Spectral tussophonobarography as a method for evaluation of the airway obstruction reversibility in asthma patients

Abstract

The purpose of this study was to evaluate reversibility of the airway obstruction in asthma patients using a method of spectral tussophonobarography permitting to perform the frequency analysis of cough sounds. As a result the cough sound spectrum was divided into 3 phases: the 1^st phase was due to quick opening of the larynx, the 2^nd, more continuous phase was relevant to the air output out of the lungs, the 3^rd, inconstant phase corresponded to the closure of the larynx at the end of the cough. The method showed significant changes of spectral and temporary parameters of the cough sounds before and after inhalation of a bronchodilator in asthma patients (common duration of cough, duration of each cough phase, frequency of maximal cough sound energy F_max, frequency containing 50% of the cough sound energy F_50%, q coefficient which is the ratio of total energy of low and middle frequencies to the energy of high frequencies). Thus, the spectral tussophonobarography is thought to be an objective method to evaluate the reversibility of the airway obstruction in asthma.