A fingertip pulse oximeter works by shining red and infrared light through your fingertip to measure the oxygen saturation in your blood.
Here's a more detailed breakdown:
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Light Emission: The device clips onto your fingertip and emits two wavelengths of light: red light and infrared light. These lights pass through your finger's tissues, including the nail, skin, and blood vessels.
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Light Absorption: Oxygenated hemoglobin (blood carrying oxygen) and deoxygenated hemoglobin (blood not carrying oxygen) absorb red and infrared light differently. Oxygenated hemoglobin absorbs more infrared light and allows more red light to pass through. Deoxygenated hemoglobin absorbs more red light and allows more infrared light to pass through.
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Light Detection: A sensor on the other side of your finger detects the amount of red and infrared light that passes through.
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Calculation: The pulse oximeter's internal computer analyzes the relative amounts of red and infrared light absorbed. Based on this, it calculates the percentage of oxygenated hemoglobin in your blood, known as the oxygen saturation (SpO2) level. This is usually displayed as a percentage on the device's screen. The device also detects changes in light absorption related to the pulsating blood flow, allowing it to determine your heart rate.
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Display: The pulse oximeter displays two key readings:
- Oxygen Saturation (SpO2): The percentage of hemoglobin in your blood that is carrying oxygen. A normal SpO2 reading is usually between 95% and 100%.
- Pulse Rate: Your heart rate in beats per minute (BPM).
In summary, a fingertip pulse oximeter utilizes the differential light absorption properties of oxygenated and deoxygenated hemoglobin to non-invasively estimate your blood oxygen saturation level and pulse rate.
