OVERVIEW

What is idiopathic pulmonary fibrosis?

Idiopathic pulmonary fibrosis is a chronic, progressive, fibrosing interstitial pneumonia of unknown cause.

It is characterized histologically and/or by high-resolution computed tomography (HRCT) findings of usual interstitial pneumonia. It predominantly affects elderly individuals. The main symptom is exertional dyspnea, which progressively worsens and is often accompanied by a dry cough.

SYMPTOMS

What are the manifestations of idiopathic pulmonary fibrosis?

• It mostly occurs after the age of 50.
• The condition is not easily detected.
• Main symptoms include cough and dyspnea after activity, which gradually worsen.
• The cough is usually dry, without phlegm.
• Progressive dyspnea means shortness of breath initially occurs after intense activity, but as the condition worsens, it also appears during non-strenuous activities.
• In later stages, chest tightness and shortness of breath may occur even at rest.
• Systemic symptoms are not obvious; occasional discomfort, fatigue, and weight loss may occur, but fever is rare.
• 75% of patients have a history of smoking.
• Half of the patients may exhibit clubbing of fingers/toes, where the distal phalanges become noticeably wider and thicker, and the nails curve upward from the base to the tip, forming a base angle between the skin and nail of 180 degrees or more.

Why is dyspnea the main manifestation of idiopathic pulmonary fibrosis?

The alveoli are lined with alveolar epithelium, beneath which lies the basement membrane. The epithelium sits on the basement membrane and exchanges gases with it. Adjacent to the alveoli is a blood vessel.

Oxygen moves back and forth between the alveoli and the blood vessel, which is lined with endothelial cells. Below these endothelial cells is another basement membrane. The space enclosed by the alveolar epithelium and these structures is called the parenchyma. Why is this empty space called the parenchyma?

Because its function is gas exchange. The two basement membranes—the basement membrane of the pulmonary vascular epithelium and the basement membrane of the alveolar epithelium—are separated by a very thin layer of tissue, only a few micrometers thick. This layer may contain small fibers, lymphatic vessels, and some cells. The area between these two basement membranes is called the pulmonary interstitium.

If there are inflammatory cells, edema, or fibroblast thickening in this area, gas exchange cannot occur, leading to hypoxia and dyspnea. Additionally, the elasticity of the lungs is compromised.

CAUSES

What are the causes of idiopathic pulmonary fibrosis?

To date, the cause of idiopathic pulmonary fibrosis remains unclear.

Who is more likely to develop idiopathic pulmonary fibrosis?

Individuals over 50 years old, males, heavy smokers, and those exposed to metal dust, wood chips, or similar environments have an increased risk of developing the disease.

DIAGNOSIS

What tests are needed to diagnose idiopathic pulmonary fibrosis?

• First, conduct a detailed medical history inquiry and physical examination.
• Next, perform blood tests, primarily to check for autoimmune-related antibodies to differentiate among interstitial lung diseases.
• The most crucial tests are chest imaging examinations: chest X-rays and CT scans. In well-equipped facilities, high-resolution CT (HRCT) can be performed to observe morphological changes in the lungs.

What are the typical HRCT findings of idiopathic pulmonary fibrosis?

Subpleural and basal reticular patterns and honeycombing. The reticular pattern resembles a screen-like appearance. Further tests such as pulmonary function tests and blood gas analysis may also be conducted.

If a definitive diagnosis still cannot be made, invasive procedures like bronchoscopy or surgical open-lung biopsy may be required for pathological confirmation.

What diseases should idiopathic pulmonary fibrosis be differentiated from?

• The clinical manifestations of idiopathic pulmonary fibrosis, particularly its imaging features, are complex and variable. One key condition to differentiate is pneumonia. In fact, many cases of idiopathic pulmonary fibrosis in China are initially misdiagnosed as pneumonia, leading to prolonged antibiotic treatments that prove ineffective before considering interstitial lung disease. Thus, pneumonia is the most common misdiagnosis.
• Idiopathic pulmonary fibrosis is also frequently misdiagnosed as chronic hypersensitivity pneumonitis (often associated with exposure to pigeons or parrots), asbestosis, silicosis (usually linked to long-term exposure to asbestos, silica, or other dusts), or connective tissue diseases (often accompanied by rashes, arthritis, multi-system involvement, and positive autoantibodies).
• Other misdiagnoses include tuberculosis and tumors. While idiopathic pulmonary fibrosis can sometimes be clinically distinguished from other pneumonias or tuberculosis, differentiation can be challenging, requiring more complex diagnostic approaches.

What other diseases can idiopathic pulmonary fibrosis cause? Can it affect other organs?

Yes.

First, gastroesophageal reflux may be associated with idiopathic pulmonary fibrosis.

Additionally, prolonged hypoxia can lead to pulmonary hypertension, which may eventually progress to conditions like cor pulmonale, affecting other organs.

TREATMENT

How to treat idiopathic pulmonary fibrosis?

So far, the use of hormones and immunosuppressants is ineffective. The recommended treatments are small-molecule compounds, such as nintedanib and pirfenidone, but these drugs only slow disease progression and cannot cure or reverse it.

Lung transplantation is currently the most effective treatment for idiopathic pulmonary fibrosis. Therefore, a strong collaboration between doctors and patients is essential. The disease should be monitored and evaluated, with treatment adjustments made based on disease progression and patient preferences to alleviate suffering and improve quality of life.

Do patients with idiopathic pulmonary fibrosis need oxygen therapy?

Patients with significant hypoxemia at rest should undergo long-term oxygen therapy.

It is recommended to receive oxygen for 12 to 15 hours or more daily to prevent hypoxia, thereby reducing damage or adverse effects on other organs and minimizing complications.

How effective is the treatment for idiopathic pulmonary fibrosis? How long can patients survive?

The prognosis for idiopathic pulmonary fibrosis is relatively poor, with a median survival of about 2.8 years—some say comparable to cancer. Currently, aside from lung transplantation, there are no effective drugs to treat idiopathic pulmonary fibrosis.

DIET & LIFESTYLE

What should patients with idiopathic pulmonary fibrosis pay attention to when going out?

Prevent influenza and pneumonia. If going to public places, it's best to wear a mask and try to avoid public areas.

What should patients with idiopathic pulmonary fibrosis pay attention to in daily life?

• Avoid overexertion, such as mountain climbing or playing sports;
• Avoid invasive examinations, such as radiotherapy or chemotherapy for lung diseases, as these may trigger acute exacerbation of idiopathic pulmonary fibrosis, which can lead to patient death—this is commonly seen in clinical practice;
• Keep warm in winter to reduce the risk of infection.

Do patients with idiopathic pulmonary fibrosis need to quit smoking?

Yes, because smoking is a risk factor for idiopathic pulmonary fibrosis.

PREVENTION

Can idiopathic pulmonary fibrosis be prevented?

Since idiopathic pulmonary fibrosis is a disease of unknown cause, it cannot be prevented. However, its risk factors can be reduced, such as quitting smoking and avoiding exposure to metal dust, wood chips, and similar environments.

Is idiopathic pulmonary fibrosis hereditary?

Familial idiopathic pulmonary fibrosis is hereditary. Sometimes, if the previous generation has it, the next generation may also develop it.

Does idiopathic pulmonary fibrosis cause cancer?

Patients with idiopathic pulmonary fibrosis are prone to developing lung cancer, with an incidence rate more than ten times higher than that of patients with other interstitial lung diseases.