Diagnosis Of Chronic Obstructive Pulmonary Disease
A diagnosis of chronic obstructive pulmonary disease (COPD) starts with a history of your symptoms. For example, a nagging cough in a smoker, gradual worsening of fatigue, or breathlessness with activity can steer a health-care provider toward the diagnosis.
A physical exam is performed to look for the causes of these symptoms and direct further testing. A combination of tests is used to rule out other problems, such as heart disease or infection.
Once a diagnosis of COPD is confirmed, a chest X-ray, chest computed tomography (CT, or CAT) scanning and lung function tests can help define the degree of lung damage.
Your health-care provider will ask about your cough and shortness of breath and will ask how long you have had any symptoms and any signs of infection, such as fever and sweats. He or she will ask if you have any chest pain, leg swelling or other heart-related symptoms and about your personal and family medical history.
Your health-care provider will particularly want to know whether you smoke, how much and for how long. In general, people who have smoked more than 20 cigarettes a day (one pack) for more than 20 years usually develop smoker's cough by their late 40s or early 50s. Such people may not complain of shortness of breath until they are in their 50s or 60s.
During the physical examination, your health-care provider will use a stethoscope to listen for signs of lung and heart problems, such as wheezing and other abnormal breath sounds and heart sounds.
Images of the lungs and blood vessels obtained with chest X-rays or computed tomography (CT, or CAT) scans can help rule out other causes of your symptoms, such as pneumonia, lung cancer, blood clots in the lung and tuberculosis. Although a diagnosis of COPD cannot be based on lung imaging, your health-care provider may suspect COPD based on the appearance of these images. The bronchial tubes may appear thickened, and the lungs may look larger than normal. You can see large air sacs or "bullae," which are large empty spaces formed by fused air sacs. Lung imaging also gives a rough estimate of the neighboring heart's size and shape.
Spirometry (also called pulmonary function testing) is an important test of lung function that is used to diagnose COPD, assess its severity and follow its progress. A spirometry machine includes a large tube through which you breathe. Spirometry is also used to test for asthma and other lung diseases.
Spirometry measures how forcefully you can breathe air in and out. When you have COPD, it takes longer to exhale, so you can't empty the lungs with the rapid air-flow of a person your age who does not have COPD.
Once COPD is diagnosed, spirometry is repeated periodically to see if lung function improves as a result of treatment or smoking cessation. Spirometry can also keep track of how fast your airway health is declining.
In addition to spirometry to test air flow patterns, some pulmonary function tests check the volume of air that you move in a typical breath. Some tests also measure the ease with which gases are moved between the air and the bloodstream.
Your health-care provider may request an electrocardiogram (ECG, or EKG) if he or she has noticed abnormalities during your physical exam or if you have a family history of heart problems. All older adults with breathing problems should have an ECG.
An ECG measures the electrical activity in your heart. Electrodes placed on your chest with adhesives are connected to a machine that records your heart's electrical signals. Changes in the normal pattern of recorded activity can show if you have ever had a heart attack or show signs of abnormal heart rhythms.
Your health-care provider may request an echocardiogram if your physical exam suggests that you have heart failure or other heart problems. Heart failure may be the cause of your breathing difficulties, or COPD may be the cause of your heart failure.
An echocardiogram measures the size and shape of your heart's chambers and certain aspects of heart function, such as the amount of blood pumped out of the ventricles with each heartbeat. Heart failure may affect the size and shape of your heart's chambers, as well as their pumping ability.
Blood tests called arterial blood gas (ABG) measurements reflect the amount of oxygen and carbon dioxide in your arteries. Most routine blood tests collect a sample of blood from your veins. Because the veins have "used" blood returning to the lung for more oxygen, arterial blood gas measurements assess the oxygen levels in the arteries, where blood is oxygen-rich. COPD can lead to a drop in oxygen levels and a rise in carbon dioxide levels.
If your doctor feels that smoking is not an adequate explanation for the amount of lung disease that you have, you might have a blood test to check for alpha antitrypsin deficiency.
Another blood test measures beta natriuretic peptide. In some cases, it provide additional information about heart function.
Pulse oximetry is another method of determining the amount of oxygen in blood, but it does not require a blood sample. An electronic probe is attached to a finger to measure oxygen saturation, which estimates blood oxygen levels through the skin.
This method is less accurate than blood tests, but it gives a good indication of whether the oxygen content in your blood is improving or getting worse.
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