Comparison of Propofol Requirement Between Patients With Pituitary Somatotroph Tumor and With Nonfunctioning Pituitary Tumor in Transsphenoidal Pituitary Surgery Under Total Intravenous Anesthesia

Investigators hypothesized that propofol dose for pituitary somatotroph patients might differ from nonfunctioning pituitary tumor, and investigators will evaluate a target controlled infusion (TCI) effect site concentration (Ce) of propofol for BIS score of 40 and LOC (loss of consciousness) in pituitary somatotroph patients in comparison with non functioning pituitary tumor patients.

On arrival in the operating room, standard monitoring devices, including electrocardiogram, pulse oximetry, noninvasive blood pressure cuff, and bispectral index (BIS) will be applied to the patients. Propofol with the modified Marsh pharmacokinetic parameters using a keo of 1.2/min will be administered through TCI pump (OrchestraBase Primea, Fresenius Vial, France). The initial target Ce of propofol will be chosen as 3.0 mg/mL (0.5 mg/mL of incremental size) based on an earlier study.

The sedation of patients will be assessed with BIS score and the modified observer's assessment of awareness and sedation (OAA/S). LOC was defined as an OAA/S lower than 2 (loss of response to spoken command to eye opening and loss of response to mild prodding or shaking). The primary end point of this study is the Ce of propofol when the BIS score is 40. The secondary end point of this study is the Ce of propofol at LOC.