This prospective observational study aims to determine the blood pressure range in which cerebral autoregulation is maintained in preterm neonates, preterm infants, term neonates, and term infants undergoing non-cardiac surgery under general anesthesia. Cerebral autoregulation will be assessed using the cerebral oximetry index, calculated from mean arterial pressure and regional cerebral oxygen saturation measured by near-infrared spectroscopy.

A total of 160 patients, 40 in each age group, will be enrolled. The lower limit of autoregulation, optimal mean arterial pressure, and upper limit of autoregulation will be estimated for each patient and compared across age groups. The results may help support age-specific intraoperative blood pressure management in vulnerable pediatric patients.

Inclusion Criteria:

Pediatric patients undergoing non-cardiac surgery under general anesthesia Expected duration of anesthesia of 60 minutes or longer

Patients who meet one of the following age criteria:

Preterm neonates: born at <37 weeks of gestation and ≤1 month of postnatal age Preterm infants: born at <37 weeks of gestation and 1-12 months of postnatal age Term neonates: born at ≥37 weeks of gestation and ≤1 month of postnatal age Term infants: born at ≥37 weeks of gestation and 1-12 months of postnatal age Written informed consent obtained from a parent or legal guardian

Exclusion Criteria:

• Presence of residual congenital heart disease
• Undergoing cardiac surgery
• Undergoing neurosurgery
• Presence of severe brain malformation

Preterm and term neonates and infants aged 0 days to 12 months undergoing non-cardiac surgery under general anesthesia for 60 minutes or longer at Seoul National University Children's Hospital.