Reducing onset-to-door times through the implementation of a prehospital large vessel occlusion bypass protocol: the Oahu experience.

BACKGROUND

The Oahu large vessel occlusion (LVO) bypass protocol is a real-world island-wide EMS initiative designed to identify patients with suspected LVOs in the field and triage them directly to a Comprehensive Stroke Center (CSC) for endovascular therapy (EVT).

METHODS

A retrospective preimplementation-postimplementation study was conducted to investigate the impact of the bypass protocol on endovascular treatment times and patient outcomes between January 1, 2017 to January 1, 2023.

RESULTS

A total of 351 patients met inclusion criteria (102 patients pre-bypass vs. 249 patients post-bypass). In an interrupted time series analysis, there was a sustained 66-min reduction in onset-to-CSC door time (p = 0.0046), and a 41-min reduction in onset-to-reperfusion time (p = 0.08) in the post-bypass period with no changes in temporal trends. Interfacility transfers for EVT declined 5-fold (55.9% to 11.6%; p < 0.001) with no delay in onset-to-thrombolytic time (p = 0.13). In multivariate logistic regression modeling, longer onset-to-reperfusion times were independently associated with worse clinical outcomes, where every 30-min delay increased the odds of a higher 90-day mRS score by 6% (OR 1.062, 95% CI 1.001-1.125, p = 0.033). The post-bypass era, itself, however, was not associated with improved 90-day good outcomes (mRS 0-2: 40.2% vs. 44.6%; adjusted OR 0.98 [95% CI, 0.57-1.69]; p = 0.93) or a shift in 90-day mRS disability (adjusted OR 0.93 [0.60-1.41]; p = 0.72), though a nonsignificant trend toward improved 90-day excellent outcomes was observed (mRS 0-1: 23.5% vs. 34.5%; unadjusted OR 1.75 [1.01-2.90], p = 0.045; adjusted OR 1.51 [0.84-2.72], p = 0.17).

CONCLUSIONS

Implementation of a system-wide EMS LVO bypass protocol successfully reduced onset-to-door and onset-to-reperfusion times within a uniquely closed catchment geography. The impact on clinical outcomes, however, remains to be seen.