Spectral tussophonobarography as a method for monitoring the effectiveness of cough treatment in patients with COVID-19

Dry cough is one of the most common complaints of patients with COVID-19, so it must be treated with antitussives. The effectiveness of prescribed therapy can be controlled by using questionnaires and spectral analysis of cough sounds. The aim was to assess the use of spectral tussophonobarography for monitoring the effectiveness of cough treatment in patients with COVID-19. Methods. The main group consisted of 60 patients with COVID-19 (45% men, 55% women, average age 38.6 (30.1; 49.6) years) with mild or moderate severity and strong complaints of cough. The disease was treated in accordance with clinical recommendations, and antitussives were also used. Cough on the 1st and 8th days of therapy was studied using a visual analogue scale and spectral tussophonobarography, then compared with the induced cough of 30 healthy individuals making up the comparison group (43.3% men and 56.7% women; average age of 36.3 (28.4; 44.8) years). Cough recordings were subjected to a fast Fourier transform algorithm. The following cough characteristics were assessed: duration (ms), ratio of low and medium frequency energy (60 – 600 Hz) to high frequency energy (600 – 6000 Hz), and frequency of maximum sound energy (Hz). Not only of the coughing act as a whole was assessed, but also of each phase separately. Results. On the 8 th day of treatment, significant changes in cough characteristics were seen compared to the 1 st day, especially in the 2 nd phase of the cough act. The duration of cough increased (T = 355.0 (276.0; 407.5) – on the 1st day; T(c) = 432.0 (386.0; 556.0) – on the 8 th day; p = 0.0000), lower frequencies began to predominate (Q = 0.281 (0.2245; 0.408) – on the 1 st day; Q(c) = 0.4535 (0.3725; 0.619) – on the 8 th day; p = 0.0000), the frequency of maximum sound energy decreased (F max = 488.5 (282.0; 1220.5) – on the 1 st day; F max = 347.0 (253.0; 488.0) – on the 8 th day; p = 0.0064). No statistically significant differences were found in the studied parameters on the 8 th day of treatment as compared with those in healthy individuals. Conclusion. Spectral tussophonobarography revealed that characteristics of cough sounds during treatment of COVID-19 were close to those of healthy individuals.