title: Systemic ropivacaine diminishes pain sensitization processes: a randomized, double-blinded, placebo-controlled, crossover study in healthy volunteers.
abstract: BACKGROUND
  Ropivacaine is a local anesthetic widely used for regional anesthesia. One of its advantages is low toxicity at plasma concentrations reached systemically during continuous peripheral or central nervous block. The objective of this study was to test the effect of systemic ropivacaine on pain, hyperalgesia, dynamic allodynia, and flare response.
  
  
  METHODS
  This randomized, double-blinded, placebo-controlled, crossover study was carried out in at the Clinical Trials Centre, University of Zurich, Switzerland. Twenty healthy male volunteers were included in the study. Exclusion criteria were contraindications or hypersensitivity to local anesthetics, vulnerable subjects (intellectually or mental impaired), drug, alcohol or nicotine abuse, known peripheral neuropathies, diabetes mellitus and/or congestive heart disease. Ropivacaine and saline were infused intravenously during a subcutaneous electrical stimulation. The stimulation software adjusted the stimulus strength according to the rating on a numeric rating scale (NRS; 0-10) maintaining a NRS of 5. Areas of punctate hyperalgesia, dynamic allodynia, and flare response were measured before and after the infusion.
  
  
  RESULTS
  The area of hyperalgesia increased significantly with saline (303 ± 380%, P < 0.05) and ropivacaine (186 ± 137%, P < 0.05). The area of allodynia (253 ± 299%, P < 0.05) and flare response (112 ± 24%, P < 0.05) increased only during the placebo infusion.
  
  
  CONCLUSIONS
  The results of this study imply that systemic ropivacaine may diminish pain sensitization processes.
authors.affiliation: Institute of Anaesthesiology, University Hospital of Zurich, Raemistrasse 100, 8091, Zurich, Switzerland.
authors.forename: Yéri
authors.initials: Y
authors.lastname: Haller
authors.forename: Andreas R
authors.initials: AR
authors.lastname: Gantenbein
authors.forename: Patrick
authors.initials: P
authors.lastname: Willimann
authors.forename: Donat R
authors.initials: DR
authors.lastname: Spahn
authors.forename: Konrad
authors.initials: K
authors.lastname: Maurer