Surgical Pleth Index: Predicting the Optimal Timing for Tracheal Intubation During General Anesthesia

Surgical pleth index (SPI) has been widely investigated in assessing the nociceptive level, and tracheal intubation is a noxious stimulus during the induction of anesthesia. This study aims to evaluate the ability of SPI to predict hemodynamic reactivity after tracheal intubation, and find the target value of SPI to guide the optimal timing for tracheal intubation.