title: [Propofol-LCT versus propofol-MCT/LCT with or without lidocaine - a comparison on pain on injection].
abstract: OBJECTIVE
  A disadvantage of Propofol (commercial preparation containing long-chain triglycerides; Propofol-LCT) is pain on injection, which is reported by 54 - 100 % of the patients. Many different approaches have been used in an attempt to decrease the pain on injection of propofol. The currently most efficacious treatment is lidocaine given intravenously with a tourniquet prior to Propofol injection. In previous studies, larger concentrations of free propofol in the aqueous phase of an emulsion were associated with more pain on injection. A new formulation of propofol (a mixture of long-chain and medium-chain triglycerides in the carrier emulsion; Propofol-MCT/LCT) reduces the incidence of pain on bolus injection. This study was designed to investigate, whether the use of Propofol-MCT/LCT alleviates pain on injection to a similar degree as pretreatment with lidocaine.
  
  
  METHODS
  Eighty patients (ASA I - III) were randomly assigned to four groups according to a double-blinded protocol, to receive either lidocaine 2 % or normal saline given iv. with a 60 seconds tourniquet time before the injection of Propofol-LCT or Propofol-MCT/LCT. (group 1: 2 ml NaCl 0,9 %, Propofol-LCT; group 2: 2 ml NaCl 0,9 %, Propofol-MCT/LCT; group 3: 2 ml lidocaine 2 %, Propofol-LCT; group 4: 2 ml lidocaine 2 %, Propofol-MCT/LCT). Assessment of pain on injection was performed after 30 % of the induction dose was given.
  
  
  RESULTS
  Pain on injection caused by Propofol-LCT with pre-treatment of lidocaine and Propofol-MCT/LCT alone is shown to be equivalent. Comparison of Propofol-MCT/LCT with pre-treatment of lidocaine and Propofol-LCT alone shows a statistical noticeable p-value of 0.035. Propofol-MCT/LCT with pre-treatment of lidocaine suggests a tendency of causing less pain compared to Propofol-MCT/LCT. Analysis of the postoperative questionnaire supplies no significant difference.
  
  
  CONCLUSIONS
  The results suggest that pain on injection is reduced equivalent using either Propofol-MCT/LCT alone or Propofol-LCT with pre-treatment of lidocaine. Pre-treatment with lidocaine before Propofol-MCT/LCT seems to have an additional effect.
authors.affiliation: Klinik für Anästhesiologie am Universitätsklinikum der RWTH Aachen, Germany. okunitz@ukaachen.de
authors.forename: O
authors.initials: O
authors.lastname: Kunitz
authors.forename: R
authors.initials: R
authors.lastname: Lösing
authors.forename: S
authors.initials: S
authors.lastname: Schulz-Stübner
authors.forename: S
authors.initials: S
authors.lastname: Haaf-Von-Below
authors.forename: R
authors.initials: R
authors.lastname: Rossaint
authors.forename: R
authors.initials: R
authors.lastname: Kuhlen
mesh_terms: D000328:Adult; D000771:Anesthesia, Intravenous; D018686:Anesthetics, Intravenous / Q000008:administration & dosage* / Q000009:adverse effects; D000779:Anesthetics, Local; D004311:Double-Blind Method; D005079:Excipients / Q000737:chemistry; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D008012:Lidocaine; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000209:etiology; D010149:Postoperative Pain / Q000453:epidemiology; D015742:Propofol / Q000008:administration & dosage* / Q000009:adverse effects; D011446:Prospective Studies; D014280:Triglycerides / Q000737:chemistry
chemical_list: D018686:Anesthetics, Intravenous; D000779:Anesthetics, Local; D005079:Excipients; D014280:Triglycerides; D008012:Lidocaine; D015742:Propofol