Spirometers

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.

Is a spirometry test safe?

A spirometry test is considered safe, though during the test and maybe for a short time after a person may feel dizzy or faint, this is the effect of the forced breaths into the spirometer. For this reason, there are some people who may need to check with a medical professional if a spirometry test is safe for them. 

People who have or recently experienced angina, have heart disease or problems with blood pressure would need to follow professional medical advice. A person who has recently been operated on should also seek advice, especially if the procedure was to the head, eyes, stomach, or their chest. This is because during a spirometry test, pressure is increased in these areas of the body.

Why should organisations perform spirometry tests?

Spirometry screening may be carried out to comply with The Control of Substances Hazardous to Health (COSHH) Regulations in the UK and to look out for the wellbeing of their employees. They are needed to detect any early damage to an employee’s lung function and are usually carried out by a trained occupational health specialist.

There are many hazards within the workplace that require lung screening. An employee could be subjected to fume, dusts, paint spraying, metal plating processes, using dyes and many other chemicals that after frequent use, could affect their respiratory system. It is therefore vital that staff have the correct PPE and monitored closely if regularly exposed to these. Learn more about occupational respiratory diseases. Learn more about occupational respiratory diseases.

What are the types of spirometry tests?

Spirometry can involve several different instruments to help diagnose a condition. All spirometers, however, will conduct the same tests to measure the amount of air a patient inhales and exhales.

The three important parameters to understand are Forced Vital Capacity (FVC), Forced Expiratory Volume in one second (FEV1), and FEV1/FVC ratio.
FVC measures the total volume of air (in litres) that you can expel forcefully from your lungs whereas FEV1 measures the maximum volume of air that can be inhaled in 1 second, and the FEV1/FVC is the ratio of the FEV1 to the FVC.

Additional testing may be performed by a doctor such as bronchodilator responsiveness testing (also known as reversibility testing). This test involves the patient taking a spirometry test, medication, and subsequent testing to see if their lung function improves.