What are common reasons for inaccurate pulse oximeters readings?

Pulse oximeter measurements can be influenced by many variables such as skin pigment, body temperature, nail polish, movement, and perfusion. If the waveform tracing is erratic and low amplitude, this might be due to a weak signal or due to the patient moving. This can make it difficult for the oximeter to interpret the oxygen saturation accurately. Common reasons for poor waveform can include poor perfusion, irregular heart rate, or poor probe placement.  All of these factors can cause both underestimation and overestimation errors in oxygen saturation readings.

References: Lifebox Pulse Oximetry Learning Module 

Keywords: waveform, perfusion, battery, error