Treatment Considerations in Stroke
Elevated blood pressure is common in the early stages of stroke. Numerous studies have analyzed overall outcomes in patients presenting with ischemic stroke and uncontrolled hypertension. In this setting, evidence suggests a poorer prognosis in patients treated aggressively with antihypertensive agents.4,21,22
The association between dramatic reduction in blood pressure and poor prognoses lies in the theory of the ischemic penumbra. This is an area around the core of ischemic tissue that receives enough blood flow to maintain neuronal activity for a few hours after initial injury, but this tissue is susceptible to further infarction. Precipitous drops in blood pressure can reduce blood flow to collateral vessels, resulting in hypoperfusion of the penumbra and leading to further neurologic damage.
Details and current treatment recommendations for each of the various types of stroke follow.
Acute intracerebral hemorrhage. Uncontrolled hypertension is often associated with intracerebral hemorrhage (ICH), either as a risk factor or a factor that contributes to the event. Once a patient has experienced an acute brain insult, blood pressure can become even more uncontrolled. Extension of the hematoma and a worsening outcome are the main concerns in treating the patient with concomitant blood pressure elevation and ICH. Also of concern is maintaining adequate perfusion to the penumbra. Additionally, transient hypoperfusion can develop when the ICP is elevated and the mean arterial pressure (MAP) is acutely lowered, thus reducing the cerebral perfusion pressure (CPP; CPP = MAP - ICP).
Researchers have acknowledged there is insufficient evidence to offer management guidelines for blood pressure reduction in patients with ICH.28 The 2007 recommendations from the American Heart Association/ American Stroke Association (AHA/ASA) for blood pressure management in patients with acute ICH29 are as follows: In the setting of ICH in patients with uncontrolled blood pressure, treatment should be aggressive if systolic blood pressure exceeds 200 mm Hg or MAP exceeds 150 mm Hg. A treatment goal to consider is reducing systolic blood pres sure to 160 mm Hg or less (or MAP to below 130 mm Hg).29 Patients with elevated ICP should undergo placement of a ventriculostomy to maintain a CPP between 60 and 80 mm Hg, although the risk for infection or intracerebral hemorrhage must be weighed against the potential benefits.29,30
When blood pressure reduction is required, the MAP should not be lowered more than 20% in a 24-hour period. Recommended agents include IV nicardipine, labetalol, enalapril, hydralazine, or esmolol.31
Acute ischemic stroke. Long-term control of blood pressure in patients who have experienced stroke remains undisputed, as it improves outcomes. However, in the setting of acute ischemic stroke (AIS), initiating blood pressure control is more liberal. Optimal control of blood pressure during management of AIS is imperative to reduce morbidity and mortality.32 Areas affected by edematous brain tissue are at increased risk for bleeding (ie, hemorrhagic expansion).
Patients who present with AIS require careful history taking to elicit their average blood pressure range; this will help the clinician determine goal pressures during management of the acute stroke phase.33 The primary rationale for treating blood pressure in this acute setting is to prevent hemorrhagic expansion at sites with potential for bleeding.34
According to the 2007 AHA/ ASA recommendations for management of blood pressure in AIS,35 patients who are eligible for thrombolysis should have a systolic blood pressure goal below 180 mm Hg and diastolic blood pressure below 105 mm Hg. Patients who will not receive thrombolytics should have blood pressure lowered only if systolic blood pressure exceeds 220 mm Hg or diastolic blood pressure exceeds 110 mm Hg.35,36 Appropriately refraining from reducing blood pressure is known as permissive hypertension.
Given the fragility of the cerebral brain tissue after AIS, permissive hypertension is intended to protect the penumbra and preserve cerebral blood flow. In patients who require blood pressure reduction because of other medical conditions (eg, decompensated heart failure), blood pressure should not be lowered more than 10% to 15% in a 24-hour period.9,31,36 No specific antihypertensives are preferred in patients with AIS: IV enalapril, esmolol, labetalol, or nicardipine can be used.31
Subarachnoid hemorrhage. The two complications of a subarachnoid hemorrhage (SAH) that most contribute to morbidity and mortality are rebleeding and vasospasms; elevated blood pressure can contribute to both. Thus, blood pressure control in patients with SAH is imperative.
Patients with acute SAH often require blood pressure monitoring via arterial line, as well as ICP monitoring. Blood pressure goals are similar to those in patients with ICH. The preferred agent for blood pressure control is nimodipine, which offers the secondary benefit of vasospasm prevention.37