Effectiveness of nitrous oxide in external cephalic version on success rate: A randomized controlled trial

Abstract

Introduction Approximately 4% of singleton pregnancies at term are in breech presentation. External cephalic version (ECV) can reduce the risks of noncephalic birth and cesarean delivery, but this maneuver can be painful. Our aim was to analyze the effect of administering inhaled nitrous oxide for analgesia on the ECV success rate. Material and methods This prospective, randomized, single‐blind, controlled trial included women with singleton pregnancies in breech presentation at term who were referred for ECV in a tertiary care center. Women were assigned according to a balanced (1:1) restricted randomization design to inhale either nitrous oxide (N2O) in a 50:50 mix with oxygen or medical air during the procedure. The main outcomes reported are the ECV success rate, degree of pain, adverse event rate, and women’s satisfaction. Trial registration: ClinicalTrials.gov Identifier: NCT01948115. Results The study included 150 women (nitrous oxide group: n = 74; medical air: n = 76). Inhaled nitrous oxide was not associated with a higher ECV success rate than medical air (24.3 vs 19.7%, P = 0.51). Among parous women (n = 34 in each group), the ECV success rate appeared higher in the nitrous oxide group, respectively 47.1% (n = 16) vs 23.5% (n = 8) (P = 0.042). Neither the median pain level nor adverse event rates differed significantly in women with inhaled nitrous oxide compared with medical air. Conclusions Use of an equimolar mixture of oxygen and nitrous oxide during ECV appears safe. Although it does not seem to change the overall success rate, it may increase success in parous women.

Exceptionally low external cephalic version success rate should be addressed

“…We read the research by Dochez et al with great interest. 1 The authors performed a meticulous randomized controlled study evaluating the effect of inhaled nitrous oxide (N 2 O) on ECV success rates, reporting acceptable safety and implying that N 2 O might be beneficial among parous women regarding ECV success rates. Although the authors are to be congratulated for performing a randomized controlled trial subjecting this novel practice to evaluation, several points regarding the study should be clarified.…”

A low success rate of external cephalic version, a French exception?

“…We thank Levin et al for their comments 1 about our article entitled "Effectiveness of nitrous oxide in external cephalic version on success rate: a randomized controlled trial". 2 Although breech presentation has long been an indication for cesarean delivery, when strict criteria are met, planned vaginal delivery remains possible. 3 In all cases, nonetheless, it is recommended that women with fetuses in breech presentation be offered external cephalic version (ECV).…”