title: Does adjusting the pH of lidocaine reduce pain during injection?
abstract: BACKGROUND
  Receiving local anaestethic injection is painful. A double-blinded randomised study with 32 healthy adult volunteers was performed, with the aim of investigating the effect of buffering lidocaine to reduce the pain during injection.
  
  
  METHODS
  Each participant received two subcutaneous injections of 4.5 ml lidocaine 1% on the lower left and right quadrants of the abdomen. One solution was plain lidocaine (pH 6.55) and the other was lidocaine buffered with sodium bicarbonate in a ratio of 9:1 (pH 7.30). After each injection the participant marked the pain experienced during the injection on a visual analogue scale (VAS; 0 = best, 100 = worst), in addition to verbally stating which injection they found was the least painful.
  
  
  RESULTS
  A total of 20 stated that they preferred the buffered solution, while eight said that they preferred the unbuffered solution (p < 0.002). The mean VAS pain-score was 15 (SD = 12) for the buffered injections and 20 (SD = 12) for the unbuffered injections (p < 0.017).
  
  
  CONCLUSIONS
  The conclusion is that the pain experienced during the injection of lidocaine can be significantly reduced by buffering the solution before injection.
authors.affiliation: a 1 Faculty of Medicine, NTNU , Trondheim, Norway.
authors.forename: Trine I
authors.initials: TI
authors.lastname: Skarsvåg
authors.affiliation: a 1 Faculty of Medicine, NTNU , Trondheim, Norway.
authors.forename: Kathrine J
authors.initials: KJ
authors.lastname: Wågø
authors.affiliation: a 1 Faculty of Medicine, NTNU , Trondheim, Norway.
authors.forename: Lena F
authors.initials: LF
authors.lastname: Tangen
authors.affiliation: a 1 Faculty of Medicine, NTNU , Trondheim, Norway.
authors.forename: Janne S
authors.initials: JS
authors.lastname: Lundbom
authors.affiliation: a 1 Faculty of Medicine, NTNU , Trondheim, Norway.
authors.forename: Tonje
authors.initials: T
authors.lastname: Hjelseng
authors.affiliation: a 1 Faculty of Medicine, NTNU , Trondheim, Norway.
authors.forename: Solveig
authors.initials: S
authors.lastname: Ballo
authors.affiliation: a 1 Faculty of Medicine, NTNU , Trondheim, Norway.|b 2 Department of Orthopaedic Surgery, St Olav's University Hospital , Trondheim, Norway.
authors.forename: Vilhjalmur
authors.initials: V
authors.lastname: Finsen
keywords: Lidocaine; bicarbonate; injection; pain