Vasomotor Responses of Mucosa of Upper Respiratory Tract to Thermal Stimuli

Abstract

Chilling of the cutaneous surface was assumed in the past to be associated with congestion of the mucous membrane of the nose and throat and that this congestion was favorable to bacterial invasion. The reverse have been the findings in the experiments conducted. A cold stimulus applied to the cutaneous surface produces a reflex vaso-constriction and a lowering of the temperature of the mucosa of the upper respiratory tract, and a hot stimulus produces a reflex vaso-dilatation.

One hundred and sixty-four experiments were performed and distributed as follows: 81 general experiments on one normal man, 52 experiments on 8 normal men, 31 experiments on 15 hyperesthetic rhinitis cases including 3 children. These experiments were conducted in a regular laboratory room with a temperature varying between 21° and 26°C., and in which drafts were minimized. The thermo-electric method was employed with a thermopile electrode applied to the mucosa of the nose and the E. M. F. measured through a potentiometer. Cold air, cold sprays, and aluminum cups, varying in diameter from 4 to 19 cm., partly filled with chipped ice were used as cold stimuli. The ice filled cups gave a skin temperature of 12.60°C. The cups were applied to the upper and lower dorsals and to the lumbo-sacral regions of the back, to the upper and lower anterior chest, to the upper and lower abdomen, and to the feet.

The findings were: I. Normal Reactions. (a) The 4 cm. ice cup was the smallest cold stimulus to produce a reflex lowering of the temperature of the mucosa of the upper respiratory tract, (b) The normal response to a short circumscribed cold stimulus (2 minutes) was first a lowering of the mucous membrane temperature, then a rise and gradual return to the initial temperature, (c) The normal response to a continuous circumscribed cold stimulus (10 minutes) to one cutaneous area or to numerous cutaneous areas applied in regular succession, i. e., when the reaction was completed in one area, the stimulus was immediately removed to another, was first a lowering of the mucous membrane temperature and then a gradual rise, stopping short in the majority of the experiments from reaching the initial temperature by 0.18 to 0.36°C.