title: The analgesic effect of epidural clonidine after spinal surgery: a randomized placebo-controlled trial.
abstract: BACKGROUND
  Clonidine is an alpha(2) adrenoreceptor and imidazoline receptor agonist, which has analgesic, sedative, and minimum alveolar anesthetic concentration-sparing effects. It has been used orally, IV, and epidurally. In spinal surgery, there is a reluctance to use local anesthetic-based epidural analgesia postoperatively because of fears of masking important signs of nerve root or spinal cord injury.
  
  
  METHODS
  We randomized 66 patients undergoing uncomplicated decompressive spinal surgery to receive an epidural infusion of either clonidine (Group C) or saline placebo (Group P) postoperatively. Morphine consumption by patient-controlled analgesia device was recorded for 36 h.
  
  
  RESULTS
  Morphine consumption was significantly lower in Group C. The mean consumption at 36 h was 35 mg (95% confidence interval 21-50 mg) in Group C, compared with 61 mg (95% confidence interval 48-74 mg) in the control group. Nausea was significantly reduced in Group C (6.5%), when compared with placebo (38.2%).
  
  
  CONCLUSIONS
  Low-dose epidural clonidine significantly reduced the demand for morphine and reduced postoperative nausea with few side effects.
authors.affiliation: Nuffield Department of Anaesthetics, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK. andrew.farmery@nda.ox.ac.uk
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Farmery
authors.forename: James
authors.initials: J
authors.lastname: Wilson-MacDonald
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000009:adverse effects; D000328:Adult; D000368:Aged; D015360:Analgesia, Epidural; D001794:Blood Pressure / Q000187:drug effects; D003000:Clonidine / Q000009:adverse effects; D004311:Double-Blind Method; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006993:Hypnotics and Sedatives; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009020:Morphine / Q000008:administration & dosage / Q000627:therapeutic use; D010147:Pain Measurement / Q000187:drug effects; D010149:Postoperative Pain / Q000188:drug therapy*; D010865:Pilot Projects; D020250:Postoperative Nausea and Vomiting / Q000453:epidemiology; D011229:Preanesthetic Medication; D013131:Spine / Q000601:surgery*; D016055:Urinary Retention / Q000139:chemically induced
chemical_list: D000316:Adrenergic alpha-Agonists; D006993:Hypnotics and Sedatives; D009020:Morphine; D003000:Clonidine