The most common method to monitor blood oxygen saturation during polysomnography is:

The most common method to monitor blood oxygen saturation during polysomnography is:

• A. Pulse oximetry
• B. Capnography
• C. Arterial blood gas
• D. End-tidal CO2

Answer: (A)

Pulse oximetry provides continuous, real-time, noninvasive SpO2 data during sleep studies. A small sensor on the finger, toe, or earlobe uses two wavelengths of light to estimate how much oxygen is bound to hemoglobin in pulsatile arterial blood, giving both oxygen saturation and often heart rate. This setup is quick, comfortable, and ideal for overnight monitoring, allowing immediate detection of desaturation events associated with apneas or hypopneas and informing scoring and safety decisions. Capnography, on the other hand, measures CO2 in exhaled air and reflects ventilation status, not the actual oxygen content of the blood, so it doesn’t provide a direct measure of oxygen saturation. An arterial blood gas gives precise PaO2 and SaO2 but requires arterial access and is not suitable for continuous monitoring during a sleep study. End-tidal CO2 is a capnography measure of CO2 at the end of exhalation, again related to ventilation rather than oxygen saturation.

Pulse oximetry provides continuous, real-time, noninvasive SpO2 data during sleep studies. A small sensor on the finger, toe, or earlobe uses two wavelengths of light to estimate how much oxygen is bound to hemoglobin in pulsatile arterial blood, giving both oxygen saturation and often heart rate. This setup is quick, comfortable, and ideal for overnight monitoring, allowing immediate detection of desaturation events associated with apneas or hypopneas and informing scoring and safety decisions.

Capnography, on the other hand, measures CO2 in exhaled air and reflects ventilation status, not the actual oxygen content of the blood, so it doesn’t provide a direct measure of oxygen saturation. An arterial blood gas gives precise PaO2 and SaO2 but requires arterial access and is not suitable for continuous monitoring during a sleep study. End-tidal CO2 is a capnography measure of CO2 at the end of exhalation, again related to ventilation rather than oxygen saturation.