Patients will then be transported to the post-operative anesthesia care unit (PACU) after extubation.All pediatric patients will receive 6-hourly paracetamol post-operatively for two days and receive sufentanyl via nurse-controlled analgesia (NCA) or patient-controlled analgesia (PCA). The prescription of post-operative NCA/PCA is also at the discretion of the anesthetist. Children under the age of 6 years will receive sufentanyl via NCA continuously at a rate of 2 mcg/(kg.48h) with a bolus option of 0.01 mcg/kg every 15 minutes.Older children will receive sufentanyl via PCA continuously at a rate of 2 mcg/( kg.48h) with a bolus option of 0.01 mcg/kg every 15 minutes.