happy, young father and mother holding healthy baby in nursery

SpO2: The 5 W’s

Aulisa Guardian Angel®TM monitors SpO2, but what does it mean and what role does it play in your health?

What is SpO2?

SpO2 tells you your blood oxygen saturation, or how much oxygen the red blood cells in your arteries are carrying. This can also be referred to as pulse oximetry by medical professionals.

Healthy SpO2 levels are generally considered to be 95-100. The numbers refer to percentages, so 90 means that 90% of your blood is saturated with oxygen. More specifically:

  • 95-100 Normal/Healthy
  • 90-95 Lower than average. Keep an eye on it, but still in the safe zone
  • Less than 90 You may want to consult your doctor

Unlike other health measurements, such as heart rate, healthy SpO2 numbers are consistent across all age groups.

Why does SpO2 matter?

SpO2 is an important measurement because oxygen helps provide the energy your muscles need to function. When SpO2 is low, you become at risk for hypoxia, which means your body tissues lack sufficient oxygen. If hypoxia happens in a small part of your body only, it causes the area to become cold and pale/blue. However, if oxygen levels drop throughout your entire body, it can cause hallucinations, disorientation, behavior changes, fatigue, tingling, and then on to more severe outcomes, such as reduced level of consciousness, hypertension, low blood pressure, slow heart rate, heart failure and so on.

Who is at risk of low SpO2?

Healthy people can have low blood oxygen saturation due to high elevations (people living at higher elevations will have lower oxygen levels) or deep-water diving (free diving or SCUBA). Think about any time you’ve gotten altitude sickness or, if you’re a diver, heard stories of people becoming disoriented underwater.

Potential causes of low blood oxygen saturation in people with health problems include sleep apnea, COPD, other respiratory conditions, anemia, problems breathing or insufficient air supply. Low oxygen saturation and hypoxia is not only a problem with adults, but is actually a common complication with premature and newborn infants, since lungs develop late in pregnancy and may be underdeveloped at birth.


When should you monitor your SpO2?

People with chronic respiratory issues or health conditions, as well as at-risk newborns should be monitored during times of sleep and rest to be sure blood oxygen levels are staying at healthy levels. SpO2 tells us something about a person’s health that we can’t see with our eyes, which makes monitoring even more important.

Where is SpO2 measured?

Most commonly, blood oxygen saturation is measured via a sensor, called a pulse oximeter, worn on the finger (or on the foot in the case of an infant). More specifically, the measurements come from the red blood cells in your fingertip.

Two wavelengths of light are passed through the blood vessels in your fingertip to a photodetector. The tiny differences in the amount of light absorbed by the hemoglobin in your red blood cells at each of the wavelengths can be detected, telling us how much oxygen your blood contains, or your SpO2.

Fingernail polish and cold hands can both throw off readings, so remember to remove any fingernail polish or fake nails prior to using a pulse oximeter (the name of the device used to measure blood oxygen saturation).

*Nothing here is meant to replace doctor supervision nor be considered medical advice.

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