Open Randomized Controlled Trial to Evaluate the Efficacy and Safety of Remifentanil Versus Nitrous Oxide in External Cephalic Version at Term in Singleton Pregnancy in Breech Presentation

Objectives: The objective is to demonstrate the superiority of remifentanil versus nitrous oxide as adjuvant analgesic treatment to increase the chances of success of external cephalic version in the management of non-cephalic presentation in women with singleton pregnancy at term. Another objective is to compare their safety, tolerability and acceptability. Methodology: single-center clinical trial, randomized, open, parallel-group and sequential design, with active comparator. Pragmatic approach. Sequential design of O'Brien-Fleming with two interim analysis. Analysis by intention to treat. Comparison of the rate of successful version, referred to analgesic effect, safety, caesarean rates and acceptability rate of the procedure for pregnant women.