title: Intrathecal low-dose hyperbaric bupivacaine-clonidine combination in outpatient knee arthroscopy: a randomized controlled trial.
abstract: BACKGROUND
  Spinal anesthesia for knee arthroscopy can be produced with a low dose of bupivacaine, but additional intrathecal drugs are often required to lower the risk of failed blocks. We investigated the effect of the addition of clonidine (0, 15 or 30 microg) to 5 mg hyperbaric bupivacaine on the duration of the motor block, analgesic quality and ability to void after the surgery in a randomized controlled trial.
  
  
  METHODS
  Seventy-five patients received spinal anesthesia using either 5 mg hyperbaric bupivacaine (B5C0), 5 mg hyperbaric bupivacaine with 15 microg clonidine (B5C15) or 5 mg hyperbaric bupivacaine with 30 microg clonidine (B5C30). The primary outcome was the duration of the motor block. Secondary outcomes included the time until spontaneous voiding, and the need for additional analgesia or general anesthesia.
  
  
  RESULTS
  The mean time to complete regression of motor block was 70 (+/-43) min in group B5C0. Adding 15 and 30 microg of clonidine increased the motor block duration by 25 [95% confidence interval (CI): 2-48] and 34 (95% CI: 11-57) min, respectively, but resulted in better analgesic quality. The mean time until spontaneous voiding was 177 min in the B5C0 group. This time increased with 18 (95% CI -13 to 49) and 44 (95% CI 15-74) min in group B5C15 and group B5C30, respectively.
  
  
  CONCLUSIONS
  The addition of 15 microg clonidine to 5 mg of intrathecal hyperbaric bupivacaine prolongs the duration of motor block and improves the quality of the block.
authors.affiliation: Department of Anesthesiology, University Medical Centre Utrecht, Utrecht, The Netherlands. I.vanTuyl@umcutrecht.nl
authors.forename: I
authors.initials: I
authors.lastname: van Tuijl
authors.forename: M J M M
authors.initials: MJ
authors.lastname: Giezeman
authors.forename: S A
authors.initials: SA
authors.lastname: Braithwaite
authors.forename: P J
authors.initials: PJ
authors.lastname: Hennis
authors.forename: C J
authors.initials: CJ
authors.lastname: Kalkman
authors.forename: W A
authors.initials: WA
authors.lastname: van Klei
mesh_terms: D000328:Adult; D000556:Ambulatory Surgical Procedures; D000700:Analgesics / Q000008:administration & dosage*; D000775:Anesthesia, Spinal / Q000379:methods*; D000779:Anesthetics, Local / Q000008:administration & dosage*; D001182:Arthroscopy; D002045:Bupivacaine / Q000008:administration & dosage*; D003000:Clonidine / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007717:Knee / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000700:Analgesics; D000779:Anesthetics, Local; D003000:Clonidine; D002045:Bupivacaine