Blood Pressure Treatment in ICU Patients with Subarachniodal Haemorrhage. -Can Blood Pressure Be Used As a Surrogate Marker for Blood Flow

Subarachnoidal hemorrhage (SAH) is a type of stroke with high mortality rates and often requires care at the intensive care unit. Cerebral blood flow (CBF) needs to be ensured so that the brain receives optimal nourishment, and this is largely controlled by regulating blood pressure (BP) using medications that affect the heart and blood vessels. Approximately 3-7 days after SAH onset, vasospasm (SAH-V) can occur. Treatment usually includes maintaining blood pressure (BP) above a certain threshold to achieve adequate cerebral blood flow (CBF). An important component of raising BP is increasing vascular resistance using vasoconstrictive medications, which paradoxically can decrease CBF.

The study objective is to investigate the correlation between BP changes and their impact on CBF in patients with suspect or verified SAH-V using MRI.

To achieve this purpose, the investigators plan to examine the relationship between BP and CBF in patients with SAH-V who require neuro-intensive care. To measure CBF, two techniquis will be used: phase-contrast MRI and arterial spin labeling.

Flow measurement with MRI:

1. Baseline images will be acquired at baseline blood pressure.
2. Mean arterial pressure (MAP) will be increased using norepinephrine. New images will be acquired when MAP is increased by approximately 20-30% from the baseline.