Effect of transversus abdominis plane block with and without clonidine on post-cesarean delivery wound hyperalgesia and pain.
OBJECTIVE
The transversus abdominis plane (TAP) block is an established technique to manage post-cesarean delivery pain. Transversus abdominis plane blocks with a local anesthetic only offer no analgesic benefits compared with intrathecal morphine. Adjuvants to extend TAP block duration and possibly reduce wound hyperalgesia, known to be a risk factor for chronic pain, have not been studied. We hypothesized that a TAP block with clonidine will affect postsurgical wound hyperalgesia and improve pain outcomes.


METHODS
Ninety women were randomly assigned to receive 1 of 3 TAP blocks after cesarean delivery: saline (placebo), bupivacaine (BupTAP), or bupivacaine + clonidine (CloTAP). The primary outcome was wound hyperalgesia index at 48 hours. Secondary outcomes included pain scores, analgesic consumption, and pain descriptors up to 12 months.


RESULTS
Wound hyperalgesia index at 48 hours (median [25th-75th percentiles]) was 1.07 (0.48-3.26) in the placebo group, 1.27 (0.59-2.95) in the BupTAP group, and 0.74 (0.09-2.25) in the CloTAP group (P = 0.48). Morphine request in the postanesthesia care unit was significantly higher in the placebo group compared with the other TAP groups (P = 0.01). Postoperative pain scores and requests for breakthrough medication at 48 hours (30% in the placebo group, 24% in the BupTAP group, and 12% in the CloTAP group, P = 0.25) or chronic pain descriptors reported up to 12 months did not differ significantly among groups.


CONCLUSIONS
Adding clonidine to a TAP block with bupivacaine did not affect wound hyperalgesia index and it did not improve short-term or long-term pain scores in women undergoing elective cesarean delivery. Further studies are warranted to determine the benefits of antihyperalgesic adjuvants in TAP solutions for specific individuals at risk for chronic pain.
Department of Anesthesiology and Pain Medicine, University of Washington Medical Center, Seattle, WA 98195-6540, USA. bollag@uw.edu
Laurent
L
Bollag
Philippe
P
Richebe
Monica
M
Siaulys
Clemens M
CM
Ortner
Michael
M
Gofeld
Ruth
R
Landau
D000009:Abdominal Muscles / Q000187:drug effects* / Q000294:innervation; D000293:Adolescent; D000328:Adult; D016362:Analgesia, Obstetrical / Q000379:methods; D002585:Cesarean Section / Q000009:adverse effects* / Q000379:methods; D003000:Clonidine / Q000008:administration & dosage*; D015331:Cohort Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008875:Middle Aged; D009407:Nerve Block / Q000379:methods*; D010147:Pain Measurement / Q000187:drug effects / Q000379:methods; D010149:Postoperative Pain / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D011247:Pregnancy; D016896:Treatment Outcome; D014945:Wound Healing / Q000187:drug effects* / Q000502:physiology; D055815:Young Adult
D003000:Clonidine