title: Tachyphylaxis to local anaesthetics. What is the clinical evidence? A systematic review.
abstract: BACKGROUND
  Tachyphylaxis or acute tolerance to local anaesthetics has been reported, but the prevalence in clinical analgesia is obscure, and the mechanisms behind this phenomenon remain unclear. We sought to examine the clinical significance of tachyphylaxis from the available literature.
  
  
  METHODS
  We performed a systematic review of the literature utilising the databases PubMed and Embase employing the search terms [Tachyphylaxis AND Local Anaesthetics AND Human] AND [Tolerance AND Local Anaesthetics AND Human].
  
  
  RESULTS
  A total of 66 records were identified. Thirty-four articles were assessed in full text for eligibility. Twenty studies were considered relevant for qualitative analyses, but only six studies were randomised controlled trials. Because of the heterogeneity of the randomised controlled trials, it was not possible to conduct a meta-analysis.
  
  
  CONCLUSIONS
  Studies documenting tachyphylaxis with clinical use of local anaesthetics are surprisingly scarce, and the mechanisms behind it remain unclear.
authors.affiliation: Department of Anaesthesiology, Division of Emergencies and Critical Care, Oslo University Hospital and Medical Faculty, University of Oslo, Oslo, Norway.
authors.forename: U E
authors.initials: UE
authors.lastname: Kongsgaard
authors.affiliation: Department of Neuroanaesthesia, Neuroscience Centre, Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: M U
authors.initials: MU
authors.lastname: Werner
mesh_terms: D000779:Anesthetics, Local / Q000009:adverse effects*; D006801:Humans; D015995:Prevalence; D016032:Randomized Controlled Trials as Topic; D013618:Tachyphylaxis
chemical_list: D000779:Anesthetics, Local