ED50 and ED95 of Isobaric Bupivacaine for Post-Partum Bilateral Tubal Ligation
Condition: Anesthesia, Local
Study type: Interventional

Summary: 
      Spinal anesthesia is one of the preferred anesthetic techniques for post-partum bilateral
      tubal ligation (PBTL). Bupivacaine is the most commonly used local anesthetic for neuraxial
      anesthesia for post-partum tubal ligation. Typically, hyperbaric bupivacaine would be
      injected into the spinal (intrathecal) space via a spinal needle; however, ongoing medication
      shortages have resulted in limited availability on a local and national level. One proposed
      alternative is isobaric bupivacaine; however, studies investigating its use for post-partum
      bilateral tubal ligation are limited.

      The purpose of this prospective study is to determine the minimal effective dose (ED50 and
      ED95) of isobaric bupivacaine for adequate anesthesia during post-partum tubal ligation after
      vaginal delivery.
    

Detailed description: 
      This prospective study proposes to enroll 40 post-partum women who are undergoing elective
      post-partum bilateral tubal ligation. The patient will be positioned sitting, and combined
      spinal anesthesia will be performed at L2-3 or L3-4 level. The presence of an epidural
      catheter enables the provider to supplement the spinal anesthetic if required. The starting
      dose of isobaric bupivacaine will be 10 mg based on prior similar studies1,4 and our
      institution's current practice. The dose of intrathecal isobaric bupivacaine was decided by
      using the up-down sequential method.

      The motor block will be graded by a modified Bromage score: Score 1 = complete block, unable
      to move feet or knees; 2 = almost complete block, able to move feet only; 3 = partial block,
      just able to move knees; 4 = detectable weakness of hip flexion while supine, full flexion of
      knees; 5 = no detectable weakness of hip flexion while supine; and 6 = able to perform
      partial knee bend. The score of 1 or 2 within 10-15 minutes of injection will be evaluated as
      successful motor block.

      The success of the sensory spinal block will be noted when bilateral T6 sensory level to
      pinprick is attained after 10 mins from the intrathecal drug administration, this is in
      accordance with previous studies1.

      If spinal anesthesia is inadequate, the epidural catheter will be dosed up for
      supplementation. All observations, including block characteristics and the associated outcome
      (i.e., adequate or inadequate block), will be evaluated by a dedicated anesthesia provider.

      Intraoperative adverse effects, such as hypotension, bradycardia, nausea, or vomiting,
      pruritus, or shivering were noted. Hypotension is defined as a decrease of more than 20% in
      basal systolic blood pressure within 30 minutes of intrathecal injection. The management of
      blood pressure including dose of pressor: phenylephrine and ephedrine will be at the
      discretion of the attending anesthesiologist. The use of pressor and anti-emetics will also
      be recorded.

      The study will be take place in standard clinical context. The study does not deviate from
      our current practice, which includes the use of combined spinal anesthesia where the epidural
      catheter is available if supplemental local anesthetic is required.
    

Intervention name(s): Dose adjustment of bupivacaine
Intervention type(s): Other
Intervention description(s): Spinal bupivacaine dose will be adjusted according to previous patient experience.
Other intervention name(s): Spinal bupivacaine dose adjustment
Intervention MeSH terms: Bupivacaine
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Other