Background: Various additives have been used to increase the duration of analgesia provided by bupivacaine administered by single-shot caudal injection in children.
Methods: 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.
Results: 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.
Conclusions: 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.