An evaluation of the postoperative antihyperalgesic and analgesic effects of intrathecal clonidine administered during elective cesarean delivery.

Background: Intrathecal clonidine improves intraoperative anesthesia and postoperative analgesia after cesarean delivery. Clonidine also possesses antihyperalgesic properties. Hyperalgesia contributes to postoperative pain and may be associated with increased risk of chronic pain after surgery. In this study, we evaluated the postoperative antihyperalgesic effect of intrathecal clonidine after caesarean delivery.
Methods: Ninety-six parturients undergoing elective cesarean delivery were randomly assigned to receive intrathecal bupivacaine-sufentanil (BS group), bupivacaine-sufentanil-clonidine 75 microg (BSC group), or bupivacaine-clonidine 150 microg (BC group). The primary outcome was the extent and the incidence of periincisional punctate mechanical hyperalgesia as assessed by response to application of a von Frey filament at 24 and 48 h after cesarean delivery. Postoperative morphine requirements and pain scores, as well as residual pain at 1, 3, and 6 mo, were also assessed.
Results: The BC group had a significantly reduced area of periincisional hyperalgesia at 48 h (median, 25th-75th percentiles): 1.0 (1.0 - 3.3) cm(2) vs 9.5 (5.0-14.0) cm(2) in the BS group vs 5.0 (2.5-12.3) cm(2) in the BSC group (P = 0.02 with the BS group). The incidence of hyperalgesia at 48 h was also lower in the BC group: 16% vs 41% in the BS group vs 34% in the BSC group (P = 0.03 with BS group). Postoperative morphine consumption, pain scores, and incidence and intensity of residual pain did not differ among groups.
Conclusions: Intrathecal clonidine 150 mug combined with bupivacaine had a postoperative antihyperalgesic effect expressed as a significant reduction in the extent and incidence of periincisional punctate mechanical hyperalgesia at 48 h after elective cesarean delivery compared with intrathecal bupivacaine-sufentanil and intrathecal clonidine 75 mug-bupivacaine-sufentanil.