for L&S transport, which reduced L&S transport in this urban New Jersey community from 49.6% to 29.0% for patients transported by ALS providers.

(Marques-Batista 2010)
112 patients transported with L&S found that only five of those patients received a time-critical intervention upon arrival to the emergency department, and none of these procedures was done within the 2.62 minutes saved by L&S transport

(Newgard 2010)
The Resuscitation Outcomes Consortium studied the outcomes for injured patients treated by 146 EMS agencies, transporting to 51 Level I and II trauma centers, in ten North American communities. This large study found no association between survival and EMS time intervals – including response time and transport time.

Does it save time?

L&S use generally only shortens response and transport time intervals by 1.7-3.6 minutes, and transport time only by 0.7-3,8 minutes.
Greenville, NC; Saved average of 43.5 seconds

Fatalities:

9.6 fatalities per 100,000 people per capita related to transportation.
Rear Occupants are 2.7 times more likely to die in a crash (Kahn, 2001)

  • Exceeds rate for LEOs and FFs
  • Rear occupants 2.7 times more likely to be killed in ambulance crash

But our Fracile Response Time needs to be 8 minutes!

  • Stems from 1979 study in Seattle of cardiac arrests
  • What matters more is when the first arriving aid is present.
  • Now we have widespread T-CPR, rapid dispatch, bystander CPR, and LEO responses w/ AEDs.

EMSA Response Time Standards:

  • Priority one calls – 10.59
  • Priority two calls – 24.59
  • Respond to only 33% of calls w/ L/S
  • Have NOT observed any changes in cardiac arrest survival rates.

Time Critical Conditions:

  • Rendering a coronary intervention sooner by 10 minutes would decrease death by only 0.4%
    • Rather, work on earlier notification, reduced scene times, and in-hospital workflow.
  • Best chance of survival from OOHCA is to obtain ROSC on scene.

Public Perception:

Anecdotally, it is possible some patients hesitate to call EMS for medical emergencies, because they are uncomfortable with L&S responses and increased attention. See the ubiquitous “caller requests no lights or sirens” dispatch.

A 1988 phone survey of the public in Connecticut cited sirens and noise (67/604 respondents) as the primary reason for being uncomfortable in calling EMS during an emergency, and this response was followed by “getting lots of attention” (49/604 respondents). (Smackery 1988) Critz reported that the families of terminally ill patients who died at home sometimes felt anger with EMS, and L&S response was listed as one of the reasons for this.


One-third of drivers responding to a survey in the United Kingdom reported feeling stress when navigating away from approaching emergency vehicles with L&S, and the authors believed that drivers found the interactions with emergency vehicles inconvenient and potentially dangerous. (Saunders 2003)

Legal:

Wolfberg 1996 found that ambulance crashes are the most common cause of insurance claims greater than 10,000 dollars in EMS agencies


Listen to the Podcast


References:

Kupas DF. Lights and siren use by emergency medical services (EMS): above all do no harm. S. Department of Transportation National Highway Traffic Safety Administration Office of Emergency Medical Services website. May 2017. Available at https://www.ems.gov/pdf/Lights_and_Sirens_Use_by_EMS_May_2017.pdf. Accessed March 19, 2018.

Watanabe, B. L., Patterson, G. S., Kempema, J. M., Magallanes, O., & Brown, L. H. (2019). Is Use of Warning Lights and Sirens Associated With Increased Risk of Ambulance Crashes? A Contemporary Analysis Using National EMS Information System (NEMSIS) Data. Annals of Emergency Medicine. https://doi.org/10.1016/j.annemergmed.2018.09.032

Curbside to Bedside

Curbside to Bedside is a blogcast created by front line EMS Clinicians to provide simple and relevant initial and continuing prehospital EMS education.

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