The choice of controlled hypotension during repair of intracranial aneurysms: techniques and complications.

Induced hypotension is frequently used during cerebral aneurysm dissection and clipping to reduce the risk of rupture. The ideal hypotensive agent does not exist and many drugs are currently used for the purpose of inducing hypotension. When used correctly serious complications are rare. These complications are either related to (1) the physiological effects of hypotension on the vital organs, namely, the brain, the heart, the lungs, the liver and the kidneys, or (2) the pharmacology of the respective hypotensive agent used which currently include the direct vasodilators-sodium nitroprusside and nitroglycerin; inhalation agents--isoflurane, enflurane and halothane; ganglionic blocker--trimethaphan; alpha/beta blockers- labetalol, esmolol; calcium channel blockers; and the experimental compound adenosine. Familiarity with both the physiology and pharmacology of induced hypotension will reduce the risk of complications of this useful technique.