During general anesthesia, objective monitoring for analgesia is still lacking. The administration of opioids relies on the experience of the anesthesiologist. There are some monitors, e.g., Analgesia Nociception Index (ANI), showing that they can evaluate analgesia in adults. Recently, a Newborn Infant Parasympathetic Evaluation (NIPE) monitor was released for assessing analgesia in children with age less than 2 years. The investigators aim to assess the efficacy of NIPE as a guide for intraoperative fentanyl administration in children under 2 years.

During balanced anesthesia, hypnosis can be monitored with BIS, muscle relaxation can be monitored with a train-of-four, however, analgesia lacks precise monitoring. The anesthesiologist administers narcotics according to clinical signs and experience. Analgesia Nociception Index (ANI) has been introduced as an objective monitor for analgesia in adults. Recently, a Newborn Infant Parasympathetic Evaluation (NIPE) monitor has been introduced to assess analgesia in children under 2 years, however, clinical studies regarding its clinical efficacy are scarce.

The objective of this study is to assess the efficacy of NIPE as a guide for intraoperative fentanyl administration in children under 2 years.

Inclusion Criteria:

• Newborn up to 2 years old
• ASA Status 1-2
• Undergoing elective surgery of upper part of body

Exclusion Criteria:

• Premature
• Arrhythmia
• Concomitant use of regional anesthesia
• Plan for ICU admission