Chronic Obstructive Pulmonary Disease (COPD) (cont.)
How is COPD diagnosed?
COPD usually is first diagnosed on the basis of a medical history which
discloses many of the symptoms of COPD and a physical examination which
discloses signs of COPD. Other tests to diagnose COPD include chest x-ray,
computerized tomography (CT or CAT scan) of the chest, tests of lung function
(pulmonary function tests) and the measurement of oxygen and carbon dioxide
levels in the blood.
COPD is suspected in chronic smokers who develop
shortness of breath with or without exertion, have chronic persistent cough with
sputum production, and frequent infections of the lungs such as bronchitis or
pneumonia. Sometimes COPD
is first diagnosed after a patient develops a respiratory illness necessitating
hospitalization. Some physical findings of COPD include enlarged chest cavity
and wheezing. Faint and distant breath sounds are heard when listening to the
chest with a stethoscope. Air is trapped in the lungs from the patient's
inability to empty their lungs with exhalation. This extra air dampens the
sounds heard and results in the overinflated chest cavity.
In patients affected predominantly with emphysema, the
chest x-ray may show an enlarged chest cavity and decreased lung markings
reflecting destruction of lung tissue and enlargement of air-spaces. In patients
with predominantly chronic bronchitis, the chest x-ray may show increased lung
markings which represent the thickened, inflamed and scarred airways.
Computerized tomography (CT or CAT scan) of the chest is a specialized x-ray
that can accurately demonstrate the abnormal lung tissue and airways in COPD.
Chest x-rays and CT scans of the chest also are useful in excluding lung
infections (pneumonia) and cancers. CT scan of the chest usually is not
necessary for the routine diagnosis
and management of COPD.
The most commonly used pulmonary function test is spirometry, a test which
quantitates the amount of airway obstruction. During spirometry, the patient
takes a full breath and then exhales fast and forcefully into a tube connected
to a machine that measures the volume of expired air. The FEV1 (the volume of
air expired in 1 second) is a reliable and useful measure of airflow
obstruction. This is compared to the total amount of air blown out of the lungs,
the forced vital capacity (FVC). The ratio of the FEV1 to the FVC is usually
70%. When obstruction is present, this ratio is reduced; the lower the RATIO,
the greater the airway obstruction. The FEV1 can be determined again after
treatment with bronchodilators. Improvement in FEV1 after bronchodilator
treatment means that airway obstruction is reversible. Demonstrating improvement
in FEV1 also helps doctors select the proper bronchodilators for patients.
Measurements of FEV1 AND FVC can be repeated over time to determine how rapidly
airway obstruction is progressing.
Oxygen and carbon dioxide levels can be measured in samples of blood obtained
from an artery, but this
requires inserting a needle into an artery. A less invasive method to measure
oxygen levels in the blood is called pulse oximetry.
Pulse oximetry works on the principle that the degree of redness of hemoglobin (the
protein in blood that carries oxygen) is proportional to the amount of oxygen,
that is, the more oxygen there is in blood, the redder the blood. A probe
(oximeter) is placed around a fingertip. On one side of the finger the
probe shines a light. Some of the light is transmitted through the fingertip,
and the transmitted light is measured on the opposite side of the finger by the
probe. Depending on the redness of the blood within the fingertip (that is, the
amount of oxygen in the blood) more or less light is transmitted through the
fingertip. Thus, by measuring the amount of light transmitted, it is possible to
determine the amount of oxygen in the blood.
Next: What treatment is available for COPD? »
- tetracycline, Sumycin - Specifies the medication tetracycline (Sumycin), a drug used for many different infections including respiratory tract infections due to Hemophilus influenzae, Streptococcus pneumoniae, or Mycoplasma pneumoniae.
- Pneumococcal Vaccination - Learn about pneumococcal vaccination (pneumonia vaccine) recommendations and side effects, and find out who should and should not be vaccinated.
- Lung Cancer - Get the facts on lung cancer treatment, diagnosis, staging, causes (smoking), types (adenocarcinoma, squamous cell), prevention, symptoms, warning signs and survival rates.
Latest Medical News
Specialty RSS
