Concerning pulse oximetry true is
Light absorption of both oxy and deoxy haemoglobin is equal at isobestic point of 805 nm. Bilirubin, carboxyhemoglobin and methaemoglobin can affect the reading of pulse oximeter. Pigmented skin doesn’t influence the reading.
Oxyhemoglobin and deoxyhemoglobin light absorption is equal at the isobestic point of 660nm
Measurements are accurate in the presence of high levels of bilirubin
Measurements are accurate in presence of carboxyhaemoglobin
Measurements are accurate in presence of pigmented skin.