Letters to the Editor: Letters & Announcements
We thank Maleck et al. for their interest and comments on our article (1) and agree with their conclusions on the lack of advantage of Propofol-Lipuro™ compared with other propofol formulations concerning pain on injection. However, Maleck et al. state that Disoprivan™ was used in our study and that it would be worthwhile to investigate other propofol formulations. As clearly described in our article, we used Propofol Fresenius™; apparently the same formulation as was used by Schaub et al. (2). The results of the latter study seem to confirm the results of our study and indicate, in conjunction with the results from Röhm and Kunitz (3,4), that Propofol-Lipuro™ offers only a small advantage over Disoprivan™ concerning pain on injection. Measures with regard to reduction of pain on injection are valuable with the use of Propofol-Lipuro™ as well. This only emphasizes our notion that there are a variety of different approaches to reduce pain on injection of propofol and that the issue is far from settled.
It must be noted that the studies cited by Maleck et al. are different from ours in that a different approach in reducing pain on injection of propofol is described (2–4). Whereas we used propofol with premixed lidocaine, in the other mentioned studies lidocaine was preinjected before propofol with or without tourniquet. A small sample size might have contributed to the lack of statistically significant results in those studies. In our own study, we were particularly interested to investigate the pain on injection of two different solutions. The propofol emulsion with premixed lidocaine and the different lipid formulation of propofol may have effects on the pH of the solution and the amount of free propofol in the aqueous phase and thus some influence on the experience of pain.
Finally, we agree with Maleck et al. that further studies using a combination of approaches aimed at the reduction of pain on injection of propofol are indicated to improve perioperative patient comfort.
Sigrid Adam, MD
Jasper van Bommel, MD, PhD
Maaike Dirckx, MD
David Jonsson, MD
Jan Klein, MD, PhD
Department of Anesthesiology
Erasmus Medical Center
Rotterdam, The Netherlands
1. Adam S, van Bommel J, Pelka M, et al. Propofol-induced injection pain: Comparison of a modified propofol emulsion to standard propofol with premixed lidocaine. Anesth Analg 2004;99:1076–9.
2. Schaub E, Kern C, Landau R. Pain on injection: a double-blind comparison of propofol with lidocaine pretreatment versus propofol formulated with long- and medium-chain triglycerides. Anesth Analg 2004;99:1699–1702.
3. Röhm KD, Piper SN, Schöllhorn TAH, et al. Injektionsschmerz unter propofol-MCT/LCT und propofol-LCT: Vergleich einer prophylaxe mit lidocain. Anästhesiol Intensivmed Notfallmed Schmerzther 2003;38:643–7.
4. Kunitz O, Lösing R, Schulz-Stübner S, et al. Propofol-LCT versus propofol-MCT/LCT mit oder ohne lidocaine: Vergleichende untersuchung zum injektionsschmerz. Anästhesiol Intensivmed Notfallmed Schmerzther 2004;39:10–4