Potential Role of Diaphragmatic Muscle Weakness as a Cause of Persistent Exertional Dyspnea in Patients With COVID-19 Disease Without Hospitalization

Since the beginning of the COVID pandemic, more and more recovered patients have a number of persistent symptoms including exertional dyspnea and fatigue even months after recovering from acute coronavirus disease 2019 (COVID-19). These symptoms often cannot be explained because routine clinical diagnoses, including extensive cardiac and pulmonary examinations, do not reveal any relevant abnormalities.

In our previous study (Regmi et al) with 50 patients formerly hospitalized due to acute COVID-19 infection, it was shown that diaphragm muscle weakness contributes to persistent exertional dyspnea about one year after hospitalization for COVID-19, regardless of mechanical ventilation. Additionally, the severity of exertional dyspnea correlated with the extent of diaphragmatic weakness.

Since laboratory findings, pulmonary function tests and cardiological routine examinations did not reveal any significant impairments, this was the first time that a potential pathophysiological correlate is objectively associated with dyspnea in long COVID-19 syndrome. The results of our study were clinically relevant because the persistent symptom burden in patients after surviving COVID-19 infection remains very high. In addition diaphragm training presents itself as a potential therapeutic target, since in other diseases such as COPD, such training has been shown to improve the symptoms. Therefore, the investigators believe that the results provide important perspectives, both for the pathophysiological understanding and for the potential treatment of persistent exertional dyspnea in patients.

However, a considerable gap exists here: a significant number of patients who suffer from an acute COVID-19 infection but do not have a severe course during the initial infection, so that hospitalization is not necessary, still complain of different persistent symptoms. Here, too, despite an extensive cardiopulmonary work-up, there is a lack of a sufficient explanation of the lasting complaints. It is precisely in these patients that a possible role of diaphragmatic weakness on the symptoms is yet to be investigated using already established gold standard techniques.