Diaphragm Muscle Weakness Might Explain Exertional Dyspnea 15 Months after Hospitalization for COVID-19

• Published in: American journal of respiratory and critical care medicine Vol. 207; no. 8; pp. 1012 - 1021
• Main Authors: Regmi, Binaya, Friedrich, Janina, Jörn, Benedikt, Senol, Mehdi, Giannoni, Alberto, Boentert, Matthias, Daher, Ayham, Dreher, Michael, Spiesshoefer, Jens
• Format: Journal Article
• Language: English
• Published: United States American Thoracic Society 15.04.2023
• Subjects: Aged; COVID-19; COVID-19 - complications; Diaphragm; Diaphragm (Anatomy); Dyspnea; Dyspnea - etiology; Female; Hospitalization; Humans; Middle Aged; Muscle strength; Muscle Weakness - diagnosis; Muscular Diseases; Muscular system; Original; Recovery (Medical); Severe acute respiratory syndrome coronavirus 2; Thoracic Diseases; pulmonary function; coronavirus; dyspnea; diaphragm muscle strength
• ISSN: 1073-449X; 1535-4970; 1535-4970
• DOI: 10.1164/rccm.202206-1243OC

Dyspnea is often a persistent symptom after acute coronavirus disease (COVID-19), even if cardiac and pulmonary function are normal. This study investigated diaphragm muscle strength in patients after COVID-19 and its relationship to unexplained dyspnea on exertion. Fifty patients previously hospitalized with COVID-19 (14 female, age 58 ± 12 yr, half of whom were treated with mechanical ventilation, and half of whom were treated outside the ICU) were evaluated using pulmonary function testing, 6-minute-walk test, echocardiography, twitch transdiaphragmatic pressure after cervical magnetic stimulation of the phrenic nerve roots, and diaphragm ultrasound. Diaphragm function data were compared with values from a healthy control group. Moderate or severe dyspnea on exertion was present at 15 months after hospital discharge in approximately two-thirds of patients. No significant pulmonary function or echocardiography abnormalities were detected. Twitch transdiaphragmatic pressure was significantly impaired in patients previously hospitalized with COVID-19 compared with control subjects, independent of initial disease severity (14 ± 8 vs. 21 ± 3 cm H O in mechanically ventilated patients vs. control subjects [  = 0.02], and 15 ± 8 vs. 21 ± 3 cm H O in nonventilated patients vs. control subjects [  = 0.04]). There was a significant association between twitch transdiaphragmatic pressure and the severity of dyspnea on exertion (  = 0.03). Diaphragm muscle weakness was present 15 months after hospitalization for COVID-19 even in patients who did not require mechanical ventilation, and this weakness was associated with dyspnea on exertion. The current study, therefore, identifies diaphragm muscle weakness as a correlate for persistent dyspnea in patients after COVID-19 in whom lung and cardiac function are normal. Clinical trial registered with www.clinicaltrials.gov (NCT04854863).