Prospective to a randomized double-blind controlled trial to assess efficacy of double caudal analgesia in hypospadias repair

Abstract

Background/Purpose: A prospective, randomised, double-blind, controlled trial to evaluate efficacy of double-caudal versus single-caudal injection for postoperative analgesia in hypospadias repair was performed. Methods: Between October 1998 and September 2000, 160 boys underwent distal hypospadias repair. The first 80 boys were analyzed prospectively for postoperative analgesia after double-caudal bupivacaine, which involves the administration of a second bupivacaine injection into the caudal extradural space at the end of surgery. Pain was assessed using the Children's Hospital of Eastern Ontario Pain Scale (CHEOPS). The study groups were: group 1, unstented Thiersch-Duplay urethroplasty (50); and group 2, stented Mathieu type repair (30). Results of this cohort formed the basis for a prospective, randomised, double-blind control trial comparing double-caudal against a single injection before operation. The further 80 patients were allocated randomly: group 3, single caudal injection of 1 mL kg−1 of 0.25% plain bupivacaine at the start of surgery with unstented Thiersh-Duplay repair (25); group 4, similar single caudal injection but stented Mattieu type operation (15); group 5, second caudal and at end of operation (0.5 mL kg−1 on each occasion) with unstented Thiersh-Duplay repair (25); and group 6, similar to group 5 but with stented Mattieu type repair (15). Results: Patient demographics (age and weight) and mean duration of operative time were similar for all groups. There was no significant difference in early pain scores at 0 to 2 hours with a good correlation coefficient (r = 0.88). At 4, 6, and 8 hours there was a significant difference in pain scores between double and single caudals (P <.05). There was a significant difference in mean duration of caudal analgesia and need for oral analgesia between single caudal 3.45 versus 7.85 hours for double caudal (P <.001). Mean duration of caudal analgesia and requirement for oral analgesia after single caudal in group 3 (unstented) was 3.5 versus 3.4 hours in group 4 (stented). In double caudals this lengthened to 9.4 hours in group 5 (unstented) versus 6.3 hours in group 6 (stented; P <.05). This also was significant when operation time was excluded. Conclusions: A prospective study of double caudal analgesia showed good postoperative pain control after hypospadias surgery. This was followed by a prospective, randomised, double-blind controlled trial that has confirmed that double caudal injection of bupivacaine prolonged the duration of pain relief after hypospadias repair. The second or top-up caudal did not increase the total dose but supplemented and prolonged postoperative analgesia. J Pediatr Surg 37:168-174. Copyright © 2002 by W.B. Saunders Company.