Pulse ox

Pulse Oximetry is a non-invasive method used to monitor the oxygen saturation of a patient's blood. This is achieved by passing a beam of red and infrared light through a pulsating capillary bed and then measuring the amount of light absorbed by the oxygenated and deoxygenated blood within this bed. The ratio of the amount of red light absorbed compared to the amount of infrared light absorbed is then used to calculate the oxygen saturation of the patient's blood.

Principle of Operation

The principle of operation of pulse oximetry is based on the red and infrared light absorption characteristics of oxygenated and deoxygenated hemoglobin. Oxygenated hemoglobin absorbs more infrared light and allows more red light to pass through. Deoxygenated (or reduced) hemoglobin absorbs more red light and allows more infrared light to pass through. Red light is in the 600-750 nm wavelength light band. Infrared light is in the 850-1000 nm wavelength light band.

Clinical Significance

Pulse oximetry is especially important in emergency medicine and in ICU settings, where patients' oxygen levels can change rapidly. It provides continuous, non-invasive monitoring of oxygen saturation, allowing for immediate detection of hypoxia, a condition that can lead to organ damage and potentially death if not promptly addressed.

Limitations

While pulse oximetry is a valuable tool, it has its limitations. It can only measure the percentage of hemoglobin that is oxygenated, and does not provide information about the total amount of oxygen in the blood or the body's overall oxygen consumption. It can also be affected by factors such as poor circulation, low body temperature, and the presence of nail polish or artificial nails.

See Also

• Blood Gas Test
• Hemoglobin
• Hypoxia
• Intensive Care Unit

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