Any discoloration of the nail bed can affect the transmission of light through the digit. dark nail polish, such as blue, green, brown, or black colors, and bruising under the nail can limit the transmission of light and result in an artificially decreased Spo2 value. If the nail polish cannot be removed, the sensor can be placed in a lateral side-to-side position on the finger to obtain readings if no other method of sampling the arterial bed is available
