Mendonca 2001.

Methods	Randomization and treatment allocation method: yes Blinding of outcome assessment: unclear Blinding of participants: no Study period: not stated
Participants	Number: 60 enrolled Inclusion criteria: ASA physical status II to III patients scheduled to undergo general anaesthesia, 50 years of age and older with a history of smoking 10 cigarettes a day for 20 years Exclusion criteria: severe cardiovascular disease, morbid obesity, allergy to inhalational anaesthetics, requiring rapid sequence induction
Interventions	No pre‐medication and a Mapleson D breathing system Group 1: 8% vital capacity breathing in 66% N2O Group 2: 8% tidal breathing in 66% N2O Group 3: incremental tidal breathing sevoflurane in 66% N2O
Outcomes	Time to dropping the weighted syringe Induction event (single cough, laryngospasm, breath holding, movement of a limb, excessive salivation, hypotension and hypoxia were recorded) Smell of the anaesthetic
Notes	Location: UK Setting: operating room Source of funding: not stated
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "...patients were randomly allocated using sealed envelopes to one of the three breathing techniques"
Allocation concealment (selection bias)	Low risk	Quote: "...patients were randomly allocated using sealed envelopes to one of the three breathing techniques"
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Not stated
Incomplete outcome data (attrition bias) All outcomes	Low risk	No missing data
Selective reporting (reporting bias)	Low risk	Study authors reported all planned outcomes