The effects of intravenous lidocaine on pain during injection of medium- and long-chain triglyceride propofol emulsions

Propofol formulated in medium- and long-chain triglycerides (MCT/LCT) is thought to cause less pain on injection. In this study we sought to determine if adding lidocaine to propofol-MCT/LCT is more effective in decreasing pain compared with propofol-MCT/ LCT alone or conventional propofol-lidocaine mixtures. Seventy-five patients were randomized into three groups. Group A received conventional propofol-lidocaine mixtures with 20 mg lidocaine, group B received propofol-MCT/LCT with saline, and group C received propofol-MCT/LCT with 20 mg lidocaine. The incidence of pain was 24% in groups A and B and 4% in group C. The number needed to treat to prevent pain was 5. We conclude that propofol-MCT/LCT-lidocaine mixtures significantly reduce pain.