Decreasing response phase lights and siren use through modification of dispatch priority response for 9-1-1 responses...

Emergency medical services (EMS) responses to personal emergency response systems (PERS) activations predominantly involve low-acuity patients. Recent evidence demonstrates that while most PERS calls are dispatched lights and siren (L&S), only 1% result in L&S transport. Reduction of L&S use through modified dispatch priority response for PERS calls has not been evaluated. Our objective was to evaluate the efficacy of modifying dispatch priority response mode for PERS calls to non-L&S response, the resulting reduction in response phase L&S use, and potential impact on time critical interventions.

We conducted a retrospective observational pre-post analysis comparing PERS responses in two 11-month periods before (January-November 2023) and after (January-November 2024) revising the dispatch priority response for PERS calls to non-L&S in December 2023. We evaluated response mode and transport mode. The primary outcome was total hours/month of response phase L&S use, with L&S duration computed as the interval between unit dispatched and arrival (patient contact) or call cancellation. Descriptive statistics were computed followed by interrupted time series analysis (ITSA) to assess the impact of the intervention on the primary outcome and maintenance of the effect across the post-intervention period (p for post-intervention linear trend).

Analysis included 3,262 PERS calls (pre-intervention = 1,634; post-intervention = 1,628). L&S response occurred in 98% (n = 1,601) of pre-intervention calls and 12% (n = 192) of post-intervention calls (p < 0.001). The prevalence of L&S transport was similar in both periods (0.9% vs 0.9%, p = 0.99). The ITSA revealed an immediate 13.8-hour/month decrease in response phase L&S use (95% confidence interval: -16.2 to -11.3) that was sustained across the post-intervention period (p > 0.05). Total response phase L&S hours decreased 86%, from 172 hours in the pre-intervention period to 24 hours during the post-intervention period. Importantly, only four post-intervention calls (0.2%) involved a non-L&S response followed by L&S transport, with just one of these requiring advanced life support interventions.

Modifying dispatch priority response for PERS calls reduced L&S responses and yielded a marked decrease in hours of L&S use which was maintained overtime. As the industry advocates for safer, more judicious L&S use, additional low-acuity call types should be identified for similar dispatch priority response revision.