One key limitation of pulse oximetry is:

One key limitation of pulse oximetry is:

• A. It is invasive and requires arterial blood sampling.
• B. It provides completely accurate readings in all conditions.
• C. Movement artifact, poor perfusion, and abnormal skin pigmentation can degrade accuracy.
• D. It can only measure COHb.

Answer: (C)

Pulse oximetry estimates arterial oxygen saturation by sending two wavelengths of light through tissue and detecting the pulsatile arterial signal. It’s quick and noninvasive, but its accuracy isn’t perfect in real-world conditions. Movement artifact can create rapid signal fluctuations that misleadingly skew readings. Poor perfusion—such as in cold extremities or shock—weakens the pulsatile signal and makes the saturation estimate unreliable. Abnormal skin pigmentation can alter how light is absorbed, introducing bias in the calculation. Taken together, these factors can degrade the accuracy of pulse oximetry, which is why they are a well-recognized limitation of the device.

Pulse oximetry estimates arterial oxygen saturation by sending two wavelengths of light through tissue and detecting the pulsatile arterial signal. It’s quick and noninvasive, but its accuracy isn’t perfect in real-world conditions. Movement artifact can create rapid signal fluctuations that misleadingly skew readings. Poor perfusion—such as in cold extremities or shock—weakens the pulsatile signal and makes the saturation estimate unreliable. Abnormal skin pigmentation can alter how light is absorbed, introducing bias in the calculation. Taken together, these factors can degrade the accuracy of pulse oximetry, which is why they are a well-recognized limitation of the device.