RESUMEN
BACKGROUND: Propofol formulated with medium- and long-chain triglycerides (MCT/LCT) causes less pain on injection than standard Propofol, but the incidence of pain persists between 28 and 67 percent. Such a broad range begs the question so the authors wanted to clarify whether the addition of lidocaine to medium- and long-chain triglyceride emulsion propofol results in any clinically significant lessening of pain on injection. The authors conducted a randomized, prospective, double-blinded study to compare the injection pain felt following the administration of propofol-MCT/LCT (Propofol-Lipuro) to propofol-MCT/LCT plus 20 mg lidocaine for the induction of anesthesia. MATERIAL AND METHOD: The present study included 270 non-premedicated ASA I-II adult patients scheduledfor elective surgery under general anesthesia. Patients were allocated randomly into two groups to receive either propofol-MCT/LCT alone or propofol-MCT/LCT plus 20 mg lidocaine. The study solution was injected at 1 mL/second by one anesthesiologist and patients graded any associated pain using a four-point scale. RESULTS: The overall incidence of pain on injection was 31/133 (23%) in the propofol-MCT/LCT plus lidocaine group vs. 45/135 (33%) in the propofol-MCT/LCT alone group. The difference in the incidence of pain on injection between groups failed to achieve statistical significance (p = 0.23) and no significant difference in intensity of pain between the two study groups occurred CONCLUSIONS: The authors concluded that the addition of lidocaine (20 mg) to the propofol-MCT/LCT does not significantly reduce the incidence or severity of the pain on injection.