Ischaemic brain following emergency blood pressure lowering in hypertensive patients

[The hypertensive emergency situation : Recommendations for initial drug therapy management]

The hypertensive emergency situation is characterized by an acute-mostly life-threatening-blood pressure derailment with the risk of acute end organ damage. It is an acute manifestation of arterial hypertension, which manifests in a variety of symptoms. The etiology is in most cases long-term (chronic) hypertension as a result of low compliance or inadequate antihypertensive therapy. It can also occur as a first manifestation of arterial hypertension. It requires timely antihypertensive drug therapy, which should be initiated in an intensive or intermediate care unit. The choice of antihypertensive therapy regimen should be based on the underlying end organ damage. Fast-acting, easily controllable and intravenously administered substances should be preferred. The most commonly used substances (groups) are urapidil, nitroglycerin, beta blockers and short-acting calcium channel blockers. With a few exceptions, a deliberate, rapid reduction in blood pressure of no more than 20-25% of the initial value is sufficient for extracerebral causes. A subsequent systolic blood pressure target of 160/100 mm Hg should be aimed for within the next 2-6 h. An overly rapid drop in blood pressure can lead to reduced blood flow to the central nervous system due to changes in autoregulation. Exceptions to this rule are acute aortic dissection and flash pulmonary edema-in these cases, prompt blood pressure normalization should be achieved. The initial acute therapy should be followed by a more detailed investigation of the cause and a long-term therapy setting based on this.

[Hypertensive emergencies]

Critical cases of high blood pressure are common clinical occurrences that may account for as many as 25% of all medical emergencies. About 75% of these increases in blood pressure can be judged as hypertensive urgencies, 25% are even hypertensive emergency situations. Nevertheless, only less than 1% of the hypertensive population experiences hypertensive urgency or emergency situations. Hypertensive emergencies are defined as acute cardiac, vascular or cerebral target organ damages. In these cases an acute lowering of blood pressure is inevitable. The rate and intensity of blood pressure depression is dependent on the localization of organ damages. For cardiac and vascular damages it is absolutely necessary to lower the blood pressure rapidly to near normal values. On the contrary, cerebral organ damages are better treated by a moderate lowering of blood pressure peaks to slightly increased blood pressure levels. In hypertensive urgencies no target organ damages occur. For these patients a slow lowering of blood pressure values to normal levels is adequate.

Effect of intravenous nimodipine on blood pressure and outcome after acute stroke

BACKGROUND AND PURPOSE

The Intravenous Nimodipine West European Stroke Trial (INWEST) found a correlation between nimodipine-induced reduction in blood pressure (BP) and an unfavorable outcome in acute stroke. We sought to confirm this correlation with and without adjustment for prognostic variables and to investigate outcome in subgroups with increasing levels of BP reduction.

METHODS

Patients with a clinical diagnosis of ischemic stroke (within 24 hours) were consecutively allocated to receive placebo (n=100), 1 mg/h (low-dose) nimodipine (n=101), or 2 mg/h (high-dose) nimodipine (n=94). The correlation between average BP change during the first 2 days and the outcome at day 21 was analyzed.

RESULTS

Two hundred sixty-five patients were included in this analysis (n=92, 93, and 80 for placebo, low dose, and high dose, respectively). Nimodipine treatment resulted in a statistically significant reduction in systolic BP (SBP) and diastolic BP (DBP) from baseline compared with placebo during the first few days. In multivariate analysis, a significant correlation between DBP reduction and worsening of the neurological score was found for the high-dose group (beta=0.49, P=0. 048). Patients with a DBP reduction of > or =20% in the high-dose group had a significantly increased adjusted OR for the compound outcome variable death or dependency (Barthel Index <60) (n/N=25/26, OR 10. 16, 95% CI 1.02 to 101.74) and death alone (n/N=9/26, OR 4.336, 95% CI 1.131 16.619) compared with all placebo patients (n/N=62/92 and 14/92, respectively). There was no correlation between SBP change and outcome.

CONCLUSIONS

DBP, but not SBP, reduction was associated with neurological worsening after the intravenous administration of high-dose nimodipine after acute stroke. For low-dose nimodipine, the results were not conclusive. These results do not confirm or exclude a neuroprotective property of nimodipine.