Effect of preinduction low-dose ketamine bolus on intra operative and immediate postoperative analgesia requirement in day care surgery: A randomized controlled trial

BACKGROUND: Availability of narcotics is an issue in developing countries, and low-dose ketamine offers an alternative to these drugs. OBJECTIVE: The objective of this study is to evaluate the effect of a preemptive dose of low-dose ketamine on intra operative and the immediate postoperative analgesic requirements. DESIGN: Randomized double-blind control trial. SETTINGS: This study has been performed in the operating rooms and postanesthesia care unit at Aga Khan University Hospital, Karachi, Pakistan. MATERIALS AND METHODS: Totally, 60 adult American Society of Anesthesiologists I and II patients undergoing day care surgery were randomly allocated into two groups, Group A (ketamine group) and Group B (saline group). INTERVENTION: All patients underwent general anesthesia. Propofol 2 mg/kg was used as an induction agent; laryngeal mask airway (size 3 for females and 4 for males) was inserted. Following induction patients in Group A received ketamine 0.3 mg/kg and Group B saline bolus in a blinded manner. All patients were administered injection fentanyl 1 μg/kg as an analgesic and anesthesia was maintained with oxygen 40%, nitrous oxide 60% and isoflorane 1-2 minimum alveolar concentration. Patients breathed spontaneously on Lack circuit. Postoperatively rescue analgesia was provided with intravenous morphine 0.1 mg/kg when patient complained of pain. MAIN OUTCOME MEASURES: We observed analgesic effects of low-dose ketamine intra operatively and narcotic requirements in immediate postoperative period for day care surgeries. RESULTS: There was no significant difference in demographic data in between groups. Saline group required more rescue analgesia (morphine) postoperatively (P < 0.001). No significant psychotomimetic symptoms were noted in either group. CONCLUSION: Low-dose ketamine 0.3 mg/kg provided adequate co-analgesia with fentanyl 1 μg/kg and was effective in a reduction of morphine requirement in the postoperative phase with minimal adverse effects.