Ketamine for co-induction of anaesthesia in oral surgery

Abstract

Ketamine has additive interaction with propofol and analgesic properties. The aim was to determine if ketamine co-induction reduced propofol induction doses, improved pain relief and produced any adverse effects. Forty ASA I and II patients scheduled for extraction of third molars were enrolled in a randomised, double blind study. Group ketamine patients (n=20) received ketamine 0.3 mg/kg prior to induction with propofol running at 300 ml/h. Group control patients (n=20) received a corresponding volume of normal saline. All patients were intubated and maintained on N2O:O2 admixture and isoflurane. Post-operatively, patients were given i.v. fentanyl boluses, oral Panadeine Forte or Oxycodone as rescue medication for pain. Data collected consisted of propofol induction doses, blood pressure and heart rate readings at 1 min intervals, visual analogue score (VAS) pain scores at various intervals and fentanyl requirements in recovery. Duration of surgery and time to discharge were also recorded. Possible side effects of nausea, dreams and hallucinations were noted. There was no significant difference in propofol induction doses, pain requirements and pain scores between the two groups. However, there was significant increase in the blood pressure (P<0.006) and heart rate (P<0.009) at induction. The discharge time in the ketamine group was not prolonged and no adverse side-effects like bad dreams or emergence delirium were noted. We conclude that low-dose ketamine at 0.3 mg/kg does not reduce the induction dose of propofol or improve the post-operative pain of oral surgery. However, this dose does not affect recovery or produce unpleasant side-effects, making it a possibility for use in day surgery.