We retrospectively investigated the incidence of adverse effects of postoperative epidural morphine analgesia. Methods: Epidural morphine analgesia was performed in 227 patients undergoing open chest or open abdominal surgery. General anesthesia was induced with thiamylal or propofol, and maintained with sevoflurane after a successful epidural catheterization. Morphine, 2 to 4 mg with 1% mepivacaine 2 ml was injected into the epidural space before start of the operation; thereafter, morphine 2 to 4 mg a day with 0.2% ropivacaine 12 to 24 ml a day was continuously infused into the epidural space. Any unfavorable symptoms or signs recorded in the patients' medical charts during morphine analgesia were adopted as adverse effects.
Results: The adverse effects included nausea and/or vomiting (18.5%), pruritus (16.3%), vertigo/dizziness (9.7%), hallucination/confusion (7.9%), somnolence (7.0%), perspiration (3.1%), and myoclonus (0.4%). Respiratory depression caused by epidural morphine was not present. The incidence of discontinuation of epidural analgesia by the next day was 4.4%. The reasons were hypotension (1.3%), nausea and/or vomiting (1.3%), pruritus (0.9%), vertigo/dizziness (0.4%), and hallucination/confusion (0.4%).
Conclusions: The major adverse effects of epidural morphine analgesia were nausea and/or vomiting, pruritus, and vertigo/dizziness.