Background. One of the disturbing symptoms in patients with post-COVID-19 syndrome, especially in asthmatics, is dyspnea. In some cases a depressing feeling of shortness of breath can be caused by weakness or fatigue of the respiratory muscles.
Aim: to evaluate the respiratory muscle strength in asthma patients with post-COVID-19 syndrome and significant dyspnea.
Methods. A total of 37 patients with asthma and post-COVID-19 syndrome (16 men, 21 women, from 22 to 73 (mean age (52.7±2.3)) years) were examined. Modified Medical Research Council (mMRC) dyspnea scale score in patients was ?2 points. Control group ? 30 patients with asthma without post-COVID-19 syndrome (14 men, 16 women, from 21 to 75 (mean age (55.9±2.6)) years), with mMRC dyspnea score 0-2 points. For all patients the maximal inspiratory and expiratory pressure (PImax, PEmax) assessment (Master Screen PFT, Cardinal Health) and chest CT were performed.
Results. In all patients of the main and control groups chest CT scans were normal. In patients with post-COVID-19 syndrome the mean PImax was (50.0±3.1)%, the mean PEmax - (67.3±5.4)% of predicted, that is statistically significantly lower then in patients without post-COVID-19 syndrome in whom the mean PImax was (58.6±1.7)%, the mean PEmax was (89.8±6.1)% of predicted, p<0.01. The Pearson correlation coefficient for PImax and mMRC was unsignificant (r=0.16), but for PEmax and mMRC was significant inverse correlation (r=-0.31).

Conclusion. In patients with asthma and post-COVID-19 syndrome respiratory muscle weakness/fatigue occurs especially in inspiratory muscle. At the same time the expiratory muscle weakness is accompany with dyspnea increasing.