Epidural space localization using loss of resistance technique with air (ALOR) is controversial in obstetric analgesia due to a minor efficacy and risk of complications, compared with loss of resistance technique with saline (SLOR). This randomized prospective study will compare the efficacy and incidence of most common complications of both techniques in obstetric analgesia.
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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Masking
DOUBLE
Enrollment
400
The epidural puncture will be performed in the L3-L4 or L4-L5 interspinous space in a seated position. A local anaesthesia with 2-5 mL of 2% lidocaine will be applied subcutaneously using a 25Gm 25mm needle. The epidural space will be localized using a Perifix® set by inserting the Tuohy needle in the ligamentum flavum or the interspinous space. The obturator will be then withdrawn and the low resistance syringe filled with 3-5mL of air will be connected. After localizing the epidural space, the catheter will be inserted 3-5 cm. An aspiration test will be performed through the catheter in a decline position with a 2 mL syringe, and a 3mL test dose with bupivacaine 0,25% plus epinephrine 1/200.000 will be administered to exclude an intradural or an intravascular position of the catheter.
The epidural puncture will be performed in the L3-L4 or L4-L5 interspinous space in a seated position. A local anaesthesia with 2-5 mL of 2% lidocaine will be applied subcutaneously using a 25Gm 25mm needle. The epidural space will be localized using a Perifix® set by inserting the Tuohy needle in the ligamentum flavum or the interspinous space. The obturator will be withdrawn and the low resistance syringe filled with 3-5mL of saline solution will be connected. After localizing the epidural space, the catheter will be inserted 3-5 cm. An aspiration test will be performed through the catheter in a decline position with a 2 mL syringe, and a 3mL test dose with bupivacaine 0,25% plus epinephrine 1/200.000 will be administered to exclude an intradural or an intravascular position of the catheter.
Analgesia obtained 30 minutes after the puncture of the epidural block (variation of pain score)
Time frame: 30 min
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