Does addition of lidocaine to medium- and long-chain triglyceride propofol emulsions significantly reduce pain on injection?

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.

Comparison on pain on injection of a small particle size-lipid emulsion of propofol and standard propofol with or without lidocaine.

Pain on injection, reported in 28-90% of patients, is one of the most described side effects of the intravenous application of propofol. Many different approaches have been used in attempts to minimize propofol induced pain, with varied results. Using a randomized, double-blind protocol design, the author-section pain following the administration of two different particle size formulations of propofol with or without lidocaine in 388 nonpremedicated ASA I-II adult patients scheduled for elective surgery under general anesthesia. Patients were allocated randomly to receive either a small particle size lipid emulsion of propofol (Anepol: average particle size 140.5 nm), or standard propofol (Propofol: average particle size 193.3 nm), by dividing into 4 groups. Group 1 received 2 ml NaCl 0.9% and Propofol, group 11 received 2 ml lidocaine 2% and Propofol, group III received 2 ml NaCl 0.9% and Anepol and group IV received 2 ml lidocaine 2% and Anepol into a dorsal vein of the hand. Pain during propofol injection was evaluated over 5-10 seconds, until loss of conscious, using a four point scale. Sixty-seven patients (69.1%) complained of pain in group 1, as compared with 50%, 41.2% and 39.2% in group II, III and IV (p < 0.05). The reported severity of injection pain was not significantly different between the groups. The authors conclude that small particle size propofol causes less pain on injection than standard propofol.