How Is Idiopathic Pulmonary Fibrosis
Diagnosed?
Idiopathic pulmonary fibrosis (IPF) produces the
same kind of scarring and symptoms as some other lung diseases. This makes it
hard to diagnose. Seeking medical help, preferably from a pulmonologist (a
doctor who specializes in lung problems), as soon as you have symptoms is
important.
To diagnose IPF, your doctor will ask about your
medical history, perform a physical exam, and do several tests to rule out
other causes of your symptoms and learn how badly your lungs are damaged.
Medical History
A complete medical history is important. Your doctor
will ask about:
- Your age
- Your history of smoking
- Things in the air at your job or elsewhere that
could irritate your lungs
- Your hobbies
- Your history of legal and illegal drug use
- Other medical conditions that you have that can
trigger an immune system response
- Your family's medical history
- How long you've had symptoms
Diagnostic Tests
There is no single test for diagnosing IPF. Your
doctor will probably conduct several different tests, including the
following.
Chest X Ray
A chest x ray takes a picture of your heart and
lungs. It can show shadows that suggest scar tissue. Many people with IPF have
normal chest x rays at the time theyre diagnosed.
High-Resolution Computerized Tomography
High-resolution computerized tomography (HRCT) scan
is an x ray that provides sharper and more detailed images than a regular chest
x ray. It can show scar tissue and how much lung damage you have. This test can
help your doctor spot IPF at an early stage or rule it out. It also can help
your doctor decide how likely you are to respond to treatment.
Lung Function Tests
Your doctor will do a breathing test called
spirometry to find out how much lung damage you have. A spirometer is a device
that measures how much air you can blow out of your lungs after taking a deep
breath. It also measures how fast you can breathe the air out. If there is a
lot of scarring in your lungs, you will not be able to move a normal amount of
air out of them.
Pulse Oximetry
Your doctor attaches a small device to your finger
or earlobe to see how much oxygen is in your bloodstream.
Arterial Blood Gas Test
The doctor takes a small amount of blood from an
artery in your arm, usually in your wrist. Its then checked for oxygen
and carbon dioxide levels. This test is a more accurate way to check the level
of oxygen in your bloodstream. Your blood can also be tested to see whether you
have an infection that may be causing your symptoms.
Skin Test for Tuberculosis
Your doctor injects a small amount of a substance
that reacts to tuberculosis (TB) under the top layer of skin on one of your
arms. If you have a positive reaction, a small hard lump will develop at the
injection site 48 to 72 hours after the test. This test is done to rule out
TB.
Exercise Testing
Exercise testing is used to find out how well your
lungs move oxygen and carbon dioxide in and out of your bloodstream when
youre active. During this test, you walk or pedal on an exercise machine
for a few minutes. Electrodes attached to your chest and an
EKG
(electrocardiogram) machine show your heart rate, a blood pressure cuff
monitors your blood pressure, and a pulse oximeter attached to a finger or ear
lobe shows how much oxygen is in your blood.
Sometimes doctors place a catheter in an artery in
one of your arms to draw samples of your blood that will provide a more
accurate measure of the oxygen and carbon dioxide in it. They may also ask you
to breathe into a tube that separates the air you breathe out from room air and
provides a precise measure of the amount of oxygen youve taken in and
carbon dioxide you're breathing out.
Lung Biopsy
Looking at samples of tissue from several places in
your lungs under a microscope is the best way for your doctor to diagnose IPF.
A lung biopsy can help your doctor rule out other causes of your condition,
such as
sarcoidosis,
cancer, or infection. It can also show your doctor how far your condition has
advanced. Doctors use several different procedures to obtain samples of your
lung tissue:
- Bronchoscopy. Your doctor inserts a flexible,
rubber tube with a tiny light and camera on the end through your nose or mouth
into your lungs to look at your airways. He or she then inserts a forceps
through the tube to collect tissue to examine. This procedure is usually done
under local anesthesia on an outpatient basis.
- Bronchoalveolar lavage. During bronchoscopy, your
doctor may inject a small amount of salt water (saline) through the
bronchoscope into your lungs. This fluid washes the lungs and helps bring up
cells from the area around the air sacs for examination under a
microscope.
- Video-assisted thoracoscopy. This is the
procedure that doctors use most to obtain lung tissue. Your doctor inserts a
small, lighted tube with a camera (endoscope) into your chest through small
incisions between your ribs. The endoscope provides a video image of the lungs
and allows your doctor to collect samples of tissue. This procedure must be
done in the hospital, under general anesthesia.
- Thoracotomy. Your doctor removes a few small
pieces of lung tissue through an incision in the chest wall between your ribs.
Thoracotomy is done in the hospital under general anesthesia.
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