Relation between fentanyl dose and patient state index during spinal anesthesia for elective cesarean section.

Background: In spinal anesthesia for cesarean section, the addition of fentanyl to the local anesthetic has been reported to improve perioperative analgesia. However, there is only limited knowledge on sedative effects of the added fentanyl. We examined whether the patient state index® (PSI) can detect and present the light sedated level with patients undergoing cesarean section.