Pulse oximetry is a non-invasive and painless test that measures your oxygen saturation level, or the amount of oxygen in your blood. It can help quickly detect even small changes in how effectively oxygen is being delivered to the body’s most distant extremities, including the legs and hands.
A pulse oximeter is a small, clip-like device attached to a body part, such as a finger or earlobe. It is most commonly placed on a finger and is often used in critical-care settings such as emergency rooms or hospitals. Some doctors, such as pulmonologists, may also use it in their offices.
The goal of pulse oximetry is to check how well the heart is pumping oxygen throughout the body.
It can be used to monitor the health of individuals with conditions that may affect blood oxygen levels, especially when they are in the hospital.
A pulse oximeter is used if a patient has been diagnosed with:
Chronic obstructive pulmonary disease (COPD)
Asthma
Pneumonia
Lung cancer
Anemia
Heart failure
Congenital heart defects
A pulse oximeter is also helpful if you want to:
Assess how well new lung medications are working
Evaluate whether breathing assistance is needed
Assess lung ventilation function
Monitor oxygen levels during procedures requiring sedation
Determine how effective supplemental oxygen therapy is, especially when starting treatment
Evaluate someone’s ability to tolerate increased physical activity
Check whether a person briefly stops breathing during sleep, as in sleep apnea
During a pulse oximetry reading, a small clip-like device is placed on a finger, earlobe, or toe. Beams of light pass through the blood in the area to measure oxygen levels. It does this by detecting changes in light absorption between oxygenated and deoxygenated blood. The process is painless.
The pulse oximeter then displays your oxygen saturation level along with your heart rate.
Pulse oximetry can be performed in both inpatient and outpatient settings. In some cases, a doctor may recommend having a pulse oximeter for home use.
The process typically includes:
A clip-like device is placed on a finger, earlobe, or toe. You may feel mild pressure, but no pain or pinching. In some cases, a small adhesive sensor may be placed on a finger or forehead. You may be asked to remove nail polish if the device is attached to a finger.
You will keep the sensor on for as long as needed to monitor pulse and oxygen saturation. If assessing exercise tolerance, the reading will be taken during activity and recovery. During surgery, the sensor is placed beforehand and removed when you are awake and stable. Sometimes it is used only briefly for a single reading.
After the test, the clip or sensor is removed.
Pulse oximetry is generally a very accurate test, especially when using high-quality equipment found in most medical facilities. It typically provides readings within a 2-percent margin of error. For example, if the reading shows 82%, the actual saturation level may be between 80% and 84%. Factors such as movement, temperature, or nail polish can affect accuracy.
Normally, oxygen saturation should be above 89%. This level is needed to keep cells and the body functioning properly. Temporary drops below this threshold usually do not cause damage, but repeated or long-lasting low levels can be harmful.
95% saturation is considered normal for most healthy individuals.
92% may indicate possible hypoxemia, meaning inadequate oxygen reaching tissues.
After the test, the results must always be evaluated.
This helps determine whether additional tests or treatments are needed. For example, if you’re assessing how well supplemental oxygen therapy is working, pulse oximeter readings will help determine whether more oxygen is required or whether current delivery is sufficient.
Ask your doctor what the next steps are if the readings indicate low oxygen levels.
Prepared based on Healthline material.
