Magnesium Sulfate Plus Lidocaine Reduces Propofol Injection Pain: A Double-blind, Randomized Study

Abstract

PurposePropofol injection can cause distressing pain, and no method can inhibit it completely. Neither lidocaine nor magnesium sulfate (MgSO4) was sufficient to prevent pain from the injection of propofol. This prospective, double-blind, placebo-controlled study was designed to investigate the efficacy of the MgSO4 plus lidocaine on suppressing propofol injection pain. MethodsThree hundred women received 300 mg MgSO4 (Group M), 40 mg lidocaine (Group L), or 300 mg MgSO4 plus 40 mg lidocaine (Group M+L). This was followed by administration of 50 mg propofol. Pain scores, behavior-related responses, and diameter of the vein were recorded following the injection of propofol. FindingsPatients in Group M + L had lower pain scores. Patients’ behavior-related responses in Group M + L were also better compared with the other groups. There were no differences in pain scores between Group L and Group M. The target vein diameter change in Group M and Group M + L was more obvious than in Group L. ImplicationsAdministration of 300 mg MgSO4 plus 40 mg lidocaine reduces propofol injection pain very well. No complications were observed in the treatment groups.