Fatigue and exercise intolerance after survived COVID-19-infection might be related to weakness of the respiratory muscles. The aim of the project is to measure respiratory muscle function and strength in our respiratory physiology laboratory in patients who were not hospitalized during the acute COVID-19-infection but still complain of different persistent symptoms including exertional dyspnea and fatigue.
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.
Study Type
OBSERVATIONAL
Enrollment
25
Comprehensive assessment of respiratory muscle function to the point of its invasive assessment with recordings of twitch transdiaphragmatic pressure in response to magnetic phrenic nerve stimulation and stimulation of the lower thoracic nerve roots.
Jens Spiesshoefer
Aachen, North Rhine-Westphalia, Germany
Twitch transdiaphragmatic pressure in response to supramaximal magnetic stimulation of the phrenic nerve roots
Recording of twitch transdiaphragmatic pressure (Unit: Pressure in cmH2O)
Time frame: 1 year
Respiratory mouth pressures
Measurement of respiratory (inspiratory and expiratory) mouth pressures (Unit: Pressure in cmH2O)
Time frame: 1 year
Diaphragm ultrasound
Comprehensive evaluation of diaphragm excursion (amplitude during tidal breathing, sniff maneuver and maximal inspiration in cm, corresponding velocity in cm/sec, respectively) and thickening on ultrasound (thickness at functional residual capacity, at total lung capactiy in cm), Markers of Diaphragm excursion and thickening will be combined to classify diaphragm function as normal, mildly, moderately or severly impaired.
Time frame: 1 year
Exercise intolerance
Comprehensive evaluation of symptoms (breathlesness based on NYHA class, on a visual scale ranging from 1-10, respectively) and exercise capacity (6 minute walking distance). These measurements will be combined to classifiy patients as presenting with exercise intolerance or no exercise intolerance.
Time frame: 1 year
Lung function
Comprehensive assessment of lung function by bodyplethysmography (most importantly forced vital capacity, forced expiratory volume after 1 second, intrathoracic gas volume, residual volume) and capillary blood gas analysis (most importantly pO2 in mmHG and pCO2 in mmHG). These measurements will be combined to classify patients as showing normal, restrictive, obstructive lung function impairment, as being hypoxic, hypercapnic, respectively.
Time frame: 1 year
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EMG
Diaphragm and accessory respiratory muscle electromyography
Time frame: 1 year