Prospective response surface modeling of analgesia nociception index using propofol, fentanyl and sevoflurane synergism for laryngeal mask airway placement

BACKGROUND: Anesthetic agents exhibit synergistic effects that are difficult to quantify, especially when multiple drugs are used. No response surface model (RSM) exists for analgesia based on the Anti-Nociception Index (ANI). Our objective is to develop a three-drug RSM for ANI to explore analgesic interactions and simulate drug administration with propofol, fentanyl, and sevoflurane. METHODS: ANI was prospectively monitored in 52 females undergoing breast surgery during laryngeal mask airway (LMA) insertion. A change in ANI (delta-ANI) of less than 20% after insertion was defined as a non-reactive response, with sensitivity analyses using