Which statement about last known well timing is correct?

Which statement about last known well timing is correct?

• A. It is only used to determine hospital bed assignments.
• B. It establishes the therapeutic window for reperfusion therapies and imaging decisions.
• C. It has no impact on imaging choices.
• D. It determines the exact dose of tPA to administer.

Answer: (B)

Last known well timing anchors the moment symptoms began or were last absent, and that anchor sets the time frame for both treatment options and imaging decisions. Knowing this time helps determine eligibility for reperfusion therapies, such as intravenous thrombolysis within the standard time window and thrombectomy based on imaging and time criteria. It also guides what imaging to perform—CT or MRI with perfusion assessments—to separate irreversibly damaged tissue from salvageable brain tissue and to decide if the patient qualifies for therapy within the applicable window or needs advanced imaging selection, like perfusion imaging for wake-up strokes. It does not determine bed assignment, and the tPA dose is based on body weight, not timing.

Last known well timing anchors the moment symptoms began or were last absent, and that anchor sets the time frame for both treatment options and imaging decisions. Knowing this time helps determine eligibility for reperfusion therapies, such as intravenous thrombolysis within the standard time window and thrombectomy based on imaging and time criteria. It also guides what imaging to perform—CT or MRI with perfusion assessments—to separate irreversibly damaged tissue from salvageable brain tissue and to decide if the patient qualifies for therapy within the applicable window or needs advanced imaging selection, like perfusion imaging for wake-up strokes. It does not determine bed assignment, and the tPA dose is based on body weight, not timing.