Pulmonary fibrosis

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at April 18, 2016
StartDiseasesPulmonary fibrosis

Approximately 140,000 Americans are affected by a condition called pulmonary fibrosis, which interferes with the ability to breathe air in and out as well as with the exchange of oxygen and carbon dioxide at the alveolar level. Pulmonary fibrosis is an irreversible process. Without a lung transplantation, patients typically have a life span of between three and five years.

Contents

Definition & Facts

Pulmonary fibrosis is characterized by scarring of the connective tissues that support the blood vessels in the lungs. These connective tissues also anchor the tiny air sacs, called alveoli, where the exchange of oxygen and carbon dioxide take place. As connective tissues progressively thicken, lungs cannot expand completely. The movement of respiratory gases through the walls of the alveoli is also compromised.

Some people who develop pulmonary fibrosis have been exposed to radiation or asbestos fibers. Others have medical conditions like lupus and scleroderma that are known to affect connective tissues. In the majority of cases, though, no single factor can be identified as the cause for this condition. These cases are described as “idiopathic pulmonary fibrosis” because their etiology is unknown.

Symptoms & Complaints

Pulmonary fibrosis makes it increasingly difficult to breathe. This leads to shortness of breath (dyspnea) as the lungs struggle to keep up with the body’s oxygen demands. Many patients develop a persistent dry cough. Shortness of breath leads to dizziness and chronic fatigue. Many patients with pulmonary fibrosis suffer from sleep apnea.

As the underlying oxygen deficit intensifies, other serious medical problems can occur. Patients are at risk for developing infections of the lung like pleurisy and pneumonia. Their lungs can collapse spontaneously (pneumothorax) since scar tissues prevent the lungs from filling up with air. Patients with pulmonary fibrosis are also prone to pulmonary emboli, which can damage the underlying lung tissue even more.

As tiny lung capillaries and arterioles lose their ability to expand, the heart’s right ventricle must work harder and harder to pump blood throughout the lungs. Eventually, this can lead to pulmonary hypertension and heart failure.

Chronically low levels of oxygen in the bloodstream can lead to physical abnormalities over time like clubbed fingers and barrel-shaped chests. The energy required to breathe expends additional calories, so frequently patients with pulmonary fibrosis appear thin and malnourished. Compromised cardiac function can lead to the collection of fluid (edema) in the extremities, so people with pulmonary fibrosis often have pitting in their feet and ankles.

Causes

Pulmonary fibrosis is more prevalent among men than it is among women. Adults between the ages of 40 and 70 have the highest risk, and approximately 65% of those affected by the condition are over the age of 60. Certain chemotherapy drugs and cardiac medications are potential risk factors, and these drugs are most commonly used by individuals in this age category.

Some medical researchers believe that pulmonary fibrosis may begin as an inflammatory response. In tissues like the lungs that don’t have the capacity to regenerate, inflammation can lead to scarring. Scar tissue can’t support specialized cells, so functional impairment occurs. This theory appears to be supported by the fact that pulmonary fibrosis often arises in conjunction with autoimmune diseases like lupus erythematosus, rheumatoid arthritis, and scleroderma.

There are also higher incidences of pulmonary fibrosis among individuals who’ve been exposed to environmental toxicants like cigarette smoke, asbestos fibers, radiation, and silica dust that are known to precipitate inflammatory responses. In most individuals, however, the cause of this debilitating condition cannot be determined with any degree of specificity. Some types of pulmonary fibrosis run in families, which may suggest a genetic factor although it’s also possible that family members are exposed to the same environmental factors.

Diagnosis & Tests

Pulmonary fibrosis is diagnosed through a combination of physical examinations, imaging studies, pulmonary function tests, and biopsies. Patients may present with clinical signs such as a blue coloration around the mouth (perioral cyanosis) and clubbed fingers. Auscultation with a stethoscope may reveal the presence of rales – which are crackling respiratory sounds - as well as unusual heart sounds that are indicative of cardiac involvement.

CT scans can show the extent of the pulmonary scarification, while pulmonary function tests will show reduced total lung capacity as well as a reduction in diffusion capacity affecting both the diffusion of oxygen and carbon dioxide. Frequently, the diagnosis of pulmonary fibrosis can be made on the basis of these clinical findings without the need for more invasive studies. However, the definitive test for pulmonary fibrosis is a biopsy that demonstrates the presence of scar tissue conclusively.

Treatment & Therapy

Treatment options for pulmonary fibrosis are extremely limited. Pulmonary fibrosis is a progressive condition, and its effects cannot be reversed. Palliative measures like supplemental oxygen can make breathing less taxing and ease the load on the right ventricle. Patients may also be treated with corticosteroids such as prednisone and colchicine in an effort to suppress any further inflammatory responses that could be triggering the formation of new scar tissue in the lungs. Two relatively new drugs, nintedanib and pirfenidone (Esbriet®) have also show some success in slowing the progression of the condition.

A nutritious diet that’s relatively high in calories is an important part of pulmonary fibrosis therapy, since many patients find it difficult to maintain a healthy weight. Respiratory infections exacerbate dyspnea and associated symptoms, so patients are well advised to be vaccinated for influenza and to avoid situations where they might be exposed to causative organisms.

Cigarette smoke can also intensify symptoms, so patients who smoke should stop smoking and make every effort avoid second-hand smoke. Lung transplants may be a treatment option for some patients, but transplant centers typically refuse to perform this surgery on patients who are more than 60 years of age.

Prevention & Prophylaxis

Since the underlying causes of pulmonary fibrosis are unknown in most instances, prevention in the classic medical sense of the word is not possible. Smoking puts people in a higher risk category as does exposure to chemicals and harmful particulate matter. Avoiding cigarettes and secondhand smoke and taking proper precautions when handling potentially toxic inhalants may offer some measure of protection.