QS Study

Lung Function Tests can contain one test that you have to repeat 3-8 times, and so may only take up to half an hour which means they can take over an hour to complete. This actually depends on the reason you are having the tests. Spirometry is one of the most familiar lung function tests. It measures how much air you can inhale and exhale. It also measures how fast you can empty the air out of your lungs.

Common Lung Function Test in Clinical Practice

Lung function test

(1) Tests of all the volumes and capacities of the lung,

(2) Test to evaluate the mechanism of breathing by spirometer –

  • Measurement of vital capacity: Male 4.62 female 3.12
  • Test of timed vital capacity (forced expiratory volume in the first second) Normal value = 83%.
  • Measurement of maximal voluntary ventilation. (or maximal breathing capacity) Normal value 6-15 lt/sec.
  • Measurement of residual volume by helium dilution method.

(3) Testing involving diffusion capacity

  • Diffusion capacity of oxygen = 21 ml/ min / mmHg
  • Diffusion capacity of CO2 = 400-500 ml /min/ mmHg.

(4) Test to evaluate the alveolar ventilation:

  • Determination of dead space volume. Normal value: 150 ml
  • Uniform distribution of air measured by a nitro meter.

(5) Test to evaluate alveolar ventilation-perfusion ratio: normal value: 0.8.

(6) Test to evaluate the pulmonary capillary blood pressure. [Normal value: about 7 mmHg).

(7) Test to evaluate the functional integrity of individual lobe of the lung by broncho – spirometer.

(8) Bronchography.

(9) Bronchoscopy.

(10) CT scan.

Lung function test in different clinical conditions:

This is shown in the following table –