What is a spirometer used for?
Spirometers are used by a qualified medical professional to assist in the diagnosis of illnesses that may affect a patient’s lung function. This may be a nurse or doctor within a private clinic, a hospital, or a trained occupational health specialist within a company.
A spirometer may also be used periodically to assess the condition of a person’s lungs i.e., in the workplace where respiratory sensitisers are present and can influence lung function.
A spirometry test involves a small medical instrument called a spirometer, along with a mouthpiece. A patient will take a deep breath and breathe with force into the mouthpiece which is attached to the spirometer. The results of the spirometry test are then analysed and interpreted accordingly.
What does a spirometer measure?
Relaxed (or slow) Vital Capacity (VC) - The volume of air that can be slowly expelled from the lungs from a point of maximal inspiration to maximum expiration.
Forced Vital Capacity (FVC) - The volume of air that can be forcibly expelled from the lungs from a point of maximal inspiration to maximum expiration.
Forced Expiratory Volume in 1 second (FEV1) - The volume of air that can be forcibly expelled from the lungs from a point of maximum inspiration in the first second of an FVC manoeuvre.
FEV1/FVC ratio or FEV1% - The FEV1/FVC ratio is the FEV1 expressed as a percentage of the FVC (or VC if this is greater).
When should a spirometry test be performed?
A spirometry test is particularly advised if a patient experiences a symptom that relates directly to the healthy functioning of their lungs. For instance, this could be a persistent ongoing cough, a chest infection, unexplained difficulty in breathing, an irritation or they are over 35 and smoke.
Another reason for performing a spirometry test would be if someone is under consideration for surgery or a doctor may need it as part of several tests, even if it’s not directly related to the lungs, it may help to diagnose another condition.
People who work in industries where they are exposed to fumes, chemicals and dust are also recommended for testing.
What is Forced vital capacity (FVC)?
Forced vital capacity (FVC) is the amount of air that can be forcibly exhaled from the lungs after taking a full inhalation breath. An FVC test can help distinguish between obstructive lung diseases, such as asthma and COPD, and restrictive lung diseases, such as pulmonary fibrosis and sarcoidosis.
FVC can also help doctors assess the progression of lung disease and evaluate the effectiveness of treatment. An abnormal FVC value may be chronic, but sometimes the problem is reversible and the FVC can be corrected. Learn more about which lung diseases spirometry can help diagnose.