The obstructive nasal septum. Effect of simulated deviations on nasal airflow resistance.

Effects of simulated septal deviations on nasal airflow resistances were assessed by rhinomanometry in healthy human adults. Obstructions 5 x 15 mm protruding 1 to 5 mm into the nasal lumen were applied to the septum in untreated and decongested nasal cavities. The most resistive septal site was located opposite the caudal edge of the upper lateral cartilage where a 3-mm deviation increased resistance substantially in untreated noses, but produced no resistive effect when the mucosa was decongested, whereas a 4-mm deviation increased resistance severely at this site in untreated and decongested noses. Deviations at the caudal end of the septum that overlapped the upper lateral cartilage were markedly resistive also, while near the cavum they were less resistive. Decongestion reduced resistance and length of this anterior-resistive nasal segment. By contrast, within the cavum neither deviations of 5 mm nor mucosal status affected resistance. It is concluded that airflow resistance of the nasal cavum is unresponsive to septal deviations and mucosal status, but the anterior part of the nose is most susceptible and differences of 1 mm in lumen can be critical.