Girault 2003.

Methods	Randomized cross‐over study comparing HME to HH.
Participants	Inclusion criteria: people with acute or chronic respiratory failure difficult to wean from mechanical ventilation. Mean age: 69 years. Exclusion criteria: non‐co‐operative people, unable to have an oesophageal tube. Respiratory diagnosis: 100%. Mean SAPS score: 44. Setting: ICU, France.
Interventions	HME (hygroscopic): Hygrobac (DAR). n = 11. HH (heated wire): MR730 (Fischer & Paykel). n = 11. Time in study: 2 × 20 min for HME (7 cm H2O/min and 18 cm H2O/min ventilation pressure), 2 × 20 min for HH (7 cm H2O/min and 18 cm H2O/min ventilation pressure).
Outcomes	Mortality. * Minute ventilation. Work of breathing. SaO2. PaO2 (kPa). PaCO2 (kPa). * Data not used as this was unlikely to be a valid outcome in a cross‐over study.
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Incomplete outcome data (attrition bias) All outcomes	High risk	3/15 participants withdrawn from study early because they could not "tolerate" HME and 1 participant refused to continue study.
Selective reporting (reporting bias)	Low risk	No protocol available but a range of respiratory variables reported for this short‐term study.
Other bias	Low risk	None identified.