NCT00004696.

Study name
Methods	Randomized clinical trial
Participants	Patients will be eligible if they are less than 12 months (part I) and less than 3 months (part II); had no hepatic or renal abnormalities; had no pulmonary disease causing baseline hypercarbia; had no pulmonary hypertension contraindicating use of 5% CO2 in rebreathing studies; had no allergies; and had no severe developmental delay that precludes analgesia scoring.
Interventions	Morphine postoperatively as intermittent intravenous bolus doses or as a continuous intravenous infusion targeted to reach a steady‐state concentration
Outcomes	Blood gases, continuous oximetry, and CO2 response curves and analgesia (using an infant pain score)
Starting date
Contact information
Notes	None

CO2: carbon dioxide