Effect of controlled blood pressure increase on cerebral blood flow velocity and oxygenation in patients with subarachnoid haemorrhage

Background Patients with aneurysmal subarachnoid haemorrhage (SAH) might have impaired cerebral autoregulation, that is, CBF – and thereby oxygen delivery – passively increase with an increase in CPP. This physiological study aimed to investigate the cerebral haemodynamic effects of controlled blood pressure increase in the early phase after SAH before any signs of delayed cerebral ischaemia (DCI) occurred. Methods The study was carried out within 5 days after ictus. Data were recorded at baseline and after 20 min of noradrenaline infusion to increase mean arterial blood pressure (MAP) by a maximum of 30 mmHg and to an absolute level of no more than 130 mmHg. The primary outcome was the difference in middle cerebral artery blood flow velocity (MCAv) measured by transcranial Doppler (TCD), while differences in intracranial pressure (ICP), brain tissue oxygen tension (PbtO2), and microdialysis markers of cerebral oxidative metabolism and cell injury were assessed as exploratory outcomes. Data were analysed using Wilcoxon signed‐rank test with correction for multiplicity for the exploratory outcomes using the Benjamini‐Hochberg correction. Results Thirty‐six participants underwent the intervention 4 (median, IQR: 3–4.75) days after ictus. MAP was increased from 82 (IQR: 76–85) to 95 (IQR: 88–98) mmHg (p‐value: