Nausea and vomiting

GABA 5HT

Vestibular nuclei

ACh H1

CTZ

5HT3 D2

Cerebral cortex

Gut wall

5HT3

Vomiting centre

ACh H1 5HT2

•Gastric atony•Retroperistalsis•Thoracic and abdominal muscle contractions

Vagal/splanchnic afferents

Vestibular nucleiCTZ

Vomiting centre

•Gastric atony•Retroperistalsis•Thoracic and abdominal muscle contractions

Movement/vertigo

Vestibular nucleiCTZ

Vomiting centre

•Gastric atony•Retroperistalsis•Thoracic and abdominal muscle contractions

Raised ICP

Hyponatraemia

Fear/anxiety

Vestibular nucleiCTZ

Vomiting centre

•Gastric atony•Retroperistalsis•Thoracic and abdominal muscle contractions

HypercalcaemiaUraemiaMorphineCytotoxic

chemotherapy

Vestibular nuclei

CTZ

Vomiting centre•Gastric atony•Retroperistalsis•Thoracic and abdominal muscle contractions

Cytotoxic chemotherapy

Intestinal Distension

Abdominal RXT

Gastric irritants

Case studies

• Pick the most appropriate antiemetic in each case

Management

• Treat reversible causes• Remember unrelated causes e.g gastroenteritis• Choose the most appropriate antiemetic for the

cause• Prescribe the same antiemetic regularly and prn• If oral absorption in doubt, use sc route• Remember non-drug treatments• Consider dexamethasone• REVIEW

Common anti-emetics

• Prokineticfor gastric stasis, functional bowel obstructionMetoclopramide 10mg tds

or 30-60mg/24hr CSCI• Acting on CTZ trigger zone

for chemical causes of vomiting eg morphine, renal failureHaloperidol 1.5-3mg stat/nocte

or 2.5-5mg sc stat and 2.5-10mg/24hr CSCI

Common anti-emetics

• Antispasmodic and antisecretoryif bowel colic and/or need to reduce GI secretionsBuscopan 20mg stat

60 – 120mg/24hr CSCI• Acting in the Vomiting Centre

for raised ICP, motion sickness or mechanical bowel obstructionCyclizine 50mg tds

150mg/24hr CSCI• Broad-spectrum

for mechanical obstruction, or if others failLevomepromazine 6-12.5mg nocte

Nausea and VomitingCause Clinical

PictureRx

Metabolic (drugs, uraemia, hypercalcaemia)

Persistent nausea 1) Haloperidol2) Levomepromazine

Gastric stasis Occ. nausea relieved by vomiting

1) Metoclopramide2) Domperidone

Bowel obstruction(abdo. ca./autonomic neuropathy)

Nausea relieved by vomiting ± colic ± faecal vomit

1) Metoclopramide2) Buscopan/

levomepromazine3) Cyclizine

↑ ICP, brainstem disease

Headache Cyclizine ± dex.

Vestibular disease Movement related 1)Cyclizine2) Levomepromazine•Bentley A, Boyd K. Palliative Medicine 2001;15:247-53.

Summary

• Try to establish the cause and choose an appropriate antiemetic, rather than picking your favourite

• Avoid combinations that may antagonise each other

• Choose an appropriate route