Investigations in Asthma
A number of tests are available to demonstrate lung function as outlined below:
Chest x- ray
Chest x-ray is usually normal in uncomplicated asthmatics, but useful in excluding other causes of breathlessness. Also, an x-ray is obtained if the patient needs to be hospitalised as a result of severe asthma.
Reversibility Test
This test is done to see whether the obstruction can be relieved by the use of a short-acting bronchodilator such as” ventolin”. An improvement of 15% or more (as measured on the peak flow meter) is diagnostic of asthma.
Exercise Testing
Exercise is a trigger for many people with asthma. In the exercise test, the peak flow is measured beforehand, and then after the exercise, at intervals of 5, 10 and 15 minutes. The exercise itself should last 6 minutes. Asthma can be diagnosed if there is a fall in peak flow of 15% or more, after exercise.
Physical Examination
The affected person complains of wheeze, tightness of the chest, and breathlessness. The attack may begin suddenly, and the wheezing is particularly noticeable when the person breathes out (i.e. on expiration). The patient, on observation, will have obvious effort on breathing, sitting upright, leaning forward, using chest and neck muscles to aid breathing, and they may be sweating and anxious. In severe cases, the face may be obviously blue around the lips (central cyanosis), and they may be very distressed. On listening to the chest with a stethoscope, wheezing will be noticeable, especially on breathing out. Between attacks, the chest is likely to be clear.
