To evaluate the effect of an EMS bypass protocol for large vessel occlusions, on the rate of stroke admissions, proportion of stroke patients receiving intravenous tPA, and time to thrombolysis at primary stroke centers.  

Over the last few years, we implemented an EMS bypass protocol based on the RACE score to help triage patients with suspected large vessel occlusions, directly to endovascular capable centers (ECC).  Improved door to puncture times have been noted at ECCs with implementation of pre-hospital stroke scales.  Increased bypass of stroke patients is a concern for primary stroke centers (PSC) due to reduced revenue and experience in managing acute stroke patients.  Few studies have evaluated the impact of an EMS bypass protocol on primary stroke centers.

Prospectively collected data from January, 2013 to December, 2018, was reviewed from three PSCs in Lucas County, Ohio, which has an estimated population of 431,000. The cohort was divided into pre and post-EMS bypass protocol implementation, and comparisons were made to determine differences in rate of stroke admissions, proportion of stroke patients receiving intravenous tPA, and door-to-needle times.

After implementation of the EMS bypass protocol, the rate of stroke admissions decreased by 6 % at PSCs. There was an increase in the proportion of patients (5 % to 6.3%) who received intravenous tPA at PSCs. Mean door to needle times at PSCs improved by over 10 minutes, after implementation of the EMS bypass protocol (80.3 to 70.3 minutes; p< 0.0001).

Implementation of stroke severity based EMS bypass protocol does not significantly reduce stroke admissions at PSCs. It may however, have secondary effects on PSCs which need further studying.