Larynx resistance in cough

Abstract

The response of the glottis in the cough reflex provoked by mechanical excitation of the trachea has been studied in dogs without anesthesia. The response to mechanical excitation of the larynx has been also studied. The resistance of the glottis was determined by recording the tracheal pressure and air flow, in intact respiratory way. The results show, in agreement with previous work from the same authors, that the glottis is not closed at any stage of the respiratory eyele during coughing. The cough can be considered as a dilatation reflex of the glottis, synergistic with the sudden con- traction of the expiratory muscles, because of the diminution of larynx resistance in coughing when referred to the control in tranquil respiration. These results demón­ strate that the oíd theory on cough cannot be sustained, because the assumption of a closure of the glottis prior to the expiratory phase lacks experimental support. The response to glottis excitation limited to the upper part of the cords is characterized by a sudden increase of the resistance of the glottis, with inhibition of respiration.