Effects of Intravenous Magnesium Sulfate on the Prevention of Pain Following Injection of Microemulsion Propofol

Objective: The aim of this study was to investigate the effects of intravenous magnesium sulfate on the prevention of pain during the injection of microemulsion propofol. Magnesium is a known calcium channel blocker and a physiological N-methyl-D-aspartate receptor antagonist. Methods: American Society of Anesthesiologists I and II adults (n= 114) undergoing general anesthesia for surgery were randomly assigned into two groups (n= 57 per group). This study was designed in prospective and double-blind manner. Patients in the LM group (n= 57) received pretreatment with 2% lidocaine (40 mg) and magnesium sulfate 10 mg/kg, while patients in group L (n= 57) received pretreatment with 2% lidocaine (40 mg) and normal saline (2 mL) accompanied by venous occlusion. Induction with microemulsion propofol (Aquafol) 2 mg/kg was accomplished following the release of venous occlusion. Pain intensity was assessed on a four-point scale according to patient movement (grade 0, no movement; grade 1, movement in wrist only; grade 2, movement in the upper arm & shoulder of injected arm; grade 3, generalized movement). Systolic blood pressure, diastolic blood pressure, and heart rate were evaluated. Results: A significant difference in pain intensity following injection of microemulsion propofol between the groups was found (P< 0.05). In addition, the incidence of hypertension after injection was lower in the LM group than in the L group (P< 0.05). Conclusion: The combination of magnesium and lidocaine are effective in attenuating the pain induced by microemulsion propofol injection when compared with lidocaine alone.