Stroke Recognition & Last Known Well

Why this matters

Stroke treatment depends on the clock. Last known well is the last time the patient was seen normal, not the time you found them. A wrong time can take away treatment options. Missing a posterior stroke can do the same thing. A long scene can do the same thing. First, recognize the stroke and check glucose. Give oxygen only if they are hypoxic. Package quickly and give a clear hospital alert. Do not give a thrombolytic in the field. A full neurology exam in the living room does not help.

Recognition Themes

• Face, arm, and speech tools, such as a Cincinnati-style screen, catch many anterior strokes.
• BEFAST adds balance and eyes, then face, arms, speech, and time. That catches more presentations.
• Posterior clues include sudden severe dizziness or vertigo with other neurologic signs, double vision, slurred speech, unsteady gait, and a sudden vision change. Do not call these “just dizzy.”
• Mimics include low or high glucose, Todd paralysis after a seizure, migraine, intoxication, sepsis, and fainting. Still run the stroke pathway when the criteria are met and the protocol says so.
• A child with a sudden one-sided deficit is still a stroke until the hospital says otherwise. Follow the pediatric destination in your protocol. This page does not list a pediatric clot-busting dose.
• For possible large-vessel occlusion, many systems add a second scale such as LAMS, RACE, VAN, or FAST-ED. That scale helps decide whether a thrombectomy-capable hospital is the first door. Use only the tool your protocol names.

Last Known Well — Get It Right

• Last known well is the last time the patient was seen normal, not the time they were found.
• In a wake-up stroke, last known well is usually the last time they were seen normal before sleep, unless you have a better time.
• Write the clock time and the name and relationship of the person who saw them.
• Anticoagulants, recent surgery, a prior stroke, and baseline deficits are high-value facts for the emergency department.

Clinical sequence

1. Protect the airway, breathing, and circulation. Protect the airway if they are vomiting or altered.
2. Check glucose per protocol. Treat low glucose if you find it.
3. Give oxygen if they are hypoxic. The 2026 stroke guideline says to keep saturation above 94% when you give oxygen. Do not chase a saturation above 94% as a goal to push higher. Do not put a non-rebreather on a talking patient who is already saturating well. This is not the heart-attack cutoff of oxygen only under 90%, and it is not the post-arrest band of 90 to 98%.
4. Use a brief stroke screen. Add your system’s large-vessel scale if it is required. Do not delay transport for extra tests.
5. Keep them from eating or drinking. Aspiration risk is real.
6. Keep the head elevated if your protocol supports it and there is no trauma reason to do otherwise.
7. Do not lower blood pressure on your own unless your protocol specifically directs it. Do not start nitroglycerin, including a patch, to treat the stroke or to bring the pressure down. The 2026 stroke guideline says prehospital nitroglycerin does not improve outcome and can cause harm. Driving the systolic pressure down to 130 or 140 in the ambulance does not improve outcome.
8. Call a stroke alert early. Destination follows your system. Some systems send a suspected large-vessel occlusion to the closest thrombectomy hospital when transfer would be slow. Others still go to the nearest hospital that can give a clot-busting drug. A mobile stroke unit is an option only where your system has one. Where it exists, 2026 AHA/ASA teaching prefers it over a standard ambulance for suspected stroke that may be eligible for thrombolysis. Your protocol owns the routing rule. Do not give a thrombolytic in the field.
9. Keep the scene short. Fifteen minutes or less is a common quality target. Take the history while you package.

Common errors

• Do not write “onset when 911 was called” instead of the true last known well.
• Do not skip the glucose check.
• Do not stay for a perfect exam while the clock runs.
• Do not miss posterior circulation signs.
• Do not start nitroglycerin because the blood pressure is high.

Practice

Related: Altered Mental Status.

Sources & Further Study

Named guidelines for further study. They are not clinical orders and do not replace your protocol or medical direction.

• NASEMSO National Model EMS Clinical Guidelines (2022) — U.S. EMS model language; your protocol still decides care
• 2026 AHA/ASA Guideline for the Early Management of Patients With Acute Ischemic Stroke (replaces the 2018 guideline and 2019 update)
• AHA Mission: Lifeline Stroke / EMS stroke systems of care
• 2026 AIS EMS themes: use a validated stroke screen (Class 1), check glucose, record last known well, and treat a scene time of 15 minutes or less as a quality metric. Notify the hospital before you arrive, and choose the destination by local thrombectomy and transfer performance. If they are hypoxic, maintain saturation above 94%. Do not chase a higher number, and do not use a non-rebreather by default when they are already saturating well. A mobile stroke unit is preferred over a standard ambulance only where one exists. Your protocol owns routing. Do not give a thrombolytic in the field. Do not start nitroglycerin for a suspected stroke. A field plan to drive systolic pressure to 130 or 140 does not improve outcome. A child with a sudden one-sided deficit still follows the stroke pathway and the pediatric destination in your protocol.
• Follow your stroke alert and destination protocol.