THE review article about strokes in surgical patients omitted an important, although rare, cause of strokes. Patients undergoing shoulder surgery in the sitting or beach chair position risk a hypotensive/hypoperfusion ischemic stroke because the mean arterial pressure (MAP) in the brain is significantly lower than the cuff blood pressure measured at the arm (heart level). This intraoperative event is especially devastating because it occurs in relatively healthy patients who usually have no risk factors for stroke; they are simply undergoing shoulder surgery to improve their quality of life.

How does this happen? The beach chair position sits the patient at about 70 degrees. The brainstem MAP is about 20 to 40 mmHg lower (depending on the patient’s height) than the measured cuff blood pressure. The additional height to the cerebral cortex lowers brain MAP another 6 to...

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