Spirometry

Spirometry is a common pulmonary function test used to assess lung function by measuring the volume and speed of air a person can inhale and exhale. It is widely used to diagnose and monitor respiratory conditions such as asthma, chronic obstructive pulmonary disease (COPD), and other lung disorders.

The test involves breathing forcefully into a device called a spirometer, which provides key metrics like Forced Vital Capacity (FVC) and Forced Expiratory Volume in one second (FEV1). Spirometry is a simple, non-invasive, and effective tool for evaluating lung health.

Pulmonary Function Tests

Tests known as pulmonary function tests (PFTs) measure how well your lungs are functioning. Lung capacity, volume, flow rates, and gas exchange are all measured by the tests. Your healthcare professional can use this information to diagnose and treat certain lung conditions.

Types of Pulmonary Function Test:

There are two tests for performing PFTs. These two tests can be combined to perform other testing. The information your healthcare provider is seeking will determine this:

• Spirometry
• Plethysmography

Spirometry

A mouthpiece connected to a tiny electronic machine is called a spirometer.

One kind of pulmonary function test is spirometry. By monitoring the amount of air that enters and exits your lungs during breathing, it assesses how well your lungs are functioning. Although frequent deep breathing may cause lightheadedness or dizziness, spirometry is safe.

Plethysmography

The tests are conducted while standing or sitting inside an airtight box.

Spirometry: What is it?

One popular kind of pulmonary function test is spirometry, which is pronounced spy-rom-uh-tree. A lung function test is another term for a pulmonary function test. A spirometry test calculates how much air is in your lungs by measuring the airflow through them. Additionally, it provides information to your doctor about how well you breathe and how powerful your lungs are. Spirometry is secure. It is frequently ordered by medical professionals to assess lung function.

Different types of Spirometer

Basic Incentive Spirometer:

• Incentive spirometers are portable devices that help in the healing of the lungs following surgery, illness, or infection. This is a very simple device that uses a piston system to function.

• The amount of air the lungs take in is actively measured by pistons on the interior of the tube rising when the user breathes in. The sole measurement that an incentive spirometer can offer is inhaled air.

• By encouraging lung activity and preventing fluid accumulation, an incentive spirometer helps avoid the development of pneumonia.

Professional Spirometer:

• Spirometers of the professional grade frequently use the same kind of pressure sensor technology, which measures exhaled air using a pressure plate.

• The distinction is that these devices are typically far more costly and may only be ordered with a prescription. PEF (Peak Expiratory Flow Rate), FEV1 (Forced Expiratory Volume in the first second you exhale), and FVC (forced viral capacity) may all be measured using a professional spirometer, which is extremely accurate.

• They are frequently big, heavy devices that are wired to a little computer or screen. This kind of monitor is difficult for non-prescription users to obtain and impractical for everyday home use.

Digital Peak Flow Meter:

• Peak flow meters quantify the amount of air that is exhaled from the lungs, as opposed to an incentive spirometer. Additionally, these devices can measure FEV1 (Forced Expiratory Volume in the first second you exhale) and PEF (Peak Expiratory Flow Rate).

• Because they are digital, they are electronic devices that use an internal turbine system to measure exhaled air. Internal turbine systems have the drawback of having a shorter lifespan due to their susceptibility to dust and damage.

Other Digital Smart Spirometers:

• Digital Smart Spirometers are not rechargeable and only monitor PEF and FEV1, just like Digital Peak Flow meters. Unlike SpiroLink, they do not measure FVC and instead function using an internal turbine system.

• Despite having Bluetooth and compatible apps, digital smart spirometers frequently lack a digital screen, which makes it challenging to operate them without the appropriate software.

SpiroLink (Digital Smart Spirometer)

• It is a cutting-edge digital spirometry tool that may be used both at home and on the road. SpiroLink stands apart from most other digital spirometers or peak flow meters. This clinical-grade gadget uses a pressure sensor to detect PEF, FEV1, and FVC precisely instead of an internal turbine system. The pressure sensor’s design prolongs the device’s life by preventing harm from dust, dirt, or mucus.

Indication

Spirometry checks to see if your lungs are working as they should. Additionally, it helps in the diagnosis of lung and airway conditions such as:

• Asthma.
• COPD stands for chronic obstructive pulmonary disease.
• Cystic fibrosis.
• Pulmonary fibrosis.
• Chest tightness, pain or pressure.
• Coughing, especially coughing with mucus.
• Difficulty taking a deep breath.
• Shortness of breath (dyspnea).
• Wheezing.

Spirometry can additionally:

• Find out how much lung capacity you have.
• Track changes caused by chronic lung conditions over time.
• Recognize any abnormalities in lung function early on and, in certain situations, assist in directing treatment.
• Check for airway narrowing.
• Determine the likelihood that inhaled drugs can help your symptoms.
• Indicate if your lung function has changed as a result of exposure to specific chemicals.
• Prior to surgery, assess your risk of respiratory problems.

Contraindications

• Aneurysm
• Unknown cause of hemoptysis
• A pneumothorax
• Unstable heart condition, recent myocardial infarction, or pulmonary embolism
• Acute conditions like nausea or vomiting that impair test performance
• Recently performed abdominal or thoracic surgeries
• Surgery for the eyes
• Pleural effusion
• After a Myocardial Infarction(MI).

Risks 

• In general, spirometry is a safe test. After taking the test, you might experience shortness of breath or lightheadedness for a brief while.
• If you have recently experienced a heart attack or another heart illness, you are not eligible to take the test because it involves some physical exertion. The test typically results in serious respiratory issues.

Calibration:

• The equipment used for spirometry needs to be calibrated before use, or at the very least, the calibration needs to be checked before the start of the session. Devices require different calibration methods.

• For more details, see the instructions that came with your spirometer. If the calibration is incorrect, some meters must be sent back to the manufacturer for repair. Spirometric measurements should ideally be taken once a week using a biological control, which is a healthy team member.

Positioning of the patient:

The following is the proper stance for measurements:

• As long as the patient is sitting up straight and there are no limitations, standing is preferable to sitting since there is a difference in the amount of air the patient can exhale from a sitting position compared to a standing or lying supine
• Legs uncrossed and feet flat on the floor: no abdominal muscles are used to support the position of the legs.
• Loosen clothes that are too tight.
• Implants are typically left in place; unless they are extremely loose, it is preferable to have some structure around the mouth.
• Use a chair with armrests because patients may feel dizzy and sway or faint when they exhale as much as they can.
• Since your patient might not be able to sit in a chair in a hospital setting, they should remain in the same position, which is typically supine, and have this recorded for any further tests.

Technique:

• Spirometry can be performed using a variety of methods. Typically, though, the patient inhales as deeply and forcefully as they can, then exhales as quickly and forcefully as they can, continuing until no air remains. The FEV1 and FVC maneuver is used to calculate PEF.

• Don’t be afraid to speak louder to the patient, especially as the maneuver comes to a close, because encouragement makes a great difference. Until no more air can be expelled, the patient must continue to blow. On a forced maneuver, some patients may have trouble exhaling entirely, especially those with obstructive illness.

Test for Spirometry

Your test may be performed in a specialized lung-function laboratory or in your doctor’s office. Your nose will be fitted with gentle clamps. The spirometer’s mouthpiece is the sole way to breathe in and out thanks to the clips.

After that, you will inhale deeply and use the mouthpiece to blow hard into the spirometer. Both the amount of air you exhale and the amount you breathe in are measured by the spirometer.

To make sure your results are precise and repeatable, you will run the test at least three times.

Additionally, your doctor might advise you to inhale a medication that facilitates airway opening. After that, you will test the spirometer once more. Test findings before and after you breathed the medication will be compared by your healthcare professional. After that, they will determine whether the medication can be used as part of your treatment plan.

Duration for Spirometer

The kind of spirometry that your doctor orders will determine this. However, the test often takes 15 to 30 minutes to finish.

Does a spirometry test cause pain?

A spirometry test is not uncomfortable.

However, the deep inhalation and exhalation may cause you to feel lightheaded, exhausted, or dizzy. Coughing may also result by blowing into the spirometer. After you finish the exam, these symptoms will likely disappear quickly. If you require a break during testing, inform your healthcare provider.

Additionally, spirometry may raise your heart rate. If you have ever experienced a heart attack or any other heart-related issues, let your healthcare professional know.

What may I expect after a spirometry?

• You can resume taking any medications that your doctor advised you to stop taking after the test. You can also resume your routine, which includes working out.
• When to expect your test results will be communicated by your healthcare practitioner.
• Following a spirometry test, they might also occasionally measure lung volume and diffusion capacity. These tests assess both the volume of your lungs and their capacity to deliver oxygen to your blood. These tests help in the diagnosis of specific lung or breathing disorders by supporting spirometry. These tests may be performed regularly by your provider to monitor the progress of your breathing.

Results

Your healthcare professional will calculate a normal reading for your demographics based on these factors. Two primary components are measured by spirometry:

• FVC stands for forced vital capacity. The maximum volume of air you can forcibly and exhale after inhaling deeply is known as FVC.
• FEV1, or forced expiratory volume. The amount of air you exhale in a second is known as your FEV1.
• Your healthcare practitioner will compare your test results to the average reading for your population after you take it. 80% or more above the average demographic reading is considered normal.
• Your healthcare professional can also use your findings to identify the type of lung illness you have. These could consist of:

Obstructive Lung Diseases: It is challenging to exhale all of the air in your lungs when you have damage to your lungs or airways. Cystic fibrosis, COPD, bronchiectasis, and asthma are common causes of obstructive lung disease.

Restrictive Lung Diseases: Your lungs cannot expand completely. Amyotrophic lateral sclerosis (ALS), interstitial lung disease, muscular dystrophy, sarcoidosis, and scoliosis are among the common causes of restrictive lung disease.

Measurement of FVC

FVC, or the maximum volume of air you can forcibly exhale after taking your deepest breath, is one of the main spirometry metrics. Your breathing is being restricted if your FVC is lower than normal.

Lung diseases that are restrictive or obstructive may be the cause of an abnormal FVC. In addition to having either restrictive or obstructive lung disease alone, you may also have a combination of both conditions at the same time.

To identify the type of lung disease present, various spirometry tests are needed.

Measurement of FEV1

FEV1 is the second important spirometry metric. This is the most air that you can expel from your lungs in a single second.

Your doctor can use this measurement to assess the severity of your breathing problems. You may have a serious breathing obstruction if your FEV1 reading is lower than normal.

Your doctor will rate the severity of any breathing issues based on your FEV1 measurement.

Ratio of FEV1/FVC

Physicians frequently compute your FEV1/FVC ratio after analyzing your FVC and FEV1 independently. The percentage of your lung capacity that you can exhale in one second is shown by the FEV1/FVC ratio.

The higher the percentage a doctor determines from your FEV1/FVC ratio, the healthier your lungs are, provided that you do not have restrictive lung disease that influences this ratio.

A low ratio indicates that your airways are being blocked.

FAQs

Reference

• Akins, D. (2021, June 2). Different types of spirometers | CMI Health. CMI Health Store. https://www.cmihealth.com/blogs/news/different-types-of-spirometers?srsltid=AfmBOorLGKRtNtIJVfzkiwfCb22hprnifYe_eJOzFq_iSkz_gWjf2F2c

• Professional, C. C. M. (2025b, February 11). Spirometry. Cleveland Clinic. https://my.clevelandclinic.org/health/diagnostics/17833-spirometry

• Cirino, E. (2024, March 22). What to know about a spirometry test. Healthline. https://www.healthline.com/health/spirometry#next-steps