Lung (or pulmonary) function tests are performed for a variety of reasons: diagnosing airway obstruction, measuring reactions to treatments for asthma or chronic obstructive pulmonary disease, and determining the severity of your asthma.
Your doctor may ask you to perform tests to help develop an asthma management plan. You may perform peak flow tests yourself at home (using your peak flow meter) as part of monitoring the success of your treatment and the status of your asthma. Your doctor will instruct you in how to do the test and record the results. You may also be tested with a spirometer in your doctor’s surgery or local laboratory.
Lung function tests are part of the routine diagnostic work-up and management of patients with respiratory conditions such as asthma and chronic obstructive pulmonary disease (emphysema and chronic bronchitis), and include spirometry tests and peak flow meter measurements.
Spirometry is a test of lung function that measures the amount of inhaled and exhaled air using a device called a spirometer. It gives a measure of the maximum amount of air you can breathe out (after taking a deep breath in) and how much you can breathe out in one second. A spirometer issues a graph of respiratory movements and function known as a spirogram.
Peak flow meters measure the greatest speed that can be reached when you breathe out through the meter as hard and fast as possible from the biggest breath in you can manage.
Your doctor may use a peak flow meter to monitor your asthma and management progress regularly, but spirometry is the test of choice for doctors to determine the severity of asthma at any given point in time.
You can use your own peak flow meter to conduct peak flow measurements at home as part of your asthma management plan. Peak flow readings should always be done using the same peak flow meter as there is variation among different meters.
Your doctor or respiratory physician wants to determine how well your lungs are functioning and there are a few measurements they can take using a spirometer, including the following.
Last Reviewed: 23 August 2009