Umbilical arterial blood flow and plasma prostaglandin E2 concentrations during arousal and breathing movements in fetal sheep.

To investigate the effects of lung distension and oxygenation on umbilical blood flow (UBF) and plasma prostaglandin E2 (PGE2) in relation to arousal and stimulation of breathing movements, we studied eight chronically instrumented, unanesthetized fetal sheep between 137 and 143 d of gestation. Electrocorticogram, electro-oculogram, nuchal and diaphragmatic electromyograms, arterial pH and blood gas tensions, Hb oxygen saturation, body temperature, and UBF were recorded in each fetus. Electrocorticogram, electro-oculogram, and nuchal electromyograms were used to define sleep states. No sooner than 4 d after surgery, fetal lungs were distended with 100% O2 or N2 in a randomized order via an in situ Y-endotracheal tube. PGE2 concentrations were analyzed by RIA. A significant increase in fetal arousal and stimulation of breathing during nonrapid eye movement sleep was observed during lung distension with O2 as compared with control periods and lung distension with nitrogen. In all sleep states, UBF significantly decreased during oxygenation as compared with the control values. However, no significant correlation was observed between the time of the onset of arousal and the decrease in UBF. Lung distension with N2 resulted in increased plasma PGE2 concentrations, whereas, no change was observed during oxygenation. Our data suggest that an increase in fetal partial pressure of arterial O2 leads to a decrease in UBF. However, the onset of arousal and stimulation of breathing during lung distension and oxygenation were not dependent on a decrease in plasma PGE2 concentrations.

Preinduction cervical ripening: a comparison of intracervical prostaglandin E2 gel versus the Foley catheter.

OBJECTIVE: Both prostaglandin E2 gel and an intracervical balloon catheter have been shown to be effective for cervical ripening. The purpose of this study is to compare the efficacy of intracervical prostaglandin E2 gel with an intracervical Foley catheter for preinduction cervical ripening. STUDY DESIGN: A randomized, prospective study was conducted in the Maternity Care Center at the Foothills Hospital at Calgary, Alberta, Canada. Patients with a Bishop score < or = 4 and meeting inclusion and exclusion criteria were included. Thirty patients were randomized to receive prostaglandin E2 gel and 36 to receive an intracervical Foley catheter on the evening before induction. Induction then proceeded the following morning by the preferred method of the attending physician. RESULTS: The groups were comparable with respect to maternal age, parity, gestational age, reason for induction, and initial Bishop scores. Both groups had a significant change in Bishop score (4.1 +/- 0.4 and 4.8 +/- 0.5, respectively, p < 0.001); however, there was no significant difference between the groups. There was no significant difference in side effect profile, intrapartum complications, or delivery mode. Six cesarean sections (17.6%) were performed in the Foley group and seven (25%) in the prostaglandin E2 gel group (not significant). The induction-to-delivery interval was 16.0 +/- 1.7 hours in the Foley group and 21.5 +/- 3.2 hours in the prostaglandin E2 gel group (p = 0.014). Apgar scores, cord gases, and neonatal birth weight showed no difference between the groups. CONCLUSION: This study has shown that for preinduction cervical ripening there is no difference in efficacy between intracervical prostaglandin E2 gel or an intracervical Foley catheter.