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Respirometer - Uses, Benefits, and Drawbacks

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A respirometer is a medical instrument often used for pulmonary rehabilitation. Read the article further to know more about this device and its uses.

Written by

Dr. Asna Fatma

Medically reviewed by

Dr. Kaushal Bhavsar

Published At April 25, 2023
Reviewed AtApril 13, 2024

What Is a Respirometer?

A respirometer or an incentive spirometer is a medical device or equipment that measures the amount of air that is inspired (breathed in) and expired (breathed out) by the lungs. A respirometer is also used to check the functioning capabilities of the lungs. This instrument aids in the retraining of the lungs and guides patients to breathe more slowly and deeply, both of which may be challenging for those who have had surgery or a flare-up of chronic obstructive pulmonary disease (COPD). A respirometer is similar to an exercise machine for the lungs that help in pulmonary rehabilitation in patients with pulmonary diseases or damage. This pulmonary rehabilitation helps in increasing the breathing capacity of the lungs.

What Are the Different Parts of a Respirometer?

The respirometer consists of the following:

  • Three air chambers.

  • Three colored balls within these air chambers (working as indicators).

  • Base.

  • Tube for breathing in and out.

  • Mouthpiece.

When the patient breathes in, the balls within the air chambers move upward, and the height up to which these balls go is equal to the amount of air inhaled while breathing into it. If the ball in the first chamber stays up for more than one second, then the amount of air inhaled is equal to 600 mL/cc. If the ball in the second chamber stays up for one second, then the volume of air inhaled is 900 mL/cc. Similarly, if all three balls stay up for one second, then the air inhaled will equal 1200 mL/cc.

Who Should Use a Respirometer?

Patients with the following conditions should use a respirometer:

  • Asthma: The airways constrict, tighten, and produce mucus as a result of asthma. This, eventually, causes difficulty in breathing and reduced respiratory flow.

  • Pneumonia: Mucus and other liquids accumulate in the air sacs of the lungs as a result of pneumonia. A respirometer aids in clearing the lungs of fluid and mucus.

  • Chronic Obstructive Pulmonary Disease (COPD): A series of illnesses known as COPD harm the lungs permanently. Although the lung damage from COPD cannot be repaired, the symptoms can be lessened with a respirometer.

  • COVID (Coronavirus disease): Patients with COVID have compromised lung functioning due to the debilitating effects of the virus on the lungs. A respirometer helps in pulmonary rehabilitation in post-COVID patients.

  • Fibrosis: Cystic fibrosis may cause fluid buildup in several organs of the body, including the lungs.

  • Atelectasis: This is a condition that hinders proper inflation of the lungs.

  • Rib Injuries: It may hurt to cough or to breathe after trauma, and the ribs may become tender to touch. Walking, running, or climbing stairs may become difficult or uncomfortable.

What Are the Benefits of Using a Respirometer?

The benefits of using a respirometer are:

  • It helps strengthen the lungs.

  • Helps the lungs become more efficient in supplying the body with oxygen.

  • Prevents lung infections.

  • Reduce symptoms of conditions like asthma and COPD.

  • Respirometers available in the market help in improving lung ventilation. Ventilation is the volume of air that enters the lungs while breathing in and the volume of air that leaves the lungs while breathing out.

  • It helps in loosening mucus from the lungs. Exhaling prevents the accumulation of fluids and mucus in the lungs.

  • Respirometers help in preventing complications in the lungs. Full lung expansion through slow deep breathing helps in the removal of any fluids that might be the cause of lung diseases like pneumonia.

What Are the Drawbacks of a Respirometer?

The drawbacks of using a respirometer include the following:

  • Continuous use of the respirometer can cause lightheadedness in the patient.

  • Aggressive use of respirometers can lead to lung collapse (pneumothorax) in patients with emphysema.

  • The use of a respirometer is contraindicated in patients who have recently had eye surgery or patients with aneurysms (swelling of blood vessel walls).

  • Improper cleaning and disinfection of the respirometer may cause infection spread. Patients using a respirometer must also exhale fully, increasing the risk of spreading airborne bacteria like influenza and COVID-19. It is advisable to avoid using respirometers in public places.

How to Use Respirometer at Home?

A respirometer can be used in the following way:

  • Attach the breathing tube with the air inlet.

  • Clean the mouthpiece with a clean cloth.

  • Sit upright and in a comfortable position.

  • Hold the respirometer upright.

  • Put the mouthpiece in the mouth and close it firmly with the lips.

  • Inhale slowly and deeply with the lips sealed tightly around the mouthpiece.

  • As the patient breathes in, the balls inside the air column move up. The patient should try to hold their breath for two to five seconds and keep the ball afloat.

  • The patient may be able to move up one, two, or all of the three balls depending upon their pulmonary strength.

  • The patient should take normal breaths in between.

What Is Triflow Exercise?

The tri-flow exercises are easy lung exercises done with the help of a respirometer. Many types of respirometers are available and they can be purchased online. This exercise helps in lung training and rehabilitation. In addition, this exercise increases the breathing capacity of the lungs.

The method:

  • Put the mouthpiece inside the mouth and inhale (breathing in) deeply and slowly and try to hold the balls within the air chambers afloat for as long as possible.

  • Repeat this multiple times or for at least five minutes.

  • Now, invert the respirometer and hold it in that position.

  • Put the mouthpiece inside the mouth and try to exhale (breathing out) deeply and slowly and try to hold the balls within the air chambers afloat for as long as possible.

  • Repeat this multiple times or for at least five minutes.

  • These exercises should be done at least three to four times daily.


Respirometers are goal-oriented lung exerciser that helps strengthen the lungs. The device may be challenging for patients with lung disease to use the device at first, but with time and regular usage, it gets better. A respirometer can not cure lung disease, but it can help alleviate its symptoms. Therefore, a respirometer is commonly advised for patients with asthma, pneumonia, COVID, and COPD.

Frequently Asked Questions


What Is a Respirometer Used For?

A device used to measure the rate of respiration is called a respirometer. The rate at which carbon dioxide or oxygen is exchanged is used to measure respiration. In addition, they help understand how aging or certain substances influence breathing rates.


What Are a Respirometer’s Fundamental Characteristics?

Respirometers are most commonly used to determine if mechanical ventilators are providing an adequate amount of gas. They are typically used to perform intermittent measurements of tidal and minute volume. Simple respirometers comprise a sealed container, the tested organism, and an absorbent material (such as soda lime pellets) to absorb carbon dioxide emissions.


What Components Make up a Respirometer?

Basic respirometers consist of a sealed container and a material to absorb the carbon dioxide emitted, like pellets of soda lime. The displacement of fluid in a glass tube attached to the sealed container is used to calculate oxygen uptake rates.


Why Is the Respirometer Using Glass Beads?

Beads are used in the respirometer to ensure equal volume in the respirator. Any changes in volume brought on by variations in temperature or atmospheric pressure can be detected using just the vial containing glass beads. To absorb any carbon dioxide released during breathing, an alkali, such as sodium hydroxide, is present in both tubes.


Which Gas Is Released During the Respiration of Cells?

Carbon dioxide is released during cellular respiration. Oxygen and glucose combine during cellular respiration to generate ATP. Carbon dioxide and water are produced as the byproduct of the process. Cellular respiration is a metabolic process by which glucose is broken down to produce energy.


What Is Meant By Closed Respirometry?

Closed respirometry is a process used to measure gaseous exchange in animals. It is commonly used due to the simplicity of the process. In this process, the respiratory medium remains the same with little replacement.


What Causes the Water in the Respirometer to Move?

The respirometer is usually immersed in a pan containing water. Water moves from a place of low pressure to high pressure. Water moves into the pipette as the oxygen is used up in respiration. Here, the movement of water occurs due to the pressure gradient.


Who Is the Respirometer Intended For?

A respirometer is a device that measures the rate of exchange of oxygen or carbon dioxide to determine its rate of respiration. A respirometer is usually recommended for people suffering from asthma, pneumonia, COVID-19 (coronavirus), or COPD (chronic obstructive pulmonary disorder). A respirometer will not cure an existing lung disease, but it will help to relieve its symptoms.


Does a Respirometer Benefit the Lungs?

Respirometers are an example of lung exercisers that improve lung strength. It might not be used to heal a lung disorder. However, it can help to relieve the symptoms of a lung disorder. Moreover, it can strengthen the lung muscles.


What Are the Respirometer’s Limitations?

A respirometer does not account for variations in gas volume brought on by variations in experiment temperature or pressure. The breathing rate of the organisms may change when potassium hydroxide or sodium hydroxide absorbs carbon dioxide because it changes the composition of the gases in the respirometer.


What Are the Other Names for Respirometers?

A respirometer can also be called an oxygraph. It can have many brand names depending on the manufacturer. It is used to check the functional capacities of the lungs.

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Dr. Kaushal Bhavsar
Dr. Kaushal Bhavsar

Pulmonology (Asthma Doctors)


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