We know that a key determinant of outcome in hemorrhagic stroke is haematoma volume(Stroke 1997;28:1-5), so that a large haematoma, or haematoma expansion is associated with poor outcomes. We also know that intracerebral haemorrhage and associated high blood pressure, has a poor clinical outcome (JHypertension 2005;23:1217-23)
The first thing to make clear is that hemorrhagic stroke is different to ischaemic stroke. In ischaemic stroke, all the fuss related to lysis, is about perfusing and salvaging the penumbra of ischaemic brain tissue, surrounding the dead central tissue.
This penumbra doesn’t exist around hemorrhagic tissue. This region is said to be in a hibernating state and the low cerebral blood flow is matched by a low metabolic rate. CT perfusion scans show no adverse effect on perihaematoma blood flow, with early aggressive BP control to a systolic of less than 150mmHg (Stroke 2013;44:620-26)
What should we lower the blood pressure to?
The INTERACT 2 trial (NEJM 2013;368:2355-65) is the largest randomised trial of patients with intracerebral haemorrhage and blood pressures up to 220mmHg, where control was within 6 hours, to two systolic blood pressure groups:
Overall the trial did not show a reduction in death or disability, although there was a trend towards improved functional outcomes in the <140mmHg group.
What is also important is that the group with aggressive blood pressure control to < 140mmHg did not show early neurologic deterioration or adverse events. What it did show, was a lower haematoma volume.
The ATTACH Trial was interesting from this point of view as it had similar arms, but also a third arm that looked at aggressive BP control i.e.., 110-140mmHg. Again, no adverse events with aggressive blood pressure lowering.
Only one study has ever shown poor outcome from aggressive blood pressure lowering to 140mmHg (J Intern Med. 2004;255:257–265)
What about subarachnoid haemorrhage?
Not much great evidence here. We know that rebleeding with potentially catastrophic effects can occur in the first 12 hours. This rebleeding is strongly associated with hypertension ie., systolic blood pressure >160mmHg (Arch Neurol.2005;62:410-416). Most recommendations here are consensus opinion.
What do the guidelines say?