Nausea and Vomiting

Key points

• Effective treatment of nausea results in a huge improvement in quality of life.
• Nausea and vomiting are common problems.
• Nausea is frequently multifactorial, and sometimes no cause is identifiable. Gastric stasis and biochemical problems may be common mechanisms in palliative care patients. Treat underlying causes wherever possible, as well as the symptom.
• Always provide as required antiemetics for palliative care patients.
• If a patient has nausea or vomiting, prescribe antiemetics regularly and by an appropriate route to achieve reliable absorption. The subcutaneous route, or sublingual wafers (if tolerated) are usually preferred to intramuscular or intravenous administration.  Suppositories may be acceptable for some patients.
• Discuss diet and eating concerns with the patient and carer. Trying to eat large amounts or inappropriate foods can worsen nausea and vomiting, and some foods may trigger nausea.

Assessment

• Think in terms of peripheral vs central causes
  • central causes of nausea include central nervous system (CNS) disease, biochemical abnormalities, infection, food and medication, anxiety, or depression
  • peripheral causes include gastrointestinal or intra-abdominal problems, such as reduced gastric emptying, obstruction, peritoneal disease, ascites.
• Ask about unheralded vomiting - causes to exclude are gastric outlet obstruction (vomiting of large volumes often including undigested food) and cerebral disease (often worst in the mornings).
• Do not forget to also monitor for common side effects of antiemetics (extrapyramidal side effects and akathisia; constipation from 5HT3 (serotonin) blocker; sedation).
• Always consider gastrointestinal obstruction as a possible cause of vomiting. Palliative care referral is appropriate for these patients. Selected patients may also benefit from surgical management.

Approach to management

• Prescribing is traditionally based on identifying the mechanism of the nausea and selecting an agent which acts on the most likely pathway involved. In multifactorial nausea, several pathways may be involved.
• Selection of a prokinetic agent is appropriate if nausea is caused by gastric stasis / reduced gastric emptying, but may potentially worsen pain and vomiting if used in obstruction.
• Rehydration may improve nausea. The subcutaneous route is usually appropriate.
• Optimise the management of constipation. The choice of aperients should be reviewed if the patient cannot tolerate them, or if large volumes of fluid are required. Occasionally rectal measures (suppositories or enemas) may be a better option for the patients with uncontrolled nausea and vomiting.