Pulse Oximetry

Pulse oximetry may be used in a variety of different situations. These include seeing how well lung medications are working, checking your ability to handle increased physical activity, determining whether you need a ventilator to facilitate breathing, checking if you experience obstructive sleep apnea (OSA), and during or after surgery that requires sedation.

Pulse oximetry is also used to routinely check the health of people suffering from conditions that affect blood oxygen levels, such as heart attack, heart failure, chronic obstructive pulmonary disease (COPD), anemia, lung cancer, pneumonia, and asthma. These conditions can lead to lower overall oxygen saturation, so it’s important to get this regularly checked.

A small electronic device will be clipped onto a part of your body, typically a fingertip. Your doctor may ask you to remove any fingernail polish or artificial nails to prepare for the test. This helps achieve the most accurate test results, as nail polish or artificial nails can interfere with the light used for this test. During the test, the device will emit a light that passes through the fingernail, skin, tissue, and blood.

On the other side of the finger, a sensor is placed there that will measure the amount of light that passes through the finger without getting absorbed by the tissue and blood. By measuring this light transmission, the device is able to calculate the level of oxygen saturation in your blood.

When the test is completed, your doctor will have a measurement known as a pulse oximeter reading which details the blood oxygen saturation level you currently have. A resting oxygen saturation level should be between 95% and 100% to be considered a normal amount for healthy people at sea level. For those living at higher elevations, oxygen saturation levels are typically slightly lower.

If your pulse oximeter reading drops below 92%, contact your doctor as soon as possible, as this may be a sign of hypoxia. Hypoxia is a medical condition in which not enough oxygen can reach the tissues throughout your body. If your blood oxygen saturation levels fall to 88% or lower, you should seek emergency medical treatment, as this can lead to life-threatening organ damage if left untreated.

For people with other medical conditions, such as lung disorders like COPD, your resting oxygen saturation levels may be below the normal range. This can still be considered acceptable, though it is important to discuss with your doctor what typical oxygen saturation levels are for specific medical conditions.

Most pulse oximeter readings fall within a range of accuracy between 2% to 4% from the actual blood oxygen level. This means that your reading may show a result that can be anywhere from 2% to 4% lower or higher than the actual level of oxygen in your blood. There are many factors that can affect the accuracy of your results, such as the aforementioned fingernail polish or artificial nails.

Other factors that may sway your results include dyes that may be used for diagnostic tests or medical procedures, as these can impair the light transmission. Excessive motion, such as shivering and shaking, can also create an error in your results. The accuracy of the results may also be affected by your skin temperature and thickness, as well as whether you smoke tobacco products. Pulse oximetry is also shown to be less accurate for people who have a darker skin pigmentation.