EPIDURAL MORPHINE - A CLINICAL DOUBLE-BLIND-STUDY OF DOSAGE

  • 1 January 1985
    • journal article
    • research article
    • Vol. 64  (8) , 786-791
Abstract
The optimal dose of epidural morphine was determined by establishing a dose-effect reationship. The 139 patients who had orthopedic operations on the lower extremities received continuous lumbar epidural anesthesia with bupivacaine, 0.75% with or without the addition of 1,2,3,4 or 5 mg of morphine hydrochloride. Analgesia and side effects were determined during the first 24 h postoperatively. In the 12 h period after epidural anesthesia, arterial blood gas tensions were compared between those patients who received 5 mg morphine (n = n13) and those who received no morphine (n = 14). Patients who received .gtoreq. 2 mg of morphine were less likely to require the administration of postoperative systemic analgesics (P < 0.05). The addition of .gtoreq. 2 mg of morphine to bupivacaine, 0.75%, reduced postoperative pain intensity (P < 0.05); 5 mg of morphine reduced pain intensity for the longest time. Frequency of catheterization and pruritus increased dose-dependently. The mean PaCO2 [arterial CO2 tension] after 5 mg of epidural morphine averaged 5 mm Hg higher than in the control group, indicating minor respiratory depression, better analgesia or both. The dose of 3 mg of epidural morphine added to the local anesthetic is recommeded for postoperative analgesia after surgery of the lower extremity; it is a compromise that provides adequate analgesia with an acceptably low frequency and intensity of side effects.

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