'Long COVID' linked to lasting airways disease

Date:
March 15, 2022
Source:
Radiological Society of North America
Summary:
Disease of the small airways in the lungs is a potential
long-lasting effect of COVID-19, according to a new study. The
study found that small airways disease occurred independently of
initial infection severity. The long-term consequences are unknown.



FULL STORY ========================================================================== Disease of the small airways in the lungs is a potential long-lasting
effect of COVID-19, according to a new study published in the
journal Radiology. The study found that small airways disease occurred independently of initial infection severity. The long-term consequences
are unknown.


========================================================================== "There is some disease happening in the small airways independent of the severity of COVID-19," said study senior author Alejandro P. Comellas,
M.D., professor of internal medicine and faculty in the Division of
Pulmonary and Critical Care Medicine at the Carver College of Medicine, University of Iowa in Iowa City. "We need to investigate further to see
whether it is transient or more permanent." Early reports indicate that
more than 50% of adult survivors of SARS-CoV- 2 infection experience
post-acute sequelae of COVID-19 (PASC), more commonly known as "long
COVID." Respiratory symptoms, including cough and dyspnea, are reported
by nearly 30% of patients with long COVID, including those who experienced
mild infection.

The study grew out of observations from University of Iowa clinicians
that many patients with initial SARS-CoV-2 infection who were either hospitalized or treated in the ambulatory setting later showed signs of
chronic lung disease such as shortness of breath and other respiratory symptoms.

Dr. Comellas and colleagues put a protocol in place to perform both
inspiratory and expiratory CT in these patients. Inspiratory CT, performed after patients inhale, is the standard imaging technique for viewing lung tissue, but post- exhalation expiratory scans are needed to assess air trapping, a condition in which people are not able to empty their lungs
when they breathe out. Air trapping is found in many obstructive airway diseases, such as asthma and chronic obstructive pulmonary disease (COPD).

For the study, the researchers compared CT findings in people who
had COVID-19 and persistent symptoms with those of a healthy control
group. They enrolled 100 adults with confirmed COVID-19 who had remained symptomatic more than 30 days following diagnosis, along with 106 healthy participants. The 100 COVID-19 survivors, median age 48 years, included
67 who were classified as ambulatory, or not requiring hospitalization,
17 who were hospitalized, and 16 who required care in the intensive care
unit (ICU) during acute infection.



==========================================================================
The researchers detected air trapping on expiratory chest CT images in
the COVID-19 group. The mean percentage of total lung affected by air
trapping ranged from slightly more than 25% in the ambulatory group to
almost 35% in the hospitalized group, compared with only 7.2% in healthy controls. Air trapping persisted in eight of the nine participants who underwent imaging more than 200 days after diagnosis.

These imaging results show a high prevalence of long-lasting air trapping, regardless of the initial severity of infection.

Quantitative analysis of expiratory chest CT images, performed with
the help of a sophisticated type of artificial intelligence known
as supervised machine learning, showed evidence of small airways
disease. While small airways disease is not fully understood, evidence
suggests it may be related to either inflammation or remodeling of
the small airways that prevents air from being able to be exhaled from
the lungs.

"For the first time, we're describing small airways disease in this
population of COVID-19 patients with persistent symptoms," Dr. Comellas
said. "Something is going on in the distal airways related to either inflammation or fibrosis that is giving us a signal of air trapping."
The median time from diagnosis to chest CT imaging was approximately
75 days.

The researchers noted that persistence of respiratory abnormalities
in this timeframe raises concern for permanent airway remodeling and
fibrosis following SARS-CoV-2 infection.

Dr. Comellas and colleagues intend to follow the patients in the study
registry and see how many improve and recover and how many remain with
abnormal findings.

"If a portion of patients continues to have small airways disease, then
we need to think about the mechanisms behind it," he said. "It 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."

========================================================================== Story Source: Materials provided by
Radiological_Society_of_North_America. Note: Content may be edited for
style and length.


========================================================================== Journal References:
1. Josalyn L. Cho, Raul Villacreses, Prashant Nagpal, Junfeng Guo,
Alejandro
A. Pezzulo, Andrew L. Thurman, Nabeel Y. Hamzeh, Robert J. Blount,
Spyridon Fortis, Eric A. Hoffman, Joseph Zabner, Alejandro
P. Comellas.

Quantitative Chest CT Assessment of Small Airways Disease
in Post-Acute SARS-CoV-2 Infection. Radiology, 2022; DOI:
10.1148/radiol.212170
2. Brett M. Elicker. What Are the Long-term Pulmonary Sequelae
of COVID-19
Infection? Radiology, 2022; DOI: 10.1148/radiol.220449 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220315105608.htm

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