Tests and diagnosisBy Mayo Clinic staff
Because pulmonary edema requires prompt treatment, you'll initially be diagnosed on the basis of your symptoms and a physical exam and chest X-ray. You may also have blood drawn — usually from an artery in your wrist — so that it can be checked for the amount of oxygen and carbon dioxide it contains (arterial blood gas concentrations). Your blood will also be checked for levels of a substance called B-type natriuretic peptide (BNP). Increased levels of BNP may indicate that your pulmonary edema is caused by heart problems. Other blood tests will usually be done, including tests of your kidney function, blood count, as well as tests to exclude a heart attack as the cause of your pulmonary edema.
Once your condition is more stable, your doctor will ask about your medical history, especially whether you have ever had cardiovascular or lung disease.
Tests that may be done to diagnose pulmonary edema or to determine why you developed fluid in your lungs include:
- X-ray. A chest X-ray will likely be the first test you have done to confirm the diagnosis of pulmonary edema.
- Electrocardiography (ECG). This noninvasive test can reveal a wide range of information about your heart. During an ECG, patches attached to your skin receive electrical impulses from your heart. These are recorded in the form of waves on graph paper or a monitor. The wave patterns show your heart rate and rhythm, and whether areas of your heart show diminished blood flow.
Echocardiography (diagnostic cardiac ultrasound exam). Another noninvasive test, echocardiography uses a wand-shaped device called a transducer to generate high-frequency sound waves that are reflected from the tissues of your heart. The sound waves are then sent to a machine that uses them to compose images of your heart on a monitor.
The test can help diagnose a number of heart problems, including valve problems, abnormal motions of the ventricular walls, fluid around the heart (pericardial effusion) and congenital heart defects. It also accurately measures the amount of blood your left ventricle ejects with each heartbeat (ejection fraction, or EF). It can also estimate if there's increased pressure in the right side of the heart. Although a low EF often indicates a cardiac cause for pulmonary edema, it's possible to have cardiac pulmonary edema with a normal EF.
- Transesophageal echocardiography (TEE). In a traditional cardiac ultrasound exam, the transducer remains outside your body on the chest wall. But in TEE, a soft, flexible tube with a special transducer tip is inserted through your mouth and into your esophagus — the passage leading to your stomach. The esophagus lies immediately behind your heart, which allows for a closer and more accurate picture of your heart and central pulmonary arteries. You'll be given a sedative to make you more comfortable and prevent gagging. You may have a sore throat for a few days after the procedure, and there's a slight risk of perforation or bleeding from the esophagus.
- Pulmonary artery catheterization. If other tests don't reveal the reason for your pulmonary edema, your doctor may suggest a procedure to measure the pressure in your lung capillaries (wedge pressure). During this test, a small, balloon-tipped catheter is inserted through a vein in your leg or arm into a pulmonary artery. The catheter has two openings connected to pressure transducers. The balloon is inflated and then deflated, giving pressure readings.
- Cardiac catheterization. If tests such as an ECG or echocardiography don't uncover the cause of your pulmonary edema, or you also have chest pain, your doctor may suggest heart catheterization with coronary angiogram. During cardiac catheterization, a long, thin tube called a catheter is inserted in an artery or vein in your groin, neck or arm and threaded through your blood vessels to your heart. If dye is injected during the test, it's referred to as a coronary angiogram. During this procedure, treatments such as opening a blocked artery can be performed, which may quickly improve the pumping action of your left ventricle. Cardiac catheterization can also be used to measure the pressure in your heart chambers, assess your heart valves, and look for causes of pulmonary edema.
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