title: Preoperative alpha2-adrenergic receptor agonists prevent the deterioration of renal function after cardiac surgery: results of a randomized, controlled trial.
abstract: OBJECTIVE
  To evaluate the influence of the alpha2-adrenergic receptor agonist clonidine on creatinine clearance as a measure of renal function.
  
  
  METHODS
  Prospective, double-blind, randomized, placebo-controlled clinical trial.
  
  
  METHODS
  University hospital.
  
  
  METHODS
  Patients undergoing coronary artery bypass graft surgery (n = 48) with normal risk.
  
  
  METHODS
  Administration of clonidine (4 micrograms/kg iv)) or placebo 1 hr before induction of anesthesia.
  
  
  RESULTS
  Induction and maintenance of anesthesia (etomidate, midazolam, and fentanyl) and cardiopulmonary bypass technique (nonpulsatile, normothermic, intermittent cold blood cardioplegia) were standardized in all patients. The night before surgery and the first and third night after surgery, creatinine clearance was calculated from a 12-hr urine collection period. Venous blood samples for determination of plasma antidiuretic hormone (ADH) concentrations were taken the evening before surgery, immediately before induction of anesthesia and the evening after surgery (n = 16). Arterial catecholamine plasma concentrations were determined (high-performance liquid chromatography) before induction, 15 mins after induction of anesthesia, immediately after sternotomy, before initiation of cardiopulmonary bypass, as well as 5, 15, and 30 mins after initiation of cardiopulmonary bypass (n = 16). The total amount of anesthetics, infusions, transfusions, diuresis, and blood loss was not different between the groups. Creatinine clearance decreased over the first postoperative night from 98 +/- 18 (preoperatively) to 68 +/- 19 mL/min (p < .05) in placebo-treated patients. Creatinine clearance remained unchanged in clonidine-treated patients (90 +/- 19 [preoperatively] to 92 +/- 17 mL/min). There was a significant difference in creatinine clearance between the groups during the first postoperative night (p < .05; Mann-Whitney U test). In the third postoperative night, mean creatinine clearance of both groups was not different (75 +/- 31 vs. 86 +/- 28 mL/min). ADH concentrations were not different between the groups at any time, while plasma catecholamine concentrations were always significantly lower in clonidine-treated patients.
  
  
  CONCLUSIONS
  Preoperative treatment with clonidine (4 microgram/kilogram) prevents the deterioration of renal function after cardiac surgery. This effect might be due to clonidine-induced reduction in the sympathetic nervous system response to coronary artery bypass graft surgery.
authors.affiliation: Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Bergmannsheil, Bochum, Germany.
authors.forename: P J
authors.initials: PJ
authors.lastname: Kulka
authors.forename: M
authors.initials: M
authors.lastname: Tryba
authors.forename: M
authors.initials: M
authors.lastname: Zenz
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology / Q000627:therapeutic use*; D002395:Catecholamines / Q000097:blood; D002851:Chromatography, High Pressure Liquid; D003000:Clonidine / Q000494:pharmacology / Q000627:therapeutic use*; D001026:Coronary Artery Bypass; D003404:Creatinine / Q000652:urine*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D011300:Preoperative Care; D014667:Vasopressins / Q000097:blood
chemical_list: D000316:Adrenergic alpha-Agonists; D002395:Catecholamines; D014667:Vasopressins; D003404:Creatinine; D003000:Clonidine