Diagnosing Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis is a rare and serious condition in which the tiny air sacs within the lungs and the surrounding tissue become thick and scarred. The scar tissue impairs the lungs’ ability to move oxygen into the bloodstream, making it more difficult to breathe. 

The lungs contain thousands of small tubes, called bronchioles. At the end of these tubes are air sacs, or alveoli. Each of these sacs is covered in a mesh of blood vessels known as capillaries, which connect to a larger network of arteries and veins that carry blood throughout your body. When you breathe, air passes from your nose or mouth through the bronchioles to the alveoli, allowing oxygen to enter the blood. 

In people with idiopathic fibrosis, the air sacs and the tissue surrounding them become thickened, interfering with the transport of oxygen to the blood. People who have idiopathic pulmonary fibrosis experience shortness of breath and fatigue, and they develop a dry cough. 

The condition is referred to as idiopathic because the cause is unknown. However, experts have identified certain risk factors. Smoking is a risk factor, although it is not clear why some smokers develop idiopathic pulmonary fibrosis and others do not. People who have been exposed to asbestos, a mineral fiber found in some building materials, and other environmental toxins are also at increased risk of developing this condition. 

Idiopathic pulmonary fibrosis usually affects people age 60 and older.

Diagnostic Tests

The symptoms of idiopathic pulmonary fibrosis can mimic several other lung conditions. To diagnose this condition, an NYU Langone doctor takes a medical history and performs a physical exam, during which he or she listens to your lungs with a stethoscope. If there is a crackling sound, the doctor may order one or more tests to rule out other lung conditions.

Chest X-ray

A chest X-ray produces a picture of the structures in your chest, such as your heart and lungs. It can also detect shadows in your lungs that might indicate scar tissue.

Because evidence of idiopathic pulmonary fibrosis may not be evident on chest X-rays, further testing is often required. 

CT Scan

If the X-ray does not provide enough information, your doctor may order a CT scan, in which cross-sectional, three-dimensional images of the body are produced using a series of X-ray images and a computer. A CT scan can reveal the extent of scarring in the lungs. 

Pulmonary Function Testing 

Pulmonary function testing assesses lung function by measuring how much air your lungs can hold, how quickly you are able to inhale and exhale, and how much oxygen your lungs are able to deliver to the blood. 

Spirometry is the most frequently used pulmonary function test. It measures how quickly you can move air out of your lungs. During the test, you take a deep breath, then exhale into a mouthpiece attached to a recording device called a spirometer.

The spirometer collects information about your lung volume and capacity. This information is printed in a chart or graph called a spirogram. The test helps your doctor understand if and to what extent your breathing is compromised.

Lung Biopsy

If the results of imaging and lung function tests are inconclusive, your doctor may recommend a lung biopsy, or tissue sample. A biopsy can confirm idiopathic pulmonary fibrosis and rule out other conditions. 

To obtain the sample of lung tissue, NYU Langone doctors perform a bronchoscopy, or a surgical lung biopsy. A bronchoscopy is an outpatient procedure that takes about 30 minutes. You are given sedation to help you relax. 

During the procedure, the doctor passes a bronchoscope—a thin, flexible tube with a camera at the end—through the nose or mouth and into the lungs. The camera transmits images of your windpipe—the tube through which air passes—onto a screen. The doctor collects tissue samples from several areas of the lungs. These samples are then examined under a microscope. 

Video-Assisted Thoracic Surgery

If a substantial amount of tissue is needed to confirm a diagnosis of idiopathic pulmonary fibrosis, the doctor may perform video-assisted thoracic surgery, a minimally invasive procedure that involves removing lung tissue.

During this procedure, your surgeon makes four incisions in the chest on one side of the lung. He or she then inserts a thoracoscope—a thin, hollow tube with a camera at the end—into one of the incisions. The camera projects an image onto a video screen that guides your surgeon. The doctor inserts surgical instruments through the other incisions and removes a sample of lung tissue. 

Video-assisted thoracic surgery requires general anesthesia. You remain in the hospital for one to three days afterward so your doctor can monitor you for possible complications. 

Either type of lung biopsy can be used to help to rule out sarcoidosis, an inflammatory condition that affects multiple organs, including the lungs, as well as lung cancer and infection. A biopsy can also reveal how far idiopathic pulmonary fibrosis has progressed, which can help doctors create a treatment plan.

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