Letters to the Editor: Letters & Announcements
To the Editor:
We read with interest the Schaub et al. study (1) and have concerns. The authors have compared the pain on injection in propofol with lidocaine pretreatment versus propofol formulated with long- and medium-chain triglycerides. In the lidocaine group, lidocaine 2% 2 mL (40 mg) IV and in the long- and medium-chain triglycerides group NaCl 0.9% 2 mL was given 1 min before the injection of propofol with a tourniquet in place on the forearm.
Ischemia/reperfusion injury, which may occur during tourniquet application, results in neutrophil-mediated endothelial cytotoxicity and activation, generation of free radicals, and triggering of cytokines and chemokines (like kinin) (2). However, the mechanism responsible for propofol pain on injection is unknown; the activation of pain mediators such as kinin cascade system has been suggested (3).
Both of these mechanisms have a common kinin component. It is possible that ischemia/reperfusion injury aggravates the propofol pain on injection. So the more frequent (46%) incidence of pain with propofol formulated with long- and medium-chain triglycerides in Schaub et al. study compared with that reported by other investigators using this formulation (1) could be explicated. Furthermore, significantly more frequent incidence of pain among the long- and medium-chain triglycerides group compared with the lidocaine group may not be unexpected.
Payam Eghtesadi-Araghi, MD
President of Parsteb Pajouheshyar Medical Sciences Research Institute (NGO)
Seyed Mojtaba Marashi, MD
Assistant Professor of Anesthesiology
Department of Cardiac Surgery
Dr. Shariati Hospital Complex
Tehran University of Medical Sciences
1. 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;99:1699–702.
2. Siemionow M, Arslan E. Ischemia/reperfusion injury: A review in relation to free tissue transfers. Microsurgery 2004;24:468–75.
3. Scott RP, Saunders DA, Norman J. Propofol: Clinical strategies for preventing the pain of injection. Anaesthesia. 1988;43:492–4.