Avoiding propofol injection pain in children: a prospective, randomized, double-blinded, placebo-controlled study

Abstract

BackgroundPain on injection limits the use of propofol in children. The combination of lidocaine and propofol is widely used to reduce pain. A new solvent [medium-chain triglyceride (mct)/long-chain triglyceride (lct)] has been advocated to be less painful than standard (lct) propofol in adults, but no information is available of its usefulness in pre-school children. We designed a prospective, randomized, double-blinded, placebo-controlled study to assess injection pain with two different propofol emulsions, each given with or without lidocaine in children <7 yr. MethodsA total of 160 ASA I–III children were randomly assigned to receive lct–propofol or mct/lct–propofol, 5 mg kg−1, with lidocaine 10 mg ml−1 or saline. The site and size of venous cannulation and restlessness before injection were recorded in each patient. A pain score graded 0–6 was established based on spontaneous verbal and motor reaction during injection, each graded 0–3. Kruskall–Wallis and Mann–Whitney tests were used for statistical analysis. ResultsMedian pain scores decreased in all groups compared with lct–propofol–saline (P<0.001) and were least in the lct/mct–propofol–lidocaine group (P<0.001). Painless injection (score, 0–2) occurred in 92.5% of patients in the mct/lct–propofol–lidocaine group compared with 41–77% in the others (P<0.001). ConclusionsMct/lct–propofol caused significantly less pain than lct–propofol in preschool children. Mixing of lidocaine with mct/lct–propofol resulted in a further significant decrease, virtually eliminating the pain on injection.