Optimal dose of intrathecal clonidine added to sufentanil plus bupivacaine for labour analgesia.

PURPOSE The combination of intrathecal (IT) 5 microg sufentanil plus 1.25 mg bupivacaine is useful for inducing labour analgesia, albeit of short duration 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 microg (group C0), 15 microg (C15) or 30 microg (C30) of clonidine IT in addition to 5 microg sufentanil plus 1.25 mg bupivacaine IT for labour analgesia. The quality of pain relief was assessed on 0-100 visual analogue scale by the author. The occurrence of side effects was also evaluated before the request for additional analgesia. RESULTS Clonidine (C15 and C30), produced a longer duration of analgesia than 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 analgesia than C0, (P < 0.01). The most cephalad level of sensory block was higher in C30 than C15 (median T3 vs T4, P < 0.05) but lowest in C0 (median T7 vs T3,T4, P < 0.01). Side effects, sedation and hypotension, occurred more frequently in C30 than in either C0 or C 15, (9 vs 2,5 and 9 vs 1,3, respectively, P < 0.05). CONCLUSION The optimal dose of intrathecal clonidine to enhance labour analgesia with the current sufentanil-bupivacaine regimen is 15 microg. In view of the side effect profile, doses greater than 30 microg clonidine are unlikely to be useful.