Bloc caudal chez l'enfant : analgésie et effets respiratoires de l'association bupivacaïne-fentanyl

Abstract

A study of the duration of analgesia and of the respiratory response to hypercapnia was carried out in 14 children who had had a caudal block with either bupivacaine alone (group B) or combined with fentanyl (Group B + F). Fourteen ASA I or II 5 to 10-year-old children undergoing genital and urinary surgery were included. They were not premedicated. At first, general anaesthesia was induced with halothane and nitrous oxide in oxygen. Thereafter, caudal anaesthesia was then carried out with 1 ml · kg −1 of 0.25 % bupivacaine with adrenaline 1 in 200,000. Group B + F patients were also given 1 μg · kg −1 of fentanyl in 1 ml of normal saline, and those in Group B 1 ml of normal saline. The level of sensory loss on leaving the operating theatre as well as the duration of motor paralysis were monitored. Postoperative pain was scored with Hannalah and Broadman's score (0 to 10) 2, 4, 8 and 24 h after the caudal block. Respiratory rate (f R), tidal volume (V T) and minute ventilation (V̇ E) were assessed 10 min before induction of general anaesthesia, and 30, 60 and 120 min after the caudal anaesthesia. Petco 2 was also measured before induction of general anaesthesia, and 60 and 120 min after caudal anaesthesia ; at the same times, the ventilatory response to hypercapnia was assessed using Read's method with a Douglas bag containing 7 % CO 2 and 93 % O 2. Pain score was 0 in Group B + F patients throughout the study, whereas it was 0, 1.4 ± 2.9, 5.2 ± 2.3 and 4.3 ± 1.6 respectively 2, 4, 8 and 24 h after the caudal blockade in Group B patients. The differences between the groups were significant at 8 and 24 h (p < 0.05). All the patients could stand up 4 h after the caudal block and urinate before the 8 th hour. Five out of seven had nausea (Group B + F). In both groups, f R and Petco 2 did not change significantly throughout the study, whereas V T and V̇ E decreased (p < 0.05) 30 min after the start of caudal anaesthesia. The slope of the response to CO 2 remained unaltered throughout with respect to control values. It was therefore been shown that combining fentanyl with bupivacaine for caudal anaesthesia in children prolonged postoperative analgesia without inducing any delayed respiratory depression.