MULTICENTER STUDY ON THE CLINICAL-VALUE OF FETAL PULSE OXIMETRY .1. METHODOLOGIC EVALUATION

OBJECTIVE: Our purpose was to evaluate the feasibility of intrapartum fetal pulse oximetry, the distribution of fetal oxygen saturation valu es, and the relationship with the neonatal outcome in a population wit h an abnormal fetal heart rate. STUDY DESIGN: A prospective multicente r observational study was performed from June 1994 to November 1995. F etal oxygen saturation was continuously recorded with use of a Nelicor N-400 fetal pulse oximeter in case of an abnormal fetal heart rate du ring labor. Simultaneous readings of fetal oxygen saturation and fetal blood analysis were obtained at inclusion and before birth. Feasibili ty, adverse effects, distribution of fetal oxygen saturation values, a nd relationship with neonatal outcome were assessed, RESULTS: One hund red seventy-four patients were included. From 172 attempted sensor pla cements, the procedure was impossible in three cases and fetal oxygen saturation values were obtained in 164 cases (95.3%). Physicians consi dered sensor placement an easier task than an attempt at fetal blood a nalysis [easy in 87.5% vs 78.9% far fetal blood analysis, p = 0.03). T he mean reliable signal time (+/-SD) was 64.7% +/- 32% during the firs t stage. There were no serious adverse effects in the study population . The mean fetal oxygen saturation during the first stage of labor was 42.2% +/- 8.0% (10th to 90th percentile range 30% to 53%). Fetal oxyg en saturation was significantly correlated with scalp pH (r = 0.29, p = 0.01) but not with neonatal umbilical artery pH or gas values. There was a significant association between low fetal oxygen saturation (<3 0%) and poor neonatal condition. CONCLUSION: The feasibility of fetal pulse oximetry is satisfactory in clinical practice. It is easy to use and provides a fair rate of recorded values, even in a population wit h suspicion of fetal distress. A low fetal oxygen saturation is signif icantly associated with an abnormal neonatal outcome.