Epidural Bolus for Labor Analgesia During Labor

At Mount Sinai Hospital, epidural analgesia for labor pain is delivered by programmed intermittent epidural bolus (PIEB), in combination with pushes of medication activated by the patient, a technique called patient controlled epidural analgesia (PCEA). Studies have shown that delivering analgesia in this manner can prolong the duration of analgesia, diminish motor block, lower the incidence of breakthrough pain, improve maternal satisfaction and decrease local anesthetic consumption comparing to a conventional continuous infusion. The use of this PIEB technique in routine practice has reduced the total consumption of local anesthetic and the percentage of patients requesting additional boluses (PCEA or manual rescues). However, at the same time, sensory blocks above those targeted for labor pain relief have been reported in our institution, suggesting that the spread of the freezing medication is wider than necessary. Based on the information already available in the literature, the investigators will conduct this study to determine the best regimen of PIEB achievable with a slower delivery speed. The hypothesis of this study is that PIEB boluses with 125 mL/h will decrease by 50% the incidence of women presenting sensory block to ice equal or higher than T6 as compared to a delivery rate of 250 mL/h.