Effect of intravenous administration of lidocaine on the ED50 of propofol induction dose during gastroscopy in adult patients: A randomized, controlled study

What is known and Objective Propofol provides a prominent sedation effect in gastroscopy. However, sedation with propofol alone during gastroscopy might result in circulatory and respiratory depression. This study aimed to test the hypothesis that the addition of intravenous lidocaine to propofol-based sedation could decrease the ED50 of propofol induction dose during gastroscopy in adult patients while the respiratory and haemodynamic stability were not compromised. Methods Patients undergoing gastroscopy were randomly enrolled into lidocaine + propofol (L + P) group or normal saline + propofol (NS + P) group. Subjects were initially administered intravenous bolus of 1.5 mg/kg lidocaine in L + P group or equivalent volume of 0.9% saline in NS + P group. Anaesthesia was then induced with a single bolus of 1.0 mu g sufentanil followed by injection of propofol in all patients. The induction dose of propofol for each individual patient was determined by the protocol of Dixon "up-and-down" method for both groups. The primary end point was the ED50 of propofol induction dose. Results Totally, 48 patients were enrolled and completed this study. Compared with the NS + P group, the ED50 of propofol induction dose was significantly reduced in the L + P group (2.01 mg/kg vs. 1.69 mg/kg) (U = 61.5, p < 0.001). What is new and Conclusion The addition of intravenous lidocaine significantly reduced the ED50 of propofol induction dose during gastroscopy in adult patients. Trial registration The present clinical trial was registered at (registration No. ChiCTR1900024025, 23 June 2019).