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

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.