HUMAN FETAL INTRAPARTUM OXYGEN-SATURATION MONITORING - AGREEMENT BETWEEN READINGS FROM 2 SENSORS ON THE SAME FETUS

OBJECTIVE: Our purpose was to assess the level of agreement between ox ygen saturation values obtained from two identical sensors used on dif ferent sides of the face of the same human fetus during labor. STUDY D ESIGN: Two identical fetal pulse oximeter sensors were placed on 12 fe tuses during uncomplicated labor at less than or equal to 38 weeks' ge station. Oxygen saturation, fetal heart rate, and uterine activity wer e recorded. The agreement between synchronous values of oxygen saturat ion was assessed by calculating the mean difference and SD of the diff erence. The SD of a single sensor was estimated as the SD of the diffe rence divided by the square root of 2. RESULTS: The mean oxygen satura tion value returned from one sensor was 49.2% and from the other 49.9% ; the mean difference was -0.7%. The SD of the difference was 7.5%, an d the 95% limits (+/-2 SDs of the difference) were -15.5% to 14.1%. Th e SD from a single sensor was estimated as 5.3%. CONCLUSIONS: There wa s no clinically significant difference between the oxygen saturation v alues returned from two identical sensors on the one fetus. The magnit ude of the SD from a single sensor must be taken into account when an arbitrary ''cutoff'' or ''action'' oxygen saturation value in a clinic al setting or trial is defined.