PBL 2 Flashcards
what foods/drinks should you avoid with d+v?
fruit juice fizzy drinks greasy food spicy food high fat and sugar foods dairy caffeiene
what meds can be given for diarrhoea?
bismuth subsalicylate (pepto-bismol_ loperamide
what are examples of antiemetic drugs for acute vomiting?
phenothiazines e.g. prochlorperazine antihistamines e.g. cyclizine metoclopramide domperidone ondansetron dexamethasone
how long should you stay off school/work after d+v?
at least 2 days after the last episode
how does bismuth subsalicylate work?
decreases the flow of fluids into the bowel, reduces inflammation and may kill organisms that can cause diarrhoea
what is oral rehydration therapy?
a balanced mixture of electrolyte salts and glucose used to prevent and treat dehydration, especially due to diarrhoea
what is ORT made up of?
sodium chloride, sodium citrate, potassium chloride and glucose.
how does ORT work?
it uses the Na+/glucose cotransport mechanism to passively absorb water across the intestinal mucosa
what are potential side effects of ORT?
vomiting
hyperkalaemia hypernatremia
what are some contraindications of ORT?
shock, severe dehydration, intractable vomiting, coma, acute abdomen, absent bowel sounds, severe renal impairment, visible water retention, hyperkalaemia, chronic heart failure
what is diarrhoea defined as?
loose watery stools 3+ times in 24 hours
whats the difference between acute, persistant and chronic diarrhoea?
acute <2 weeks
persistant 2-4 weeks
chronic >4 weeks
what is inflammatory diarrhoea?
inflammation of GI epithelium usually as a result of invasive pathogens or chronic IBD. usually comes with systemic symptoms too
associated with vomiting and the ingestion of contaminated food
what is non-inflammatory diarrhoea?
can be secretory or osmotic. secretory diarrhoea is where we have increased water + electrolyte secretion and decreased absorption. With osmotic diarrhoea, come ingested nutrients aren’t absorbed so they pull water into the lumen through osmosis
stools are bloody and mucusy, severe abdo pain and fever
what would a cause of diarrhoea be at 6 hours after ingesting food? what about 8-16hrs? or >16 hrs?
<6hrs = staph aureus or bacillus cereus
8-16hrs = clostridium perfringens
>16 hrs = enterotoxigenic E.COli
what are some causes of inflammatory diarrhoea?
salmonella
giardia
c.diff
TB
where is the vomiting centre? what receptors does it have?
in the medulla oblongata
muscarinic receptors
where is the chemoreceptor trigger zone? what receptors does it have?
in medulla oblongata but outside the blood brain barrier so detects blood
dopamine 2 and 5HT receptors
describe the physiology of motion sickness?
problems in the vestibule in the labrynth of the ear causes the vestibulocochlear nerve to send signals to the vestibular nuclei in the pons. it stimulates the histamine 1 and muscarinic receptors which stimulates it, causing a signal to be sent to the CTZ. These receptors are triggered, stimulating the CTZ to send a signal to the vomiting centre to initiate the vomiting reflex
outline the physiology of emesis caused by cytotoxic agents?
enterochromaffin cells release serotonin in response to cytotoxic agents which can stimulate 5HT3 receptors on vagal nerve fibres around the area. This takes the information to the vomiting centre to trigger the vomiting reflex.
whats the pro-dromal phase of the vomiting reflex?
relaxation of gastric muscles followed by small intestinal retrograde peristalsis
whats the ejection phase of the vomiting reflex?
retching and vomiting including expulsion of gastric contents