If you are new to monitoring blood oxygen, or have a new diagnosis, it is important to monitor your oxygen levels regularly. Blood oxygen is typically quite stable, but may vary depending on many factors, and slightly from one meter to the next. If you’ve noticed a difference in your readings and want to learn more, take these pointers!
Get a Baseline: What’s Normal for You?
If you are newly monitoring, or have a new diagnosis, you must first establish a baseline.
To get a baseline, measure your blood oxygen three times per day for 3 days.
The average of these 9 readings approximates your ‘baseline’.
When first prescribed oxygen
Regularly with oxygen therapy
During or just after exercising
During sleep: when you have trouble sleeping or sleep apnea
When traveling to a higher altitude location
Most oximeters give a reading +/-2% of what your saturation would be if obtained by an arterial blood gas. The best reading is achieved when the hand is clean, warm, and relaxed.
Factors that could cause a higher-than-normal reading:
Factors that could cause a lower-than-normal reading:
Nail polish & artificial nails
Very dark skin
Sickle cell disease
Other factors that may cause an inaccurate or unmeasurable reading:
Bright light directly to the probe, like sunlight
Very low oxygen saturation levels (below 80%)
Movement during the measurement
Review Reliability: Blood oximeters do not require calibration because the design and measurement technique either incorporates a continuous calibration of the device, or does not require it by measurement technique. The SpO2 (blood oxygen) reading should always be considered an estimate of oxygen saturation. For example, if an FDA-cleared pulse oximeter reads 90%, then the true oxygen saturation in the blood is generally between 86-94%.