Modulating effects of lignocaine on propofol

Pain is a well known complication of propofol injection. Premixing with lignocaine 0.1 mg.kg-1 and injection into a large forearm vein has been recommended. The amount of lignocaine to be added is often empirical when the vein on the dorsum of the hand is used. In this study we attempt to determine the optimal amount of lignocaine necessary to reduce pain when propofol is injected into a hand vein. Our study shows that a propofol emulsion containing 0.05% lignocaine is effective in reducing the incidence of propofol injection pain. The addition of lignocaine also reduces the incidence of excitatory effects. Increasing the dosage of lignocaine above 0.05% does not improve the results.