Programmed Intermittent Epidural Bolus for Labor Analgesia During First Stage of Labor 2

Brief Summary: Until recently, at Mount Sinai Hospital, epidural analgesia for labor pain was delivered with a pump that could only provide continuous infusion of the freezing medication in combination of pushes of medication activated by the patient, a technique called patient controlled epidural analgesia (PCEA). In the last decade or so, the literature has suggested that this continuous infusion of medication is not as effective as previously thought, and suggested that instead of continuous infusion, intermittent programmed pushes should be used. The investigators now have devices that are able to do that. Programmed intermittent epidural bolus (PIEB) is a new technological advance based on the concept that boluses of freezing medication in the epidural space are superior to continuous epidural infusion (CEI). The investigators are currently using pumps set up with PIEB, in addition to what the patient can deliver herself (PCEA). Studies have shown that delivering analgesia in this manner prolong the duration of analgesia, reduce motor block, lower the incidence of breakthrough pain, improve maternal satisfaction and decrease local anesthetic consumption. The investigators have recently concluded a study at MSH using PIEB where they observed excellent results. However, some patients exhibited higher than necessary sensory blocks. The investigators believe that the technique can be optimized by using the same dose of the freezing medication, but using a smaller volume of local anesthetic at a higher concentration. This optimization may also further reduce the amount of medication used by each patient. The hypothesis of this study is that there is an optimal interval time between PIEB boluses of 30 to 60 minutes at a fixed volume of 5 ml of bupivacaine 0.125% with fentanyl 2mcg/ml that will provide women the necessary drug requirements, thus avoiding breakthrough pain and need for PCEA or physician intervention.