Nausea, vomiting and motion sickness (4.1) Flashcards
What are the possible causes of nausea and vomiting?
Gastrointestinal, cardiovascular diseases, neurologic processes, metabolic disorders, viral or bacterial infections, psychogenic causes, medications, drug withdrawal, miscellaneous
Nausea may/may not precede vomiting
How is nausea and vomiting controlled centrally in the medulla
- Vomitting center
- Chemoreceptor trigger zone (CTZ)
What are the main neurotransmitters involved in nausea and vomiting?
- Histamine (at histamine H1 receptor)
- Acetylcholine (at muscarinic mACh receptor)
- Dopamine (at dopamine D2 receptor)
- 5-hydroxytryptamine (5-HT) (at 5-HT3 receptor)
- Substance P (neurokinin-1 receptor at CTZ)
- Enkephalins (u at vomiting centre and delta at CTZ)
What is the vomiting centre activated by?
- Cerebral cortex
- Vestibular apparatus
- CTZ
- Afferent fibers from gut
CTZ is activate by substances, which stimulates what?
- 5HT3 receptors
- Dopamine D2 receptors
- Muscarinic M1 receptors
Noxious substances present in gut may activate vagal nerves to solitary tract nucleus
For N and V;
A) Who is the patient
B) What are the symptoms
C) How long have the symptoms been present
D) Action taken
E) Medications
F) Medical conditions
G) Allergies
A)
- very young or elderly
- infant
- pregnant woman
B)
- vomiting (projectile vs regurgitation, blood)
- diarrhea, constipation
- migraine
- fever
- dizziness/vertigo
- Abdominal pain
C)
- Adult: longer than 2 days
- Infants/children <2 years old: refer (vomiting > 3 hours)
D)
E)
- Opioids, antibiotics, digoxin, NSAIDs, alcohol, oestrogens
F)
G)
How do antiemetic agents work? Give some examples
Antagonize the actions of main neurotransmitter involved in causing N and V
>Dopamine: dopamine D2 receptor antagonists
>Serotonin: Serotonin 5HT3 receptor antagonists
>Acetylcholine: Anticholinergics
>Histamine: Antihistamines
>Substance P: NK1 receptor antagonists
- Herbal substances (ginger, spearmint, peppermint, clove, anise, cinnamon) –> mild antiemetic property
Antagonizing D2 receptors in certain regions of the brain causes changes. What are these areas of the brain and what are the changes that occur as a result of the antagonizing D2 receptors?
- Mesolimbic, memory and behaviour –> antipsychotic actions
- Mesocortical, mental function and behaviour –> reduce psychotic Sx
- Nigrostriatal, motor function –> Parkinson like Sx, EPSE
- Tuberoinfundibular, affect prolactin release –> increase prolactin
Self-care for nausea and vomiting?
- Avoid solid foods and over eating
- Bland foods when symptoms improve
- Avoid rich foods (re-introduce dairy, meat and spicy, sugary, fatty foods gradually)
- restore gut flora (acidophilus)
- pregnancy: vitamin B6 upto 50mg bd
What are some symptoms of motion sickness
- nausea and or vomiting
- pallor
- cold sweats
- excessive salivation
- headache
- hyperventilation
For motion sickness;
A) who
B) what
C) How long
A)
- Young children (<2yrs of age rare)
- Age determines choice of treatment
B)
- Mode of travel
- Length of journey
C)
- Previous history of motion sickness
What are some alternative treatment options for motion sickness?
- Ginger
Adults: 2-3 tablets 30 mins before departure repeat every 2 hours as needed
- Acupressure wrist bands
self-care for motion sickness?
- Focus on still objects
- Lie on back
- Avoid reading
- Keep head still
- Close eyes
- Limit food/drinks esp alcohol
- Fresh air
- relaxation techniques
