Long COVID and Post-exertional Pulmonary Diffusion

Study Overview
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Brief Summary
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Aim of investigators was to study whether abnormalities of lung diffusing capacity for nitric oxide (DLNO) and carbon monoxide (DLCO) in long COVID may have a clinical impact in relation to exercise intolerance.

Detailed Description
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Prolonged recovery from acute coronavirus disease 2019 (long COVID) is characterized in about 30% of subjects from breathlessness and fatigue also during daily activities often associated to decreased lung diffusing capacity for carbon monoxide (DLCO) at rest. Aim of investigators was to study whether abnormalities of lung diffusing capacity for nitric oxide (DLNO) and DLCO in long COVID may have a clinical impact in relation to exercise intolerance. Combined DLNO and DLCO were simultaneously measured at rest and immediately after a short bout of treadmill walking in 32 dyspneic subjects ≥3 months after the COVID-19 acute phase. A group of healthy subjects served as a control group.

Official Title
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Lung Diffusing Capacities for Nitric Oxide and Carbon Monoxide in Long COVID With Dyspnea at Rest and After Mild Exercise

Conditions
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Long COVID, Breathlessness, Exercise Intolerance, Alveolar Lung Disease, Pulmonary Gas Exchange

Intervention / Treatment
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* Diagnostic Test: Lung volumes, spirometry and standard single-breath DLCO were measured at rest while combined DLNO and DLCO were measured at rest and post-exercise


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: History of dyspnea, fatigue, and exercise intolerance persisting or occurring at least 3 months after the COVID-19 acute phase and lasting ≥2 months. Exclusion Criteria: History of diseases potentially causing dyspnea or affecting pulmonary gas transport, i.e., bronchial asthma, lung bullous disease, chronic obstructive pulmonary disease, pulmonary interstitial fibrosis or vasculitis, hematological diseases, systemic collagen diseases, congestive heart failure, liver or renal diseases, and morbid obesity.
Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Long COVID<br>Caucasian subjects with a history of SARS CoV-2 infection confirmed by nasopharyngeal swab with real-time polymerase-chain reaction were included in the study. They were referred to investigators' pulmonary function laboratory after being tested negative for SARS-CoV-2, because of dyspnea, fatigue, and exercise intolerance persisting or occurring at least 3 months after the COVID-19 acute phase and lasting ≥2 months. | Diagnostic Test: Lung volumes, spirometry and standard single-breath DLCO were measured at rest while combined DLNO and DLCO were measured at rest and post-exercise<br>* DLNO and DLCO were measured at rest and 5-10 s after a bout of treadmill exercise simulating usual walking<br>|
| Healthy controls<br>Anthropometrically-matched healthy subjects, without history of COVID-19 and vaccinated against SARS-CoV-2 infection. | Diagnostic Test: Lung volumes, spirometry and standard single-breath DLCO were measured at rest while combined DLNO and DLCO were measured at rest and post-exercise<br>* DLNO and DLCO were measured at rest and 5-10 s after a bout of treadmill exercise simulating usual walking<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Combined DLNO and DLCO changes after mild exercise | pulmonary gas exchange abnormalities in dyspneic long COVID subjects | through study completion, an average of 6 months |