Persons who have an ischemic stroke often present with elevated blood pressure caused by a physiologic response to ischemia and the anxiety of hospitalization. Because the blood pressure in these patients usually drops spontaneously within a few days, the recommendation is not to treat moderate blood pressure elevations early in the hospitalization. It has been postulated that sudden lowering of blood pressure during the first few days following acute ischemic stroke can reduce cerebral perfusion in the affected area and worsen prognosis. Although this has been confirmed by monitoring blood pressures in the hospital, data about the preadmission period are not available. Vlcek and associates studied whether the effect of blood pressure lowering within the first 24 hours following ischemic stroke results in worsening of neurologic outcomes.
Patients who were seen initially by emergency medical services within 48 hours after the onset of neurologic symptoms were included in the study. Preadmission blood pressures (as well as blood pressures during 24 hours after admission) were recorded, as were all administrations of antihypertensive medications. Functional status, which was the primary study outcome, was measured on admission and again on days 5 through 7.
Relative changes in systolic and diastolic blood pressure from preadmission to admission appeared not to be associated with poor neurologic outcomes at five to seven days. The use of antihypertensive medications at preadmission or for 24 hours after admission was not associated with poor neurologic outcomes. Relative changes in systolic and diastolic blood pressures from admission to 24 hours after admission showed a significant association with poor neurologic outcome with diastolic blood pressure changes only. Analysis showed that a diastolic blood pressure decrease of greater than 25 percent from admission until 24 hours after admission was associated with a 3.8-fold increase in odds for poor neurologic outcome on functional reexamination at day 5. This observation seemed to be independent of baseline diastolic blood pressure values.
The authors conclude that early excessive diastolic reduction of more than 25 percent after ischemic stroke is associated with worsened neurologic outcomes. This observation is independent of the initial diastolic blood pressure value and of concomitant risk factors, stroke localization, and the use or nonuse of antihypertensive medication. Close blood pressure monitoring is strongly recommended during the first few days following the acute event. Moderate reduction in blood pressure probably has no negative impact on outcome.