A novel multivariate STeady-state index during general ANesthesia (STAN).

Area of Science:

• Anesthesiology and Critical Care Medicine
• Biomedical Signal Processing
• Physiological Monitoring

Background:

• Assessing the nociception/anti-nociception balance during general anesthesia is crucial for surgical safety.
• Existing monitoring systems (EEG/EMG, autonomic reactions) aim to objectively evaluate this balance.
• There is a need for advanced methods to reliably assess patient steady-state under anesthesia.

Purpose of the Study:

• To introduce and validate a novel multivariate index, the Steady-state ANalysis (STAN), for assessing patient steady-state during general anesthesia.
• To evaluate STAN's responsiveness to noxious stimuli (laryngoscopy/intubation, tetanic, incision) under varying analgesic (remifentanil) doses.
• To compare STAN's performance against established monitoring parameters like BIS.

Main Methods:

• Developed a new multivariate index (STAN) using wavelet analysis of physiological signals (ECG, PPG, BP, respiration rate, EEG, EMG).
• Collected continuous physiological data from 34 patients undergoing general anesthesia with three different remifentanil infusion rates (2.0, 3.0, 4.0 ng/ml).
• Analyzed STAN's response to specific noxious stimuli and compared it with BIS, heart rate, blood pressure, and EMG using statistical tests.

Main Results:

• The STAN index demonstrated adequate responsiveness to noxious stimuli, particularly laryngoscopy/intubation (18.5-43.1% change).
• STAN effectively detected the dose-dependent attenuation of noxious stimuli by remifentanil.
• The index identified steady-state periods in approximately 50% of the total recorded study time.

Conclusions:

• The proposed wavelet-based multivariate index (STAN) offers a novel and effective approach for assessing patient steady-state during general anesthesia.
• STAN accurately reflects the nociception/anti-nociception balance and the effects of analgesia.
• This new index shows promise for improving objective patient monitoring in anesthesia.