Ionides 1994.

Study characteristics
Methods	Single‐centre randomised controlled trial
Participants	Infants mechanically ventilated who required the use of pancuronium and/or morphine or fentanyl, according to the attending physician's judgement, were included Exclusion criteria: asphyxia (Apgar score ≤ 3 at 5 minutes); foetal drug exposure; sepsis; major congenital anomalies Among the 27 neonates enrolled, 2 were excluded because of inadequate blood sampling, 3 received only pancuronium, and the remaining 22 were randomly assigned to fentanyl or morphine
Interventions	Fentanyl group (n = 10): 3 mcg/kg as a single intravenous dose Morphine group (n = 12): 0.1 mg/kg as a single intravenous dose 4 newborns in the fentanyl group and 2 in the morphine group received both pancuronium and opioid; pancuronium was always administered first, followed by opiate in 1 hour
Outcomes	β‐Endorphin concentration before and 1 hour after administration of each medicine; HR; systolic and diastolic BP
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Patients were assigned by medical record number
Allocation concealment (selection bias)	High risk	The chosen sequence did not allow for allocation concealment
Blinding of participants and personnel (performance bias)	Unclear risk	Blinding was not clearly ensured
Blinding of outcome assessment (detection bias)	Unclear risk	Blinding was not clearly ensured
Incomplete outcome data (attrition bias)	Low risk	All infants accounted for 2 infants subsequently excluded because of inadequate blood sampling
Selective reporting (reporting bias)	Unclear risk	Trial not registered; protocol not available
Other bias	Unclear risk	The randomisation process between morphine and fentanyl groups was started after the attending physician decided whether to use pancuronium, opiates, or both