Background: Clonidine administration in the setting of paediatric anaesthesia is associated with a number of desirable effects, e.g. preoperative sedation, analgesia and reduced anaesthetic requirements. The aim of the current study was to compare postoperative outcome variables using a prospective, randomized, double-blind design after premedication with clonidine or midazolam.
Methods: One hundred paediatric ASA physical status 1 patients (age 1-11 year) scheduled for adeno-tonsillectomy were assigned to receive rectal premedication with midazolam (300 microg kg(-1) and atropine 40 microg kg(-1); group M, n = 52) or clonidine (5 microg kg(-1 and) atropine 40 microg kg(-1); group C, n = 48) prior to a standardized sevoflurane anaesthetic. The incidence of immediate postoperative pain (0-2 h), as assessed by repeated Objective Pain Scale (OPS) scores, was chosen as the primary end-point of the study. Degree of sedation (modified Vancouver sedation scale 0-3), occurrence of postoperative vomiting (POV), and incidence of shivering and immediate postoperative confusion were registered as secondary end-points. After hospital discharge parents were instructed to continue the evaluation of pain, sedation, POV and sleep pattern during a 24-h period. Parents were also asked for their preference concerning the postoperative behaviour of their child (calm, sedated vs. alert, active).
Results: In the early postoperative period patients in the clonidine group had a significantly lower sum of 5 OPS scores (median = 8.0) compared to group M (median = 11.5) (P = 0.011). Administration of clonidine was also associated with a slightly higher sum of sedation scores (median = 13) in the early postoperative period compared to children receiving midazolam (median = 12) (P < 0.001). No episode of shivering was observed in the clonidine group but was present in five of the patients in the midazolam group (P = 0.057). In younger children (< 5 years) the incidence of postoperative confusion was lower in the clonidine group (P = 0.001). No difference in the frequencies of POV incidences, degree of postoperative pain, need for analgesics, or sleep pattern during the first 24 postoperative hours could be observed between the groups according to the parental evaluation. Children premedicated with clonidine were more calm and sedated compared to children in the midazolam group (P = 0.024) as judged by their parents. A significant majority of parents (75%; P < 0.001) preferred a calm and sedated child during the first postoperative 24-h period.
Conclusion: Rectal premedication with clonidine was associated with a significant reduction of pain in the early postoperative period compared to midazolam and was also associated with moderately increased sedation during the first 24 postoperative hours. The sedative effect of clonidine is in agreement with the unambiguous finding of a parental preference for a calm and sedated child during the first 24 postoperative hours.