Patients will be recruited up to the day of surgery. They will be then randomized using a computer generated table of random numbers to two groups: Group A (IV acetaminophen 1000 mg over 15 minutes at the start of surgical closure) and Group B (placebo group-same volume of saline solution administered in the same fashion).This dose has been commonly used in other studies involving IV acetaminophen.6 Both drugs will be identical and will be prepared by hospital pharmacy. After placement of standard ASA monitors, induction will be performed with 0.1mcg/kg/min of remifentanil IV, propofol 1.5-2.5 mg/kg IV and succinylcholine 1-2 mg/kg IV. Tracheal intubation will be performed using a MAC 3 blade and a size 7 endotracheal tube. Maintenance will be achieved with remifentanil infusion titrated to keep the blood pressure within 20% of baseline values and sevoflurane titrated to keep a bispectral index monitor between 40 and 60. Patients will receive ondansetron 4mg IV and dexamethasone 4 mg IV for postoperative nausea and vomiting prophylaxis. In the recovery room patients will receive hydromorphone IV in divided doses to keep pain \<4/10(scale where 0 means no pain and 10 is the worst pain) and metoclopramide 10 mg IV as rescue antiemetic. Data will be collected by a research assistant blinded to the group allocation. Data collected will involve pain at PACU arrival (NRS-0-10), presence of nausea and vomiting, severity of nausea and vomiting, total opioid consumption in PACU, time to discharge using a Modified Postanaesthetic Discharge Scoring System (MPADSS) 9, total opioid consumption 24 hours, QoR40 24hours after surgery.8
