Diaphragm Muscle Atrophy Contributes to Low Physical Capacity in COVID-19 Survivors

Fatigue and dyspnea are the most commonly reported long-term complaints in individuals previously infected with SARS-CoV-2. This study aimed to comprehensively evaluate diaphragm muscle function in post-COVID-19 patients and investigate whether potential diaphragm dysfunction contributes to physical functioning impairment. A total of 46 patients who qualified for pulmonary rehabilitation were examined. Diaphragm muscle function parameters were evaluated using ultrasonography, while the severity of dyspnea, aerobic capacity, and the amount of energy used by the body during physical activity were assessed using the six-minute walk test, mMRC scale, and Metabolic Equivalent Task (MET), respectively. We identified that 69.5% of patients had diaphragm atrophy and 6.5% had diaphragm paralysis. The percentage of atrophy was not related to age, gender, BMI, oxygen therapy usage during the COVID-19 infection course, and disease severity. Patients who experienced cough, fever, and no loss of smell during the COVID-19 course had significantly greater diaphragm inspiratory thickness values, while patients with cough and no smell disorders had a significantly lower percentage of diaphragm atrophy. Diaphragm functional parameters were strongly associated with selected variables of exercise tolerance, such as distance in the six-minute walk test, oxygen saturation levels, fatigue, and exertion on the Borg scale. In conclusion, diaphragm muscle dysfunction is a serious long-term post-COVID-19 consequence and can be viewed as a major contributing factor to prolonged functional impairments.