Nausea and vomiting Flashcards
What’s anticipatory nausea and vomiting?
- usually associated with chemotherapy
- N/V occurs before a new chemotherapy cycle in response to conditioned stimuli such as smells, sights and sounds of the treatment room etc
- it is when a person has experienced N/V related to chemo
Pathophysiology: generated by the cerebral cortex through the fear and anxiety related to the memory of previous experience
What’s regurgitation?
Regurgitation → backflow of fluid in the body
- usually across partially or wholly failing valve mechanism
- it can happen passively (e.g. when pressure on the stomach is applied)
What’s expectoration?
Expectoration → to expel secretions from the lungs (ie coughing up)
- secretions in the back of the throat can trigger a gag reflex and make someone nauseated or to vomit (therefore may be confused with actual vomiting)
What’s the vomiting centre?
Type of receptors
Medulla Oblongata
- muscarinic receptors in the medulla oblongata
- when they are stimulated → vomiting reflex
What other (4) parts send the signals to the medulla oblongata and stimulate vomiting reflex?
+ their receptors
- vestibular nuclei (cochlear)→ muscarinic and histamine receptors
- chemoreceptor trigger zone → 5HT receptor, Dopamine 2 receptor
- higher brain centres → muscarinic receptors, D2 (triggered by repulsive vomiting)
- peripheral (GI &Viscera) → enterochromaffin cells in the stomach (5HT receptors)
*all these stimulate vomiting reflex
What cancers metastasise to the brain?
- breast
- lung
- melanoma
Metoclopramide
- class
- receptors it acts on
- SEs
Metoclopramide
Class: Prokinetic agent
Receptors: D2 & 5HT4 & 5HT3
SEs:
- can cause colic
- parkinsonian features
- oculogyric crisis (especially in kids and youth, so don’t prescribe)
Domperidone
- class
- receptors it acts on
- contraindication
Domperidone
Class: prokinetic agent
Receptors: D2
Contraindication: not in HF as it is cardiotoxic
Haloperidol
- class
- receptors it acts on
- SEs
- contraindications
Haloperidol
Class: butyrophenone
Receptor: D2
Haloperidol is good n nausea and vomiting but also with confusion (as it has a sedating effect)
SEs: extrapyramidal side effects, sedation, prolong QT
Contraindications: cardiac problems (cytotoxic) Parkinson disease and above
Cyclizine
- class
- receptors it acts on
- SEs
Cyclizine
Class: antihistamine
Receptors: H1 and muscarinic cholinergic
SEs: constipation, irritation at SC site
Levomepromazine
- class
- receptors it acts on
- SEs
Levomepromazine
Class: Phenothiazine
Receptors: H1 & 5HT2 & muscarinic & D2
*used often as it acts on broad-spectrum receptors (as antagonist)
SEs: drowsiness at higher doses, constipation, anti-muscarinic (but all these are milder due to broad spectrum action)
Ondansetron
- class
- receptors it acts on
- SEs
Ondansetron
Class: 5HT3 antagonist
Receptors: 5HT3
- It acts on gut specific receptors
- Good for chemotherapy induced nausea
SEs: constipation
Lorazepam
class
receptors
indicaiton
Lorazepam
Class: benzodiazepine
Receptor: GABA
Indication: for anxiety/ anticipatory nausea
What drug and why do we commonly prescribe with cyclizine SC?
small amount of dexamethasone to minimise injection site irritation
Antibiotics commonly cause nausea?
- Flucloxacillin
- Clarithromycin
- Metronidazole (with alcohol)
Diet advise in N/V
- eat little and often (rather than large meals)
- carbs are better tolerated (fats and proteins delay gastric emptying)
Can we use metoclopramide + cyclizine?
No, as they have antagonistic effects
Chemical causes of N/V (3)
- Drugs → e.g. opiates, antibiotics, chemotherapy
- Toxins → e.g. ischaemic bowel, tumour products
- Metabolic → organ failure, electrolyte imbalance, ketoacidosis
GI-related causes of N/V (4)
- Pharyngeal irritation → Herpes, Candida, excess of sputum
- Gastric stasis → anticholinergics/ opiates, mechanical resistance (ascites, organomegaly)
- Stretch of GI tract → constipation, mesenteric mets
- other GI irritation → e.g. reflux
Cranial causes of N/V
- raised ICP → cerebral primary or mets, intracranial bleeding
- meningism → inflammation, irritation by tumour, cerebral infections
Other (2) causes of N/V
- movement associated → vestibular, visceral distortion, motion sickness
- anxiety and anticipatory
Common reversible causes of N/V + their management
- severe pain → good pain control
- infection → antibiotics
- cough → treat underlying cause/opioids and antitussives
- hypercalcaemia → rehydration and IV bisphosphonates
- gastric irritation → stop irritant drugs (e.g. NSAIDs, use of PPI/H2 antagonists)
- oropharyngeal candida→ nystatin/ fluconazole and good mouth care
- constipation → laxatives, rectal measures, altering constipating meds
- tense ascites → consider paracentesis
- raised ICP → use corticosteroids
- emetogenic drugs → stop or reduce dose
- anxiety → pharmacological and psychological meanagement
Features of vomiting due to gastric stasis
- large volume of vomits
- infrequent vomiting
- relief of symptoms after vomiting
- also: oesophageal reflux, epigastric fullness, early satiety, hiccups
Symptoms of N/V due to gastric outflow obstruction
- symptoms similar to gastric stasis e.g. large volume of vomits, relieve after vomiting
- forceful vomiting
- rapid dehydration
‘Squashed stomach syndrome’
- whats that
- feature of N/V due to this
‘Squashed stomach syndrome’ → reduction in the gastric cavity by tumour or external compression
Symptoms:
- infrequent vomiting
- relief after vomits
- low volume vomits
Symptoms of N/V due to oesophageal blockage
- vomiting soon after eating/ drinking
- vomits consist of what has just been swallowed
- sensation of food sticking
Symptoms of N/V due to bowel obstruction
- intermittend nausea (often relieved by vomiting)
- worsening nausea
- faeculant vomit as obstruction progresses
- abdominal pain (may be colicky)
- abdominal distention (may be absent if obstruction is high)
Symptoms of N/V due to increased ICP
- efortless vomiting (often in the morning)
- vomiting may be associated with headache and papilloedema
*neurological signs e.g. photophobia may be absent
Symptoms of N/V associated with:
- motion - associated emesis
- chemically induced nausea
- anxiety-related nausea
- motion - associated emesis → N/V on movement
- chemically induced nausea → constant nausea, variable vomiting
- anxiety-related nausea → may be triggered by a previously experienced stimulus; relieved by distraction
What types of drinks to have in N/V?
- cool rather than hot
- fizzy rather than still (except when in obstruction)
- citrus flavoured (possibly are better tolerated)
Drugs used in management of N/V due to gastritis, gastric stasis, bowel obstruction (due to peristaltic failure)
Prokinetic anti-emetics
- metoclopramide
- domperidone
Alternatives: Ondansetron, cyclizine
Drugs used in the management of N/V due to chemicals (drug, toxins metabolic causes)
Anti-emetics acting principally on chemoreceptor trigger zone
- Haloperidol
- Ondansetron
Drugs used in the management of N/V due to raised ICP or vestibular symptoms
Anti-emetic acting peripherally in the vestibular system and vomiting centre
- Cyclizine
- *Add dexamethasone due to irritation of the skin in SC route*
Which anti-emetic to use when the cause of vomiting is unknown or if the anti-emetics specific for identified cause (e.g. metoclopramide for gastric stasis) failed?
Broad-spectrum anti-emetics
Levomepromazine
What other anti-emetics we can add to levomepromazine (broad-spectrum) when any other therapy fails?
- Levomepromazine + 5HT3 antagonist (e.g. ondansetron)
- Levemepromazine + benzodiazepine (e.g. lorazepam or midazolam)
- Levomepromazine + dexamethasone (stop dexamethasone if no benefit after one week)
What two anti-emetics can worsen constipation?
- 5HT3 antagonists → ondansetron
- anticholinergics → e.g. cyclizine, hyoscine butylbromide/hydrobromide
Nabilone
- MoA
- when to use?
Nabilone
MoA: cannabinoid drug; central actions at the level of the cerebral cortex
Use: potentially helpful in managing intractable N/V uncontrolled by other drugs
Aprepitant
- MoA
- when to use
Aprepitant
MoA: Neurokinin-1 (substance P) receptor antagonist
Use: given 1 hour prior first dose of chemotherapy
