///2012 Abstract Details
2012 Abstract Details2019-08-02T19:38:42-05:00

Intrathecal bupivacaine dosing for post partum tubal ligation: a retrospective analysis of inadequate and failed blocks

Abstract Number: T-32
Abstract Type: Original Research

Shannon Tew MD1 ; Ashraf S Habib MD2

Background: The optimal dose of intrathecal bupivacaine for postpartum tubal ligation (PPTL) is not clear. A previous study suggests that 30% greater local anesthetic dose is required 8-24 hours postpartum as compared to cesarean section dosing (1). However, a recent study suggests that 7.5 mg of hyperbaric bupivacaine provides adequate anesthesia for PPTL compared to doses of 10.0 or 12.5 mg (2). We therefore performed a retrospective database analysis to assess the success rate of spinal anesthesia for PPTL following the use of different bupivacaine doses.

Method: Following IRB approval, we examined anesthetic records of women who underwent PPTL under spinal anesthesia with bupivacaine from 2003 to 2012. The block was deemed inadequate if a general anesthetic (GA) or repeat spinal/epidural were performed or if adjuvant medications were required such as ketamine, propofol, or IV fentanyl >50 mcg. The requirement of a repeat block or conversion to GA was considered a failed block. Cases in which there was no evidence of any block after the spinal were excluded from analysis. Patients were categorized into 3 groups based on bupivacaine dose: group 1 (7.5-10 mg), group 2 (>10-12 mg), and group 3 (>12-13.5 mg). We also performed a second analysis comparing our standard spinal dose for cesarean section (12 mg) to 7.5 mg and 13.5 mg. Primary endpoints were the incidence of inadequate and failed spinal anesthetic.

Results: 309 women met the inclusion criteria and were included in the analysis. The results are summarized in the table. Baseline characteristics were not different among the 3 groups. An inadequate block occurred in 23% of cases with 38%, 23%, and 13% in groups 1, 2, and 3, respectively (p=0.11). There was a trend in the incidence of failed block between the groups (p=0.07). When including only 7.5, 12 and 13.5 mg doses, there was an overall statistically significant difference in inadequate and failed blocks among the groups (p=0.04 and p=0.03, respectively).

Conclusion: Using low doses and cesarean section doses of bupivacaine is associated with a relatively high rate of inadequate blocks for PPTL. Large randomized-controlled studies are needed to further evaluate the dose-effectiveness of bupivacaine for PPTL.

References:

1) Anesth Analg 1986; 65:897-900.

2) Reg Anesth Pain Med 2002; 27:284-288.



SOAP 2012