Programmed Intermittent Epidural Bolus for Labor Analgesia During First Stage of Labor: A Sequential Allocation Trial to Determine the Optimum Interval Time Between Boluses of a Fixed Volume of 2.5ml of Bupivacaine 0.25% Plus Fentanyl 8 mcg/ml
Condition: Labor Pain
MeSH terms: Labor Pain
Study type: Interventional

Summary: 
      Programmed intermittent epidural bolus (PIEB) is a technique of epidural analgesia in which
      boluses of local anesthetic solutions are injected into the epidural space at a fixed time
      interval. Despite the increasingly popular use of PIEB for labor analgesia, the optimum
      regimen of drug delivery has yet to be determined. The outcomes of a chosen regimen will
      depend on the local anesthetic solution used (drug, concentration and mass) and the
      parameters established for the PIEB, typically associated with patient controlled epidural
      analgesia (PCEA). Also, the optimum regimen will depend on the anesthetic and obstetric
      outcomes of interest.

      The investigators have conducted several studies aiming at establishing the optimum PIEB
      regimen for the patient population at Mount Sinai Hospital. High sensory block levels
      obtained in some of the previous studies conducted at Mount Sinai Hospital and in other
      studies in the literature, in spite of not determining adverse effects, suggest an imperfect
      use of the technique, with an exaggerated and unnecessary spread of the epidural mixture. It
      is possible that by limiting the spread of the local anesthetic mixture, better analgesia can
      be provided with less overall consumption of local anesthetic. The investigators wanted to
      conduct a study using boluses of 2.5 mL of bupivacaine 0.25% with fentanyl 8 mcg/mL. This
      would maintain the same dose of local anesthetic used in previous studies, but in a much
      smaller volume. This concentration and volume of bupivacaine has not been tried before as a
      PIEB regimen.

      The hypothesis of this study is that the optimum interval time between PIEB boluses of 2.5 mL
      of 0.25% bupivacaine plus fentanyl 8 mcg/ml will be between 30 and 60 minutes.
    

Detailed description: 
      The investigators have conducted several studies aimed at establishing the optimum PIEB
      regimen for the patient population at Mount Sinai Hospital. The first study was to determine
      the effective interval of PIEB in 90% of women during first stage of labor (EI90), while
      using a fixed bolus of 10 mL of bupivacaine 0.0625% with fentanyl 2 μg/mL. This study showed
      that the PIEB time interval to provide effective analgesia is approximately 40 minutes, which
      corresponds to an hourly consumption of 9.4 mg of bupivacaine. In that study, however, 44% of
      the women experienced sensory blocks to ice above the T6 level (although not associated with
      motor block or hypotension).

      The investigators subsequently conducted another study with the same anesthetic solution and
      the same PIEB interval of 40 minutes, to determine the effective volume (dose) of local
      anesthetic to produce the same outcome of effective analgesia without breakthrough pain. The
      conclusion was that the volume (dose) could not be reduced without compromising efficacy of
      the technique, and not surprisingly, the sensory block distribution was very similar to that
      in the first study. The investigators believe that the high sensory block levels obtained the
      previous studies and in other studies in the literature suggest an imperfect use of the
      technique, with an exaggerated and unnecessary spread of the epidural mixture. The
      investigators then conducted a third study to determine the effective time interval between
      boluses of more concentrated bupivacaine 0.125% 5ml plus fentanyl 2 mcg/ml. The EI90 for
      boluses of 5ml of bupivacaine 0.125% with fentanyl 2 mcg/mL was found to be approximately 35
      minutes. Similar to the two previous studies, the incidence of women exhibiting sensory block
      to ice >T6 was still high, approximately 58.4%.

      This study will further pursue the effect of volume reduction while maintaining the dose of
      local anesthetic. It may be true that a bolus of 5mL was still too large of a volume to limit
      the epidural spread. A more limited spread could lead to better usage of the local
      anesthetic, even reducing its hourly consumption.
    

Intervention name(s): Bupivacaine
Intervention type(s): Drug
Intervention description(s): 0.25% bupivacaine plus fentanyl 8 mcg/ml
Other intervention name(s): Marcaine
Intervention MeSH terms: Bupivacaine
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Treatment
Keywords: Epidural; Labor analgesia; Programmed intermittent epidural bolus