NAUSEA & VOMITING Flashcards
(53 cards)
Cause of N&V in gastric adenocarcinoma?
Tumour infiltration in gastric wall which disrupts peristalsis and thus causes a functional gastric-outlet obstruction
How can gastric cancer cause hiccups?
Stimulation of the vagus nerve as a result of gastric distension
Main indication for ondansetron in palliative n&v?
Chemotherapy-induced nausea and vomiting
(There are other indications but this is the important one to know)
Moa of ondansetron in CINV?
Selective antagonist of 5HT3
Chemotherapy is associated with release of 5HT from enterochromaffin cells of the small intensetine and induces a vomiting reflex through stimulation of 5HT3 receptors on fatal afferent
Ondansetron blocks the indication of this reflex
Common indications for syringe driver?
Persistent nausea and vomiting
Severe dysphagia
Unable to swallow e.g. due to mucositis
Reduced conscious level
Poor alimentary absorption
Problems associated with n&v as treatment side effects?
May not be able to have the full dose because of it - may impact on prognosis e.g. if chemotherapy
Can reduce compliance with drugs
Can be a concern to relatives
Impacts quality of life
Can cause physical damage
Can impair nutrition and hydration
It can impact on novel drug development
Where in the brain is the vomiting centre?
Medulla oblongata
Which receptors are found in the vomiting centre?
ACh Muscarinic receptors
H1 receptors
5HT2 receptors
NK1 receptors
Where is the CTZ found in the brain?
Dorsal surface of the medulla oblongata
Note: it’s present outside the blood brain barrier!
Receptors found in CTZ?
D2 receptors
5HT3 receptors
Why is the CTZ the area susceptible to cytotoxic agents?
As it’s situated outside the blood brain barrier!
Pathophysiology of motion sickness?
Labyrinth sends signals to the vestibular nuclei in the pons of the brainstem via the vestibulocochlear nerve
H1 receptors and Muscarinic receptors are stimulated
Signals passed on to CTZ and then on to the vomiting reflex = vomit
Pathophysiology of emotion, pain or stimulus-related (smell/sight) vomiting?
All these inputs get sent from the higher brain centre to the vomiting centre to stimulate it via muscarinic receptors and initiate the vomiting reflex
Pathophysiology of cytotoxic agents in stomach induced vomiting?
Cytotoxic agents present in the stomach = enterochromaffin cells release serotonin = stimulates 5HT3 receptors on vagal nerve fibres = signal taken to vomiting centre = vomit
Vomiitng reflex?
Relaxation of lower oesophageal sphincter
Contraction of diaphragm and abdominal muscles = increases abdominal pressure
Autonomic changes : increase peristalsis, salvation and HR
Closure of epiglottis
= expulsion of food
What are the 6 broad nausea and vomiting syndromes in palliative care?
Reduced gastric motility - may be related to opioids
Chemically mediated e.g. chemo, hypercalcaemia, drugs, toxins
Visceral/serosal - due to constipation or oral candidiasis
Raised ICP e.g. cerebral mets
Vestibular e.g. opioid related, motion related or base of skull tumours
Cortical - due to anxiety, pain, fear, anticipatory nausea
Features of n&v that may suggest gastric stasis as the cause?
Large volume of vomitus
Infrequent vomiting
Relief of Sx after vomiting
Reflux
Epigastric fullness
Early satiation
Hiccups
Succussion splash on auscultation
Features of n&v that may suggest gastric outflow obstruction as the cause?
Forceful vomiting
Rapid dehydration
Features of n&v that may suggest oesophageal blockage as the cause?
Vomiting soon after eating/drinking
Vomitus comprising what has just been swallowed
Sensation of food sticking
Features of n&v that may suggest bowel obstruction as the cause?
Intermittent nausea That is worsening
Faeculent vomiting
Abdominal pain that is colicky
Abdominal distention
Features of n&v that may suggest raised ICP as the cause?
Effortless vomiting
Worse in morning
Associated with headache and papilloedema
Features of n&v that may suggest chemically induced nausea as the cause?
Constant nausea with variable vomiting
Investigations for vomiting in palliative care?
Bloods - U&Es, Ca2+, LFTs, BG - exclude hypercalcaemia and uraemia and check for hypokalaemia
Urine dip to exclude UTI
Abdominal radiography me be used to exclude constipation or US to detect ascites
What simple measures may help nausea and vomiting in palliative care?
Make sure pt has access to large bowel, tissues and water
Calm environment away from food being prepared
Small palatable meal which are mostly carbohydrates
Cool fizzy drinks
Relaxation and acupressure bands
CBT can be considered for anticipatory n&v
