Hwang 1999.

Methods	Randomized trial
Participants	Neonates admitted to the NICU of Kyungpook University Hospital, requiring surgery (sample size = 12) or mechanical ventilation
Interventions	After operation, one group received fentanyl and the other was given saline.
Outcomes	Behavioral distress using postoperative comfort scores, heart rate, blood pressure and blood glucose were evaluated before and after operation. Cortisol concentration and beta endorphin were measured before and at the end of operation and at 60 minutes after fentanyl infusion.  In neonates undergoing surgery, fentanyl infusion diminished the elevation of postoperation heart rate and blood glucose (P < 0.05) and induced the improvement of postoperation comfort scores (P < 0.05).
Notes	Translation from Korean not obtained