Episode 33: Ischemic stroke with Thomas Lawson

Evaluation of ischemic stroke, decisions for tPA and thrombectomy, supportive critical care, and monitoring for cerebral edema—with returning guest Thomas Lawson (@TomLawsonNP), nurse practitioner in the neurocritical care unit at OSU Wexner Medical Center and James Cancer Hospital. Thomas is now also a PhD student at the OSU College of Nursing where he studies the epidemiology of delirium in critically ill stroke patients, and recently cofounded the Board Review Associates AG-ACNP board review course.

Takeaway lessons

  1. The first priorities after suspected ischemic stroke is head CT to rule out hemorrhage, screening for tPA rule-outs, and establishing a “last known normal” time. The window for systemic tPA is 3-4.5 hours from known onset of symptoms, although the sooner the better.
  2. Patients who are not candidates for tPA should receive some form of perfusion imaging (such as a CT perfusion scan) to characterize the size of the infarct and at-risk penumbra, as well as angiography (e.g. CTA) to assess for the presence of large-vessel occlusions (e.g. ICA, M1), which may mean there is an opportunity for endovascular interventions such as thrombectomy. Smaller vessel occlusions are a less evidence-supported zone and are more dependent on the interventionalist’s judgment.
  3. If there is an opportunity for thrombectomy in a patient who is not a tPA candidate (and these days, potentially even one who is), yet your center cannot perform it, consider stat transfer to somewhere that can.
  4. The preferred initial (and follow-up) neurologic exam is the NIH stroke scale. Check a blood glucose and blood pressure as well.
  5. Post-tPA and/or thrombectomy patients should go to a neuro-capable ICU for hourly neurologic checks and blood pressure control.
  6. BP should be maintained under 180/105 after tPA, or usually somewhat lower (e.g. <160) after thrombectomy alone. Use labetalol and/or hydralazine but have a low threshold for using a drip, usually nicardipine. The newer, quicker-titrating drip clevidipine can be useful too. Later, blood pressure targets can be down-titrated and eventually brought towards “normal” — but watch out for pressure-dependent neurologic function from imperfectly-reperfused stenoses.
  7. Sodium should ideally be normal-ish early. If edema occurs later in the setting of large strokes, you may need to drive sodium up to provide an osmolar gradient, either by a hypertonic infusion or intermittent boluses.
  8. Chemical DVT prophylaxis should be held 24 hours after tPA (along with aspirin and pretty much anything else that could make you bleed), after which you’ll repeat a CT to screen for bleeding. If still none, you can and should start heparin or LMWH. When to start or resume full anticoagulation is a more nuanced question, as large strokes always portend a risk of hemorrhagic conversion.
  9. A non-urgent MRI is usually nice to evaluate the degree of infarction, although it infrequently changes care.
  10. Medium- and long-term recovery is variable and depends heavily on the patient and various other factors including luck. Early, high-quality rehab is key.

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