ABSTRACT
UNLABELLED: When used alone, lipid-soluble epidural opioids are thought to produce analgesia supraspinally via systemic absorption. However, spinal opioids and local anesthetics have been shown to act synergistically at the spinal level in animal studies. We, therefore, tested the hypothesis that sufentanil requirements will be less when given epidurally than IV in patients simultaneously given epidural bupivacaine after major abdominal surgery. Forty patients were anesthetized with isoflurane and epidural bupivacaine for major abdominal surgery. After surgery, each was given a continuous epidural infusion of bupivacaine at a rate of 5 mg/h and sufentanil patient-controlled analgesia (PCA). In a randomized, double-blinded fashion, the sufentanil was given either epidurally or IV. PCA settings were the same in each group. For 60 hrs after surgery, the following variables were measured: pain scores at rest, during mobilization, and during coughing; extension of sensory block; side effects; and sufentanil consumption. Pain scores, extension of sensory block, and the incidence of side effects did not differ between the two groups. Consumption of sufentanil in the epidural group was half that of the IV group (48 h after surgery: 107 +/- 57 microg versus 207 +/- 100 microg for the epidural and IV groups, respectively; P < 0.05). We conclude that spinal mechanisms contribute to the analgesia produced by epidural sufentanil in combination with a local anesthetic. IMPLICATIONS: When combined with epidural bupivacaine, the sufentanil requirement was 50% less when given epidurally than IV. Epidural sufentanil thus appears to have a spinal mechanism of action.
