Intravenous Acetaminophen For Postoperative Pain in the Neonatal Intensive Care Unit

The goal of this pilot randomized clinical trial is to determine the effect of the addition of IV acetaminophen to opioid-based pain regimes for infants admitted to the neonatal intensive care unit (NICU) after surgery. This is a pilot trial; the main goals are to make sure our study methods work before performing a larger study. The main clinical aims are: 1. Determine if adding IV acetaminophen reduces pain 2. Determine if adding IV acetaminophen reduces opioid use 3. Determine if adding IV acetaminophen reduces complications Participants will be randomized to two groups: Comparator: Fentanyl and IV acetaminophen Control: Fentanyl and placebo Patients will receive either IV acetaminophen or placebo at regular intervals for seven days after surgery. Patients will be followed daily during that period. Charts will be reviewed at 90-days for final outcomes.