The Efficacy of Intravenous Patient-Controlled Remifentanil Versus Morphine Anesthesia After Coronary Artery Surgery

Abstract

To compare the effect of remifentanil and morphine after coronary artery surgery in a patient-controlled analgesia (PCA) protocol. A prospective, randomized, double-blind clinical study. Single institution, university hospital. Sixty cardiac surgical patients undergoing primary coronary artery bypass graft (CABG) surgery. After the operation, patients were allocated to 1 of 2 groups. In the first group (group R, n = 30), the following intravenous PCA protocol was programmed: remifentanil infusion, 0.05 microg/kg/min; bolus, 0.25 microg/kg; and lockout time, 5 minutes. In the second group (group M, n = 30), the intravenous PCA protocol was as follows: morphine infusion, 0.3 mg/h; bolus, 1 mg; and lockout time, 5 minutes. In addition to intravenous opioids, paracetamol was administered during the study. In both groups, tramadol was added to the regimen after PCA had been terminated at 24 hours after surgery. In addition to tramadol and paracetamol, 10 mg of morphine sulfate was administered if the numeric rating scale (NRS) score for pain was 3 or more after the first postoperative day. Pain was assessed with an NRS in each patient at rest, while coughing, and during movement for 72 hours. Sedation levels were measured with the Ramsay sedation scale. Overall effectiveness of pain relief was evaluated with a 4-stage scale ("very good," "good," "moderate," or "bad"). During coughing, the NRS values were statistically significantly lower in group R than they were in group M at 12 and 24 hours after surgery (median 1 vs 3 at 12 hours and 2 v 3.5 at 24 hours) (p < 0.05). On movement, NRS values were statistically significantly lower in group R than they were in group M at 12 hours after surgery (median 1 v 2.5) (p < 0.05). After the first 24 hours, the requirement for additional analgesia was similar in both groups. The overall effectiveness of pain relief was rated "very good" or "good"' in 87% of patients in group R and in 72% of patients in group M (p > .05). There was no difference in patient satisfaction between the 2 groups. On the basis of the reduction of pain scores (with cough and movement) at 1 or 2 postoperative time points, PCA-remifentanil infusion is a better analgesic technique; overall, both PCA techniques provided for effective pain scores (<3). In patients in whom PCA morphine is contraindicated after CABG surgery, PCA remifentanil is a safe alternative.