Ask the Expert – Nausea/Vomiting

Dr. Elizabeth Paulk:

Nausea is a prevalent symptom, especially in patients at the end of life. Up to 68% of cancer patients experience nausea during the course of disease, and 13-17% suffer from it in the last weeks of life. Around 45% of AIDS patients, 17-48% of heart disease patients, and 30-43% of end-stage renal disease patients are nauseated. There are no formal, evidence-based guidelines available for nausea management, put the key principles are:

1. Treat the nausea based on the underlying etiology

2. Remember that there are many neurotransmitters involved, so use “dirty” drugs that affect many different ones. Promethazine, for example, is anticholinergic, antihistaminic, and mildly anti-dopaminergic.

3. Your strategy should be similar to the management of hypertension – stack the drugs up. Once the nausea is controlled, you can start eliminating agents. Often patients will require two or more agents for control.

The way to remember how to treat nausea is the acronym, VOMITS

  • Vestibular Causes (acetylcholine and histamine) –> scopolamine patch or promethazine
  • Obstruction of Bowel by Constipation (this does not apply to complete bowel obstruction – see below) (acetylcholine, histamine, and likely serotonin 3) –> start with a drug that stimulates the myenteric plexus, like senna, and escalate as needed.
  • dysMotility of upper gut (cholinergic, histaminic, 5HT3, 5HT4) –> Use prokinetics which stimulate 5HT4 receptors, like metoclopramide
  • Infection, Inflammation (Cholinergic, Histaminic, 5HT3, Neurokinin 1) –> Promethazine (e.g. for labyrinthitis), prochlorperazine, aprepitant
  • Toxins stimulating the chemoreceptor trigger-zone in the brain such as opioids (Dopamine 2, 5HT3) –> Prochlorperazine, Haloperidol, Ondansetron
  • Scared (for those with severe anxiety or anticipatory nausea) –> benzodiazepines like valium can be very helpful, but should not be used as monotherapy.

Tips:

  • Remember that dexamethasone is also a powerful anti-emetic, and if you are not having success with the strategies above, consider it as an additional agent.
  • Promethazine and prochlorperazine are very different drugs. Promethazine is most useful for vertigo and gastroenteritis due to infections and inflammation. Prochlorperazine is preferred for opioid related nausea.
  • For complete bowel obstruction, the primary management strategy is bowel rest. Octreotide is very helpful in this context.