Vomiting and Nausea Flashcards
The vomiting centre is located?
in the dorsal part of the medulla oblongata
The chemo receptor trigger zone is located?
In the floor of the fouth ventricle (brain)
Lies OUTSIDE blood brain barrier
Motion sickness and disease of the inner ear act on which nerve?
vestibulocochlear nerve
sends signals to the vomiting center
Pathways to nausea emesis?
- Blood borne chemical stimuli via Chemoreceptor Trigger zone (morphine, digoxin, chemotherapy)
Major central pathway to emesis/nausea is?
Vomiting center
Which emesis receptors does the CTZ express?
Histamine (H1 !!! not 2!!) M1 Dopamine (D2) Serotonin (5HT3) Opoid
Which emesis receptor does the pharynx and GI tract express?
Serotonin (5HT3)
Which emesis receptors do the vestibular nuclei express?
Mucarinic M1
Histamine H1
Which emesis receptors does the VC express?
Muscarinic M1/M3
Serotonin 5HT3
Histamine H1
In the gut ____ from e.g. bacteria, drugs or ethanol stimulate _____ cells. This leads to mediators such as _____. This leads to depolarization and AP of ____ afferent to ___ and ___
toxins, enterochromaffin like, serotonin (5HT3), Vagal, CTZ and nucleus trctus solaris
What are the events in vomiting?
Suspension slow wave intestinal activity
Retrograde contractions from ileum to stomach
Relaxed sphincters! LOS
Close epiglottis
Contraction of diaphragm + abdominal muscles compress stomach
ejection + repeat
Consequences sever vomiting?
- Dehydration
- HYPOCHLORAEMIC METABOLIC ACIDOSIS (loss gastric protons +chloride)
- hypokalaemia (reflex K+ excretion kidneys)
- mallory weiss tear
- aspiration
Prochlorperazine, droperidol,trifluoperazine chlorpromazine, haloperidol, levomepromazine
are examples of WHAt
dopamine antagonists
Dopamine antagonists act ___ by blocking _____
centrally, Chemoreceptor trigger zone
Metoclopramide, Domperidone are examples of WHAT
prokinetic drugs
What are the effects of prokinetic drugs?
- Increase gastric peristalsis
- Increase LOS tone
-BLOCKS D2 dopamine receptors in CTZ!!!!
Granisetron, ondansetron, palonosetron
are examples of WHAT
5HT3-Receptor Antagonists
5HT3-Receptor Antagonists block receptors in ___, ____ and ____
GIT and CNS, VC
T/F
5HT3-Receptor Antagonists side effect is earache
F
HEADACHE
Promethazine, cyclizine, cinnarizine
are examples of WHAT
H 1 ANTAGONISTS
T/F
H1 antagonists cause CNS depression and sedation
T
T/F
many H1 antagonists exert an additonal anti serotonin receptor effcet
F!
exert additional ANTIMUSCARINIC effect
Hyosine (scopolamine), Dicyclomine
are examples of
anticholinergics
Adjuvant antiemetics are?
group of drugs that are used with standard antiemetics to enhance its effects
Examples of adjuvant antiemetics?
Corticosteroids
Cannabinoids
Benzodiazepines
Neurokinin 1 receptor antagonists
Treating chemotherapy induced nausea?
Triple therapy
1) Serotonin antagonist
2) dexamethasone corticosteroid
3) aprepitant neurokinin 1 receptor antagonist
T/F
Post-operative nausea and vomiting treatment is the same regardless of anaesthetic used and the type and duration of surgery
F
Varies !!
T/F
Pregnancy associated Nausea and Vomiting is treated using Neurokinin 1 receptor antagonists
F change diet ginger wrist acupressure INTRACTABLE VOMITING MAY RESULT IN NUTRITIONAL AND IONINC IMBALANCES
Hyperemesis gravidarum?
Fluid and electrolyte disturbances or nutritional deficiency develops from intractable vomiting in pregnancy
First line Hyperemesis gravidarum?
antihistamine such as promethazine or cyclizine.
