Comparison of Adenosine and Remifentanil Infusions as Adjuvants to Desflurane Anesthesia

Background: Because adenosine has been alleged to produce both anesthetic and analgesic sparing effects, a randomized, double-blinded study was designed to compare the perioperative effects of adenosine and remifentanil when administered as intravenous adjuvants during general anesthesia for major gynecologic procedures. Methods: Thirty-two women were assigned randomly to one of two drug treatment groups. After premedication with 0.04 mg/kg intravenous midazolam, anesthesia was induced with 2 μg/kg intravenous fentanyl, 1.5 mg/kg intravenous propofol, and 0.6 mg/kg intravenous rocuronium, and maintained with desflurane, 2%, and nitrous oxide, 65%, in oxygen. Before skin incision, an infusion of either remifentanil (0.02 μg. kg -1 . min -1 ) or adenosine (25 μg. kg -1 . min -1 ) was started and subsequently titrated to maintain systolic blood pressure, heart rate, or both within 10-15% of the preincision values. Results: Adenosine and remifentanil infusions were effective anesthetic adjuvants during lower abdominal surgery. Use of adenosine (mean ± SEM, 166 ± 17 μg. kg -1 . min -1 ) was associated with a significantly greater decrease in systolic blood pressure and higher heart rate values compared with remifentanil (mean ± SEM, 0.2 ± 0.03 μg. kg -1 . min -1 ). Total postoperative opioid analgesic use was 45% and 27% lower in the adenosine group at 0-2 h and 2-24 h after surgery, respectively. Conclusions: Adjunctive use of a variable-rate infusion of adenosine during desflurane-nitrous oxide anesthesia was associated with acceptable hemodynamic stability during the intraoperative period. Compared with remifentanil, intraoperative use of adenosine was associated with a decreased requirement for opioid analgesics during the first 24 h after operation.