'NOPAIN-ROP' trial: Intravenous fentanyl and intravenous ketamine for pain relief during laser photocoagulation for retinopathy of prematurity (ROP) in preterm infants: A randomised trial.

objectivesTo investigate if intravenous fentanyl or intravenous ketamine can provide adequate analgesia in preterm infants undergoing laser photocoagulation for retinopathy of prematurity (ROP).

designOpen-label randomised trial.

settingTertiary care institution.

participantsPreterm infants who underwent laser photocoagulation for ROP.

interventionsInfants were randomised to receive fentanyl as intravenous bolus dose of 2 µg/kg, followed by an intravenous infusion of 1 µg/kg/hour increased to a maximum of 3 µg/kg/hour or intravenous ketamine as bolus dose of 0.5 mg/kg, followed by further intermittent intravenous bolus doses of 0.5 mg/kg to a maximum of 2 mg/kg in the initial phase and intravenous fentanyl (bolus of 2 µg/kg followed by infusion of 2 µg/kg/hour to a maximum of 5 µg/kg/hour) or intravenous ketamine (bolus dose of 1 mg/kg followed by intermittent bolus doses of 0.5 mg/kg to a maximum of 4 mg/kg) in the revised regimen phase.

main outcome measuresProportion of infants with adequate analgesia defined as the presence of both: (1) all the Premature Infant Pain Profile-Revised scores measured every 15 min less than seven and (2) proportion of the procedure time the infant spent crying less than 5%.Secondary outcomes included apnoea, cardiorespiratory or haemodynamic instability, feed intolerance and urinary retention requiring catheterisation during and within 24 hours following the procedure.

resultsA total of 97 infants were randomised (fentanyl=51, ketamine=46). The proportions of infants with adequate analgesia were 16.3% (95% CI 8.5% to 29%) with fentanyl and 4.5% (95% CI 1.3% to 15.1%) with ketamine. Ten infants (19.6%) in the fentanyl group and seven infants (15.2%) in the ketamine group had one or more side effects. In view of inadequate analgesia with both the regimens, the study steering committee recommended using a higher dose of intravenous fentanyl and intravenous ketamine. Consequently, we enrolled 27 infants (fentanyl=13, ketamine=14). With revised regimens, the proportions of infants with adequate analgesia were higher: 23.1% (95% CI 8.2% to 50.2%) with fentanyl and 7.1% (95% CI 1.3% to 31.5%) with ketamine. However, higher proportions of infants developed apnoea (n=4; 30.7%), need for supplemental oxygen (n=5, 38.4%) and change in cardiorespiratory scores (n=7; 53.8%) with fentanyl but none with ketamine.

conclusionsFentanyl-based and ketamine-based drug regimens provided adequate analgesia only in a minority of infants undergoing laser photocoagulation for ROP. More research is needed to find safe and effective regimens that can be employed in resource constrained settings. TRIAL REGISTRATION NUMBER: CTRI/2018/03/012878.