Comparison of three remifentanil dose-finding regimens for coronary artery surgery.
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.
Howie
Michael B
MB
Department of Anesthesiology, The Ohio State University Hospitals, Columbus, OH 43210, USA.
Michelsen
Luis G
LG
Hug
Carl C
CC
Porembka
David T
DT
Jopling
Michael W
MW
Warren
Samuel M
SM
Shaikh
Soraya
S
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
D000701:Analgesics, Opioid; D018685:Anesthetics, Inhalation; D014151:Anti-Anxiety Agents; D010880:Piperidines; D007530:Isoflurane; D008140:Lorazepam; D000077208:Remifentanil