Minimum pulse pressure and peripheral temperature needed for pulse oximetry during cardiac surgery with cardiopulmonary bypass.

The lowest values of pulse pressure (dPP) and peripheral temperature (Tp) associated with reliable readings from three different pulse oximeters (Biox Ohmeda 3700, Datex Satlite, and Nellcor N-200) were assessed, along with the ability of the pulse oximeters to work immediately before and after total cardiopulmonary bypass (CPB). The lowest mean dPP with a reliable O2 saturation reading was 13 mm Hg and the lowest mean Tp was 23.6 degrees C. The dPP needed for a reliable reading before total CPB did not differ significantly from that needed after total CPB. No significant differences in performance were found among the three oximeters during the study.