Nausea and Vomiting Flashcards
what is another name for area postrema ?
chemoreceptor trigger zone (CTZ)
what receptors are on the CTZ?
D2 receptors (dopamine) 5HT3 receptors (serotonin)
what does the CTZ trigger ?
the vomiting centre
is the CTZ inside or outside the BBB?
outside
can kwells (hyoscine hydrobromide) cross the BBB?
yes
what is hyoscine hydrobromide ?
an antiemetic
because hyoscine hydrobromide can cross the BBB what side effect does it have?
sedation
state two higher centres that trigger the vomiting centre?
cerebral cortex
limbic system
what receptors does the higher centres have?
serotonin and GABA receptors
what receptors does the vestibular apparatus have?
H1 receptors
Achm receptors
what systems trigger the vomiting centre?
Vestibular apparatus
CTZ
higher centres
GI tract
what nerve has Achm receptors from the GI tract?
vagus nerve
what receptors does the vomiting centres have?
H1
Achm
5HT2
is morphine water or fat soluble ?
water soluble
state some fat soluble opioids ?
fentanyl
alfentanyl
where does morphine stimulate?
CTZ
state some metabolic causes of vomiting?
hypercalcaemia uraemia hyponatraemia ketoacidosis infection addisons pregnancy
what are the signs of squashed stomach syndrome ?
early satiety
delayed gastric emptying
hepatomegaly
ascites
state some non drug management for vomiting?
small frequent meals
calm environment
treat constipation
state two pro kinetic antiemetics ?
metoclopramide
domperidone
what receptors do pro kinetic antiemetics act on?
dopamine
what is a side effect of metoclopramide ?
extra pyramidal symptoms
what is the treatment for anticipatory nausea?
lorazepam
diazepam
midazolam
what is the treatment for increased ICP vomiting ?
dexamethasone
cyclizine
what is the treatment for metabolic causes of vomitng ?
metoclopramide
haloperidol
what is the treatment for chemo/RT causes of vomiting ?
ondansetron
granisetron
tropisetron
how do the -setron drugs work for chemo vomiting?
bind to 5HT3 (serotonin) receptors
there is a big release of serotonin when there is apoptosis which occurs a lot with chemo
what is a side effect of hyoscine hydrobromide ?
sedation
when there is an unknown cause or multifactorial cause for vomiting what medication should be used?
levomepromazine
what is levomepromazine?
very potent broad spectrum anti emetic
what receptors does levomepromazine act on?
D2, 5HT2, H1, Achm, alpha 1 adrenergic
what are side effects of levomepromazine?
postural hypotension
drowsiness
which antiemetic should be used in opioid induced vomiting ?
metoclopramide (promotes bowel movements)
what does the presentation of obstructed and metabolic vomiting look like?
obstructed - nausea relieved by vomiting, large volume
metabolic - nausea all the time, hypercalcaemia would cause polyuria due to the kidneys trying to excrete as much calcium as possible which would then led to dehydration and hypotension and may cause an AKI
what are the normal ranges for Ca?
2.2.-2.6
what are the common causes of hypercalcaemia ?
bony mets
ectopic release of PTHP
what is the treatment for hypecalcaemia?
rehydrate
bisphosphonates
what is the treatment for chemo induced vomiting ?
ondansetron
what is the antiemetic for bowel obstruction?
metoclopramide
+ steroids
what is the antiemetic for squashed stomach syndrome?
metoclopramide
- infusion over 24 hrs
what are three types of laxatives?
osmotic - lactulose
stimulant - bisacodyl, senna
softens - docusate sodium
what should also be prescribed when giving a opioid?
laxative
what should also be prescribed when giving a NSAID?
PPI
what three cancers commonly spread to bone?
breast
lung
prostate
state some reasons for antiemetics not working ?
not absorbing medication properly wrong established cause and wrong antiemetic wrong dose non compliance may need 2 antiemetics
