- Figure: Cerebral autoregulation resulted in a constant level of blood flow to the brain over a wide range of systemic BPs. However, once systemic BP fell below or rose above a certain threshold, autoregulation was lost and the level of cerebral BP mirrored that of systemic pressures.
- For example, mean pre-study MAP among controls was 112 mm Hg (144/94mm Hg). Cerebral autoregulation did not fail until the MAP declined to 70 mm Hg (94/58 mm Hg). Thereafter, symptoms of cerebral ischemic (malaise, somnolence) developed.
- In contrast, mean pre-study MAP among hypertensives was 146 mm Hg (196/122 mm Hg). When the MAP fell to less than 120 mm Hg (168/96 mm Hg), autoregulation was lost and symptoms of cerebral hypoxia became manifest.