Spirometry: how to use it

Spirometry is one of the most popular lung function tests, thanks to its being non-invasive and easy to perform, and to its capability to provide accurate and useful insights on a patient’s respiratory health.

But how does spirometry work exactly? Here is our beginners’ guide to spirometry.

What is spirometry

Spirometry is a pulmonary function test that measures how much air a patient is able to exhale and how fast. It is particularly useful in the diagnosis and management of lung conditions like asthma, COPD (chronic obstructive pulmonary disease), or pulmonary fibrosis.

The key parameters of spirometry are:

• Forced Expiratory Volume in 1 second, or FEV1, i.e. the amount of air a patient can exhale in 1 second
• Forced Vital Capacity, or FVC, i.e. the total amount of air a patient can exhale by blowing out as fast as possible
• FEV1/FVC ratio

The three parameters mentioned above are already enough to identify obstructive and/or restrictive respiratory patterns, but many devices can also provide flow rate graphs, as well as measure other parameters, such as:

• Vital Capacity, or VC, i.e. the volume of air that can be exhaled by blowing out at a steady rate
• Inspiratory Vital Capacity, or IVC, i.e. the amount of air that can be inhaled after a full expiration
• Peak Expiratory Flow, or PEF, i.e. the maximal flow that a patient can exhale by blowing out as fast as possible

What is a spirometer?

A spirometry test is performed by taking a deep breath and then exhaling as fast as possible into a device called a spirometer.

There are different types of spirometers based on the use they were designed for. Professional spirometers may provide more insightful readings and be equipped with printers and large displays, while personal use spirometers are usually smart and portable and can send test reports to physicians and healthcare professionals.

The devices are generally made up of a technological body connected to a mouthpiece shaped like a tube and can provide real-time results.

What to do before using a spirometer

Using a spirometer is a simple task that requires just a few steps to be done properly.

Calibration

Spirometry results are usually expressed as a percentage relative to the so-called predicted values, i.e., a reference range based on the average results obtained by healthy patients sharing the same anthropometric data as the patient taking the test. For this reason, spirometers are calibrated according to factors like age, height, gender, and ethnicity.

In professional settings, calibration is usually done for each single patient, while personal-use spirometers often feature long-term calibration for simpler use.

Sanification

In order to prevent infections from spreading, spirometers are usually sterilized after each use, and consumable pieces are replaced. It is also advisable to wash hands or wear rubber gloves for more safety.

App connection

Most personal use spirometers feature a smart connection to a dedicated App so that results can be stored and shared with healthcare professionals and physicians, allowing for accurate anamnesis and follow-ups.

How to prepare for a spirometry test

No dietary changes are required before a spirometry test.

In case a patient is following medical treatment for a diagnosed respiratory condition, it is advisable not to take medications for at least 4 hours before the test, otherwise, they may lead to inaccurate results. It is possible to perform the test before and after taking the drug to evaluate the effectiveness of the medication itself.

Smoking should also be avoided, as it may lead to airway irritation and cough.

How to use a spirometer for a pulmonary function test

Once you ensure the device is calibrated and sanitized, you can proceed with the test.

• Sit upright, back straight and feet flat on the floor, and loosen belts or tight clothing. This prevents dizziness and allows your lungs to fully expand within your thoracic cavity
• Take a few regular breaths at first, so that you attune to your own breathing, then start taking deeper breaths
• Position your mouth tightly on the mouthpiece, so that no air is able to escape. Take a deep breath and then blow out as fast as possible in the mouthpiece

The test is usually repeated after 10-15 minutes to confirm the results.

Where to get the best spirometer for accurate testing

MIR is a global leader in the field of spirometry and oximetry solutions. With over 30 years of experience, MIR products are available in more than 100 countries and are used in professional diagnostic, primary care, personal care, and clinical trials.

Find out more on the official website.