Emergency versus standard response: time efficacy of London's Air Ambulance rapid response vehicle.

Objective The potential increased risk of an emergency response using a rapid response vehicle (RRV) should only be accepted when it allows a clinically significant time saving for management of patients who are critically injured or sick. Air ambulance services often use an RRV to maintain operational resilience. We compared the RRV response time on emergency versus standard driving to inform emergency services of time efficacy of emergency response in an urban environment. Methods Prospective observational controlled study of response data of emergency and standard driving. An identical RRV shadowed the medical team until the team was dispatched to a job (emergency driving). The shadow RRV then drove to the same given location from the same origin location in equal traffic conditions being compliant with all traffic signals, road signs and speed limits (standard driving). Results The emergency response resulted in an estimated reduction in median response time of 14 min (95% CI 9 to 19) which represented a time saving of 54.9%. The estimated difference in distance travelled (0.6 km) was not statistically significant. Median speed was significantly higher when using an emergency response (46.1 IQR 39-53.4 km/hour) versus standard response (20.1 IQR 16.3-24.7 km/hour), with an estimated difference of -24.5 km/hour (95% CI -28.8 to -20.5). Conclusions The current study found RRVs to be significantly quicker when responding with lights, sirens and traffic rule exemptions compared with a response being compliant with all traffic signals, road signs and speed limits.