[The relation of vertebral artery blood flow velocity to mean arterial pressure during anesthesia with enflurane or isoflurane].

The relation of vertebral artery blood flow velocity (VABFV) to mean arterial pressure (MAP) during anesthesia with enflurane or isoflurane was examined. The subjects were 17 patients on the knee-chest position. Anesthesia was induced with thiamylal and fentanyl. The patients were placed on the knee-chest position after tracheal intubation. Ventilation was adjusted to maintain a constant level of PaCO2 (30-40 mmHg). The patients were divided into two groups. Anesthesia was maintained with enflurane and 67% N2O in group E (8 patients), or with isoflurane and 67% N2O in group I (9 patients). VABFV was measured with a transcranial Doppler sonography (TCD), and MAP was measured through a radial artery catheter. The mean VABFV and MAP were recorded at five-minute intervals. VABFV was found to change with the change in the MAP for the same degree in both groups. The results suggest that cerebral autoregulation is disturbed during either isoflurane-N2O or enflurane-N2O anesthesia.