Use of Transversus Abdominus Plane Block to Reduce Postoperative Pain after Cesarean Delivery in Laboring and Nonlaboring Parturients-An Interim Analysis
Abstract Number: 93
Abstract Type: Original Research
Cesarean section involves a significant amount of postoperative pain. The transversus abdominus plane (TAP) block reduces postoperative pain after lower abdominal surgery, (1) but results have varied for post-Cesarean pain relief. (2) We evaluated the efficacy of the TAP block in both laboring and nonlaboring parturients for post-Cesarean delivery.
After IRB approval and written consent, laboring and nonlaboring women undergoing Cesarean delivery were randomized to TAP block or placebo in addition to intrathecal morphine and intravenous ketolorac. At the end of the procedure, the TAP group received bilateral blocks with 20mL of 0.25% bupivacaine under ultrasound guidance. The placebo group received a sham exam. Each patient was assessed at 0, 2, 4, 8, and 24 hours. The primary outcome was time to first analgesia. Other outcomes, including visual analog scale (VAS) pain scores, analgesic consumption, incidence of nausea and pruritus were examined. P-values less than 0.05 were considered significant. Time to analgesia was assessed by Kaplan-Meier analysis.
13 laboring and 19 nonlaboring parturients were enrolled. Laboring women had higher PACU VAS pain scores (1.8 vs 0.4, p=0.02) and shorter time to first analgesia (157min vs 264min, p=0.04) compared to nonlabor. There was a trend toward improved pain scores and analgesic requirements comparing TAP and placebo. Significantly, the labor placebo group had a shorter time to first analgesia (P<0.02, Figure 1).
Our interim findings show that the TAP block effectively reduces postoperative pain in laboring women, but not in women scheduled for elective Cesarean delivery. If trends continue, the results should be significant. The difference between these two groups might be explained by viscero-visceral interactions by which pathophysiology in one organ can influence physiology and responses to pathophysiology in other organs. (3) Uterine and cervical pain from labor may act to sensitize the central nervous system resulting in heightened postoperative pain from surgical incision. A longer, more painful labor would raise probability for viscero-visceral interactions resulting in increased postoperative pain; therefore, TAP block may be especially beneficial for laboring women undergoing Cesarean delivery.
1. McDonnell JG, Anesth Analg 2008, 106:186-191
2. Costello JF, Reg Anesth Pain Med 2009, 34:586-9
3. Berkeley KJ, Phys Behav 2005, 86:272-80