title: Comparison of three remifentanil dose-finding regimens for coronary artery surgery.
abstract: OBJECTIVE
  To identify the remifentanil dosing regimen providing safe and optimal anesthetic conditions during coronary artery bypass graft surgery and to evaluate postoperative recovery characteristics.
  
  
  METHODS
  Open-label, randomized, parallel group.
  
  
  METHODS
  Three centers in the United States.
  
  
  METHODS
  Seventy-two patients with left ventricular stroke volumes >or=50 mL.
  
  
  METHODS
  Patients were randomized to remifentanil doses of 1 microg/kg/min (group 1, n = 23); 2 microg/kg/min (group 2, n = 24), or 3 microg/kg/min (group 3, n = 25). Somatic, sympathetic, and hemodynamic responses indicating inadequate anesthesia were treated with bolus doses of remifentanil, 1 to 2 microg/kg, and infusion rate increases, and, if necessary, isoflurane 0.5% to 1.0% was added as a rescue anesthetic. In the intensive care unit, the remifentanil infusion was reset to 1 microg/kg/min, with midazolam administered for supplemental sedation and morphine for analgesia.
  
  
  RESULTS
  The durations of anesthesia, surgery, and cardiopulmonary bypass were similar for the 3 study groups. In addition, dose of lorazepam premedication, time to loss of consciousness, preoperative left ventricular ejection fraction, age, weight, and sex were similar for the 3 study groups. Remifentanil alone (infusion and boluses) prevented and controlled all responses to stimulation in 44% of group 3, 37% of group 2 and 9% of group 1 patients intraoperatively. Isoflurane (0.5%-1% inspired) rescue was successful in the remaining patients in each group. Hypotension indicating discontinuation of isoflurane and reductions of remifentanil infusion rates occurred in 64% to 75% of all patients. The optimal range of remifentanil infusion was 2 to 4 microg/kg/min with isoflurane to supplement the opioid. Fifty-one patients (71%) met the criteria for extubation within 6 hours postoperatively; because of surgical practice differences, only 30 patients (59%) were actually extubated.
  
  
  CONCLUSIONS
  After lorazepam premedication, remifentanil infusion (2-4 microg/kg/min) supplemented intermittently with low inspired concentrations of isoflurane provided an effective anesthetic regimen for coronary artery bypass graft surgery. Early extubation times were feasible after remifentanil continuous infusions (1-5 microg/kg/min) used as the primary anesthetic component intraoperatively and for analgesia (<or=1 microg/kg/min) in the immediate postoperative setting.
authors.affiliation: Department of Anesthesiology, The Ohio State University Hospitals, Columbus, OH 43210, USA.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Howie
authors.forename: Luis G
authors.initials: LG
authors.lastname: Michelsen
authors.forename: Carl C
authors.initials: CC
authors.lastname: Hug
authors.forename: David T
authors.initials: DT
authors.lastname: Porembka
authors.forename: Michael W
authors.initials: MW
authors.lastname: Jopling
authors.forename: Samuel M
authors.initials: SM
authors.lastname: Warren
authors.forename: Soraya
authors.initials: S
authors.lastname: Shaikh
mesh_terms: D000701:Analgesics, Opioid / Q000627:therapeutic use*; D018685:Anesthetics, Inhalation / Q000627:therapeutic use; D014151:Anti-Anxiety Agents / Q000627:therapeutic use; D001794:Blood Pressure / Q000187:drug effects; D001026:Coronary Artery Bypass; D004305:Dose-Response Relationship, Drug; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007530:Isoflurane / Q000627:therapeutic use; D008140:Lorazepam / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D010880:Piperidines / Q000627:therapeutic use*; D011292:Premedication; D000077208:Remifentanil; D013997:Time Factors
chemical_list: D000701:Analgesics, Opioid; D018685:Anesthetics, Inhalation; D014151:Anti-Anxiety Agents; D010880:Piperidines; D007530:Isoflurane; D008140:Lorazepam; D000077208:Remifentanil