Peak nasal inspiratory flow measurement and visual analogue scale in a large adult population.

Visual analogue scale and PNIF significantly correlated, although with a low degree, in a large population of rhinologic patients. Peak nasal inspiratory flow, being cheap and simple to use, could be a good candidate to assist clinicians dealing with "airway" diseases in their daily clinical practice in order to provide comprehensive information on nasal function. Peak nasal inspiratory flow can in fact give some important rough insights on VAS, but these measurements cannot be alternative to each other.