USE OF PULSE OXIMETRY TO MONITOR VENOUS SATURATION DURING EXTRACORPOREAL LIFE-SUPPORT

Objective: To assess the ability of two different pulse oximeters to d isplay continuous venous oxygen saturation through an extracorporeal b ypass circuit with a degree of accuracy comparable to direct in-line o ximetry. Design: Prospective, comparison study of pulse oximeters (tes t oximeter 1 or test oximeter 2) and an in-line oximeter (test oximete r 3). Setting: A tertiary care neonatal intensive care unit. Patients: Sixty-five consecutive neonates with severe cardiorespiratory failure undergoing extracorporeal life support. Interventions: The accuracy o f the oximeters was determined by simultaneously comparing the saturat ion displayed by the pulse oximeters (test oximeters 1 and 2) and/or t he in-line oximeter (test oximeter 3) with the measured fractional ven ous oxygen saturation obtained at regular intervals from the extracorp oreal circuit. Main Outcome Measures: Venous oxygen saturation was the criterion standard used to determine accuracy. Bias was defined as th e mean difference between observed pulse oximeter or in-line oximeter values and the measured venous oxygen saturation. Mean biases were cal culated for venous oxygen saturation measurements between 55% and 99% at intervals of 10%. Precision (the standard deviation of the bias) wa s calculated for low (55% to 75%), medium (76% to 81%), and high (82% to 99%) venous oxygen saturation values. A total of 983 venous oxygen saturation measurements were made and compared with simultaneous oxime ter readings from test oximeter 1 (n = 600), test oximeter 2 (n = 478) , and test oximeter 3 (n = 587). Results: Test oximeter 1 was the most precise instrument at each level of venous oxygen saturation (SD, 4.0 to 4.8). Test oximeter 3 demonstrated the most consistent mean bias ( range, 8), but was the most inaccurate oximeter across all levels of v enous oxygen saturation. Conclusions: In addition to its known clinica l usefulness, pulse oximetry may serve as an adequate substitute for i n-line oximetry during extracorporeal life support.