Iotti 1997.

Methods	Randomized cross‐over study comparing 2 types of HME to HH
Participants	Inclusion criteria: people receiving mechanical ventilation for acute respiratory failure. Mean age: 58 years. Exclusion criteria: COPD. Respiratory diagnosis: 100%. Severity: not stated. Setting: ICU, Italy.
Interventions	HME (hygroscopic): Umid‐Vent 2S (Gibeck). n = 10. HME: Hygroster (DAR). n = 10. HH: MR 450 (Fisher & Paykel) set at 32‐34 ºC. n = 10. Time in study: 1‐2 hr.
Outcomes	Minute ventilation. Tidal volume. PaO2. PaCO2. Breathing rate. Work of breathing.
Notes	Funding: Polytechnico S. Matteo and support from Hamilton Bonaduzz AG.
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)	Low risk	No protocol available but range of respiratory variables reported for this short‐term study.
Other bias	Low risk	None identified.