COVID-19 can cause permanent lung damage – 3 ways COVID-19 breathing can suffer for a long time

As pulmonologists and critical care physicians treating patients with lung disease, we’ve heard many of our patients recovering from COVID-19 tell us this even months after their initial diagnosis. While they may have survived the most life-threatening phase of their illness, they have yet to return to their pre-COVID-19 baseline, struggling with activities ranging from strenuous exercise to doing laundry.

These lingering effects, called lung COVID, have affected as many as 1 in 5 U.S. adults diagnosed with COVID-19. Long COVID includes a wide variety of symptoms such as brain fog, fatigue, coughing and shortness of breath. These symptoms can result from damage to or malfunctioning of multiple organ systems, and understanding the causes of long-term COVID is a special research focus of the Biden-Harris administration.

Not all breathing problems are related to the lungs, but in many cases the lungs are affected. Looking at the basic functions of the lungs and how they can be affected by disease can help clarify what is on the horizon for some patients after a COVID-19 infection.

Normal lung function

The main function of the lungs is to bring oxygen-rich air into the body and expel carbon dioxide. When air enters the lungs, it is brought close to the blood, where oxygen diffuses into the body and carbon dioxide diffuses out.

The lungs bring oxygen in and carbon dioxide out of the body.

This process, as simple as it may sound, requires extraordinary coordination of airflow, or ventilation, and blood flow, or perfusion. There are more than 20 divisions in your airway, starting from the main trachea, or windpipe, all the way to the small balloons at the end of the airway, called alveoli, that are in close contact with your blood vessels.

By the time an oxygen molecule gets to the end of the respiratory tract, there are about 300 million of these tiny alveoli it can end up in, with a total area of ​​more than 100 square meters where gas exchange takes place.

Matching ventilation and perfusion rates is critical to basic lung function, and damage anywhere along the airways can lead to breathing difficulties in a number of ways.

Obstruction – reduced airflow

One form of lung disease is obstruction of airflow in and out of the body.

Two common causes of such disorders are chronic obstructive pulmonary disease and asthma. In these diseases, the airways become narrowed due to either damage from smoking, as is common in COPD, or allergic inflammation, as is common in asthma. In both cases, patients have trouble blowing air out of their lungs.

Researchers have observed persistent airflow obstruction in some patients who have recovered from COVID-19. This condition is usually treated with inhalers that release drugs that open the airways. Such treatments may also be helpful while recovering from COVID-19.

Restriction – reduced lung volume

Another form of lung disease is called restriction or difficulty of the lungs. Restriction reduces the volume of the lungs and thus the amount of air they can take in. Restriction often results from the formation of scar tissue, known as fibrosis, in the lungs as a result of injury.

Fibrosis thickens the walls of the alveoli, making gas exchange with the blood more difficult. This type of scarring can occur with chronic lung conditions, such as idiopathic pulmonary fibrosis, or as a result of severe lung damage in a condition called acute respiratory distress syndrome, or ARDS.

ARDS can be caused by injuries originating in the lungs, such as pneumonia, or serious disease in other organs, such as pancreatitis. About 25% of patients who recover from ARDS develop restrictive lung disease.

Researchers have also found that patients who have recovered from COVID-19, especially those with severe illness, may later develop restrictive lung disease. COVID-19 patients who require a ventilator may also have a recovery rate similar to those who require a ventilator for other conditions. Long-term recovery of lung function in these patients is still unknown. Drugs to treat fibrotic lung disease after COVID-19 are currently undergoing clinical trials.

Decreased perfusion – decreased blood flow

Finally, even if airflow and lung volume are unaffected, the lungs cannot complete their function if blood flow to the alveoli, where gas exchange occurs, is impeded.

COVID-19 is associated with an increased risk of blood clots. If blood clots travel to the lungs, they can cause a life-threatening pulmonary embolism that restricts blood flow to the lungs.

In the long term, blood clots can also cause chronic problems with the blood supply to the lungs, a condition called chronic thromboembolic pulmonary hypertension, or CTEPH. Only 0.5% to 3% of patients who develop a pulmonary embolism for reasons other than COVID-19 develop this chronic problem. However, there is some evidence that severe COVID-19 infections can directly damage the blood vessels of the lungs and impede blood flow during recovery.

What’s next?

The lungs can work less optimally in these three common ways, and COVID-19 can cause them all. Researchers and clinicians are still looking for ways to best treat the long-term lung damage seen with long-term COVID.

For clinicians, closely monitoring patients who have recovered from COVID-19, especially those with persistent symptoms, can lead to faster diagnoses of long-term COVID-19. Severe cases of COVID-19 are associated with higher rates of long-term COVID-19. Other risk factors for developing long-term COVID include pre-existing type 2 diabetes, the presence of virus particles in the blood after initial infection, and certain forms of abnormal immune function.

For researchers, long-term COVID is an opportunity to study the underlying mechanisms of how different types of lung-related conditions that result from COVID-19 infection develop. By uncovering these mechanisms, researchers could develop targeted treatments to accelerate recovery and help more patients feel and breathe like their pre-pandemic selves.

In the meantime, everyone can stay up to date on recommended vaccinations and take preventive measures such as good hand hygiene and masking where necessary.The conversation

Jeffrey M. Strerk, Assistant Professor of Medicine, University of Virginia and Alexandra Kadl, assistant professor of medicine and pharmacology, University of Virginia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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