Answer:
First off, welcome back to clinical practice. It’s nice to have you helping keep our communities safe again.
As you mention, there have been some changes to the Stroke Bypass system over the past 4 years. One of the changes is the simplified timeline for consideration of Stroke Bypass from 4.5 or 6 hours depending on Endovascular Therapy (EVT) being available (BLS-PCS 3.1) to simply: 6 hours. The most updated version of the Stroke Bypass Protocol can be found in the BLS-PCS v3.3 (here). The Protocol states, “if the patient meets the criteria listed in paragraph 1, determine if the patient can be transported to a Designated Stroke Centre within 6 hours of a clearly determined time of symptoms onset or time the patient was last seen in his/her usual state of health.”
The involvement of a stroke neurologist in consultation for stroke bypass is a regional policy. Paramedic Services and Stroke Centres may choose to include this in their local Bypass agreement (i.e. Paramedic Services and the hospitals that serve as Stroke Centres negotiate some specifics of the agreement based on local/regional factors). The discussion with stroke neurologist in the field facilitates team activation and their arrival at hospital to initiate care, decreasing door to needle time (similar to STEMI). Understanding the “type” of case directly from prehospital history facilitates early neurologist warning for EVT team should that be an option. This has moved beyond field QA of medics identifying strokes. Early numbers 15 years ago showed 6 EMS transported as a stroke, for each true stroke, current data is 1.5 to 1, with stroke mimics often still being sorted out at stroke centre. Usually, the Paramedic Service is part of the Regional Stroke Team and sends out local data.
For further information on the recent changes to the Stroke Bypass Protocol and Paramedic Prompt Card, please see the Corhealth Ontario resources (here). This resource provides multiple resources including a video explaining the rationale for the changes to paramedic practice, along with references for a deep dive into the Canadian Stroke Best Practices.
With regards to timing of treatment outside the scope of paramedic and transport protocols: Tissue Plasminogen Activator (tPA), the IV medication that dissolves clot must be delivered within 4.5 hours of stroke symptom onset. Mechanical removal of a clot with EVT is ideally performed within 6 hours of stroke symptom onset. However, the time window may be extended up to 24 hours, depending on a very selected patient subgroup, with proven specific findings on advanced imaging. Again, this falls outside of the scope of practice for paramedic decision-making. Follow the BLS-PCS and any Service- Stroke Center Bypass agreements.