Pulse Oximetry – Uses, Purpose And How To Take A Reading

Pulse Oximetry – Uses, Purpose And How To Take A Reading


Pulse oximetry is a non-invasive test that measures the level of oxygen saturation in the blood.

It can quickly detect even small changes in oxygen levels. This level shows how effectively the blood is carrying oxygen to the most distant parts of the heart, including the arms and legs.

A pulse oximeter is a small, pressurized device. It is attached to a part of the body, usually a finger.

They are often used by health professionals in intensive care units, such as emergency rooms or hospitals. Some doctors, such as pulmonologists, may use it in their office. You can also use it at home.

Purpose and Uses

The purpose of pulse oximetry is to check that your blood is adequately oxygenated.

Health care professionals can use pulse oximeters to monitor the health of people with impaired blood oxygen levels, especially when they are in the hospital.

This may include:

  • Chronic obstructive pulmonary disease (COPD)
  • Asthma
  • Pneumonia
  • Lung cancer
  • Anemia
  • Heart attack or heart failure
  • Congenital heart disease

Doctors use pulse oximetry for a variety of reasons, including:

  • To assess how well a new lung medicine works.
  • To assess whether a person needs respiratory support.
  • To judge how useful the fan is.
  • To control oxygen levels during or after surgical procedures that require sedation.
  • To determine if a person needs supplemental oxygen therapy.
  • To determine the effectiveness of supplemental oxygen therapy, especially when the treatment is new.
  • Assessing a person’s ability to tolerate increased physical activity
  • Assess whether a person stops breathing briefly during sleep, for example, in case of sleep apnea, during a sleep study.

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How to take a reading?

Pulse oximetry can be useful in both inpatient and outpatient settings. In some cases, your doctor may prescribe a pulse oximeter for home use.

To take a reading with a pulse oximeter, you need:

  • If measuring from here, remove jewelry or nail polish from fingers.
  • If you connect the device here, keep your hand warm, comfortable, and below the level of the heart.
  • Place the device on your finger, earlobe, or foot.
  • Keep the device on for as long as it takes to monitor your heart rate and oxygenate your blood.
  • Remove the device after the test is complete.

In pulse oximetry, a small beam of light is passed through the blood in the finger, measuring the amount of oxygen. According to the British Lung Foundation, pulse oximeters measure changes in the absorption of light by oxygenated or deoxygenated blood. It is a painless process.

A pulse oximeter will be able to report your heart rate as well as your oxygen saturation level.

Pulse oximetry readings

Pulse oximetry is a measure of blood oxygen levels, but is usually accurate. This is especially true when using the high-quality equipment found in most doctors’ offices or hospitals. With this equipment, medical professionals can perform examinations accurately.

Credible Sources The Food and Drug Administration (FDA) requires prescription oximeters to give results with an accuracy of 4 to 6 percent.

The American Thoracic Society states that more than 89 percent of the total blood should be oxygenated. This is the level of oxygen saturation necessary to keep cells healthy.

A temporary saturation of oxygen below this level cannot cause damage. But repeated or persistently low levels of oxygen saturation can be dangerous.

An oxygen saturation level of 95% is considered normal for most healthy people. A level of 92% or less may indicate possible hypoxemia, which is a very low level of oxygen in the blood.

Readings can be affected by many factors, including a person’s skin color.

A 2020 report compared the accuracy of pulse oximetry and blood gas measurements in detecting hypoxemia in black and white patients.

The researchers found that among black patients, there were three times as many cases of pulse oximetry testing that did not detect latent hypoxemia when measuring blood gases.

Such tests are designed without taking into account the diversity of skin tones. The authors concluded that more research is needed to understand and correct these racial biases.

What’s next to follow?

After the test is completed, your doctor will have immediate access to the reading. This will help them determine if further testing or treatment is needed.

For example, if you are evaluating the effectiveness of your supplemental oxygen therapy, a reading that is still low may indicate a need for more oxygen.

Your doctor will be able to tell you what the next step is. If you use a pulse oximeter at home, they will tell you how often to take readings and what to do if they are above or below a certain level.

The Bottom Line

Pulse oximetry is a quick, non-invasive and completely painless test. It poses no risk other than possible skin irritation from the adhesive used in some types of catheters.

However, it is not as accurate as clinical blood gas measurements, especially for dark-skinned people.

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