Published online by Cambridge University Press: 07 July 2006
Summary
Background and objective: Previous studies found that lidocaine addition to propofol long-chain triglyceride was associated with a lower incidence of injection pain than medium-chain triglyceride/long-chain triglyceride formulation, but the incidence was still high (31–40%). Our study investigated whether the incidence of injection pain could be further reduced by the addition of lidocaine (10 mg, 20: 1) to propofol medium-chain triglyceride/long-chain triglyceride. Methods: In a randomized double-blind controlled trial 464 patients scheduled to undergo regional anaesthesia were assigned to receive one of the following four options: propofol medium-chain triglyceride/long-chain triglyceride + lidocaine, propofol long-chain triglyceride +lidocaine, propofol medium-chain triglyceride/long-chain triglyceride or propofol long-chain triglyceride. Propofol was injected to reach grade 3 of the Observer’s Assessment of Alertness/Sedation scale. Results: Incidence of injection pain was 18% in the propofol medium-chain triglyceride/long-chain triglyceride +lidocaine group, 31% in the propofol long-chain triglyceride +lidocaine group, 47% in the propofol medium-chain triglyceride/long-chain triglyceride group and 60% in the long-chain triglyceride group. Propofol medium-chain triglyceride/long-chain triglyceride + lidocaine was associated with a statistically significant reduced incidence of injection pain compared with propofol long-chain triglyceride +lidocaine ( P =0.0249, number needed to treat =7.7). Conclusions: Premixing propofol medium-chain triglyceride/long-chain triglyceride with lidocaine is one of the most effective measures currently available to reduce the incidence of injection pain in sedated patients during regional anaesthesia.