Bissonnette 1989a.

Methods	Randomized parallel study comparing HME to HH.
Participants	Inclusion criteria: infants weighing 5‐10 kg, ASA status I or II having peripheral surgery lasting 2‐3 hr. Mean age: HME 12 months, HH 11 months. Exclusion criteria: not stated. Respiratory diagnosis: not stated. Severity: ASA status I or II. Setting: paediatric hospital, Canada.
Interventions	HME (hygroscopic): Humid‐Vent (Gibeck). n = 10. HH: MR450 (Fisher & Paykel) set at 37 ºC. n = 10. Time in study: 120 min.
Outcomes	Body temperature. Change in body temperature.
Notes	Funding: National Institutes of Health.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not stated.
Allocation concealment (selection bias)	Unclear risk	Not stated.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not stated.
Incomplete outcome data (attrition bias) All outcomes	Low risk	100% follow‐up.
Selective reporting (reporting bias)	Unclear risk	No protocol available.
Other bias	Low risk	None identified.