What effect does refusing to remove fingernail polish prior to pulse oximetry have on the reading?

Refusing to remove fingernail polish prior to pulse oximetry can potentially lead to a false high reading. Pulse oximeters work by passing two wavelengths of light through the skin to measure the saturation of oxygen in the blood. Fingernail polish, especially if it is dark or opaque, can interfere with the light transmission, causing the device to misinterpret the signals received.

This misinterpretation can lead the pulse oximeter to believe that more oxygen is present in the blood than is actually the case, resulting in a falsely elevated reading. In practical settings, it’s recommended to remove any decorative polish or artificial nails to ensure the accuracy of the pulse oximetry measurements.