Cerebral Desaturation

The goal of this observational study is to determine the incidence of perioperative cerebral desaturation in neonates undergoing surgery for congenital malformations. The main questions it aims to answer are: 1. The perioperative factors associated with occurrence of cerebral desaturation 2. The association between perioperative cerebral desaturation, perioperative/hospital outcomes, and physiological conditions. Participants will undergo Near-infrared spectroscopy (NIRS) and electroencephalogram (EEG) monitoring for one hour before surgery, during surgery, and up to 24 hours after surgery.