ABSTRACT
Key physiological principles Inspired gas is normally heated and humidified via the nose and upper airways, the nasal septum and turbinates that increase the mucosal surface area available for evaporation. Consequences of inadequate heating/humidification include: • dehydration/damage of the cilia; • facilitation of bacterial colonization; • alteration of the periciliary fluid; • defective mucus rheology; • impaired mucociliary clearance (Fowler 2000, Hedley & Allt-Graham 1994).
