Carbon dioxide reactivity during prostaglandin E1 induced hypotension for cerebral aneurysm surgery.

The cerebral vasomotor reactivity to carbon dioxide was studied, using a thermal gradient blood flow meter in 43 patients with intracranial cerebral aneurysm under deliberate hypotension induced by prostaglandin E1 (PGE1) infusion. The patients were divided into three groups according to the neurological status. Patients in Groups A and B had subarachnoid haemorrhage due to ruptured cerebral aneurysms. Group A consisted of 23 patients with a neurological grade of I-II and Group B consisted of 11 patients with a grade of III-V. Nine patients with non-ruptured cerebral aneurysm served as controls (Group C). After the dura was opened, local cerebral blood flow (LCBF) was measured. The PGE1 was started with an initial dose of 0.1 microgram.-kg-1.min-1 and the dose was adjusted to maintain MAP at about 70 mmHg. The LCBF and carbon dioxide (CO2) reactivity were estimated during and after PGE1 administration. The LCBF did not change among groups throughout the study period. Carbon dioxide reactivity was estimated as follows: absolute; delta LCBF/delta PaCO2, and relative; % delta LCBF/delta PaCO2 after changing PaCO2 by increasing minute ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)