Localization of the Epidural Space Using the Loss of Resistance Technique for Labour Analgesia: A Randomized Controlled Trial Comparing Air Versus Saline Solution

A local ethics committee has approved the study. A statistical power calculation was performed and 177 patients per group will be necessary to confirm a 20% difference of efficacy of the block at 30 minutes (α=0,05; β=0,1). Epidural catheter will be inserted and a standardized analgesic protocol will initiate. The efficacy of the block will be assessed after 30 minutes and at delivery. The apparition of adverse effects during puncture and labour will be annotated. The need for repuncture of the block and the repercussion of the technique on the delivery and the fetus will be recorded as well. At 24 hours, investigators will assess the incidence of pain at the site of puncture (PSP) and the level of maternal satisfaction on a 0 to10 numeric scale.