Pulse oximetry is a noninvasive and painless test that measures your oxygen saturation level, or the oxygen levels in your blood. It can rapidly detect even small changes in how efficiently oxygen. Garmin SpO2 devices Garmin has introduced pulse ox sensors into a large part of its range, with the Fenix 6X, Fenix 5X, Vivoactive 4 and Forerunner 245/645/945 all using an SpO2 sensor.

Pulse oximetry is a term that frequently appears online and in news reports in connection with COVID-19. But what, exactly, is it?

Basically, pulse oximetry is a painless, noninvasive method of measuring the saturation of oxygen in a person’s blood.

Oxygen saturation is a crucial measure of how well the lungs are working. When we breathe in air, our lungs transmit oxygen into tiny blood vessels called capillaries. In turn, these capillaries send oxygen-rich blood to the heart, which then pumps it through arteries to the rest of the body. Our organs need a constant supply of oxygen to work properly. When the capacity of the lungs to transport oxygen into the blood is impaired, blood oxygen saturation declines, potentially putting our organs in danger. A pulse oximeter can quickly detect this drop in oxygen saturation, alerting people of the need for medical intervention.

If you have ever had a physical or visited a doctor for a medical procedure, you’ve had your blood oxygen saturation measured by a pulse oximeter. More recently, the spread of COVID-19, which can cause significant drops in blood oxygen saturation, has spurred a surge in the popularity of at-home pulse oximeters. (Some people who are worried they may have—or fear contracting—COVID-19, have purchased pulse oximeters with the aim of monitoring their blood oxygen levels.)

“It’s important to remember that not all changes in pulse oximetry are related to COVID-19,” says Denyse Lutchmansingh, MD, a Yale Medicine pulmonologist. “Other lung-related issues, such as pneumonia and blood clots, can also result in low readings on pulse oximetry. Thus, persistently low readings should be discussed with a doctor.”

Fingertip Pulse Oximeter Spo2 Oxygen Monitor

A small, electronic device called a pulse oximeter is clipped onto a part of the body, usually a fingertip. The device emits light that passes through the fingernail, skin, tissue, and blood. On the other side of the finger, a sensor detects and measures the amount of light that passes through the finger without getting absorbed by the tissue and blood. Using that measurement, the device calculates the oxygen saturation of the blood.

Pulse oximetry offers many advantages over traditional methods of measuring blood oxygen levels. Whereas traditional methods usually involve drawing a sample of arterial blood—a potentially painful experience for patients that requires around 15 minutes, at minimum, to analyze blood samples—pulse oximetry is noninvasive and provides near-immediate readings. What’s more, pulse oximeters can be used continuously and, therefore, can provide long-term monitoring of a person’s blood oxygen levels.

At the same time, pulse oximetry is less precise than conventional methods, such as arterial blood gas testing. Also, it does not provide as much information on other blood gases (e.g., carbon dioxide) as do tests that directly measure the blood.

Today, pulse oximeters are used across a broad range of health care settings. In general practice, they are frequently used to quickly assess someone's general health, for instance, during a routine physical examination. In fact, pulse oximeters have become so widespread that blood oxygen saturation is often referred to as the “fifth vital sign,” a piece of data collected alongside four other measurements—temperature, blood pressure, pulse, and respiration rate—to gain insight into a person’s health status.

Outside of general practice, pulse oximetry is most frequently used to monitor patients with lung and heart disorders, who are at risk of low levels of blood oxygen. In clinical settings, they are routinely used in the following situations:

• To monitor patients before, during, and after surgery, including during anesthesia
• To monitor patients on certain medications that may reduce respiration and lung function
• To assess the lung function of people with conditions that can cause reduction of blood oxygen levels, including COPD, asthma, acute respiratory distress syndrome (ARDS), anemia, pneumonia, lung cancer, cardiac arrest, and heart failure, among others
• To assess individuals with sleep disorders such as sleep apnea

When pulse oximeters are used at home, it has usually been by people with known lung conditions, who may regularly monitor their blood oxygen saturation levels with guidance from their doctors.

A resting oxygen saturation level between 95% and 100% is regarded as normal for a healthy person at sea level. At higher elevations, oxygen saturation levels may be slightly lower. People should contact a health care provider if their oxygen saturation readings drop below 92%, as it may be a sign of hypoxia, a condition in which not enough oxygen reaches the body’s tissues. If blood oxygen saturation levels fall to 88% or lower, seek immediate medical attention, says Dr. Lutchmansingh.

Note that for people with known lung disorders such as COPD, resting oxygen saturation levels below the normal range are usually considered acceptable. A physician can provide details on appropriate oxygen saturation levels for specific medical conditions.

Most pulse oximeters are accurate to within 2% to 4% of the actual blood oxygen saturation level. This means that a pulse oximeter reading may be anywhere from 2% to 4% higher or lower than the actual oxygen level in arterial blood.

A number of factors can impair the functioning or accuracy of a pulse oximeter. Nail polish and artificial nails may block the red and infrared light emitted by the device. Certain dyes used for diagnostic tests or medical procedures can also hinder light transmission. Excessive motion—shivering, shaking, or other movement—can also cause erroneous readings.

Skin temparture and thickness can also reduce the accuracy of pulse pulse oximeters, and whether a person smokes tobacco can affect the device’s accuracy. Pulse oximetry can be less accurate for people who have dark skin pigmentation. Recent evidence suggests that pulse oximetry more frequently fails to detect hypoxemia—low blood oxygen levels—in Black patients as compared to white patients.

Best Finger Pulse Oximeter

How does COVID-19 lower a person’s oxygen levels?

Many people with COVID-19 have low levels of oxygen in their blood, even when they feel well. Low oxygen levels can be an early warning sign that medical care is needed.

What is a pulse oximeter?

Pulse Oximeter Spo2 Price

A pulse oximeter measures how much oxygen is in someone’s blood. It is a small device that clips onto a finger, or another part of the body. They are used often in hospitals and clinics and can be bought to use at home.

Many people consider oxygen level an important sign of how well a body is working, just like a person’s blood pressure or body temperature. People who have a lung or heart condition may use a pulse oximeter at home to check how they are doing, as directed by their health care provider. People can buy pulse oximeters without a prescription at some pharmacies and stores.

Can a pulse oximeter tell if someone has COVID-19 or how well they are doing if they have it?

We do not recommend using a pulse oximeter as a way to tell if someone has COVID-19. Get tested if you have signs of COVID-19 or if you have been close to someone who has it.

If someone has COVID-19, a pulse oximeter may help them keep watch over their health and to know if they need medical care. However, while a pulse oximeter may help someone feel like they have some control over their health, it does not tell the whole story. Oxygen level measured by a pulse oximeter is not the only way to know how sick someone is. Some people may feel very sick and have good oxygen levels, and some may feel OK, but have poor oxygen levels.

Pulse oximetry results may not be as accurate for people with darker skin. Their oxygen levels are sometimes reported as higher than they really are. People who check their own oxygen levels, or those who check it for them, should keep this in mind when looking at results.

Oxygen levels may be low if someone feels short of breath, is breathing faster than usual, or feels too sick to do their usual daily activities, even if a pulse oximeter says their oxygen levels are normal. Call a doctor or another health care provider right away if you have these symptoms.

What are normal readings?

A normal level of oxygen is usually 95% or higher. Some people with chronic lung disease or sleep apnea can have normal levels around 90%. The “SpO2” reading on a pulse oximeter shows the percentage of oxygen in someone’s blood.

If your home SpO2 reading is lower than 95%, call your health care provider.