Faster Prehospital Workflow In The Melbourne Mobile Stroke Unit Halves Onset To Reperfusion Therapy.

Background: The Melbourne Mobile Stroke Unit (MSU) utilises a specialised ambulance with on-board CT scanner and multidisciplinary team to provide on-scene imaging, treatment and triage for central Melbourne, Australia. We describe the operational impact of the MSU on stroke onset to treatment time for acute reperfusion therapy. Methods: Data from the first 6 months of operation were collected for all patients receiving reperfusion therapy from November 2017. Workflow times were compared to contemporary published Australian data and ambulance travel times were derived using a validated Google Maps algorithm. Results: In the first 6 months of operation, the Melbourne MSU provided prehospital thrombolysis (tPA) to n=28 patients (39% of ischemic stroke<4.5h) and directed n=17 patients (24% of infarcts <6hrs) for endovascular thrombectomy (EVT), of which 6/17 (35%) required bypass of the closest non-EVT hospital. Figure 1 shows workflow times for thrombolysis and thrombectomy bypass compared to historical controls. The overall median onset-to-tPA for MSU patients was 101 mins compared to the Australian metropolitan median of 150 mins. Despite a median travel time of 15 mins to the nearest stroke centre, the calculated time saving to start of tPA was 30-60 mins. Prehospital notification for EVT allowed median hospital arrival-to-groin puncture time of 33 mins compared to historical values of 54 mins. MSU diagnosis and bypass to an EVT hospital conservatively reduced EVT delay by 60-90 mins. Discussion: Prehospital treatment and triage using the Mobile Stroke Unit in metropolitan Melbourne resulted in substantially faster commencement of reperfusion therapy. First medical contact to treatment times were approximately halved for thrombolysis and patients requiring bypass for endovascular thrombectomy. Future research will determine the effect of earlier treatment on patient outcomes and cost-effectiveness analysis.