Pulse oximeters are unable to differentiate between oxygen and carbon monoxide bound to hemoglobin. Readings in the presence of carbon monoxide are falsely elevated. pulse oximetry should never be used in suspected cases of carbon monoxide exposure. An arterial blood gas reading always should be obtained to determine the accurate oxygen saturation.
It has been suggested that dark skin may affect the ability of the pulse oximeter to detect arterial pulsations. one study found a more frequent difference between the spo2 and sao2 with black patients compared with lighter skinned patient ,another study did not find a significant difference
