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 authorsection 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 II 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 I, 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.

Keywords: Propofol, Pain on injection, Particle size, Anesthesia