If you’ve been suffering from lingering breathlessness and cough after recovering from COVID-19, you’re one of the more than 50% of COVID-19 survivors who experience lingering symptoms, collectively known as post-acute sequalue of COVID-19 (PASC), or long COVID, and the nearly 30% who experience ongoing lung-related symptoms, including breathlessness (dyspnea) and cough, even after mild COVID-19 illness. Research from the University of Iowa suggests that the root of your symptoms may be small airways disease.

What the Researchers Did

Led by professor of internal medicine Alejandro P. Cornellas, M.D. of the Carver College of Medicine’s Division of Pulmonary and Critical Care Medicine, the research team sought to learn more after school clinicians observed many COVID-19 survivors showing signs of underlying lung disease.

• Chest computed tomography (CT) images of 100 adults who had confirmed COVID-19 and symptoms lasting at least 1 month were compared to images of 106 healthy individuals.
• Median age of the COVID survivors was 48 years, with 67 survivors undergoing outpatient treatment and 33 having severe infection requiring hospitalization (16 intensive care).
• Study participants underwent both inspiratory and expiratory CT imaging of the lungs.
• Median time from COVID-19 diagnosis to CT imaging was about 75 days. 

While inspiratory CT scanning (done after inhaling) is standard protocol for viewing the lungs, expiratory scans were also used to assess whether participants had exhaled all of the air in their lungs. Air remaining in the lungs is known as “air trapping,” a condition common in obstructive airway diseases like chronic obstructive pulmonary disease (COPD).

What They Found

The study, published in the journal Radiology, found significant respiratory differences between COVID survivors and healthy controls.

• Average lung tissue percentage with air trapping was just over 25% in outpatient survivors, and almost 35% in hospitalized survivors.
• Just 7.2% of lung area in healthy controls showed air trapping.
• Eight of nine participants who had CT imaging over 200 days after COVID-19 diagnosis showed persistent air trapping.
• Regardless of initial COVID severity, the images showed a high degree of long-term air trapping.

Analysis of the expiratory images with supervised machine learning–an advanced form of artificial intelligence–pointed to small airways disease. Said Cornellas, “There is some disease happening in the small airways independent of the severity of COVID-19.”

What It Means

The study is the first time small airways disease has been described in COVID-19 survivors. Its long-term implications are unknown.

The researchers say we don’t completely understand small airways disease, but inflammation or small airway restructuring may be preventing full exhalation. “Something is going on in the distal airways related to either inflammation or fibrosis that is giving us a signal of air trapping,” Cornellas explained. The fact they observed lung abnormalities after a median of 75 days from COVID diagnosis, however, suggests SARS-CoV-2 can lead to permanent changes and fibrosis.

The researchers intend to keep studying the survivors for any improvement. If no improvement happens, Cornellas says, “[i]t could be something related to inflammation that’s reversible, or it may be something related to a scar that is irreversible, and then we need to look at ways to prevent further progression of the disease.”

*Radiological Society of North America. (2022, March 15). ‘Long COVID’ linked to lasting airways disease. MDLinx. https://www.mdlinx.com/news/-long-covid-linked-to-lasting-airways-disease/6RQ1R5yhoeCkAsmYCQShVC