The optimal anesthetic depth for interventional neuroradiology: comparisons between light anesthesia and deep anesthesia

Background: This study was designed to determine the optimal anesthetic depth for the maintenance and recovery in interventional neuroradiology. Methods: Eighty-eight patients undergoing interventional neuroradiology were randomly allocated to light anesthesia (n = 44) or deep anesthesia (n = 44) groups based on the value of the bispectral index (BIS). Anesthesia was induced with propofol, alfentanil, and rocuronium and maintained with 1−3% sevoflurane. The concentration of sevoflurane was titrated to maintain BIS at 40−49 (deep anesthesia group) or 50−59 (light anesthesia group). Phenylephrine was used to maintain the mean arterial pressure within 20% of preinduction values. Recovery times were recorded. Results: The light anesthesia group had a more rapid recovery to spontaneous ventilation, eye opening, extubation, and orientation (4.1 ± 2.3 vs. 5.3 ± 1.8 min, 6.9 ± 3.2 min vs. 9.1 ± 3.2 min, 8.2 ± 3.1 min vs. 10.7 ± 3.3 min, 10.0 ± 3.9 min vs. 12.9 ± 5.5 min, all P < 0.01) compared to the deep anesthesia group. The use of phenylephrine was significantly increased in the deep anesthesia group (768 ± 184 vs. 320 ± 82 μg, P < 0.01). More patients moved during the procedure in the light anesthesia group (6/44 [14%] vs. 0/44 [0%], P = 0.026). Conclusions: BIS values between 50 and 59 for interventional neuroradiology were associated with a more rapid recovery and favorable hemodynamic response, but also with more patient movement. We suggest that maintaining BIS values between 40 and 49 is preferable for the prevention of patient movement during anesthesia for interventional neuroradiology.