Effect of intravenous lidocaine on propofol consumption in elderly patients undergoing colonoscopy: a double-blinded, randomized, controlled trial

Background: Elderly patients undergoing colonoscopy with propofol as sedation are prone to respiratory or cardiovascular complications. Intravenous lidocaine has analgesic efficacy and reduces propofol consumption during surgery. Here, the effect of intravenous lidocaine on propofol consumption was evaluated in elderly patients undergoing colonoscopy. Methods: Patients were randomly allocated to receive intravenous lidocaine (1.5 mg/kg bolus dose, followed by a 2 mg/kg/h continuous infusion during the procedure; Group L) or a placebo (saline; Group N). During the procedure, sedation was achieved by propofol. The following outcomes were recorded: total propofol consumption; time to loss of consciousness; number of airway modifications; time to the first airway intervention; incidence of sedation-related events; pain score after awakening; endoscopists' and patients' satisfaction scores; memory level of the procedure; and adverse events within 24 h postoperatively. Results: Compared with Group N, propofol consumption was reduced by 13.2% in Group L (100.30 +/- 25.29 mg vs. 115.58 +/- 27.52 mg, respectively, p = 0.008). Kaplan-Meier curves showed that the median time to the loss of consciousness episode was shorter in Group L than in Group N (40s vs. 55s, respectively, log rank p < 0.0001). The number of airway modifications, time to the first airway intervention, incidence of sedation-related events, time to awakening, pain score after awakening, endoscopists' and patients' satisfaction scores, memory level of the procedure and adverse events within 24 h postoperatively did not differ between the two groups (p > 0.05). Conclusions: Intravenous lidocaine can reduce propofol consumption in elderly patients undergoing colonoscopy, with quicker time to loss of consciousness.