How to Use a Pulse Oximeter for Accurate Results

A pulse oximeter is a useful device for monitoring oxygen levels. It is an easy, non-invasive way to determine how much oxygen is in the blood. Learn the meaning of the numbers on a pulse oximeter and how to get accurate results.

Key takeaways:

Pulse oximeters tell medical professionals if your blood, limbs, and organs are receiving enough oxygen. These devices are commonly used to monitor oxygen levels in people with conditions affecting blood oxygen levels, such as chronic obstructive pulmonary disease (COPD), lung cancer, or pneumonia. However, they are also used for monitoring patients requiring ventilators, supplemental breathing aids, or those sedated during surgery.

What is a pulse oximeter?

A pulse oximetry test measures your blood's oxygen level or oxygen saturation. The test is a simple and painless way to see how well oxygen is being delivered to body parts farthest from the heart, like your arms and legs.

Also known as pulse ox, these devices are used for people with lung or heart conditions or who experience frequent shortness of breath. Pulse oximeters are used in hospitals, emergency rooms, and clinical settings, like physicals and doctor appointments, and regularly at home, as requested by a doctor.

Since so many people use pulse oximeters now, blood oxygen saturation is often called the “fifth vital sign.” A person's temperature, blood pressure, pulse, and breathing rate are the other four vital signs that are used to judge their health.

How to use a pulse oximeter

A pulse oximeter is a small device that looks like a clip. It is attached to a part of the body, often a finger. There are two main types of pulse oximeters: prescription pulse oximeters that have been tested by the FDA and over-the-counter pulse oximeters that do not undergo FDA review.

When using a pulse oximeter at home, take note of your health care provider’s guidelines and then follow the manufacturer’s instructions.

The FDA recommends that you be aware of the many factors that can lead to an inaccurate pulse oximeter reading, such as skin thickness, temperature, poor circulation, current tobacco use, and use of fingernail polish. Also, recent studies found that pulse oximeter readings may be inaccurate for people with darker skin.

The FDA suggests these guidelines for the most accurate pulse oximeter reading:

  • Make sure to remove any nail polish before your reading.
  • When placing the oximeter on your finger, make sure your hand is warm, relaxed, and held below heart level.
  • Don't move the part of your body where the pulse oximeter is located until the reading is complete.
  • Wait a few seconds until the number on the screen stops changing.

Importance of measuring oxygen levels

Oxygen levels that are too high or low can lead to several health issues, some of which are very severe. When the oxygen in your blood drops too low, you can experience symptoms like shortness of breath, confusion, headaches, a rapid heartbeat, and chest pain.

Oxygen saturation levels that are too high can cause lung tissue damage. Also, higher levels can cause you to breathe in too much oxygen, a state of hyperoxia. Hyperoxia causes oxygen toxicity or poisoning, leading to cell damage and even death.

It is important to measure oxygen levels to avoid these various health risks that come with very low or high oxygen saturation.

Readings on a pulse oximeter

Every pulse oximeter measures two specific numbers: the pulse rate and the oxygen saturation. Both numbers are necessary to determine your current levels.

  • Pulse rate. Most of the time, the pulse rate is the first number to show up. It is often marked with a small heart beside the number.
  • Oxygen saturation. Also known as the oxygen level in the blood, this is typically the second number on the screen.

What are normal oxygen level readings?

Healthy blood oxygen levels should be between 80 and 100 millimeters of mercury (mmHg). If measuring your blood oxygen level (SpO2) with a pulse ox, healthy levels should be between 95% and 100%. Levels around 90% are typical for people with chronic lung disease or sleep apnea. Furthermore, oxygen levels should not rise above 110 mmHg.

Clipping a pulse oximeter to the tip of a finger is all it takes to get a quick, easy, and painless measurement of the blood's oxygen levels. The results help your doctor diagnose a condition, so they'll know which treatment method to use.


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