Critical Care Scenarios
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.
* 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.* 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.* 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.* The preferred initial (and follow-up) neurologic exam is the NIH stroke scale. Check a blood glucose and blood pressure as well.* Post-tPA and/or thrombectomy patients should go to a neuro-capable ICU for hourly neurologic checks and blood pressure control.* BP should be maintained under 180/100 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.* 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.* 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.* A non-urgent MRI is usually nice to evaluate the degree of infarction, although it infrequently changes care.* 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.