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The interpretation of oxygen saturation monitor or pulse oximeter readings is a comparison of test results to the normal expected range. Analyzing the results requires an understanding of how these machines work and what each number signifies. It's important to note the “normal range” used for comparison may be inadequate to assess an individual’s health. Additionally, interpreting the results should account for inaccuracies in testing that may occur for a variety of reasons.
Understanding how each machine works assists the user in accurate interpretation. The classic oximetry device has a clip or wraparound feature that is placed on a finger or toe. A small box produces the reading. Portable sat monitors may show the measurements directly on the clip.
Pulse or beats per minute (BPM) and oxygen saturation level, which is sometimes abbreviated as SPO2 or SAT, are the two measurements a pulse oximeter takes. These can be compared to “normal” oximeter readings in the population. Usual sats are between 96-99%. BPM varies by age: infants are between 120-150, children from one to five years are 80-150; and from ages six to 12 anything between 60-120 is normal. Adolescents might have a pulse between 60-105 and adults typically have a BPM of 60-80.
The two pulse readings should be indicated separately. The easiest to read machines are marked with BPM and SPO2 or SAT. If a device is not clearly marked, consult the manual to verify which number corresponds to each measurement.
When the test is performed, which takes a minute to several minutes depending on the device, the pulse oximeter should produce a BPM and saturation reading. While this can be compared to normal range, it isn’t always useful. An individual’s health circumstances can greatly change the average expectations.
For example, oximeter readings of oxygen saturation could vary in people with lung disease or cardiac defects. Some children have readings in the low 80s, due to unrepaired heart anomalies. This is considered normal for these children, while it indicates dire circumstances for someone in good health. Alternately, athletes might have a pulse below 60 BPM, which isn’t indicative of any problems.
In most cases, regular pulse oximetry monitoring is advised for ill people. This means a physician defines the safe and acceptable range of oximeter readings. Interpretation is then based on the doctor’s guidelines, instead of using “norms” to read the test.
Single oximeter readings aren’t always reliable. It’s important not to panic if an individual has an abnormal result, especially if that person is not in distress. Movement, cold hands, or even fingernail polish can affect accuracy. When a test isn’t producing the right results, re-testing is suggested. Should readings consistently vary from what is expected, getting help is advised.