A comparison of two constant-dose continuous infusions of remifentanil forsevere postoperative pain

We evaluated the analgesic efficacy and safety of two continuous constant-d ose infusions of IV remifentanil, without infusion rate increments or the a ddition of boluses, in patients with severe postoperative pain during the f irst 4h after general anesthesia with IV propofol-remifentanil. Thirty pati ents were randomly assigned to two groups of 15 subjects each according to the remifentanil dose administered: 0.1 mug.kg(-1). min(-1) IV (Group A) or 0.05 mug . kg(-1) . min(-1) IV (Group B). Rescue analgesia was provided wi th meperidine (0.5 mg/kg IV) when pain intensity on the simple verbal scale (SVS) greater than or equal to2. The criteria for adequate analgesia (SVS 0-1, respiratory frequency >8/min. and Spo(2) >90%) after 4 h were met by 7 8% and 75% of the patients in Groups A and B, respectively (P = ns). "Meper idine rescue" analgesia was significantly more in Group B (26%) than in Gro up A (6%) (P < 0.05). There were no cases of respiratory depression, and na usea and emesis occurred in one patient in each group (6.5%). We conclude t hat IV remifentanil is an effective and safe opioid for the treatment of po stoperative pain at a constant dose of 0.1 <mu>g . kg(-1) . min(-1) with a need for rescue analgesia 4 times less than a constant dose of 0.05 mug . k g(-1) . min(-1).