title: Clonidine versus ketamine to prevent tourniquet pain during intravenous regional anesthesia with lidocaine.
abstract: OBJECTIVE
  Both clonidine and ketamine have been found to prolong the action of local anesthetics through a peripheral mechanism. Our study compares the efficacy of a low dose of clonidine or ketamine separately added to intravenous regional anesthesia (IVRA) with lidocaine to prevent tourniquet pain.
  
  
  METHODS
  We conducted a prospective randomized double-blinded study in 45 patients undergoing hand or forearm surgery, with anticipated duration exceeding 1 hour under IVRA. Proximal cuff inflation of a double tourniquet was followed by administration of 40 mL of lidocaine 0.5% and either saline, 1 microg/kg clonidine, or 0.1 mg/kg ketamine. When anesthesia was established, the inflation of the proximal and distal cuff was interchanged. Thereafter, tourniquet pain was rated on a visual analog scale (VAS) every 10 minutes. Intraoperatively, boluses of 25 microg fentanyl were provided for tourniquet pain treatment when required, and total fentanyl consumption was recorded.
  
  
  RESULTS
  Patients receiving plain lidocaine persistently reported the highest pain scores among groups (P <.001) 20 minutes after distal cuff inflation. Differences between the groups with additional treatment were noted 50 minutes after distal cuff inflation and until the end of the observation, with significantly lower VAS ratings (P <.001 to P <.01) in ketamine-treated patients. Total fentanyl consumption was significantly decreased by ketamine (70.00 +/- 25.35 microg) or clonidine (136.67 +/- 39.94 microg) compared with the plain lidocaine group (215.33 +/- 52.33 microg) (P <.001 between all groups).
  
  
  CONCLUSIONS
  The addition of clonidine 1 microg/kg or ketamine 0.1 mg/kg to lidocaine for IVRA delays the onset of unbearable tourniquet pain and decreases analgesic consumption for tourniquet pain relief, although ketamine has a more potent effect.
authors.affiliation: Department of Anesthesiology, Saint Demetrios General Hospital, Thessaloniki, Greece. gorgias@anesthesiology.gr
authors.forename: N K
authors.initials: NK
authors.lastname: Gorgias
authors.forename: P G
authors.initials: PG
authors.lastname: Maidatsi
authors.forename: A M
authors.initials: AM
authors.lastname: Kyriakidis
authors.forename: K A
authors.initials: KA
authors.lastname: Karakoulas
authors.forename: D N
authors.initials: DN
authors.lastname: Alvanos
authors.forename: M M
authors.initials: MM
authors.lastname: Giala
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000009:adverse effects / Q000627:therapeutic use*; D000328:Adult; D000765:Anesthesia, Conduction; D000778:Anesthetics, Dissociative / Q000009:adverse effects / Q000627:therapeutic use*; D000779:Anesthetics, Local; D003000:Clonidine / Q000009:adverse effects / Q000627:therapeutic use*; D004311:Double-Blind Method; D005260:Female; D005542:Forearm / Q000601:surgery; D006225:Hand / Q000601:surgery; D006801:Humans; D007649:Ketamine / Q000009:adverse effects / Q000627:therapeutic use*; D008012:Lidocaine; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures; D010146:Pain / Q000517:prevention & control*; D010147:Pain Measurement / Q000187:drug effects; D011446:Prospective Studies; D014111:Tourniquets / Q000009:adverse effects*
chemical_list: D000316:Adrenergic alpha-Agonists; D000778:Anesthetics, Dissociative; D000779:Anesthetics, Local; D007649:Ketamine; D008012:Lidocaine; D003000:Clonidine