Ear oximetry during progressive hypoxia

The BIOX III Pulse oximeter for measuring arterial oxygen saturation (SaO2) was compared during rest and under progressively hypoxic conditions, with SaO2 values based on arterial blood samples. The measurements were performed in 16 subjects undergoing tests of ventilatory response to hypoxia, by a rebreathing method. For each individual subject, there was a linear response relationship (r = 0.99), while for all 126 comparative values the regression equation was: y = 0.83 X + 14.7 (r = 0.98). The observed ventilatory response was lower when the calculations were based on oximeter readings. We conclude that the oximeter has acceptable correlation between the BIOX III and SaO2 measurements for clinical use, especially when SaO2 is above 70%.