Nausea + Vomitting

Question 1

What are the 4 areas that can trigger the vomitting centre

Answer 1

1. CTZ (Chemoreceptor trigger zone)
2. GI Tract
3. Vestibular system (motion sickness)
4. stimulation of cortex and thalamus (pain, smell, stress)

Question 3

How does the vomiting centre get chemically stimulated

Answer 3

Changes in the blood chemistry due to drugs, toxins or hormones

Question 4

What are the 3 ways that the vomitting centre can be triggered by neural stimulation

Answer 4

1. Stimulation of GI Tract (Mechanoreceptor or serotonin receptor activation)
2. Stimulation of vestibular system (Balance, motion sickness)
3. Stimulation of cortex and thalamus (result of pain, smell, sight, stress)

Question 4

What is a Mallory-Weiss tear?

Answer 4

A tear in the mucosal layer at the junction of the esophagus and stomach

Question 5

How does H1 receptor antagonists (anti-histamine) work for anti-emetic therapy

Answer 5

• acts on histamine receptors in vestibular nuclei (pons)
• good for motion sickness or morning sickness
• can cause drowsiness or sedation
  EX - dimenhydrinate (gravol), promethazine (phenergan)

Question 6

How do serotonin receptor antagonists work for anti-emetic therapy

Answer 6

• ends in -setron such as ondansetron or dolasetron
• works by blocking serotonin in CTZ and gut to reduce n/v
• good for chemo/radiation induced nausea/vomitting or post-surgery, ondasetron can also be good for morning sickness

Question 7

How do dopamine receptor antagonists work for anti-emetic therapy

Answer 7

• blocks dopamine in receptors in CTZ
• good for chemo/radiation or post op surgery
• can cause sedation, hypotension or extrapyramidial side effects

Question 8

How do anticholinergics work for anti-emetic therapy

Answer 8

• block conduction of cholinergic impulse from vestibular apparatus to vomiting centre
• effective as prophylaxis for motio or morning sickness
• can cause anticholinergic symptoms such as drowsiness, blurry vision or dry mouth

Question 9

What are symptoms of Serotonin Syndrome

Answer 9

• head ache
• agitation
• confusion
• tremors
• dilated pupils
• tachycardia
• hypertension
• hyperthermia
• dysrhytmias
• seizures
• unconsciousness