Optimal dose of intrathecal clonidine added to sufentanil plus bupivacainefor labour analgesia

Purpose: The combination of intrathecal (IT) 5 mu g sufentanil plus 1.25 mg bupivacaine is useful for inducing labour analgesia, albeit of short durat ion and slow onset. As a supplementation to this regimen, the effect of IT clonidine on the duration of analgesic action was investigated, Methods: Forty-eight healthy parturients were randomly assigned into three groups to receive 0 mu g (group C0), 15 mu g (C15) or 30 mu g (C30) of clon idine IT in addition to 5 mu g sufentanii plus 1.25 mg bupivacaine IT for l abour analgesia. The quality of pain relief was assessed on 0-100 visual an alogue scale by the author. The occurrence of side effects was also evaluat ed before the request for additional analgesia. Results: Clonidine (C15 and C30), produced a longer duration of analgesia t han C0 (mean 144 +/- sd 27.9, 165 +/- 31.8 vs 111 +/- 21.9 min, P < 0.01). Also, C15 and C30 produced a more rapid onset and a higher quality of analg esia than C0, (P < 0.0I). The most cephalad level of sensory block was high er in C30 than C15 (median T3 vs T4, P < 0.05) but lowest in C0 (median T7 vs T3,T4, P < 0.0I). Side effects, sedation and hypotension, occurred more frequently in C30 than in either C0 or C15, (9 vs 2,5 and 9 vs 1,3, respect ively, P < 0.05). Conclusion: The optimal dose of intrathecal clonidine to enhance labour ana lgesia with the current sufentanil-bupivacaine regimen is 15 mu g. In view of the side effect profile, doses greater than 30 mu g clonidine are unlike ly to be useful.