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Intramuscular Naloxone Reverses the Side Effects of Epidural Morphine while Preserving Analgesia
  1. Gregg A. Korbon, MD*,
  2. Daniel J. James, MD,
  3. Michael J. Verlander, MD,
  4. Cosmo A. DiFazio, MD, PhD§,
  5. Stuart M. Rosenblum, MD,
  6. Stuart J. Levy, MD and
  7. Phil C. Perry, MD**
  1. From the University of Virginia Hospital Medical Center, Charlottesville, Virginia
  2. *Assistant Professor of Anesthesiology, University of Virginia Medical Center, Charlottesville, VA
  3. Assistant Professor, Department of Anesthesia, Bowman-Gray Medical Center, Winston-Salem, NC
  4. Staff Anesthesiologist, University Hospital, Jacksonville, FL
  5. §Professor of Anesthesiology, University of Virginia Medical Center, Charlottesville, VA
  6. Staff Anesthesiologist, Emanual Hospital, Portland, OR
  7. Staff Anesthesiologist, Morristown Memorial Hospital, Morristown, NJ
  8. **Staff Anesthesiologist, Scotland Memorial Hospital, Laurinburg, NC


Sixteen consecutive patients who underwent cesarean section under epidural analgesia received epidural morphine sulfate (EMS) 10 mg in 10 ml of normal saline in the recovery room. Patients were randomly divided into two groups. Group I received naloxone 0.4 mg intramuscularly at 2 and 8 hours after EMS. Group II received no naloxone. Both groups were evaluated for respiratory rate, paCO2, analgesia, and side effects consisting of itching, nausea, and sedation over a 9-hour period.

In Group I, a PaCO2 increase of 7 mm Hg from baseline 8 hours after EMS was partially reversed (decrease of 3 mm Hg) 1 hour after the second dose of IM naloxone (p < .05). Other side effects were decreased as well, while analgesia was unchanged. Changes in respiratory rate did not correlate with PaCO2 increase after EMS (r = −0.08).

This study suggests that intramuscular naloxone partially reverses respiratory depression from epidural morphine, while preserving analgesia. Respiratory rate does not indicate degree of respiratory depression in the ranges experienced in our study.

  • Analgesia
  • postoperative
  • Analgesics
  • morphine
  • Anesthesia
  • obstetrics
  • Anesthetic techniques
  • epidural
  • Pain
  • postoperative

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