[Propofol-LCT versus propofol-MCT/LCT with or without lidocaine - a comparison on pain on injection].

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.

CONCLUSION

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.