Pulmonary fibrosis, as the term implies, is the damage and scarring of the lungs. Pulmonary means in the respiratory system and fibrosis is a type of scarring that can happen when the body heals damage. This scarring can often be irreversible resulting in eventual pulmonary deterioration over time.

The underlying cause of lung fibrosis is not always familiar. However, of the known causes of pulmonary fibrosis, occupational and environmental exposures top the list.

This article highlights the causes and common symptoms that could indicate underlying pulmonary fibrosis. Following this, we will discuss standard diagnostic tests and treatment strategies.

What Is Pulmonary Fibrosis? 

Pulmonary fibrosis is a progressive lung condition that scars the lungs and worsens their function. Pulmonary fibrosis is a type of restrictive lung disease.

Fibrosis within the lungs can occur following either exposure to or prolonged association with risk factors such as smoking, inhalation of environmental dust, pollution, or even GERD (gastroesophageal reflux disease). Genetics can also increase the likelihood of developing lung fibrosis. This exposure then results in injury and subsequent inflammation within the lungs. Cycles of injury and inflammation occur slowly over the years and speed up during certain events, such as respiratory infections. With time, this eventually results in irreversible fibrosis¹.

The scarring can affect all parts of the respiratory tract. Subsequently, this limits the exchange of oxygen within the lungs and to the rest of the body. This then results in the primary signs noted by those suffering from underlying lung fibrosis of fatigue and shortness of breath.

Pulmonary fibrosis is one of several variants of interstitial lung disease. The pathophysiology of most of these conditions is similar – scarring of the lung tissue.

What Causes Pulmonary Fibrosis?

Cases of pulmonary fibrosis are categorized into those which are directly linked to a known cause and those which cannot be associated with one. 

The underlying cause of lung fibrosis cannot always be found. These unknown cases account for almost 20%–50% of cases of the overall incidence of interstitial lung disease with no known cause². 

These cases are termed idiopathic pulmonary fibrosis. These patients often present in their 50s and 60s. Idiopathic pulmonary fibrosis is documented in approximately 60 cases in every 100,000 people³.

However, doctors often find the causes following a thorough history of a patient who presents with the possibility of underlying pulmonary fibrosis. There are over 200 possible causes of fibrotic damage to the lungs⁴. 

Occupational and Environmental Exposure

For starters, one of the most common reasons for pulmonary fibrosis is occupational and environmental exposure. Asbestos, silica, beryllium, and carbon dust from coal are among the most frequent culprits⁵. Exposure to air pollution, while it may not be a direct cause of pulmonary fibrosis, has been observed to speed up the process of fibrosis and cause irreversible lung damage⁶. 

Medical Conditions

Medical conditions have also been linked as a cause of pulmonary fibrosis, for example, Aone foremost medical cause is autoimmune conditions such as lupus⁷ or rheumatoid arthritis⁸.. The changes related to lung fibrosis can be either a consequence of the disease or result from the changes in the body from a medical condition. The antibodies produced in these conditions can lead to lung fibrosis, which makes individuals more susceptible to lung infection, which can further deteriorate lung function.

Medical Drugs

A few medical drugs have also been observed to cause pulmonary fibrosis following prolonged use, by causing pulmonary inflammation which can then lead to scarring and fibrosis. Chemotherapeutic drugs were found to be the top-ranked cause of drug-induced interstitial lung disease⁹. Other drugs with the potential of causing lung disease include antibiotics such as nitrofurantoin, the antiarrhythmic drug amiodarone, the antirheumatic methotrexate, and beta blockers.

What Are the Symptoms of Pulmonary Fibrosis?

Patients often present to medical practitioners following either months or years of progressive fibrosis. Some of the initial indications of underlying pulmonary fibrosis are a dry chronic cough and difficulty breathing. A chronic cough is one that lasts longer than eight weeks. Patients with lung fibrosis typically document their cough worsening during this time. Chronic coughing in pulmonary fibrosis can affect one’s quality of life and result in anxiety related to the cough as a consequence¹⁰.

As the disease progresses, patients with pulmonary fibrosis will also record an inability to perform daily tasks. They will get easily fatigued. 

Doctors will check for other possible conditions such as other lung diseases or heart failure to rule those out as contributory conditions.

Some of the physical signs you may observe if you have pulmonary fibrosis include:

• Cyanosis, a bluish tinge of the extremities
• Digital clubbing noticed as enlargement and rounded tips of nail beds
• Wheezing
• Indications of underlying autoimmune conditions, such as arthritis, neurological changes, and skin changes like a butterfly rash (a rash across both cheeks and the bridge of the nose)

How Is Pulmonary Fibrosis Diagnosed?

One of the initial steps in diagnosing pulmonary fibrosis is evaluating your exposure history (such as occupation or possible external sources) and risk factors. This is why it is crucial during the visit to tell your doctor all the medications that you are taking to rule them out as a source of pulmonary fibrosis. Your doctor will document these to guide them toward the next steps when it comes to diagnostic testing required for pulmonary fibrosis.

Initial Testing

During a physical examination, your doctor will document all your symptoms that can indicate underlying lung disease, such as chronic cough, wheezing, and shortness of breath.

Initial investigations are usually through tests such as spirometry, which tests your ability to breathe, and chest X-rays, which show if there are any unusual structures in the lungs. Both consistently show fibrosis and reduced lung volumes if the person has pulmonary fibrosis. Studies conducted earlier in the disease process may show up with close to normal lung volumes but this still prompts further investigation¹¹. Tests that determine lung capacity are also used to check the progression of the disease and predict long-term outcomes.

Following initial suspicion of pulmonary fibrosis, the following tests may then be conducted:

• High-resolution computed tomography (HRCT scan) – This is a type of CT/CAT scan
• Bronchoscopy with biopsy – Where a tube with a camera and small equipment is passed into the lungs to allow the doctors to see inside
• Bronchoalveolar lavage – A small amount of fluid is put into a section of the lungs and then retrieved to collect samples
• Video-assisted thoracoscopic biopsy – Here, an incision is made in the chest to allow samples to be taken from the chest outside the lungs

Additionally tests to investigate medical conditions that could be causing this form of restrictive lung disease, such as autoimmune conditions or occupational exposure should also be investigated during the diagnostic stage.

You can read more about respiratory disease diagnostic tests here.

What Is the Best Treatment for Pulmonary Fibrosis?

Once scarring has occurred to the lungs it is often irreversible. The key aspects of treatment are preserving the remaining lung function through supportive care and slowing down the fibrosis if possible.

Eliminating Lifestyle Causes

Initial attempts of supportive care include eliminating lifestyle causes that could be causing pulmonary fibrosis. These include stopping smoking, eliminating occupational exposure, and increasing oxygen supplementation. Patients are also advised to get vaccinations such as the flu vaccine and pneumococcal vaccine as their lungs are more susceptible to serious lung infections. Some medical conditions that have caused pulmonary fibrosis, such as lupus, have specific treatments. Managing these underlying conditions can help to slow down the progression of lung fibrosis.

Medication

A few pharmacological drugs have been developed to slow down the progression of pulmonary fibrosis. Two drugs studied for this purpose are nintedanib (under the brand names Ofev and Vargatev) and pirfenidone (available under the brand names Esbriet and Pirespa, and as a generic)¹². While such drugs do not improve mortality rates due to pulmonary fibrosis, they help to improve life expectancy. With slowed fibrosis, the lungs are less susceptible to acute respiratory distress (events which can worsen pulmonary deterioration).

Lung Transplant

Finally, if all treatment methods fail to slow the progression of lung fibrosis and the disease state is severe, patients might be considered for a lung transplant. Patients are usually evaluated for their mortality risk in the foreseeable two years based on their current lung conditions¹³ along with other factors that could contribute to the progression of pulmonary fibrosis. Then, the patient can be put on the waitlist for a lung transplant.

During the final stages, patients often get to decide how they would like to proceed. Since needs differ, palliative care, which involves only supportive care without medications or surgery, can be carried out at home or within a healthcare facility.

Conclusion

Pulmonary fibrosis is often irreversible once the scarring of the lung tissue begins. Understanding the potential signs that might indicate underlying pulmonary fibrosis is crucial to begin treatment early and preserve respiratory health. While the initial steps in treatment mainly revolve around supportive care and lifestyle changes, considering early pharmacological support is also vital. If pulmonary fibrosis is severe and the patient is willing, lung transplantation can be considered as a way to increase life expectancy.

References

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