Effects of Different Local Anesthetic Concentrations With Epidural Tap Method for Labor Analgesia

This prospective, randomized study includes 70 ASA II primigravid women with cervical dilatation between 4-6 cm and demanding epidural analgesia during spontaneous vaginal delivery. Participants with pregnancy-related diseases (such as gestational hypertension, gestational diabetes, preeclampsia) and contraindications for neuraxial block (infection, coagulation disorder, severe hypovolemia, sepsis, neurological deficit, cardiac valve stenosis or hypertrophic obstructive cardiomyopathy) will be excluded from the study. Women with fetal malpresentation and fetal anomaly will also be excluded.

Participants will randomly be divided into 2 equal groups. Immediately before epidural placement, subjects will be marked a VAS score during an active contraction. All subjects will have an intravenous catheter placed and be monitored with NST, noninvasive blood pressure and pulse oximetry.

The epidural space will be identified by a loss of resistance technique to saline. CSF flow will be observed at L3-L4 or L4-L5 level by puncturing the dura with a 27 G needle before inserting the epidural catheter. A combined spinal epidural set with 18 G Tuohy needle will be used in both groups. In the first group, 20 mL of 0.125% bupivacaine + 2 mcg/mL fentanyl solution and in the second group, 20 mL of 0.0625% bupivacaine + 2 mcg/mL fentanyl solution will be administered as the first dose through the epidural catheter. Then, the visual analog scale (VAS) score will be aimed to be below 4 in both groups. Patients with a VAS score of 4 or higher 15 minutes after the first dose received, an additional 10 mL dose of the same solution will be given. An additional 10 mL dose also will be administered when the VAS score is 4 or higher until crowning.

Before the epidural catheter placed; age, weight, height, blood pressure of the participants, gestational week, use of oxytocin during delivery, cervical dilatation amount before the procedure and fetal heart rate will be recorded. After each dose of administration, whether maternal hypotension, fetal bradycardia, pruritus, nausea-vomiting or motor block development will be monitored. The total amount of drug administered through the epidural catheter, the time between applications, and the number of bolus doses administered will also be recorded.