Increase of perfusion pressure improves the CBF and helps to avoid cellular death due to improved collateral circulation. Induced hypertension is therefore used to reduce ischemia during the temporary vascular occlusion. It may also assist treatment of vasospasm. Phenylephrine is alpha-agonist and does not cause direct cerebral vasoconstriction. The increase of the CBF caused the phenylephrine is due to the increase of systemic blood pressure.
Inducted hypertension can produce edema and cerebral hemorrhage.
In addition, it can increase the afterload and cause myocardial ischemia. Hypothermia Hypothermia is another technique used to protect the brain during surgery of intracranial aneurysms. Hypothermia produces a reduction in cerebral metabolism by decreasing cerebral electrical activity. The relationship between the degree of cerebral protection and hypothermia is not lineal. Some use moderate hypothermia during temporary vascular occlusion as another way of protecting the brain combined with induced hypertension.