///2019 Abstract Details
2019 Abstract Details2019-07-13T07:45:15-05:00

Spinal anesthesia for postpartum tubal ligation: a retrospective analysis of the association of intrathecal bupivacaine dosing with inadequate surgical blocks

Abstract Number: T2H-463
Abstract Type: Original Research

Sydney E Reed AB1 ; Matthew Fuller MS2; Ashraf S Habib MBBCh, MSc, MHSc, FRCA3

Background: Previous studies investigating intrathecal bupivacaine dosing for postpartum tubal ligation (PPTL) present conflicting conclusions. An early study reported that PPTL patients required 30% more intrathecal bupivacaine than those who underwent cesarean delivery (CD) [1]. Similarly, another study showed that the same intrathecal bupivacaine dose yielded higher sensory blocks for CD as compared to PPTL [2]. Yet a different study reported adequate surgical blocks for PPTL with 7.5 mg of hyperbaric bupivacaine, a dose lower than that used for CD [3]. As such, we performed a retrospective database analysis to assess the rates of inadequate spinal anesthesia for PPTL with different doses of hyperbaric bupivacaine.

Methods: Anesthetic records of women who underwent PPTL under spinal anesthesia with hyperbaric bupivacaine between 2003 and 2018 were examined. An inadequate block (primary outcome) was defined as requiring supplementation with IV analgesics such as ketamine, propofol, or fentanyl > 50mcg, requiring a repeat block, or conversion to general anesthesia (GA). A failed block was defined as requiring a repeat block or conversion to GA. Cases in which there was no evidence of any block after the spinal or in which IV analgesics were given before but not after block placement were excluded. Patients were categorized into three groups based on hyperbaric bupivacaine dose [7.5-9.75mg (group 1), 10.5-12mg (group 2), and ≥13.5mg (group 3)] for analysis.

Results: 448 women met inclusion criteria and were included in the analysis (n=14, 333, and 101 in groups 1, 2, and 3 respectively). The results are summarized in the table. An inadequate block occurred in 20.8% of cases [28.6%, 21.6%, and 16.8% in groups 1, 2, and 3, respectively (p = 0.41)] and a failed block occurred in 5.1% of cases [14.3%, 5.4%, and 3.0% in groups 1, 2, and 3, respectively (p = 0.15)].

Conclusion: Lower doses of bupivacaine were associated with relatively high rates of inadequate and failed blocks. However, the relatively small sample size limits the statistical power of this study to detect differences between bupivacaine dose ranges. Larger studies are needed to further evaluate the optimal dosing of bupivacaine for PPTL.

References:

1. Abouleish EI. Anesth Analg. 1986;65:897-900.

2. Teoh WH. Int J Obstet Anesth. 2008;17:228-232.

3. Huffnagle SL. Reg Anesth Pain Med. 2002;27:284-288.



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