Methoxyflurane (Penthrane) Inhalation in Labor

A study was performed to assess the value of two inhalers designed to deliver methoxyflurane (MOF) in labor. The Cyprane inhaler provided higher blood levels of MOF and a greater degree of maternal acceptance than the Analgizer, but these positives may have been related to how the Analgizer was administered. MOF does cross the placenta but in our study it was safe fur both mother and fetus except for a few episodes of mild fetal tachycardia. In one patient postpartum bleeding was severe enough to require control with oxytocin and manual massage of the uterus. The incidence of uterine inertia and atonia observed in this series should be kept in mind when MOF is 'administered during labor. The full use of the drug should be reserved for patients of low parity without potential felopelvic disproportion. MOF administration is safe in the terminal part of the second stage of labor and in combination with a pudenal block as a method of delivery. No fetal or maternal ill effects from MOF were detected in the postpartum period