Before early 2020 few people beside mountain climbers, divers, and those living at high altitude had any reason to know much about how oxygen levels in the blood affect health. Why should they? But during the recent pandemic researchers discovered that blood oxygen levels were a key indicator in how severe the virus was attacking a patient’s lungs leading many of us to wake up to the need to perform daily monitoring using an oximeter.
Oximeters are little marvels powered by one or two small batteries that use two small light-emitting diodes to penetrate the skin non-invasively. Reflected light measures how much oxygen is in the blood, which is also known as the SpO² level. Adequate levels indicate that your heart, lungs and circulatory system are in good heath.
The devices you find for home use have a reading scale that reaches to 100%. In general when you are in good health the reading at rest should be between 95% and the maximum 100%. However, various factors, such as altitude, asthma, and even the color of your skin, can influence the reading. In the case of altitude for example, the higher you are the less certain it becomes to know what a normal oxygen saturation should be.
According to professionals a reading lower than 95% should not immediately ring any alarm bells. But if this kind of reading is combined with a feeling of breathlessness, a racing pulse, or a headache and confusion, then these could be signs of an insufficiency of oxygen in the blood. The medical term for this state is hypoxemia, and health professionals recommend you seek urgent medical advice if your oximeter registers a reading of more towards 90% and you notice a blueness under the nails and in your lips.
Besides the possibility of a viral infection, a low blood oxygen level could have been caused by an underlying heart or lung disease, high altitude, or certain medicines.
Here are some oximeters. They are very small devices that can be used at home to take an oxygen saturation reading using just an index finger.