Reliability of a pulse oximeter in the detection of hyperoxemia

To evaluate the reliability of the Nellcor N200 pulse oximeter in the detection of hyperoxemia (oxygen tension > 80 mm Hg), we obtained 213 simultaneous recordings and measurements of transcutaneous oxygen saturation (SO2) and arterial oxygen tension (PaO2) in 50 patients. During 95% of measurements with PaO2 > 80 mm Hg, SO2 was > or = 96%; SO2 was also > or = 96% in 20% of measurements with PaO2 < or = 80 mm Hg (false-positive results for hyperoxemia). With the upper alarm limit set at 95%, the pulse oximeter identified 95% of hyperoxemic instances while allowing PaO2 to be kept to > 60 mm Hg.