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 × + 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%.