Persistent dyspnea in post-coronavirus disease 2019 patients: value of cardiopulmonary exercise test

Background
Dyspnea is one of the most common symptoms after severe acute respiratory syndrome-related coronavirus 2 (SARS-COV-2) infection and may persist after the resolution of infection. The extent and the characteristics of the exercise capacity of those patients are still unclear. We aim to evaluate the functional and exercise parameter patterns of those patients.


Patients and methods
A total of 35 patients with dyspnea following an infection with SARS-COV-2 and 35 age-matched and sex-matched healthy volunteers were enrolled. The modified Medical Research Council scale, diffusion capacity, spirometry, chest computed tomography (CT) severity score, 6-min walk test, and cardiopulmonary exercise test were used to evaluate functional capacity.


Results
Hospitalization days, CT severity scores, and the number of days that the two groups experienced coronavirus disease 2019 (COVID-19) symptoms differed statistically significantly. The following parameters showed statistically significant differences between the groups: forced expiratory volume in the first second (l), forced expiratory volume in the first second %, forced vital capacity%, forced vital capacity (l), lung diffusion capacity for carbon monoxide % and 6-min walk test. Oxygen consumption per minute (VO2), VO2/kg, VO2%, heart rate, oxygen pulse%, ventilatory equivalent for oxygen, and oxygen saturation were significantly higher in the nondyspneic group. In this study, the predictors for post-COVID-19 infection persistent dyspnea included days of COVID-19 symptoms with an odds ratio (OR) of 3.92, days of hospitalization with an OR of 2.65 and CT severity score with an OR of 2.31. A CT severity score greater than 4 indicates that dyspnea will persist, according to receiver operating characteristic curve analysis.


Conclusion
Following recovery from SARS-COV-2 infection, persistent dyspnea was linked to a decline in the spirometric parameters, diffusion capacity, and the cardiovascular and ventilatory response parameters of the cardiopulmonary exercise testing, which proved to be an accurate and useful tool for assessing and quantifying the condition in patients without other abnormalities. The current study offered basic instruments for assessing this syndrome. The current study provided fundamental tools to evaluate this illness. Furthermore, it shown that among patients who have recovered from COVID-19, an increase in hospitalization, days of COVID-19 symptoms, and a CT severity score higher than 4 are predictive of dyspnea persistence.