What is a Spirometer? Your Guide to Spirometry

What is a Spirometer? Your Guide to Spirometry

Medshop Editor

Medshop Editor

Published in MedShop Blog

0 min read

December 18, 2020

Lung function is an important measure of a patient’s health. If the lungs are working well, a person should be able to breathe deeply, inhale plenty of oxygen and carry out daily tasks without a problem. If the lungs are damaged or suffering from disease, something as simple as breathing can be a challenge.

Accurately measuring and monitoring lung function and airflow allows doctors to diagnose a range of illnesses and conditions and assess patients suffering from lung disease. One of the best ways of checking lung capacity and lung function is a spirometry test. Used by doctors in clinics, hospitals and surgeries around the world, this simple but effective test can be an important indicator of how efficiently the lungs are working.

If you’re currently experiencing shortness of breath or difficulty breathing, your doctor may well use a spirometer to assess your condition. Learning all about what a spirometer is and what it is used for will help you prepare for the test and fully understand your spirometry results.

What is a Spirometer?

SpiroConnect Spirometers SpiroConnect Wireless PC Based Spirometer 


A spirometer is a small machine that is attached to a mouthpiece. Some spirometers have digital displays and are able to print the results of pulmonary function tests. Other spirometers are able to connect wirelessly to computers in order to provide doctors and nurses with a more user-friendly experience. 

Spirometers are used extensively in doctor’s surgeries, clinics and hospitals. A spirometry test is a quick outpatient procedure that’s commonly used to determine lung function and capacity. Spirometers allow the results of these tests to be known almost immediately, giving doctors a very useful tool for monitoring and diagnosing their patients with issues such as bronchitis and emphysema among many others. 

What Does a Spirometer Look Like?

Welch Allyn Spirometry Accessories Welch Allyn Spirometry Accessories 

As different manufacturers use different designs, spirometers can vary significantly in their appearance. However, most devices are relatively small and all come with inhalers to allow the patient to take a deep breath into the machine.

Some spirometers have built-in digital screens and others are designed to be paired with computers or monitors. A lot of high-quality contemporary spirometers have Bluetooth connectivity. This allows them to connect to mobile phones, printers and computers and helps to boost usability.

What Does a Spirometer Measure?

A spirometer is designed to measure two main things:

  •      The amount of air you can breathe out in one second
  •      The total volume of air you can exhale in one forced breath

Doctors compare the measurements taken from a patient with other healthy people of a similar age, height and sex. If their results differ significantly from standard readings it could be an indication that something is wrong.

Comparing the results of a patient’s spirometry test with other readings allows doctors to see if a lung problem is ‘obstructive’, ‘restrictive’ or both.

  •      Obstructive diseases affect a patient’s ability to breathe by narrowing their airways. However, the capacity of the lungs themselves is generally unaffected.
  •      Restrictive lung disease limits the amount of air a patient is able to hold in their lungs. This is generally because the lungs are unable to fully expand.

What is a Spirometer Used to Diagnose?

Spirometers are used to diagnose and assess a number of conditions and diseases. Some of the most common are:

  •      Asthma – an obstructive lung disease in which the airways become periodically swollen and narrowed. Asthma is normally a long-term condition.
  •      Chronic Obstructive Pulmonary Disease(COPD) – a group of lung conditions that narrow the airway and make it difficult to breathe.
  •      Cystic fibrosis– a degenerative condition in which the lungs and digestive system become clogged with thick, sticky mucus. Cystic  fibrosisis genetic.
  •      Pulmonary fibrosis– scarring of the lungs caused by pollutants, medications and interstitial lung disease.

Doctors use spirometers to diagnose these conditions and to monitor their progression. This is often very important as a lot of lung diseases are degenerative and so become worse over time. 

How Does A Spirometer Work and What is a Spirometry Test?


As we’ve already seen, spirometers work by measuring both the amount of air you can breathe out in one second and the total volume a patient can exhale in one forced breath.

Spirometers are used to carry out pulmonary function testing. During a test, you’ll be asked to sit down and a soft clip will be placed on your nose to ensure air doesn’t escape during the test. The nurse or doctor carrying out the spirometry test will tell you exactly what you need to do and may ask you to practice exhaling before they begin.

When breathing into the spirometer, make sure you inhale deeply so your lungs are at their full capacity. You’ll then need to close your lips tightly around the mouthpiece before exhaling as quickly and as forcefully as you can. Make sure you expel all of the air from your lungs before you remove your mouth from the spirometer.

You’ll normally need to repeat the test around three times in order to get accurate readings from your exhalations. In some cases, you’ll be given bronchodilator medication after the initial test and then asked to repeat the process after around 15 minutes. This allows doctors to assess whether or not your lungs respond to the medicine.

What is a Normal Spirometer Reading?


Your spirometry test will produce two main results. These are measured in terms of FVC ratio (forced vital capacity) and FEV1 (forced expiratory volume in one second). Doctors will also look at the FEV1/FVC ratio.

FVC measures the total amount of air that you’re able to expel in one full breath. This is measured in litres.

  •      Healthy males aged 20-60 should be able to exhale 4.75 to 5.5 litres
  •      Healthy females aged 20-60 should be able to exhale 3.25 to 3.75 litres.

FEV1 measures the amount of air you can forcefully expel in one second.

  •      Healthy males aged 20-60 should have an FEV1value of 4.5 to 3.5 litres
  •      Healthy females aged 20-60 should have an FEV1value of 3.25 to 2.5


The FVC/FEV1 ratio is calculated by dividing the measured FEV1 value by the measured FVC value. The ratio is expressed in terms of percentages. Healthy adults of the same age, height and gender should have a FVC/FEV1 predicted value of between 70% and 85%. A percentage of less than 70% is considered abnormal and could be a sign of obstructive lung disease.

Types of Spirometers

There are three main types of spirometers: standard spirometers, incentive spirometers and wet spirometers.

Standard spirometers are used to check lung function and assess a patient’s condition. They’re commonly found in doctor’s surgeries and clinics and are used for diagnostic and monitoring purposes.

What is an Incentive Spirometer and What is it Used For?


Incentive spirometers are generally used to help a patient recover following surgery or illness. When a patient uses an incentive spirometer, they’ll be asked to close their lips tightly around the mouthpiece before breathing in for as long as possible. As they inhale, they’ll see the piston in the device begin to rise. They should aim to get this piston as high as possible during these rehabilitative lung function tests.

When the patient can no longer breathe in, they should remove the mouthpiece, hold their breath for 3-10 seconds and then exhale normally. Repeating these exercises on a regular basis can help to improve lung function, breathing problems, and prevent a range of complications such as pneumonia.

Incentive spirometers are handheld devices that can be used by the patient at home or in a hospital ward.

How Do You Use a Spirometer for Breathing Exercises?

In order to improve your lung function, you’ll need to repeat the process of inhaling, holding your breath and exhaling a number of times. Coughing in between breaths will help to dislodge any mucus that’s built up in your airway and further aid recovery.

If you feel dizzy or lightheaded when carrying out breathing exercises on an incentive spirometer, take a break for a few minutes before trying again.

What is a Good Incentive Spirometer Reading?

As incentive spirometers are generally used by patients recovering from illness or surgery, readings can vary widely. If your doctor has asked you to use an incentive spirometer to help your lung function, they should begin by talking to you about the test results to aim for and how they’d like your readings to improve over time.

What is a Wet Spirometer?

A wet spirometer works on broadly the same principle as a standard spirometer. However, this type of device measures lung volume by looking at the displacement of a closed chamber that’s partially submerged in water. Air blown into the inverted chamber causes it to rise and move an indicator along a scale.

As wet spirometers are less compact and less portable than standard dry spirometers, they’re less commonly used in professional healthcare settings.

How Much Does a Spirometer Cost?

 The cost of a spirometer can vary significantly depending on the brand and the functionality of the device. In general, good quality spirometers cost between $1,800-$2,800.

If you’d like to find out more about spirometry or explore our excellent range of professional spirometers, take a look around the Medshop Australia store or get in touch with a member of our team today.


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