A nasal functional test: the opeining of mouth during physical effort.

Apart from rare exceptions (cf Voydeville's Thesis, Nancy 1951), nasal airflow resistance has so far been estimated irrespective of variations in air intake needs. The object of the test presented here is to offer a quick, simple and objective method for determining the level of muscular effort at which a given subject spontaneously switches from nasal to buccal respiration. A thin flexible tube (1,5 mm across) is stuck at one end on to the subject's lower lip and the other into a carbon dioxyde analyser. The subject is then made to pedal at a speed at least 30 rev./min. on an ergometric bicycle, while a braking force increasing by 20 W ever two minutes is applied. The emission of carbon dioxyde starts being detected, and graphically recorded, only when the subject starts breathing through his mouth. Results obtained so far show that this threshold can vary as widely as from 80 to 180 W among healthy individuals. Further aplications of this test to both healthy subjects and patients with impaired nasal function would contribute towards throwing light on the still obsure notion of "nasal comfort".