An observational study in Dyspnea; Asthmatic, COPD and Fibrosis, sponsored by RWTH Aachen University. Recruiting at 1 site in Germany. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-01-28.
Sponsored by RWTH Aachen University · Observational
Dyspnea is among the most common symptoms in patients with respiratory diseases such as Asthma, chronic obstructive pulmonary disease (COPD), Fibrosis, and Pulmonary Hypertension. However, the pathophysiology and underlying mechanisms of dyspnea in patients with respiratory diseases are still poorly understood. Diaphragm dysfunction might be highly prevalent in patients with dyspnea and respiratory diseases. The association of diaphragm function and potential prognostic significance in patients with respiratory diseases has not yet been investigated.
The aim of the present project is to comprehensively measure respiratory muscle function and strength in patients with respiratory diseases. The investigators attempt to recruit 800 patients across four disease groups (Asthma, COPD, Fibrosis, and Pulmonary Hypertension) and the investigators intend to measure diaphragm and accessory respiratory muscle function and strength, lung function, and exercise tolerance, as well as the participants' symptom burden during one day at baseline in the investigators' lab. Thereafter, the investigators will follow up on patients by phone 3 months, 6 months, 12 months and 18 months after the investigators have seen them in the investigators' lab. In a small subset of patients (50 overall at most) and in those in whom a recently approved drug based therapy has been initiated (i.e. Sotatercept in PH, Nintedanib in ILD, Brensocatib in Bronchiectasis, Dupilumab in COPD, Anti IL-4/IL 13 or Anti IL 5 antibodies in eosinophilic asthma) follow up will not be by phone only but also in person to repeat the above mentioned non-invasive measurements. Based on these results, not only the association between dyspnea exercise tolerance and diaphragm function in patients with respiratory diseases can be assessed, but also the prognostic significance of diaphragm dysfunction in these patients can be determined. As such, hospitalization and exacerbation requiring the intake of steroids will be assessed and followed up on by phone, and therefore the prognostic significance of diaphragm dysfunction in predicting hospitalization and the intake of steroids can be determined.
894 studies on the registry are indexed under Dyspnea; 189 are open to participants now.
This study's planned enrollment of 800 is above the median of 106 across 272 observational studies indexed under Dyspnea.
Browse Dyspnea studies →RWTH Aachen University is the lead sponsor of 230 studies on the registry; 19 are open to participants now.
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800 patients, 4 groups
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
COPD
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Diagnostic Test: Diaphragm Ultrasound · Diagnostic Test: Intercostal Muscle Ultrasound · Diagnostic Test: Borg scale · Diagnostic Test: MRC Breathlessness Scale · Diagnostic Test: Respiratory Questionaire · Diagnostic Test: GINA classification of Asthma · Diagnostic Test: Measurement of respiratory mouth pressure · Diagnostic Test: SNIP · Diagnostic Test: 6-minute walking distance · Diagnostic Test: 60 seconds sit-to-stand test · Diagnostic Test: Electromyography · Diagnostic Test: Lung Function
Diagnostic Test: Diaphragm Ultrasound · Diagnostic Test: Intercostal Muscle Ultrasound · Diagnostic Test: Borg scale · Diagnostic Test: MRC Breathlessness Scale · Diagnostic Test: Respiratory Questionaire · Diagnostic Test: Measurement of respiratory mouth pressure · Diagnostic Test: SNIP · Diagnostic Test: 6-minute walking distance · Diagnostic Test: 60 seconds sit-to-stand test · Diagnostic Test: Electromyography · Diagnostic Test: Lung Function · Diagnostic Test: CAT-Questionnaire
Diagnostic Test: Diaphragm Ultrasound · Diagnostic Test: Intercostal Muscle Ultrasound · Diagnostic Test: Borg scale · Diagnostic Test: MRC Breathlessness Scale · Diagnostic Test: Respiratory Questionaire · Diagnostic Test: Measurement of respiratory mouth pressure · Diagnostic Test: SNIP · Diagnostic Test: 6-minute walking distance · Diagnostic Test: 60 seconds sit-to-stand test · Diagnostic Test: Electromyography · Diagnostic Test: Lung Function
Diagnostic Test: Diaphragm Ultrasound · Diagnostic Test: Intercostal Muscle Ultrasound · Diagnostic Test: Borg scale · Diagnostic Test: MRC Breathlessness Scale · Diagnostic Test: Respiratory Questionaire · Diagnostic Test: Measurement of respiratory mouth pressure · Diagnostic Test: SNIP · Diagnostic Test: 6-minute walking distance · Diagnostic Test: 60 seconds sit-to-stand test · Diagnostic Test: Electromyography · Diagnostic Test: Lung Function · Diagnostic Test: European Society of Cardiology (ESC)/ European Respiratory Society (ERS) risk group
Ultrasound of the Diaphragm at the end of inspiration and expiration
Ultrasound of the Intercostal Muscles at the end of inspiration and expiration
Questionnaire for Perceived Exertion (Borg Rating of Perceived Exertion Scale)
The MRC Dyspnoea Scale allows the patients to indicate the extent to which their breathlessness affects their mobility.
Specialized respiratory questionnaire with different domains (Emotional Domain, Dyspnea Domain, Mastery Domain, Fatigue Domain)
Patients are classified according to the GINA classification of Asthma.
Inspiratory and expiratory Measurement of respiratory mouth pressure
Measurement of Sniff Nasal Inspiratory Pressure
The maximum walking distance achieved in 6 minutes
number of repetitions achieved in sitting down and standing up in 60 seconds
electromyography of the muscles of respiration via superficial electrodes
Measurement of lung function via body plethysmography
COPD Assessment Test (CAT)
Patients with pulmonary hypertension are classified according to the ESC/ERS risk group.
Dyspnea Borg scale 1 to 10
Borg scale before and after "6 minute walking distance" test. Lower scores show fewer dyspnea, higher scores indicate more dyspnea.
Time frame: 6 months recruiting
Dyspnea Borg scale 1 to 10
Borg scale before and after "6 minute walking distance" test. Lower scores show fewer dyspnea, higher scores indicate more dyspnea.
Time frame: follow up 3 months after recruitment
Dyspnea Borg scale 1 to 10
Borg scale before and after "6 minute walking distance" test. Lower scores show fewer dyspnea, higher scores indicate more dyspnea.
Time frame: follow up 6 months after recruitment
Dyspnea Borg scale 1 to 10
Borg scale before and after "6 minute walking distance" test. Lower scores show fewer dyspnea, higher scores indicate more dyspnea.
Time frame: follow up 12 months after recruitment
Dyspnea Borg scale 1 to 10
Borg scale before and after "6 minute walking distance" test. Lower scores show fewer dyspnea, higher scores indicate more dyspnea.
Time frame: follow up 18 months after recruitment
6 minute walking distance in m
Measurement of achieved walking distance in 6 minutes
Time frame: 6 months recruiting
Sit-to stand-test (60 seconds)
Measurement of achieved repetitions of standing up and sitting down from an initial seated position in 60 seconds.
Time frame: 6 months recruiting
New York Heart Association (NYHA) classification scale 1 to 4
Patients are linked to a NYHA degree. Lower scores show fewer dyspnea, higher scores indicate more dyspnea.
Time frame: 6 months recruiting, follow up up to 18 months after last recruitment
Modified Medical Research Council (MRC) Breathlessness Scale 1 to 5
Patients are assessed and grouped according to their MRC Breathlessness Scale. Lower scores show fewer dyspnea, higher scores indicate more dyspnea.
Time frame: 6 months recruiting, follow up up to 18 months after last recruitment
Chronic Respiratory Questionnaire (CRQ)
Assessments of different domains (Emotional Domain, Dyspnea Domain, Mastery Domain, Fatigue Domain) in a standardized questionnaire on a scale from 1 to 7. The scores for each question of each dimension are added together and divided by the number of completed questions in each domain. In general, higher scores mean a worse outcome and lower scores mean a better outcome. For the dyspnea domain for example, a high score means that patients have less dyspnea, and a low score means that patients have more dyspnea.
Time frame: 6 months recruiting, follow up up to 18 months after last recruitment
COPD Assessment Test (CAT-Questionnaire) from 0 to 40 points.
Patients are evaluated and placed into the corresponding groups. Lower scores show fewer dyspnea, higher scores indicate more dyspnea.
Time frame: 6 months recruiting, follow up up to 18 months after last recruitment
Global Initiative for Asthma (GINA) classification
Patients are assessed and grouped as mild, moderate, or severe according to the GINA classification.
Time frame: 6 months recruiting, follow up up to 18 months after last recruitment
Body Plethysmography
TLC (Total lung capacity) in percent predicted.
Time frame: 6 months recruiting
Diaphragm Thickening Ratio (DTR) in percent
Via ultrasound, the diaphragm thickening ratio (DTR) was calculated as thickness at total lung capacity (TLC) divided by thickness at functional residual capacity (FRC).
Time frame: 6 months recruiting
Diaphragm thickness at Total lung capacity (TLC)
Via ultrasound, the diaphragm thickness at TLC is measured at the maximum point of inspiration.
Time frame: 6 months recruiting
Diaphragm thickness at functional capacity (FRC)
Via ultrasound, the diaphragm thickness at FRC is measured after a normal expiration.
Time frame: 6 months recruiting
Diaphragm ultrasound sniff velocity in cm/s
Via ultrasound, the diaphragm sniff velocity was assessed during tidal breathing and following a maximum sniff.
Time frame: 6 months recruiting
Intercostal Muscle ultrasound thickness at Total lung capacity (TLC) in cm
Via ultrasound, the intercostal thickness at TLC is measured at the maximum point of inspiration.
Time frame: 6 months recruiting
Intercostal Muscle ultrasound thickness at functional capacity (FRC) in cm
Via ultrasound, the intercostal thickness at FRC is measured after a normal expiration.
Time frame: 6 months recruiting
Intercostal Muscle Thickening Ratio in percent
Via ultrasound, the intercostal muscle thickening ratio was calculated as thickness at total lung capacity (TLC) divided by thickness at functional residual capacity (FRC).
Time frame: 6 months recruiting
Maximum Inspiratory Pressure (MIP) in percent predicted
Measurement of Maximum Inspiratory Pressure
Time frame: 6 months recruiting
Maximum Expiratory Pressure (MEP) in percent predicted
Measurement of Maximum Expiratory Pressure
Time frame: 6 months recruiting
Sniff Nasal Inspiratory Pressure (SNIP) in percent predicted
Measurement of Sniff Nasal Inspiratory Pressure
Time frame: 6 months recruiting
Blood Gas Analysis in cmH2O
oxygen partial pressure (pO2)
Time frame: 6 months recruiting
Blood Gas Analysis in cmH2O
carbon dioxide partial pressure (pCO2)
Time frame: 6 months recruiting
Blood Gas Analysis
pH scale
Time frame: 6 months recruiting
Blood Gas Analysis in mmol/l
Base Excess
Time frame: 6 months recruiting
Blood Gas Analysis in (I1/s) percent
Base Excess
Time frame: 6 months recruiting
Electromyography (EMG)
Measurement of electrical activity during different breathing maneuvers (Sniff, Cough, Valsalva, Mueller) via superficial electrodes placed on the diaphragm and accessory respiratory muscles (Sternocleidomastoideus muscle, intercostal muscles).
Time frame: 6 months recruiting
Started Jul 2023 (actual). Primary completion is estimated for Dec 2026, 41 months after the start.
Of 116 non-industry observational studies under Dyspnea, half reached primary completion within 26 months of starting (the median), counting those still running; a quarter within 11 and three quarters within 47. This study's planned 41 months is above that.
Counting every sponsor, half of 125 studies reached it within 24 months; a quarter within 11 and three quarters within 46.
How these figures are worked out, and which studies are left out of them.
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