Study	Reason for exclusion
Beecroft 2003	Not a randomised, controlled trial
Forman 2002	The study compared respiratory water losses and humidity between face mask and nasal mask in healthy participants without OSA, and did not address the outcomes of interest
Mediano 2006	Assessment made of carbon dioxide rebreathing
Prosise 2004	Not a randomised, controlled trial
Sanders 1994	Not a randomised, controlled trial
Smith 2003	The study compared upper airway pressure‐flow relationships in oral mask versus nasal mask, and did not address the outcomes of interest
Wilson 2004	Participants had a diagnosis of "nocturnal hypoventilation" and not all were due to obstructive sleep apnoea

OSA: Obstructive sleep apnoea