Processed EEG Monitoring During Controlled Hypotension in Patients Undergoing Rhinoplasty

Controlled hypotension is commonly used during rhinoplasty to improve surgical field visibility and reduce bleeding. However, the adequacy and safety of controlled hypotension should not be evaluated only by hemodynamic variables. Processed EEG monitoring may provide additional information about hypnotic depth and the probability of response to nociceptive stimulation.

In this prospective observational study, adult patients undergoing elective rhinoplasty under general anesthesia were monitored with standard ASA monitoring and processed EEG monitoring. Total intravenous anesthesia was maintained with propofol and remifentanil. Esmolol infusion was used as part of the controlled hypotension strategy. Intraoperative qCON and qNOX values, hemodynamic parameters, surgical bleeding scores, anesthetic drug consumption, extubation time, time to reach Aldrete score ≥9, and early postoperative cognitive recovery were recorded.

The primary objective is to evaluate the intraoperative course of qCON and qNOX values during controlled hypotension. Secondary objectives are to assess the relationship of processed EEG parameters with recovery quality, early postoperative cognitive status, anesthetic drug consumption, and surgical field bleeding.

Inclusion criteria

• Patients aged 18 years or older
• Patients scheduled for elective rhinoplasty
• Patients classified as ASA physical status I-II
• Patients planned to undergo general anesthesia with total intravenous anesthesia
• Patients in whom frontal processed EEG electrodes can be applied
• Patients who provide written informed consent

Exclusion criteria

• Emergency surgery
• Severe neurological disease
• Scalp lesion or marked dermatitis preventing processed EEG electrode placement
• Communication or hearing impairment preventing postoperative assessment
• Marked hemodynamic instability
• Multiple trauma or need for postoperative intensive care unit admission
• Pregnancy