| Study characteristics |
| Methods |
Single‐centre randomised double‐blinded clinical trial |
| Participants |
32 newborns with gestational age between 26 and 38 weeks undergoing intubation and mechanical ventilation (for at least 24 hours) were included
Exclusion criteria: asphyxia (possible hepatic or renal damage); Apgar scores below 5 at fifth minute after birth; direct hyperbilirubinaemia; neonatal hepatitis; biliary system anomalies; cardiovascular anomalies; gastrointestinal obstructions |
| Interventions |
Morphine group (n = 16): intravenous loading dose of 100 mcg/kg in the first hour, with maintenance dose of 12 mcg/kg/hour for the next 24 hours
Fentanyl group (n = 16): intravenous loading dose of 2 mcg, with maintenance dose of 0.25 mcg/kg/hour |
| Outcomes |
Ultrasonographic measurements of gallbladder dimensions (length, width, depth, and volume), as well as occurrence of hydrops of gallbladder, were evaluated on the third and sixth days after drug administration |
| Notes |
|
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Unclear risk |
Method of randomisation was not stated |
| Allocation concealment (selection bias) |
Unclear risk |
The use of sealed envelopes was stated, but it is not clear how allocation concealment was dealt with |
| Blinding of participants and personnel (performance bias) |
Low risk |
Carers were blinded |
| Blinding of outcome assessment (detection bias) |
Low risk |
Assessors were blinded |
| Incomplete outcome data (attrition bias) |
Low risk |
All infants were accounted for |
| Selective reporting (reporting bias) |
Low risk |
All outcomes were reported |
| Other bias |
Low risk |
Study appears to be free of other sources of bias |
