Diffuse parenchymal lung diseases (DPLDs)

What are Diffuse Parenchymal Lung Diseases (DPLD)?

Diffuse Parenchymal lung diseases (DPLDs) encompass more than 200 disorders that affect the parenchymal tissue of the lungs, the space between the alveoli (where gas exchange takes place) and the blood vessels.

This group of diseases is characterized by inflammation and scarring of lung tissue, making breathing difficult, and affecting the lungs' ability to transport oxygen to the blood.

The affected tissue may become stiffer or thickened, reducing lung elasticity and making breathing difficult.

This process, known as pulmonary fibrosis, is one of the main complications of ILD and is usually irreversible. It significantly affects the patient's quality of life.

Causas de las Enfermedades Pulmonares Intersticiales

ILDs can have multiple causes, although in many cases they are considered idiopathic, that is, of unknown origin.

Some of the known causes include:

1. Exposure to harmful substances: Prolonged inhalation of dust, toxic gases, or chemicals (such as asbestos or silica dust) can cause lung damage.
2. Autoimmune diseases: Disorders such as rheumatoid arthritis, lupus, or scleroderma can affect the lungs and cause inflammation of the parenchymal tissue.
3. Medications: Certain drugs used in chemotherapy, radiation therapy, or for heart disease can trigger lung damage.
4. Chronic infections: Some viral, bacterial, or fungal infections can inflame the lungs and lead to DPLD.

In some cases, no clear cause is found, as in idiopathic pulmonary fibrosis (IPF), one of the most common forms of ILD.

Symptoms of ILD

The symptoms of ILD are often similar across different forms of the disease, although they can vary in intensity depending on the progression of the condition.

The most common ones include:

• Shortness of breath (dyspnea): at first, this may be noticeable only during physical exertion, but over time, it can occur even at rest.
• Dry, persistent cough: this symptom often accompanies shortness of breath, without the presence of mucus.
• Fatigue: lack of oxygen affects the patient's energy and ability to perform daily activities.
• Chest pain: although less common, some patients experience chest pain or discomfort.
• Unintentional weight loss: this may occur in later stages due to respiratory effort and decreased appetite.

Who is affected by EPID?

In Spain, it is estimated that there are approximately 8 cases of ILD per 100,000 inhabitants. Idiopathic pulmonary fibrosis (IPF) is the most common, with an incidence of 16 cases per 100,000 people and has been increasing in recent years.

It primarily affects people over 50 years of age, although some ILDs, such as sarcoidosis, can affect adults between 20 and 40 years of age.

How parechymal lung diseases are diagnosed

Diagnosing parenchymal lung diseases can be complex due to the variety of causes and presentations. The process generally includes:

• Detailed medical history: your doctor will discuss your symptoms, exposure to risk factors, and family history.
• Imaging tests: chest X-rays and high-resolution computed tomography (HRCT) scans allow you to observe the pattern of lung damage, helping to identify fibrosis and other abnormalities.
• Pulmonary function tests: these measure the patient's breathing capacity and gas exchange.
• Lung biopsy: in some cases, a sample of lung tissue may be removed for analysis, which helps determine the specific type of ILD.

Treatment of Diffuse Parenchymal Lung Diseases

Treatment for ILD depends on the type and severity of the disease. Although pulmonary fibrosis is irreversible, there are ways to control symptoms and slow the progression of the disease.

Some options include:

1. Antifibrotic medications: these drugs, such as pirfenidone and nintedanib, can help slow the progression of fibrosis in some patients.
2. Immunosuppressants: for patients whose ILD is caused by an autoimmune response, medications that modulate the immune system may be prescribed.
3. Oxygen therapy: when lung capacity decreases significantly, oxygen therapy can improve quality of life, help the patient breathe better, and prevent complications from oxygen deprivation.
4. Pulmonary rehabilitation: exercise and education programs help improve the patient's functional capacity and psychological well-being.
5. Lung transplant: in more advanced cases and when other treatments are ineffective, a transplant may be an option.

Complications of ILDs

Parenchymal lung diseases can lead to various complications if not treated properly:

• Pulmonary hypertension: damage to the lungs can increase pressure in the pulmonary arteries, which in turn affects heart function.
• Respiratory failure: over time, the lungs can lose their ability to adequately oxygenate the blood.
• Lung cancer: patients with certain ILDs, especially those with pulmonary fibrosis, may be at increased risk of developing lung cancer.
• Recurrent respiratory infections: weakening of the lungs increases vulnerability to infections such as pneumonia.