Nausea And Vomiting Flashcards
Nausea define
An unpleasant feeling of the need to vomit associated with autonomic symptoms (pallor, sweating, tachycardia, salivation)
Retching define
Rhythmic laboured spasmodic movements of the diaphragm and abdominal muscles (often occurs with nausea and results in vomiting)
Vomiting define
The forceful propulsion of gastric contents through the mouth
Why is treating n and v important
Common
Distressing
Affects up to 70%of people with cancer
QualoL
What areas contribute to the mechanism of causing n and v
Chemoreceptor trigger zone Gut Cerebral cortex Vestibular cortex These lead to the vomiting centre This causes vomiting.
Drugs which cause n and v
Analgesia - codeine, morphine Antibiotics Iron e.g. ferrous sulfate Digoxin Antidepressants
Gastrointestinal problems which cause n and v
Gastric irritation - tumour, gastritis Gastric distension - tumour, diabetic autonomic neuropathy Bowel obstruction Oedematous gut Constipation
Metabolic causes of n and v
Hypercalcaemia
Renal failure
Hyponatraemia
Psychological causes of n and v
Anxiety
Fear
Toxic causes of n and v
Radiotherapy
Chemotherapy
Infection
Other causes of n and v (brain related)
Raised ICP
vestibular disturbance
Which substances/condition act as a stimulus for the CTZ
Opioids Uraemia Hypercalcaemia Chemo Toxins
Which neurotransmitters act on the CTZ
5HT
D2
Which substances/conditions act as a stimulus for the cerebral cortex
Anxiety
Raised ICP
hyponatraemia
Sights and smells
Which neurotransmitters act in the cerebral cortex
Histamine
Serotonin
Which substances/conditions act as a stimulus for the vestibular cortex
Movement
Which neurotransmitters act in the vestibular cortex
Muscarinic
Histamine
Which substances/conditions act as a stimulus for the gut
Radiotherapy Cytotoxics Drugs Toxins Irritants Intestinal Distension
Which neurotransmitters act in the gut
Serotonin
Dopamine
Which neurotransmitters act in the vomiting centre
Muscarinic
Histamine
Serotonin
Commonly used medication
Metocloperamide Cyclizine Haloperidol Ondansetron Levomepromazine Domperidone
Metocloperamide act on which neurotransmitters receptor
Dopamine 2 D2 receptor antagonist and a 5HT agonist
Acts peripherally does cross BBB
So acts on the gut and CTZ
Metocloperamide What is it What does is to Dose SE
Dopamine 2 D2 receptor antagonist and 5 HT4
Peripherally acting but does cross BBB
Acts as a prokinetic, useful in delayed gastric emptying
Usual dose 10mg TDS PO
SE risk of extrapyramidal SE as it crosses BBB, abdo cramps caution in complete bowel obstruction - perf
Caution in young people <20 years at risk of oculogyric crisis
Ondansetron
What is it what does it do
SE
5HT4 receptor antagonist Commonly used post surgery, chemotherapy and radiotherapy-where gut disturbance causing 5HT3 release Expensive SE constipation QTc prolongation
Cyclizine
What does it do where does it act
Dose
SE
acts centrally
Anti muscarinic and anti histamine activity
Useful for motion sickness and vomiting secondary to raised ICP
Good 1st line anti emetic in hospital
50mg TDS IV/PO/SC
SE due to anti muscarinic activity - dry mouth, constipation sedation
Which 2 antiemetics should not be prescribed together
Cyclizine and metocloperamide
Metocloperamide acts as a prokinetic through dopamine antagonism
Cyclizine slows gastric transit due to anti muscarinic effects therefore blocking the effect of metocloperamide
What condition should cyclizine not be used in
Heart failure
How can antiemetics be given
PO
IV
SC
CSCI
What treatment should be given in gastric stasis and why
Con
Reduce volume or oral intake little and often
Reduce gastric secretions H2 antagonist e.g. ranitidine
Medication
Pro kinetic agents dopamine D2 antagonist
Metocloperamide
Domperidone
What causes gastric stasis
Drug se Anticholinergics Opioids Compression of gastric outflow Tumour, hepatomegaly, ascites Stomach emptying problems Autonomic, diabetes, gastritis, peptic ulcer
What treatment should be given in gastric stasis
Address the underlying cause such as constipation Then treat with a 5HT3 antagonist Ondansetron Used in first line chemo related nausea Anticholinergic - cyclizine
Causes of GI or visceral irritation
Stimulation of the vagus /gut 5HT3 receptors
Contributing factors- GI or visceral irritation
- pharyngeal irritation x tumour, sputum, Candida
-stretch receptors of GI or GU tract- constipation, bowel ureteric obstruction, chemo/radio
- visceral capsules - hepatomegaly
What causes chemical or metabolic NV
Chemical drugs - opioids, antibiotics, digoxin, NSAIDS, SSRIs, chemotherapy
Metabolic- renal/liver failure, hyperclacawmia I’d malignancy, hyponatraemia, sepsis
How to treat chemical/metabolic NV
Dopamine D2 antagonist -haloperidol -levomepromazine Or serotonin Ondansetron
What is haloperidol
What does it do
SE
D2 receptor antagonist Works on the CTZ Commonly used in palliative care Haloperidol 1.5mg-3mg SC/PO SE Extrapyramidal SE QTc prolonging Sedation (uncommon at low doses)
What is levomepromazine
What does it do
SE
Broad spectrum antiemetic targets multiple record sites
Used as an antipsychotic but effective for nausea at low doses
Used commonly in palliative care, bowel obstruction or antiemetic and sedation needed
SE
Sedation
Postural hypotension
What causes raised ICP and what causes the NV
Stimulation of the vomiting centre H1 and AChm receptors Any cause SOL Skull mets Intracranial haemorrhage Meningeal Infiltration
What doe you treat with
Anti histamine or anti cholinergic
Also depends on cause
For a SOL
steroids to reduce oedema
Or radiotherapy
What causes you to feel sick on motion sickness
Stimulation of the vestibular system H1 and AChm receptors
Contributing factors
-stimulation of vestibular system
- opioids can increase vestibular sensitivity
- ? Intracerebral cause
How to treat motion sickness
Cyclizine
Which drug combinations should you avoid
Metocloperamide/domperidone and cyclizine cos they clock each other’s effects
IV metocloperamide and IV ondansetron
- risk serious cardiac arrhythmia
Avoid prolonged used of moetcloperamide /domperidone due to inc extra pyramidal SE
