nausea and vomiting

Question 1

define vomiting

Answer 1

forceful expulsion of gastric contents from the mouth

Question 2

what causes vomiting?

Answer 2

o powerful sustained contraction of abdominal muscles
o descent of diaphragm
o opening of gastric cardia
o gastric retropulsion

Question 3

define retching

Answer 3

Laboured, spasmodic, rhythmic contractions of respiratory muscles without expulsion of gastric contents

Question 4

what respiratory muscles are used in retching?

Answer 4

diaphragm, chest wall, abdominal wall muscles

Question 5

how does retching lead to vomiting?

Answer 5

creates a pressure gradient leading to vomiting

Question 6

define nausea

Answer 6

• Unpleasant sensation at the back of the throat. Awareness of urge to vomit

Question 7

what is nausea often accompanied by?

Answer 7

cold sweat, pallor, salivation, disinterest in surroundings, loss of gastric tone, duodenal contractions and reflux of intestinal contents into stomach

Question 8

what normally follows vomiting?

Answer 8

tiredness

Question 9

if vomiting doesnt go away then what can it lead to?

Answer 9

• Dehydration/anorexia
• Ribs broken
• Refusal of medications

Question 10

what is cyclic vomiting syndrome?

Answer 10

• Rapid-fire projectile vomiting
• Lasts a few hours to several days, followed by asymptomatic periods
• Can incapacitate

Question 11

what is the most common symptom of cyclic vomiting syndrome?

Answer 11

Nausea not relieved by vomiting is the most disturbing symptom

Question 12

what are symptoms of gastroparesis?

Answer 12

Early satiety after eating, postprandial fullness, nausea, vomiting, belching, bloating

Question 13

what are other causes of vomiting?

Answer 13

chemo-radiotherapy, infections, severe pain, metabolic diseases, pregnancy, migraine, therapeutic drugs etc

Question 14

where is the area postrema?

Answer 14

base of the 4th ventricle

not protected by the BBB

Question 15

where is the NTS in relation to the AP?

Answer 15

one synapse away

Question 16

what information does the NTS receive?

Answer 16

o Receives vagal input from the heart etc.
o Also receives input e.g. pain about nausea
o Motion e.g. motion sickness
o Psychogenic e.g. anxiety about vomiting

Question 17

what is the vomiting centre?

Answer 17

several structures within medullary reticular formation of hindbrain

Question 18

what muscles are involved in vomiting and what do they do?

Answer 18

• NTS causes contraction of the diaphragm, abdominal muscles, external intercostal muscle; Relaxation of internal intercostal muscles
• Causes pharynx/larynx closure, closure of glottis/pharynx
• LOS relaxation, oesophagus dilation, duodenal retropulsive contraction

Question 19

what is Hyoscine (scopolamine) used for and how does it work?

Answer 19

used for motion sickness – blocks effect of ACh in brainstem and/or vestibular nuclei

Question 20

what is Diphenhydramine and how does it work?

Answer 20

Diphenhydramine – H1 receptor antagonist. Crosses BBB

Question 21

what has NICE approved the use of cyclizine for?

Answer 21

nausea, vomiting, vertigo, motion sickness and labyrinthine disorders

Question 22

what type of drug is cyclizine?

Answer 22

H1 receptor antagonist

Question 23

what is serendipity used for?

Answer 23

noted to block vomiting induced by the D2 receptor agonist apomorphine
• Used for many purposes including prevention of mild chemotherapy induced vomiting

Question 24

what are the side effects of serendipity?

Answer 24

dry mouth, drowsiness, extrapyramidal reactions (if in brain), hyper-prolactinaemia

Question 25

why is domperidone free of side effects?

Answer 25

Doesn’t cross the BBB – free of extrapyramidal side effects

Question 26

what type of drug is metoclopramide?

Answer 26

D2 receptor antagonist

Question 27

what is metoclopramide used for?

Answer 27

• Widespread use as an enti-emetic
• Post-operative care
• Gastritis, migraine, dysmenorrhoea
• Drug- or treatment-induced emesis including anaesthesia, radiation and/ or chemotherapy for cancer
• Also stimulates gastric emptying (5-HT4 receptor agonist)
• Widespread use as a stimulant of upper gut motility – GORD, gastroparesis, functional dyspepsia
• A 5-HT3 receptor antagonist at higher doses

Question 28

what are cannabinoid receptor antagonists used for?

Answer 28

mild/moderate emesis

poorly effective vs severe emesis (cisplatin)

Question 29

what are 5-HT3 receptor antagonists used for?

Answer 29

Prevent chemotherapy-induced emesis, acting mostly at GI vagal nerve endings

Question 30

what is given for moderately severe forms of emesis?

Answer 30

5-HT3 receptor antagonist + dexamethasone given in combination

Question 31

name NK1 receptor antagonsists

Answer 31

• Aprepitant (Emend), fosaprepritant (IV formulation of aprepitant), rolapitant, netupitant, the primary differences being potency & duration of action

Question 32

what is given for severe forms of emesis?

Answer 32

5-HT3 receptor antagonist + NK1 receptor antagonist + dexamethasone given in combination

Question 33

what drugs are used for partial bowel obstruction?

Answer 33

metoclopramide and prucalopride

Question 34

what drugs are used for total bowel obstruction and why?

Answer 34

o Dexamethasone to reduce inflammation
o To reduce build-up of fluid in the lumen
 Octreotide - somatostatin antagonist - may also reduce pain
 Nasogastric tube, venting, gastrostomy tube

Question 35

what is olanzapine?

Answer 35

• Atypical antipsychotic

* May be used in breakthrough vomiting

Question 36

where does nausea formation come from?

Answer 36

anterior insular cortex in the forebrain

o Interoceptive brain regions that process stress, fear etc

Question 37

where does vomiting come from?

Answer 37

area postrema and NTS in the hindbrain

Question 38

what is gastroparesis?

Answer 38

Gastric retention accompanied by nausea, vomiting and/ or bloating, in the absence of obstruction

Question 39

what are the causes of gastroparesis?

Answer 39

endocrine diseases (e.g. diabetes), post-surgical, medications, virus infections, idiopathic, Parkinson’s