A Comparison of Time to Treatment between an Emergency Department Focused Stroke Protocol and Mobile Stroke Units

Background: San Francisco (California USA) is a relatively compact city with a population of 884,000 and nine stroke centers within a 47 square mile area. Emergency Medical Services (EMS) transport distances and times are short and there are currently no Mobile Stroke Units (MSUs). Methods: This study evaluated EMS activation to computed tomography (CT [EMS-CT]) and EMS activation to thrombolysis (EMS-TPA) times for acute stroke in the first two years after implementation of an emergency department (ED) focused, direct EMS-to-CT protocol entitled "Mission Protocol" (MP) at a safety net hospital in San Francisco and compared performance to published reports from MSUs. The EMS times were abstracted from ambulance records. Geometric means were calculated for MP data and pooled means were similarly calculated from published MSU data. Results: From July 2017 through June 2019, a total of 423 patients with suspected stroke were evaluated under the MP, and 166 of these patients were either ultimately diagnosed with ischemic stroke or were treated as a stroke but later diagnosed as a stroke mimic. The EMS and treatment time data were available for 134 of these patients with 61 patients (45.5%) receiving thrombolysis, with mean EMS-CT and EMS-TPA times of 41 minutes (95% CI, 39-43) and 63 minutes (95% CI, 57-70), respectively. The pooled estimates for MSUs suggested a mean EMS-CT time of 35 minutes (95% CI, 27-45) and a mean EMS-TPA time of 48 minutes (95% CI, 39-60). The MSUs achieved faster EMS-CT and EMS-TPA times (P <.0001 for each). Conclusions: In a moderate-sized, urban setting with high population density, MP was able to achieve EMS activation to treatment times for stroke thrombolysis that were approximately 15 minutes slower than the published performance of MSUs.