Adrian Harrison - Respiratory Physician
Lung Function Tests
- In General Practice and at home, peak flow meters measure the highest exhaled airflow rate. This measurement is usually lower than expected in people with asthma symptoms.
- Spirometry is an inexpensive test that measures the volume of air expelled from the lungs in the first second, and the total amount exhaled by the person doing the test. It also gives a measure of flow through small airways (or bronchioles). Restriction and obstruction are different patterns that spirometry can detect, as well as showing the severity of the abnormalities.
I perform this type of test routinely in my office on people who are breathless or where asthma or COPD are suspected.
- 'Detailed lung function tests' are performed by a lung function laboratory. These tests include the spirometric values, but the total volume of the lungs and various fractions of lung volumes are also measured. The ability of oxygen to diffuse into the blood through the alveolar walls is measured by the 'diffusing capacity', which is low in people with emphysema, interstitial lung disease and pulmonary hypertension.
Exercise tests are also performed by a lung function laboratory.
Tests for asthma: there are about four different types of tests that can be done to decide if someone has asthma. Even so, very mild asthma can still be difficult to diagnose.