Opioid-tolerant patient with chronic pain requesting multimodal analgesia for major surgery
A 45-year-old woman with a history of chronic low back pain and fibromyalgia is scheduled for an open abdominal hysterectomy. She takes oxycodone 30 mg twice daily, gabapentin 600 mg three times daily, and duloxetine 60 mg daily. She reports baseline pain 6/10 and has had prior postoperative pain poorly controlled with opioids. She is anxious about pain control and requests "something that works." She has no history of substance use disorder, but her urine drug screen is positive for oxycodone and cannabinoids.
1. Design a multimodal analgesic plan for the perioperative period, including regional techniques, non-opioid adjuvants, and opioid management.
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This patient is opioid-tolerant and at risk for poor postoperative pain control, so a multimodal, opioid-sparing plan is essential.
Regional anesthesia:
- Consider a transverse abdominis plane (TAP) block or quadratus lumborum (QL) block for abdominal wall analgesia. A TAP block with liposomal bupivacaine or standard bupivacaine can reduce opioid requirements.
- If neuraxial is acceptable, a thoracic epidural or intrathecal morphine could be considered, but the patient's chronic pain and anxiety may make epidural management challenging. Discuss risks and benefits.
Non-opioid adjuvants:
- Continue gabapentin and duloxetine perioperatively (with attention to sedation and serotonin syndrome risk).
- Scheduled acetaminophen and NSAIDs (if no contraindication).
- Ketamine infusion (low-dose, e.g., 0.1–0.3 mg/kg/h) for opioid-tolerant patients.
- Dexmedetomidine infusion for sedation and analgesia.
- Lidocaine infusion if available.
Opioid management:
- Continue baseline oxycodone to prevent withdrawal.
- Use patient-controlled analgesia with hydromorphone or morphine, with a background infusion if needed.
- Consider opioid rotation and anticipate higher requirements.
- Monitor for sedation and respiratory depression.
Psychosocial:
- Address anxiety with non-pharmacologic measures and ensure realistic expectations.
- Involve acute pain service.
2. Discuss the ethical and safety considerations of her positive cannabinoid screen and how you would handle the conversation and perioperative management.
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Ethical considerations:
- The urine drug screen result should not be used to stigmatize or deny care. Cannabinoid use is common and may be legal in her state.
- The result is relevant to anesthesia because of potential interactions (e.g., increased sedation with gabapentin, potential for withdrawal, and effects on pain perception).
- Confidentiality and non-judgmental communication are essential.
Conversation:
- Ask about cannabis use in a non-judgmental way: frequency, route, last use, and reason (recreational vs medicinal).
- Explain the implications: potential for increased anesthetic requirements, interactions with gabapentin and duloxetine, and the need to monitor for withdrawal.
- Document the discussion.
Perioperative management:
- Do not cancel surgery solely for a positive screen.
- Continue gabapentin and duloxetine; monitor for sedation.
- Consider that cannabis may increase the risk of postoperative nausea and vomiting and may interact with opioids.
- If the patient uses cannabis heavily, she may have higher opioid requirements; plan for multimodal analgesia.
- Monitor for withdrawal (irritability, insomnia, nausea) if she stops abruptly.
- Ensure she understands the plan and feels supported.