Nausea

Vignette:

A 57 year-old woman with non-small cell lung cancer has had chronic nausea and vomiting for more than two months. She has been hospitalized twice for these symptoms but is presently at home. The nausea and vomiting began prior to chemotherapy and have persisted throughout her treatments. She was evaluated by a gastroenterologist, and had an MRI to evaluate for brain metastasis. All tests were negative. Constipation has not been an issue. She is not receiving opioids as she denies pain or dyspnea. A J-tube has been placed for nutrition as the nausea makes it difficult for her to maintain her weight through diet. She initially improved with the use of metoclopramide and lorazepam, but the medications are no longer helping. What are some other possible causes for the nausea? Can we recommend other medications or treatments?

Discussion:

There are many causes of nausea in the cancer patient including metastasis, meningeal irritation, medication, mechanical obstruction, and metabolic imbalance. These causes are listed as part of the 12 "M's" of Emesis on The Institute for Palliative Medicine nausea management pocket card. After assessing the likely causes, conceptualize the neurotransmitters to target treatment.

Common medications for the treatment of nausea block the neurotransmitter action and include histamine antagonists, dopamine antagonists, serotonin antagonists, and central-acting medications such as dexamethasone. Nausea frequently has multiple causes and requires combinations of medications. A frequent mistake in management is to substitute drugs, or combine drugs, with the same mechanism of action. In addition, nausea can be 'learned' and cause anxiety if not corrected quickly.

In this patient, the effectiveness of lorazepam suggests this has been an issue. Metoclopramide is both a dopamine antagonist and prokinetic agent. It is frequently prescribed at doses too low to have an effect. That she initially improved on the medication is a clue. For this patient, a trial of haloperidol 5 mg in divided doses (a potent dopamine antagonist), dexamethasone 10 mg daily (unknown mechanism of action, but effective antiemetic), and famotidine 40 mg daily (antacid to block stomach lining irritation) may be tried. If the patient finds taking oral medications difficult and the technology exists, these medications can be mixed together in the same bag, cassette or syringe of normal saline to a 60 ml volume and infused at 2.5 ml per hour to deliver the doses over 24 hours either subcutaneously or intravenously. Copies of nausea management card and NP protocol were sent to provide additional resources.

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