• U Weber, M Krammel, S Linke, T Hamp, T Stimpfl, B Reiter, and W Plöchl.
• Department of Anesthesiology, General Intensive Care and Pain Control, Medical University of Vienna, Vienna, Austria.
• Acta Anaesthesiol Scand. 2015 Mar 1;59(3):310-8.

BackgroundThe anaesthetic potency of intravenous propofol is quantified by its Cp50 value, which is defined as the plasma concentration required to prevent movement response in 50% of patients to surgical stimuli. We hypothesised that, in addition to propofol anaesthesia, an intravenous bolus of lidocaine 1.5 mg/kg will decrease the Cp50 value of propofol during anaesthesia.MethodsWe enrolled 54 elective surgical patients undergoing propofol-based anaesthesia, and randomised them to either lidocaine 1.5 mg/kg, lidocaine 0.5 mg/kg or placebo (NaCl 0.9%) 3 min before skin incision. The propofol Cp50 value was then calculated using the 'up-and-down' method of Dixon and Massey.ResultsThere was no significant reduction in propofol requirements after the administration of 0.5 mg/kg lidocaine from 8.5 μg/ml [confidence interval (CI) 6.0-11.625] to 8.25 μg/ml (CI 6.75-9.76); however, a bolus of 1.5 mg/kg lidocaine decreased the Cp50 value of propofol by 42% from 8.5 μg/ml (CI 6.0-11.625) to 4.92 μg/ml (CI 4.5-5.78) (P < 0.05).ConclusionAn intravenous bolus injection of 1.5 mg/kg lidocaine 2% caused a significant reduction of the propofol Cp50 value.© 2015 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

This article appears in the collection: Lignocaine.

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