Pain on injection with propofol

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http:// creativecommons.org/licenses/by-nc/3.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. CC The use of propofol often results in pain on injection, which is sometimes very distressing to patients. In analysis of 6,264 patients in 56 reports, 70% of all control patients reported some degree of pain or discomfort on injection with propofol [1]. In 1998, Tan and Onsiong [2] suggested that a wise choice would be to use a combination of techniques, such as alfentanil pretreatment, mixing lidocaine with the propofol and injecting into a large vein with no carrier fluid to decrease the incidence and severity of propofol injection pain. McCrirrick and Hunter [3] found that administering propofol at 4 o C, significantly reduces the incidence of injection pain. Prior injection of cold saline reduces the incidence of pain and discomfort significantly compared with unmodified propofol and is similar to that after cold propofol and propofol with lidocaine [4]. However, the incidence of pain with cold propofol and lidocaine is not statistically different from room temperature propofol and lidocaine in children [5]. Cho et al. [6] assessed the effectiveness of cold propofol and pretreatment with remifentanil in minimizing pain associated with the injection of propofol and investigated whether a combination of cold propofol and remifentanil produced additional analgesic efficacy. They found that a combination treatment with 0.5 μg/ kg remifentanil pretreatment and cold propofol significantly reduces the incidence and severity of propofol injection pain compared with each treatment used alone. The aqueous phase, which contains free propofol, is known to be associated with the intensity of pain at the injection site. Yamakage et al. [7] recommended the use of propofol medium-chain triglyceride (MCT)/long-chain triglyceride (LCT) for reducing pain on injection, because the concentrations of free propofol are significantly smaller by 30-45% than those in propofol LCT. Mallick et al. [8] reported that premixing 40 mg of lidocaine to Lipuro Ⓡ propofol (a propofol formulated as an emulsion of 50% MCT and 50% LCT) almost abolishes the pain on injection, making induction of anesthesia less painful compared to Lipuro Ⓡ propofol alone or Diprivan Ⓡ propofol (a propofol formulated as an emulsion in a solution of 10% soybean oil containing only LCT) with lidocaine. A lipid-free microemulsion propofol (Aquafol Ⓡ) was developed to avoid …