Inaccuracy of pulse oximetry in patients with severe tricuspid regurgitation

The accuracy of pulse oximetry was studied in a group of patients with severe tricuspid regurgitation. Measurements of arterial oxygen saturation from a finger and an ear probe were compared with those from a radial arterial blood sample analysed in vitro. Lower values were obtained using the pulse oximeter; the difference ranged from +2% to -11%. The discrepancies between pulse oximeter and laboratory oximeter readings were greater in this group of patients than in a control group who did not have tricuspid regurgitation. There was, however, no correlation between the magnitude of this discrepancy and either the peak central venous pressure or the venous pulse pressure.