5th January 2024

Gastrointestinal

Nausea and Vomiting

Nausea and vomiting are common issues at the end of life, affecting over half of patients with cancer and just under half of those with end-stage heart or renal failure.

Understanding the aetiology of nausea and vomiting allows for more successful management by targeting specific neurotransmitters and other causes with suitable pharmacological and non-pharmacological techniques. Patients may need more than one medication to treat their nausea and vomiting, alongside complementary and psychosocial management. Anticipatory medications at the end of life usually include a subcutaneous PRN antiemetic, usually in the form of levomepromazine or haloperidol.

Pathophysiology of Nausea and Vomiting

A number of neurotransmitters are involved in nausea and vomiting. The vomiting centre, which is located in the brainstem, triggers the vomiting reflex. It receives input from the gastrointestinal system, the chemoreceptor trigger zone, the vestibular system and the cerebral cortex. The cerebral cortex is stimulated by pressure receptors, memory and emotions such as fear and pain.

• Chemoreceptor Trigger Zone
  • Serotonin
  • Dopamine
  • Acetylcholine
  • Histamine
• Gastrointestinal System
  • Serotonin
  • Acetylcholine
• Vestibular Apparatus
  • Histamine
  • Acetylcholine

Causes of Nausea and Vomiting

Source: Adapted from Back I, Watson M, Armstrong P, et al. Palliative Care Adult Network Guidelines. Nausea and Vomiting. [Internet]. 2021 [cited 2023 Jul 16]. Available from: https://book.pallcare.info/index.php?tid=2

Pharmacological Management of Nausea and Vomiting

Source: Adapted from Back I, Watson M, Armstrong P, et al. Palliative Care Adult Network Guidelines. Nausea and Vomiting. [Internet]. 2021 [cited 2023 Jul 16]. Available from: https://book.pallcare.info/index.php?tid=2

Non-Pharmacological Management of Nausea and Vomiting

• Small meals
• Avoid hot beverages
• Relaxation techniques
• CBT for anticipatory nausea and vomiting

Constipation

Constipation is a common issue in palliative care. It affects around 80% of patients with cancer.

Causes

• Medications such as opioids and anticholinergics
• Biochemical disturbances such as hypercalcaemia and hypokalaemia
• Neurological conditions, including spinal cord compression
• Tumour-related, for example, bowel obstruction
• The dying process
  • Decreased activity
  • Low dietary intake
  • Decreased hydration

Management

Non-pharmacological management options do exist(such as increasing mobility, maintaining diet and hydration and stopping culprit medications), but in patients nearing the end of their lives, this may be neither achievable nor appropriate.

Laxatives Commonly Used in Palliative Care 

Source: Created by Dr Tasneem Wadee. British National Formulary (BNF). Constipation: Treatment Summaries [Internet]. [cited 2023 Jul 16]. Available from: https://bnf.nice.org.uk/treatment-summaries/constipation/

Stepwise Pharmacological Management of Constipation in Palliative Care

1. Start with a stimulant laxative
   • Up-titrate to most effective and tolerated dose
2. If still not controlled, add an osmotic or softening laxative
   • Up-titrate to most effective and tolerated dose
3. If the above combination does not work, and the rectum is full, treat according to whether stool in the rectum is soft or hard
   • Soft stool: bisacodyl suppository
   • Hard stool: glycerol suppository
   • Very hard stool: Arachis oil enema (contraindicated in nut allergy)

Phosphate enemas and bulk-forming laxatives should be avoided in this subset of patients. Phosphate enemas can lead to electrolyte disturbances, and bulk-forming laxatives without adequate hydration can lead to worsening of constipation and even bowel obstruction.

Hiccups

Ongoing hiccups can be distressing for patients. They are most commonly due to gastric stasis and distention but can also be due to reflux, irritation of the diaphragm or phrenic nerve, hepatic disease or metabolic disturbances. They usually cease spontaneously.

Peppermint water, antacids or proton pump inhibitors may be used as first-line pharmacological management. Prokinetic medications, such as domperidone or metoclopramide, are also options.

Intractable hiccups that do not settle with the above management can be treated with haloperidol, baclofen, levomepromazine or nifedipine, all under the recommendation of a specialist.