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Zorluk: ZorEnd-of-Life and Palliative Care

A 52-year-old woman with advanced cervical cancer complicated by bilateral hydronephrosis is admitted to the hospital with intractable pelvic pain and rapidly progressing altered mental status. Over the past three days, her pain became increasingly difficult to control at home, prompting her outpatient physician to double her dose of sustained-release oral morphine. On evaluation, the patient is agitated, picking at her bedsheets, and disoriented to time and place. She exhibits sudden, involuntary jerking movements of her upper and lower extremities. When the physician gently palpates her arm to check her pulse, she screams, complaining that her skin "feels like it is on fire." Vital signs are temperature 37.2°C (99.0°F), pulse 110/min, respirations 16/min, and blood pressure 138/85 mm Hg. Oxygen saturation is 96% on room air. Neurologic examination reveals diffuse hyperalgesia, hyperreflexia, and multifocal myoclonus. Laboratory studies show a serum creatinine level of 3.4 mg/dL (baseline 1.1 mg/dL one month ago). Which of the following is the most appropriate next step in the management of this patient?

  1. A
    Administer intravenous haloperidol and maintain the current opioid regimen
  2. B
    Administer intravenous naloxone
  3. C
    Increase the dose of morphine to achieve adequate analgesia
  4. Rotate from morphine to intravenous fentanylCevap
  5. E
    Order an emergency noncontrast CT scan of the head

Cevap

The most appropriate next step is to rotate from morphine to intravenous fentanyl.
The correct answer addresses the root cause of the patient's symptoms: Opioid-Induced Neurotoxicity (OIN). The patient is experiencing delirium, myoclonus, and paradoxical hyperalgesia due to the accumulation of morphine-3-glucuronide (M3G), a neuroexcitatory metabolite of morphine. This accumulation is secondary to her acute kidney injury (elevated creatinine likely from obstructive uropathy). The definitive treatment for OIN is to discontinue the offending agent and rotate to an opioid that is safe in renal impairment and lacks active neurotoxic metabolites. Intravenous fentanyl is heavily metabolized by the liver into inactive metabolites and is the opioid of choice for patients with severe renal dysfunction.

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1
Identify the patient's clinical syndrome based on the physical examination and history.
The patient presents with delirium, multifocal myoclonus, and allodynia/hyperalgesia shortly after a significant increase in her morphine dose.
Recognizing this specific triad of symptoms is critical for diagnosing opioid-induced neurotoxicity (OIN).
2
Determine the underlying mechanism causing the syndrome.
The patient has acute kidney injury (creatinine 3.4 mg/dL) due to bilateral hydronephrosis from advanced cervical cancer.
Morphine is metabolized in the liver to morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G), which are renally cleared. In acute kidney injury, the neuroexcitatory metabolite M3G accumulates, leading to OIN.
3
Select the appropriate therapeutic intervention.
The management of OIN involves reducing the opioid dose, providing hydration if appropriate, or rotating to a different opioid.
Because the patient still has severe cancer pain, stopping opioids entirely is inhumane. Rotating to fentanyl or methadone is preferred, as these agents do not produce active neurotoxic metabolites that accumulate in renal failure.

Anahtar Kavram

Management of Opioid-Induced Neurotoxicity
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Konular

End-of-Life and Palliative Care

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