Pulmonary Fibrosis – Symptoms, Causes, Risk Factors And Complications

Pulmonary Fibrosis

Thyroid NodulesFibrosis is the medical term which describs scars. Scarring of lung tissue is defined as pulmonary fibrosis. This condition can be caused by several diseases, including chronic inflammatory processes (sarcoidosis, Wegener granulomatosis), infections, interactions with various environmental agents (asbestos, silica, certain gases), exposure to ionizing radiation (radiotherapy), chronic diseases (lupus erythematosus, rheumatoid arthritis) and certain medications.

In isolated cases, chronic inflammation and pulmonary fibrosis can develop without a cause which can be identified. Some of these patients may develop idiopathic pulmonary fibrosis, unresponsive to medical treatment, while others may have other types of pulmonary fibrosis such as nonspecific interstitial pneumonia, in this disease the results to suppressive therapy are favorable.

Pulmonary fibrosis is a disease known as interstitial lung disease, which is the general term for a variety of chronic lung diseases. Lungs in a patient with pulmonary fibrosis are stiff due to scarring of the lung tissue and due to fibrosis of the interstitium between lung alveoli. Scar tissue is unable to carry oxygen.

Pulmonary Fibrosis

Symptoms Of Pulmonary Fibrosis

Signs and symptoms of pulmonary fibrosis include:

• Dyspnoea (shortness of breath).
• Dry cough.
• Fatigue.
• Unexplained weight loss.
• Muscle and joint pain.

Common symptoms of pulmonary fibrosis are difficulty in breathing (especially during or after physical activity) and dry cough. Often, this symptoms occur when the disease is in an advanced stage and lung lesions are already formed (which are irreversible). Usually, breathing problems are progressively worsen and patients experience difficulty in breathing even during routine activities (talking on the phone or eating).

Causes Of Pulmonary Fibrosis

The process of breathing

During inspiration air flows to the lungs through the bronchi. Inside the lungs, the bronchi are subdivided like the branches of a tree into a million smaller airways called bronchioles, which ramify, and are provided at the ends with small sacs called pulmonary alveoli. One lung has about 300 million alveoli. In the wall of pulmonary sacs are blood vessels (capillaries) through which oxygen passes into the blood and carbon dioxide (waste product from metabolism) is removed.

Respiratory System

What happens in pulmonary fibrosis?

In case of pulmonary fibrosis, the alveoli are damaged and form scar tissue, which delimit and separate the alveoli. Normally, alveoli are very elastic, like little balloons which contract with each breath. Scars make lung tissue to be thick and rigid and pulmonary alveoli less flexible, which leads to breathing problems.

In patients suffering from pulmonary fibrosis, healing is hampered by other circumstances. Normally, when a person has an injury (cut), the body form new blood vessels that carry oxygen and nutrients to the affected cells, but in people with pulmonary fibrosis, blood vessels are filled by scar tissue.

What causes lung damage?

1.  Environmental and occupational factors. Long-term exposure to a range of toxins and pollutants can affect the lungs. Among them are: silica dust (silicosis) and asbestos fibers (asbestosis). Constant exposure to some organic substances, including grain, sugar cane and animal droppings can cause pulmonary fibrosis.
2. Radiations. A relatively small percentage of patients who are treated with radiotherapy for lung cancer or breast cancer, after a certain period of time will develop pulmonary fibrosis. Disease severity depends on: the time of radiation exposure, the amount of radiation, the administration of chemotherapy and the presence of underlying lung disease.
3. Drugs. Many of the substances involved in the drug composition, especially drugs used in chemotherapy (methotrexate, cyclophosphamide), drugs used to treat cardiac arrhythmias and other cardiovascular diseases, certain medications used to treat mental disorders, and some antibiotics ( nitrofurantoin, sulfasalazine).
4. Gastroesophageal reflux disease (GERD). Acid reflux occurs when stomach acid content in coming back into the esophagus. Gastroesophageal reflux disease plays a significant role in pulmonary fibrosis. Although patients with pulmonary fibrosis are frequently suffering from GERD, they don’t present specific symptoms of the disease – heartburn and belching.
5. Other diseases. Serious lung infections, such as tuberculosis and pneumonia can cause permanent lung damage. There are diseases that affect tissues throughout the entire body, not just the lungs, such as systemic lupus erythematosus, rheumatoid arthritis, dermatomyositis, polio, Sjogren’s syndrome and sarcoidosis. In rare cases, scleroderma is associated with a particularly severe form of pulmonary fibrosis.

Idiopathic pulmonary fibrosis: when the cause of the disease is not known

List of chemicals and of diseases that can cause pulmonary fibrosis is long, even so, most often the cause is never found. Pulmonary fibrosis whose causes are not known is called idiopathic pulmonary fibrosis. Scientists have formulated several theories on the factors that can trigger idiopathic pulmonary fibrosis, among them are viruses, and the exposure to cigarette smoke. Also, it is considered that heredity factors play an important role, even though many patients do not inherit the disease directly.

Pulmonary Fibrosis

Pulmonary Fibrosis Risk Factors

Factors that predispose to pulmonary fibrosis are:

• Age. Even if the disease can be diagnosed in children and infants, pulmonary fibrosis affects mostly middle-aged adults and old age adults.
• Sex. Men are more likely to develop pulmonary fibrosis than women.
• Toxins. People who work in mining, agriculture and construction are at increased risk of developing pulmonary fibrosis.
• Radiation and chemotherapy.

Risk factors for idiopathic pulmonary fibrosis are:

Although the causes of idiopathic pulmonary fibrosis are not known, researchers have identified certain factors that increase the risk of developing this disease:

• Smoking. This condition occurs with a higher prevalence among smokers and people who had quit smoking.
• Genetic factors. A severe form of idiopathic pulmonary fibrosis has been identified in certain families. Researchers did not identified genes the are involved in the development of the disease, but have found genetic changes in the respiratory proteins.
• Viruses. Many people have reported symptoms of pulmonary fibrosis after a viral infection, especially if it was caused by a herpes virus  and Epstein-Barr virus (causes mononucleosis).

Pulmonary Fibrosis Complications

1. Decreased blood oxygen levels (hypoxemia) – Because pulmonary fibrosis reduces the amount of oxygen that reaches the respiratory system, the patient may manifest hypoxemia. Lack of oxygen can disrupt normal functioning of the body and low levels of oxygen may be life-threatening.
2. Pulmonary hypertension – Unlike systemic hypertension, this condition occurs only in the pulmonary arteries. Onset occurs when capillaries are compressed by scar tissue, which lead to increased resistance to blood flow in the lungs (pulmonary vascular resistance). This, in turn, leads to high blood pressure within the pulmonary arteries. Pulmonary hypertension is a serious disease that progressively worsens and eventually can be fatal.
3. Right heart failure or acute pulmonary heart disease – is a serious condition characterized by the inability of the heart (right ventricle) to ensure and to pump enough blood to flow through the pulmonary arteries.
4. Respiratory failure – This is the final stage of chronic lung disease. Occurs when the blood oxygen level is dangerously low, the consequences are: cardiac arrhythmias and unconsciousness.