In vitro accuracy of three blood O2 saturation optic catheter systems.

OBJECTIVE

The measure of the precision and accuracy of three optic SvO2 systems in vitro (SAT-2 Baxter, oximetrix 3 Abbott, HEMOPRO-2 Spectramed in a wide range of saturations (24-85%) and hematocrit (20-40%).

DESIGN

In vitro comparison of the results given by a Co-Oximeter and the SvO2 systems.

MEASUREMENTS AND RESULTS

144 blood samples were tonometered with a variety of gas mixtures. Measurements of SvO2 were compared to those obtained by means of a Co-Oximeter, the difference (dSO2) between paired values were calculated. Precision was evaluated from confidence intervals (2SD) and accuracy was tested using dSO2 figures. As there was no difference in either precision or accuracy among catheters for a given system, data obtained from a given system were pooled. Mean precision was 14.2%, 8.6%, 9% for the Spectramed, Baxter and Abbott systems, respectively.

CONCLUSION

The rather low reliability of the optic method should be borne in mind in patients with low SvO2 and/or low hematocrit.