Normal nasal patency: problems in obtaining standard reference values for the surgeon.

This review examines why there is no normal range of nasal patency available to the surgeon when assessing nasal obstruction, and discusses the factors that influence nasal patency. Current normal ranges are examined and criticised because of the variability of normal values and the poor sampling methods used. Instability of physiological nasal patency is related to factors such as the nasal cycle and the nose's direct exposure to the external environment. Decongestion of the nose is proposed as a way of stabilising anatomical nasal patency, and measurements of patency in this state may be more useful to the surgeon. Population studies are needed to establish a normal range, but these studies must control for factors such as age, height, sex, and nasal shape and size related to climatic adaptation. Rather than classify populations according to unscientific categories such as race, anthropometric measures such as the nasal index are proposed.