Tramadol for pain relief in children undergoing tonsillectomy: a comparison with morphine

Introduction Pain control for paediatric patients undergoing tonsillectomy remains problematic. The combination of intra-operative morphine and rectal diclofenac results in a high incidence of post-operative nausea and vomiting as well further analgesic requirements. Tramadol is reported to be an effective analgesic and have a side effect profile similar to morphine. It is not classed as a controlled drug and is available in tablet, suppository and injection form. It is currently not licensed for paediatric use in the UK. Methods We conducted a prospective, double blind, randomised controlled trial in children scheduled for elective tonsillectomy or adenotonsillectomy at the Royal Aberdeen Children Hospital. Following local ethics committee approval and obtaining a drug exemption certificate from the Medicines Licensing Agency for an unlicensed drug in paediatrics we recruited 60 patients into three groups: morphine (0.1 mg·kg−1), tramadol (1 mg·kg−1) and tramadol (2 mg·kg−1). These drugs were given as a single injection following induction of anaesthesia. In addition, all patients received diclofenac (1 mg·kg−1) rectally. The post-operative analgesic requirements, sedation scores, signs of respiratory depression and nausea and vomiting as well as antiemetic requirements were noted at 4 hourly intervals until discharge. Statistical analysis was performed using chi-square, Kruskal–Wallis and one-way anova tests as appropriate. P < 0.05 was considered statistically significant. Results There were no statistical significant differences in age, weight, type of operation or induction of anaesthesia, 4 hourly sedation and pain scores and further analgesic requirements. There were no incidences of respiratory depression. Morphine was associated with a significantly higher incidence of vomiting following discharge to the wards (75% vs 40%, P = 0.03) when compared to both tramadol groups. The differences in anti-emetic requirements did not reach statistically significant difference (P = 0.078). Conclusions We conclude that tramadol has similar analgesic properties and side effects when compared with morphine. The pharmaceutical presentation and the availability as a non-controlled substance may make it a useful addition to paediatric anaesthesia if it becomes licensed for paediatric anaesthesia in the UK.