OBJECTIVE To compare anesthesia quality and sevoflurane consumption during standard and extended intraoperative monitoring. METHODS 74 patients were included in prospective randomized study. Patients had spinal pathology of varying severity, extension and localization. A comparative evaluation of standard and extended (with entropy) monitoring was performed during low-flow inhalation anesthesia with the automated control of the anesthetic concentration and exhaled oxygen fraction (Et-control). RESULTS Monitoring depth of anesthesia based on entropy enables more accurate dosing of inhaled anesthetics. CONCLUSIONS The study revealed that the use of entropy monitoring in high-risk surgery alleviates providing the controlled anesthesia with the optimal inhalation anesthetic concentration and minimal hemodynamic reactions of the patient.