Oximeters emit different wavelengths of light passing through the finger. What acts on that light is hemoglobin, a blood molecule responsible for carrying oxygen, absorbing different amounts of light depending on the level of oxygen it carries.
This process, counted in a simple way, is what ends up with a numerical value shown on the screen, indicating the level of oxygen saturation in the blood.
Knowing the blood oxygen saturation at the medical level is useful to know the degree of hypoxemia or respiratory insufficiency that a patient may have. This measurement by oximeter is an approximation, the diagnosis will be confirmed with other more precise tests such as blood gas analysis.
At a domestic level, the information provided by the oximeter can be used to have a first approximation of your saturation, or if you find yourself with a certain difficulty in breathing to assess whether it is appropriate to seek medical attention. The saturation of a healthy person is usually above 95, although this measurement may depend on a multitude of variables including the device used.
It is important to emphasize that this type of data is indicative and that only a medical diagnosis can shed light on a patient’s situation. Nor is it advisable to compare measurements between devices, since the measurement may vary slightly between them.
In addition to these basic recommendations, it is also important to remember that the technology itself offers a number of limitations that can make the measurement more confusing if not taken into account. For example, some nail varnishes interfere with the light beam emitted by the pulse oximeter, but in addition to this, which is little known, the following medical conditions that may influence the readings should be taken into account.
Patients with very low levels, below 80% may not be identifiable on these devices, since at lower oxygen levels there are not enough red blood cells to estimate a reliable result.
People with anemia, who do not have a sufficiently high hemoglobin (number of red blood cells). People with hypothermia, cold hands can also cause the instruments to give altered saturation levels.
Similarly, smokers may have lower oxygen saturation levels when measuring their hands due to poor peripheral circulation, as may diabetics.
Dark-skinned people may have higher readings than they actually have, which can make their assessment even more delicate if we look at this type of technology.
For all these reasons and many others, it is convenient to have an alternative to identify blood oxygen saturation levels. The Smart Dyspnea test is a functional test that uses voice to identify blood oxygen saturation levels, thanks to the improvement of a clinical test that offers a reliability of up to 91% to estimate saturation levels. Just by counting from 1 to 30 in any language, it is possible to estimate this very relevant data in today’s pandemic times. This test is not dependent on blood circulation, but is a direct measure of functional capacity in this case for a task as simple as counting.
You can try the Smart Dyspnea test at https://test.smartdyspnea.com.
Mardirossian, G., & Schneider, R. E. (1992). Limitations of pulse oximetry. Anesthesia progress, 39(6), 194–196.