DPE Technique in Labor Epidural for Morbidly Obese Women
Condition: Morbid Obesity; Labor Pain
MeSH terms: Obesity, Morbid; Labor Pain
Study type: Interventional
Phase: Phase 4

Summary: 
      The primary purpose of this study is to determine differences in block quality between the
      "dural-puncture epidural" (DPE) and standard epidural (EPL) techniques for labor analgesia in
      the morbidly obese patient. The investigators hypothesize that when compared to the standard
      EPL, the DPE technique will improve block quality .

      Study participants will be randomized by computer-generated sequence to EPL or DPE arms,
      stratified by class of obesity (BMI 35-39.9 kg/m2, 40< 50 kg/m2 and ≥ 50 kg/m2) and by parity
      (nulliparous versus multiparous). All patients will receive a neuraxial technique in the
      sitting position at L3/4 or L4/5 using loss of resistance to saline. In the DPE group, a 25-g
      Whitacre needle will be used to puncture the dura. In both groups, the epidural catheter will
      be threaded 5 cm in the epidural space with an initiation dose of 15 ml of ropivacaine 0.1%
      with fentanyl (2 mcg/ml) over 6 minutes as per standard practice. After the initial loading
      dose and epidural pump is started, the blinded investigator will enter the patient's room to
      start data collection (time 0). Data will be collected for the first 30 minutes of epidural
      placement at 3,6,9,12,15,18 21, and 30 minutes to detect the time to achieve target pain ≤
      1/10, then assessed at standardized times (ever 2 hour) until delivery. Breakthrough pain
      will be managed by a standardized protocol. Other data to be collected will include: catheter
      adjustments and replacements, physician top-ups, asymmetrical block, pain score, motor block,
      sensory level to ice, hypotension, total anesthetic dose required, and PCEA use.

      The primary outcome of this study is block quality defined by a composite of five components:
      (1) asymmetric block after 30 minutes of initiation, (2) top-up interventions, (3) catheter
      adjustments (4) failed catheter requiring replacement, and (5) failed epidural requiring
      general anesthesia or replacement neuraxial anesthesia for emergency cesarean section.
      Secondary outcomes include time to numeric pain rating scale ≤1, maternal adverse events
      (hypotension, fetal bradycardia, PDPH), motor block, duration of second stage of labor, total
      labor epidural time, total anesthetic dose required, PCEA use, and mode of delivery.

      There is no increased risk/safety issue with placing a dural puncture technique than with
      epidural for labor analgesia.
    

Detailed description: 
      Purpose of the study:

      The primary purpose of this study is to determine if there are differences in block quality
      between the DPE and standard EPL techniques for labor analgesia in the morbidly obese
      patient. Establishing superiority of a technique is multifaceted and complex; therefore, the
      design of the study will define a set of measureable outcomes to assess these properties,
      which will be addressed in the subsequent sections. The investigators hypothesize that when
      compared to the standard EPL, the DPE technique will significantly improve block quality in
      this population.

      The secondary purpose of the study is to find an optimal maintenance regimen for epidural
      analgesia in the morbidly obese population. For the maintenance of epidural analgesia, it is
      common practice to use either continuous epidural infusion or a programmed intermittent bolus
      using a solution of ropivicaine 0.1% with fentanyl (2 mcg/mL). To date, there are no
      randomized prospective studies that investigate maintenance regimens in the morbidly obese
      parturient population. What has been shown is that super morbidly obese patients have
      increased intra-abdominal and intracranial pressure which increases pressure in the epidural
      space. Because of this elevated pressure, the epidural spread is increased, resulting in
      higher sensory blocks than necessary for adequate labor analgesia.15 An important consequence
      is that the morbidly obese parturient may experience additional undesirable side effects to a
      labor epidural: increased respiratory function, increased incidence of hypotension, and
      increased motor block.

      Design and procedures:

      The investigators propose a prospective, double-blinded, randomized trial. According to our
      patient population and incidence of morbid obesity, enrollment would likely occur over a 2 to
      3-year period. The investigators have a delivery rate of 3500 per year. Previous data from
      our institution show that at least 11% of our patients are morbidly obese. The investigators
      will therefore expect 800-900 morbidly obese women to deliver at our institution per year.
      The investigators anticipate to complete enrollment for the study in 1-2 years.

      Epidural technique:

      Once the patient requests a labor epidural, the usual standard of care for epidural placement
      will be initiated. The patient will have at least one 18g intravenous catheter and will
      receive 500-1000 milliliter (mL) fluid administration. Vitals will be monitored by the labor
      nurse, including continuous pulse oximetry, non-invasive blood-pressure monitoring, and
      external tocodynamometry. Anesthesia time-out will be performed by the anesthesia provider
      with participation from the nurse and the patient.

      All patients will receive a neuraxial technique in the sitting position at L3/4 or L4/5 using
      loss of resistance to saline. In the DPE group, a 25-g Whitacre needle will be used to
      puncture the dura. In both groups, the epidural catheter will be threaded 5 cm in the
      epidural space with an initiation dose of 15 ml of ropivacaine 0.1% with fentanyl (2 mcg/ml)
      over 6 minutes as per standard practice. Labor analgesia will be maintained by programmed
      intermittent bolus with 6 ml of the same solution every 45 minutes starting 30 minutes after
      the initial dose. Patients will have patient-controlled epidural analgesia (PCEA) available
      with an 8 ml dose per demand, every 10 minutes, for a maximum dose of 45 ml for every hour.

      Assignment of Study Cohorts:

      Study participants will be randomized by computer-generated sequence to EPL or DPE arms,
      stratified by class of obesity (BMI ≥35<40 kg/m2, ≥40<50 kg/m2 and ≥ 50 kg/m2) and by parity
      (nulliparous versus multiparous). Patients will be assigned to one of the four study arms by
      computer-generated, randomized sequence in order to balance baseline characteristics across
      the arms. This will be a double-blinded study. After the consented and enrolled participant
      requests labor epidural, a study member will give the anesthesia provider a sealed envelope
      with study assignment. The envelope will contain the instructions for placement of epidural
      with wither standard EPL or DPE technique and specified maintenance regimen of either
      Programmed Intermittent Epidural Bolus (PIEB) or Continuous Epidural Infusion (CEI).

      Protocol for Breakthrough Pain

        -  If the patient has uneven or unilateral level, the provider will withdrawal catheter 1cm
           from skin and bolus 5ml of epidural mix. As fetal heart rate allows for maternal
           repositioning, the patient will lay lateral position with unblocked side in the
           dependent position. (up to 3 catheter adjustments)

        -  If the patient has bilateral levels at that below T10 to ice, the patient will be
           administered 5 ml off epidural pump, up to 3 times in 15 minutes.

        -  If the patient has pain despite T10 levels, the provider will administer Fentanyl 100
           mcg via epidural.

        -  If analgesia continues despite these interventions up to 3 times within 30-60 minutes,
           the attending anesthesiologist will determine if epidural catheter needs replacement.
    

Intervention name(s): Dural puncture epidural (DPE); Standard Epidural (EPL); Dural puncture epidural (DPE); Standard Epidural (EPL)
Intervention type(s): Procedure; Procedure; Drug; Drug
Intervention description(s): Epidural with spinal needle placed to confirm cerebral spinal fluid (CSF) position. No intrathecal dosing; Standard epidural placement; Epidural with spinal needle placed to confirm CSF position. No intrathecal dosing. Ropivacaine 0.1% and Fentanyl 2mcg/mL.; Standard epidural placement. Ropivacaine 0.1% and Fentanyl 2mcg/mL.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Treatment