Blood oxygen levels can be measured using several methods, most commonly through pulse oximetry and arterial blood gas (ABG) tests.
Pulse Oximetry: The Common Method
Pulse oximetry is a non-invasive and painless method that measures the oxygen saturation in your blood. This is usually done using a pulse oximeter, a small clip-like device placed on a finger or toe. The device works by emitting light through the finger and measuring the amount of light absorbed by oxygenated and deoxygenated hemoglobin in the blood. This provides a reading of the percentage of oxygenated hemoglobin, known as SpO2 (peripheral oxygen saturation). Readings are typically accurate within 2% of the actual value. [^1, ^2, ^3, ^4, ^5, ^6, ^7, ^8, ^9, ^10] Many smartwatches now incorporate pulse oximetry technology, allowing for convenient on-demand measurements. [^3, ^7] Pulse oximetry has become a standard of care in medicine because of its ease of use and immediate results. [^1]
Arterial Blood Gas (ABG) Test: A More Comprehensive Approach
The arterial blood gas (ABG) test is a more invasive method. It involves drawing a small sample of blood from an artery (usually in the wrist or groin) and analyzing it in a laboratory. The ABG test provides a more comprehensive measurement of blood gases, including oxygen levels (partial pressure of oxygen, or PaO2), carbon dioxide levels, and blood pH. This test offers a more detailed assessment of lung function compared to pulse oximetry. [^6] While it gives more specific data than pulse oximetry, it is more invasive and typically performed in a clinical setting.
Comparing the Methods
| Method | Invasiveness | Accuracy | Information Provided | Setting |
|---|---|---|---|---|
| Pulse Oximetry | Non-invasive | Within 2% | SpO2 (oxygen saturation percentage) | Anywhere (with device) |
| Arterial Blood Gas (ABG) | Invasive | Very Accurate | PaO2, CO2 levels, pH | Clinical setting |
In summary, pulse oximetry offers a simple, readily available method for measuring blood oxygen saturation, while the ABG test provides more detailed information through a slightly more complex procedure. The choice of method depends on the clinical context and the level of detail required.
[^1]: Pulse Oximetry
[^2]: Pulse Oximetry
[^3]: How to use the Blood Oxygen app on Apple Watch
[^4]: Oxygen level testing
[^5]: Pulse oximetry - Wikipedia
[^6]: Arterial Blood Gas (ABG) Test
[^7]: Measuring Blood Oxygen Levels on my Galaxy Watch
[^8]: Pulse Oximetry
[^9]: Blood Oxygen app on Apple Watch
[^10]: A pulse oximeter can measure oxygen saturation. It is a noninvasive device placed over a person's finger. It measures light wavelengths to determine the ratio of the current levels of oxygenated hemoglobin to deoxygenated hemoglobin. The use of pulse oximetry has become a standard of care in medicine.
