The Contribution of Continual Foetal OxygenSaturation (FSpO2) by Means of Intrapartum FoetalPulse Oximetry (IFPO) to the Diagnosis of Acute FoetalHypoxia

Overview

Objective:
The aim of the study was to evaluate the possibility of lowering the Caesarean Sectionrate in patients presenting the signs of intrauterine hypoxia on CTG tracing by evaluating thefoetal oxygen saturation (FSpO2) by means of intrapartum foetal pulse oximetry (IFPO).Design: Open prospective study.Setting: 1 st Department of Gynecology and Obstetrics, Medical Faculty of Masaryk University,Brno.Methods: From January 1, 1999 to December, 1999 68 patients were enroled in the study. For theapplication of the IFPO sensor the patient had to meet the following criterias: patient’s informedconsensus, pregnancy > or = 36 weeks, regular uterine contractions, rupture of membranes, cervi-cal dilatation of > or = 2 cm, singleton pregnancy, cephalic occiput presentation, no sings ofvaginal infection, acute foetal hypoxia on CTG tracing: (baseline heart rate < 100 beats/min ofdifferent patterns. Progressive bradycardia: baseline heart rate gradualy decreases betweencontractions (DIP II, DIP 0). Persisting bradycardia, baseline < 80 beats/min. Baseline tachy-cardia (> 150 beats/min) with reduced variability and/or severe variable (DIP 0) and late decele-rations (DIP II).The IFPO used - Nellcor N-400. In all patients that fulfilled the above mentioned criteria duringthe first stage of labor the sensor was applied preferably on the posterior cheek of the foetus andthe FSpO2 values were continuously monitored up to the complete dilatation. The treshold of theintrapartum foetal hypoxia (FSpO2 values) was considered < 30 % for more than 10 minutes.In cases of normal FSpO2 values the delivery was conducted vaginaly even if the CTG tracingcontinued to signalise intrauterine hypoxia. In case of pathologic FSpO2 values, Caesarean Secti-on was performed.Results: IFPO is an easy feasible method and in all cases the values of FSpO2 were obtained. Themethod has no serions side effects neither in the mother nor in the foetus. Newertheless thepresence of the sensor in the uterine cavity provokes often unpleasant feelings and limitates themother in free movements. In all suspicious CTG tracings (17) no Caesarean Sections were perfor-med after the verification of the foetal hypoxia by means of FSpO2 evaluation. In 51 patientsa pathologic CTG tracing indicating the performance of Caesarean Section was present. AfterFSpO2 evaluation the Caesarean Section was performed only in 11 (21,6 %) patients. The remai-ning 40 (78,4 %) delivered vaginaly. Between these two groups there was statistical difference inthe values of FSpO2 and postpartum cord pH. The state of newborns evaluated according to theApgar score did not significantly differ in the two groups.Conclusion: These preliminary results indicate that taking in an account foetal SpO2 evaluated byIFPO in the 1 st stage of labor in cases of pathologic CTG tracing (late and variable deceleration)indicating Caesarean Section, > 50 % of these may be saved with identic perinatal outcome (Apgarscores, cord pH).

Key words:
foetal oxygen saturation (FSpO2), intrapartum foetal pulse oximetry (IFPO), acute