What Should Pulmonary Fibrosis Patients Know About The Risks Of COVID-19? Can The Coronavirus Cause Lung Fibrosis?

Numerous studies have so far confirmed that COVID-19 patients with a severe clinical picture are at great risk of developing permanent lung damage, due to lung remodeling caused by inflammation of the connective tissue normally found in the lungs.

Since the damage done in pulmonary fibrosis is irreversible, proper diagnostics and regular check-ups of these patients is of great importance when it comes to slowing down the progress of lung fibrosis, thereby minimizing the potential damage in these patients.

What is pulmonary fibrosis?

Pulmonary fibrosis is a condition in which, during the process of repair, scar tissue is formed inside the lungs, replacing the connective tissue normally found there. Pulmonary fibrosis may be triggered by numerous factors, such as:

• Inflammation (tuberculosis and some other forms of pneumonia), 
• Exposure to environmental hazards (asbestos, heavy metals, ionizing radiation)
• Conditions which affect pulmonary blood vessels (embolism and hypertension)
• A side effect of some medications (such as chemotherapy)
• Autoimmune diseases that affect the connective tissue (rheumatoid arthritis, lupus)

Although in some cases the underlying cause cannot be found (so-called idiopathic pulmonary fibrosis), it is thought that genetics may play an important role in the development of this serious condition. Pulmonary fibrosis is usually diagnosed at an older age, more often in men. Other than the risk factors previously noted, it is important to mention the ones which you can regulate, of which cigarette smoking is the most dangerous one, following diabetes and high blood pressure.

Namely, when your body tries to fix the damage done to the air sacs (alveoli) during the process of inflammation, the normal lung tissue is replaced with scars, making those parts of the lungs non-functional, meaning that oxygen is less likely to be absorbed in the blood vessels, thereby creating further complications.

Sometimes, a chain reaction of the immune system, known as a cytokine storm, can cause significant damage to the lungs, causing permanent damage in the process, also manifested by pulmonary fibrosis. Another complication is related to increased coagulation of the blood, where blood clots are formed, which, other than issues such as a heart attack or a stroke, may also lead to lung damage.

All of this is of serious importance for COVID-19 patients, because now we see that the virus can leave long lasting and serious damage even when the patients survive the initial infection.

In what relation is pulmonary fibrosis to COVID-19?

So far, we’ve learned that the SARS-CoV-2 can present very differently in different patients, from asymptomatic cases to life-threatening ones. Given the fact that the novel coronavirus is a respiratory virus, so far it is implied that it leaves its most serious consequences on the lungs of those patients who have had a more severe clinical picture. 

Since COVID-19 manifests as pneumonia (almost always in both lungs), from there it may progress into ARDS (acute respiratory distress syndrome), an another life-threatening condition which demands the transport of the patients to the ICU, and therefore, artificial ventilators for those patients who can’t breathe on their own.

While we’re at it, it’s important to mention that fibrosis may actually also be linked with (that is, caused by) artificial ventilation, especially if oxygen is applied under high pressure. If they happen to recover, these patients will likely suffer the long-lasting consequences of this infection, such as shortness of breath and fatigue. This is one of the reasons for which COVID-19 rehabilitation programs are now emerging in countries at the cutting edge of fighting the coronavirus.

How does COVID-19 affect patients with preexisting pulmonary fibrosis?

Unfortunately, pulmonary fibrosis and COVID-19 seem to share the very same risk factors, meaning that these patients are potentially at a very high risk of severe COVID-19 complications. To be clear, although these patients are more likely to show COVID-19 symptoms when infected, this doesn’t necessarily mean that they belong to higher risk groups for contracting COVID-19.

Since COVID-19 is a new disease, and therefore, no one ever had prior immunity to it, theoretically all people on the planet are prone to infection.

Pulmonary hypertension (increased blood pressure in the arteries of the lung) is a frequent complication of pulmonary fibrosis, and this condition severely impairs normal blood flow, which further worsens a COVID-19 patient’s state. Moreover, pulmonary hypertension can further lead to an increased blood pressure in the right side of the heart, which is known as pulmonary heart disease (cor pulmonale).

This condition makes the heart weaker, and therefore unable to pump blood efficiently, eventually leading to fluid building up in your body, and in some cases even death. Since the heart and the lungs are closely interconnected, this decrease in lung function, usually manifested with the lack of oxygenated blood, may result in lung failure.

Since COVID-19 is a relatively new disease, we have limited data on the long-term effect of pulmonary fibrosis in new patients, and therefore, further studying of this disease will give us these answers eventually. Given the fact that SARS-CoV-2 is closely related to viruses that have caused SARS and MERS in the recent past, we can partly learn from these earlier experiences too. However, in order to form a clear picture, some medical centers recommend that these patients should undergo at least a control chest X-ray three months after they have been discharged from the hospital. 

How are patients with pulmonary fibrosis treated?

To this day, treatments are usually aimed to reduce the symptoms, as well as applying medications that help in slowing down the progress of this disease. This is why it is of great importance to diagnose pulmonary fibrosis early on, when the symptoms are mild, and scarring is minimal. In severe cases, patients with this condition require lung transplantation.  

Because of its seriousness, it is of extreme importance that pulmonary fibrosis, amongst other COVID-19 complications, needs to be identified as quickly as possible in these patients. By doing this, not only will we have more information of COVID-19 effects on the health of the population, but we may also develop new strategies in treating these patients, and maybe even prevent these complications in the future.