nausea and vomiting
DESCRIPTION
Nausea and vomiting. Cerebral cortex. Vestibular nuclei. CTZ. GABA 5HT. ACh H1. 5HT 3 D 2. Gut wall. Vagal/splanchnic afferents. Gastric atony Retroperistalsis Thoracic and abdominal muscle contractions. Vomiting centre. 5HT 3. ACh H1 5HT 2. Movement/vertigo. Vestibular nuclei. - PowerPoint PPT PresentationTRANSCRIPT
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