INVESTIGATIONS

Clinical examination

The first step in diagnosing COPD is a good evaluation.

I. Detailed medical history

This includes information on :

  • Past and present smoking
  • Exercise capacity of the person for example whether a person has trouble climbing stairs or talking or the distance he or she can walk
  • Occupational history : To rule out any industrial pollutants
  • Family history

II. Physical examination of the patient

The doctor examines the chest area and listens the breathing sounds with a stethoscope to observe any abnormality.

  • In chronic bronchitis the doctor hears wheezing or gurgling sounds (rhonchi).
  • In emphysema there is :
    • Decreased breath sounds.
    • Abnormal breath sounds called as rales.
    • Barrel shaped chest.

 

Laboratory investigations

Your doctor may recommend the following tests to evaluate your breathing.

I. Pulmonary Function test

This is an ideal test for determining the presence and severity of COPD. Lung volumes are measured with the help of an instrument called Spirometer. The volume measures required for detecting COPD are :

  • Forced Vital Capacity (FVC) : This is the maximum volume of air that can be exhaled ( breathe out) forcibly after inhaling (breathe in) as deeply as possible.
  • Forced Expiratory Volume (FEV1) : This is the maximum volume of air exhaled in one second.
  • Residual Volume (RV) : When measuring the vital capacity the whole air is not removed from the lungs. This remaining volume of air in the lungs is called as residual volume
  • Total Lung Capacity (TLC) : This is the combination of the forced vital capacity and residual volume.

To learn your FEV1 and FVC, hold the tube of a Spirometer in your mouth, inhale as much air as possible, then exhale forcefully into the Spirometer for six seconds or more.

Calculating a ratio of FEV1 to FVC is the best method to determine the presence and severity of COPD. Normally this ratio is greater than 70%.

FEV1 is another indicator for lung function. In COPD it shows an average decline of 2-3 times the normal rate of 20-30 milliliters per year. A greater than expected annual fall in FEV1 is the most sensitive test for COPD and a very good predictor of disability and early death.

In COPD the residual volume increases markedly. This occurs because of the collapse of the weakened airways before all the normally expired air can leave the lungs i.e. some air remains trapped. This increased RV makes breathing even more difficult.

Before making a diagnosis of COPD the results of several different tests must be compared.

II. Chest X-Ray

  • In chronic bronchitis an x-ray is rarely useful.
  • In emphysema early stage cannot be detected by x-ray. However in later stages the x-ray may show
    • A flattened diaphragm.
    • Loss of blood vessel marking.
    • Increased lung inflation in upper areas and abnormally large amount of air spaces which is indicative of emphysema.
    • In AAT deficiency emphysema their is large amount of air in lower lungs.

III. Blood test

In familial emphysema blood test shows deficiency of Alpha 1 Antitrypsin. Polycythaemia (increased red blood cells) is seen which occurs in order to compensate for hypoxemia.

IV. Measure of arterial blood gases

Main function of the lungs is to remove carbon dioxide from the blood and add oxygen. therefore the measure of arterial blood gases acts as another important indicator of lung function. As COPD progresses, the amount of oxygen in the blood decreases and that of carbon dioxide increases.

V. Sputum culture

It is done especially to rule out infection or if infection is present to find out the cause of infection.

VI. Computerised tomography of the chest

It has much greater sensitivity and specificity than plain chest radiography in diagnosing and assessing the severity of emphysema. CT scan identify areas of bullous (over inflated alveoli) disease that may be amenable to surgery.

VII. ECG

To rule out any heart problems.

VIII. Pulse Oximetry

A special device clipped onto the finger or earlobe, can indirectly measure the amount of oxygen in the blood. This test is usually used for monitoring purposes.