A 58-year-old woman presents with a 3-day history of nausea and vomiting. She has a history of breast cancer with wide-spread bone metastases. The cancer has progressed and chemotherapy was unsuccessful, and she is only receiving supportive care only. She tells you she vomits a large amount (mostly undigested food) several times most days. She is intermittently nauseated and feels better for a time after vomiting. Her GP recently started her on morphine for pain in her shoulders, which she has been taking several times each day.
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1. What are the common causes of nausea and vomiting in palliative care?
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Correct answer:
Nausea and vomiting is a common symptom in palliative care and is said to occur in up to 70% of patients with cancer and 50% of patients with non-malignant disease. The most common causes in palliative care are gastric stasis and gut dysmotility, cerebral irritation, medication side effects and biochemical abnormalities.
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2. What is the most likely cause of nausea and vomiting?
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Correct answer:
Morphine acts on smooth muscle and the central nervous system resulting in stimulation of the chemoreceptor trigger zone and an increase in smooth muscle tone especially at the sphincters of the gastrointestinal tract. Nausea and vomiting as a result of gut dysmotility is characterized by intermittent nausea and large volume vomits of undigested food that relieves the feelings of nausea.
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3. Which anti-emetic would you use and why?
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Metoclopramide stimulates motility of the upper gastrointestinal tract. It improves gastric emptying by increasing the gastro-oesophageal tone and peristaltic activity of the jejunum and duodenum. In addition, metoclopramide has some dopamine antagonist activity. These modes of action make metoclopramide the most appropriate anti-emetic in the management of opioid-induced nausea and vomiting.
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4. Three days later, she has stopped vomiting but is now constantly nauseated. The nausea is exacerbated by the smell of food. Blood tests show that she is hypercalcaemic. What is the most likely cause of the nausea?
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Correct answer:
Through stimulation of the dopamine receptors in the chemoreceptor trigger zone, nausea and vomiting can be caused by biochemical imbalances such as hypercalcaemia. It is characterized by constant severe nausea with little relief from vomiting and is often exacerbated by the smell of food.
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5. Which anti-emetic would you use and why?
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Correct answer:
Haloperidol is a potent dopamine antagonist and is effective in the management of chemically induced nausea and vomiting through the blocking of dopamine receptors in the chemoreceptor trigger zone.
