Dreyfuss 1995.

Methods	Randomized parallel study comparing HME to HH.
Participants	Inclusion criteria: people receiving mechanical ventilation for > 48 hr. Mean age: HME 58 years, HH 62 years. Exclusion criteria: not stated. Respiratory diagnosis: HME 64%, HH 63%. Mean SAPS score: HME 16, HH 16. Setting: ICU, France.
Interventions	HME (hygroscopic/hydrophobic): Hygrobac II (DAR) changed daily. n = 61. HH: Bennett cascade (Puritan‐Bennett) or MR460 (Fischer‐Paykel). n = 70. Time in study (median): HME 10 days, HH 12 days.
Outcomes	Artificial airway occlusion. Mortality. Pneumonia. Pneumonia‐related mortality. Atelectasis. Tracheal aspirations. Saline instillations per day. Cost ‐ no SD.
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	Data from participants available at follow‐up.
Selective reporting (reporting bias)	Low risk	No protocol available but all 3 primary outcomes reported.
Other bias	Low risk	None identified.