Various additives have been used to increase the duration of analgesia provided by bupivacaine administered by single-shot caudal injection in children.
A prospective, randomized, double-blind controlled study in 50 ASA I–II children (34 boys and 16 girls) aged 1–6 yr undergoing upper abdominal surgery was conducted. Patients were divided into two groups to receive either morphine 30 µg kg–1 (MB) or clonidine 2 µg kg–1 (CB) in bupivacaine 0.2% (1.25 ml kg–1) for caudal analgesia. The duration of analgesia (FLACC scale) and sedation and side-effects such as vomiting, itching, respiratory depression, hypotension, and bradycardia were observed.
The mean duration of analgesia was 16.5 (3.6) h in the CB group compared with 10.2 (2.3) h (P<0.01) in the MB group. Subjects who received clonidine (CB) were sedated for longer [7.1 (0.8) h] compared with the MB group [3.8 (0.7) h; P<0.01]. Vomiting was observed in 4% and 12% of subjects in the CB and MB groups, respectively. Sixteen per cent of subjects reported itching in the MB group (P=0.03), and none in the CB group. No hypotension, bradycardia, or respiratory depression was observed in any subjects.
Caudal clonidine 2 µg kg–1 in bupivacaine 0.2% provides a longer duration of analgesia and sedation compared with caudal morphine 30 µg kg–1 in bupivacaine 0.2% without significant side-effects in children undergoing upper abdominal surgery.