Alfentanil increases intracranial pressure when intracranial compliance is low.

Intracranial pressure increases following the administration of alfentanil 1 mg are reported in five patients with suspected normal pressure hydrocephalus who were undergoing infusion of saline into a lateral ventricle to measure cerebrospinal fluid outflow resistance. The increase in intracranial pressure was accompanied by a fall in mean arterial pressure. These observations show that, when the intracranial compliance is reduced, alfentanil can cause considerable increases in intracranial pressure and decreases in cerebral perfusion pressure.