The three phases of blood pressure in stroke.

Studies of three large series of hypertensive patients having strokes have shown that systemic blood pressure responds to stroke during the acute phase. The blood pressure is elevated on the day of admission to the hospital in 82% of patients and then decreases to normotensive levels during the subacute stage in 59%. During the chronic phase of stroke, normal blood pressure persists in 26% of these patients. The three phases of blood pressure change after stroke are likely a physiologic response to ischemia of the brain followed by recovery of brain function. The identification of these three states of blood pressure in stroke underlines the importance of prudence and caution in administering antihypertensive drugs to patients who have had a stroke.