THE ACCURACY OF A FIBEROPTIC OXIMETER OVER A WIDE-RANGE OF ARTERIAL OXYGEN-SATURATION VALUES IN PIGLETS

A piglet model was used to evaluate the accuracy of a fiberoptic oxime ter over a wide range of arterial oxygen saturation (SaO(2)) values. I n eight anaesthetized piglets, the inspired oxygen concentration was v aried from 30% to 6% resulting in a SaO(2) range from 100% to 15%. Pai red data of the Opticath(R) fiberoptic catheter, which was placed in t he descending aorta, and blood sample SaO(2) values assessed by a mult iwavelength oximeter, were analysed. After in vitro calibration accord ing to the manufacturer's instruction, the fiberoptic catheter started to underestimate the SaO(2) below 78%, worsening towards lower SaO(2) values. The overall bias was -3.4% and the precision 3.8%. An off-lin e fit with a non-linear model resulted in a standard deviation of resi duals of 2.68. After several in vivo calibration adjustments when the fiberoptic oximeter deviated more than 4% from the blood sample value, the bias was eliminated over the total SaO(2) range and the precision was 3.7%. The Opticath(R) fiberoptic oximeter could have an accuracy for the whole SaO(2) range between 15-100% close to the accuracy of th e multiwavelength oximeter, when the fiberoptic oximeter is adapted fo r the underestimation below 78% SaO(2).