Caudal tramadol for postoperative analgesia in pediatric hypospadias surgery

Ninety boys, aged 13-53 months, undergoing repair of hypospadias, were allocated randomly to receive 0.8 ml kg-1 of one of three solutions into the caudal extradural space: group B received bupivacaine 2 mg kg-1, group T received tramadol 2 mg kg-1 in 0.9% saline and group BT a mixture of both. Postoperative pain was assessed hourly for 12 h after injection using a modified TPPPS pain score and additional analgesia was administered to those children whose pain scores were > 3/10. Nine patients (30%) in group T required additional analgesia within 1 h of surgery compared with only two (6.7%) and three (10%) patients in groups B and BT, respectively (P = 0.04). Mean duration before additional analgesia was required in the remaining patients was 9.3 (SD 3.0) h in group B, 10.7 (2.2) h in group T and 10.5 (2.0) h in group BT (P > 0.20). There were no significant differences between the groups in mean ventilatory frequency, sedation scores, incidence of emesis, facial flushing or pruritus. We conclude that caudal tramadol had a slow onset of action and that the addition of tramadol to bupivacaine, when both drugs were administered caudally, did not significantly prolong the duration of action of bupivacaine.