Deriaz 1992.

Methods	Randomized parallel study comparing HME to HH.
Participants	Inclusion criteria: people with ASA status I or II scheduled for gynaecological surgery. Mean age: 40 years. Exclusion criteria: not stated. Respiratory diagnosis: not stated. Severity: ASA status I or II. Setting: hospital, France.
Interventions	HME (hydrophobic): Ultipor hydrophobic (Pall). n = 25. HH: Aquapor (Dräger) set at 42 ºC. n = 25. Time in study (mean): HME 155 min, HH 116 min.
Outcomes	Body temperature.
Notes	Funding: not stated.
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	Unclear risk	Number enrolled not stated.
Selective reporting (reporting bias)	Unclear risk	No protocol available.
Other bias	High risk	Participants in HME group anaesthetized for significantly longer than those in HH group (HME 155 min, HH 116 min).