Nausea and Vomitting Flashcards
What is vomiting
Vomiting is forceful expulsion of gastric contents from the mouth
What muscles contract to cause vomitting
- abdominal muscles
- diaphragm
what muscles relax to cause vomitting
- stomach- - gastric lining
- relaxing of the lower oesophageal sphincter and upper oesophageal sphincter
what can cause vomitting
gastric retropulsion
what is another word for vomiting
emesis
What is retching
- this is spasmodic rhythmic contractions of respiratory muscles that gives the feeling of wanting to vomit without expulsion of gastric contents
- generates pressure gradient that leads to vomitting
what muscles is retching caused by
including diaphragm
chest wall
abdominal wall muscles
what is nausea
- unpleasant sensation at the back of your throat
- awareness of urge to vomit
what is nausea accompanied by often
cold sweat
pallor
salivation
disinterest in surroundings
loss of gastric tone
duodenal contractions
reflux of intestinal contents into stomach
nausea can sometimes be…
relived by vomit
what happens in nausea doesn’t go away
- dehydration and anorexia- this is because it makes you not want to eat
- ribs are broken
- refusal of medication - life prolonging - as medications can make you vomit
What is cyclic vomiting syndrome
- rapid projectile vomit
- lasts few hours to several days followed by asymptomatic periods
- 9.6 and 14.4 episodes/ year in paediatrics & adults
- can incapacitate
- nausea is the more relevant symptom
what is not relieved by vomitting in cyclic vomiting syndrome
nausea
describe signs of gastroparesis
Early satiety after eating Postprandial fullness Nausea Vomiting Belching Bloating
list some causes of nausea and vomitting
- chemo-radiotherapy
- infections
- severe pain
- metabolic diseases
- migraine
- pregnancy
- intracranial disease
- labyrinthine/vestibular disorder
what is the basic pathway of vomititng
- The nucleus tracts solitaires relieves sensory inputs
- this causes different brainstem nuclei to coordinate vomiting
describe hes ensory inputs to intikte vomiting
- the chemoreceptor trigger zone is present in the area postrema, this gets all the sensory inputs that circulate in the blood so for example come from the liver, it also gets sensory inputs from the vagus nerve
- the area postrema projects into the NTS which can project into other brainstem nuclei and cause vomitting
- the vagus receives input from all the organs and projects this into the NTS
what brainstem nuclei causes the coordination of vomiting
- several structures within the reticular formation of the hindbrain
- NTS
- area postrema
- Dorsal motor nucleus of the vagus
- reticular formation
- ventrolateral medulla
what does the NTS receive inputs from
Inputs from abdominal/ thoracic vagus, pharyngeal, glossopharyngeal & trigeminal nerves, spinal tract, area postrema, hypothalamus, cerebellum & vestibular/ labyrinthine systems, cerebral cortex
what is the role of the NTS
Role in integrating, modulating, regulating many autonomic reflexes involved in vomiting
Name some old drugs that were used for nausea and vomtting
Muscarinic (M) receptor antagonists
Histamine H1 receptor antagonists
Dopamine D2 receptor antagonists
name some examples of dopamine D2 antagonist
Phenothiazines
Metoclopramide
Domperidone
what were muscarinic M receptors antagonist used fro
- prevent motion sickness
- blocks acetylcholine in the brainstem and/or vestibular nuclei
e. g. Scopolamine (hyoscine)
name an example of muscarinic M receptor antagonist
Hyoscine (scopolamine)
name some examples of histamine H1 receptors
diphenhydramine
dramamine - given to make them less drowsy
cyclizine
describe how cyclizine is used
Histamine H1 receptor antagonist
- pKi 8.4 (human receptor)1
Ability to inhibit pre-ganglionic cholinergic and vagal nerve activity
what is cyclizine recommended for by NICE
- Nausea
- vomiting
- vertigo
- motion sickness
- labyrinthine disorders
what were the side effects of
- muscarcinoc antagotnis
- D2 antagonists
- H2 antagonist
- muscarcinoc antagotnis = dry mouth
- D2 antagonists = extrapyramidal reactions
- H2 antagonist = drowsiness
name some extrapyramidal side effects
- pseudoparkinsonism
- tardive dyskinésie
- akathisia
- actue dystonia
describe the characteristics of the extrapyramidal side effects
pseudoparkinsonism
- stooped posture
- shuffling gait
- rigidity
- bradykinesia
- tremors at rest
tardive dyskinésie
- protrusion and rowing of the tongue
- chewing motion
- facial dyskinesia
- involuntary movements of the body and extremities
akathisia
- restless
- trouble standing still
- paces the floor
- feet in constant motion rocking back and forth
actue dystonia
- facial grimacing
- involuntary upward eye movement
- muscular spams of the tongue, face, neck and back
- layrgensl spams
what D2 antagonist is free of extrapyramidal side effects but what side effect does it cause
does not cross blood-brain barrier; free of extrapyramidal side effects
ventricular arrhythmia, especially at higher doses or with other drugs acting as CYP 3A4 inhibitors
what does metoclopramide do
- Dopamine D2 antagonist
- stimulates gastric emptying - 5-HT4 receptor agonist - at high doses
what is metoclopramide used as
Widespread use as an anti-emetic*
post-operative care
gastritis, migraine, dysmenorrhoea
drug- or treatment-induced emesis including anaesthesia, radiation and/ or chemotherapy for cancer
Widespread use as a stimulant of upper gut motility
gastro-esophageal reflux disease
gastroparesis
functional dyspepsia
describe the patterns of vomitting that were seen with cisplatin treatment
- vomtting a lot just after treatment and then it would gradually slow down
- then you would get anticipatory vomitting
name some cannabinoid receptor agonists
nabilone
levoantradol
what are cannabinoid receptor agonist used to treat
May treat mild/ moderate emesis
Poorly effective vs severe emesis (cisplatin)
Appetite promoting
what do anti cancer drugs do that causes vomiting
ANTI-CANCER CHEMOTHERAPEUTIC DRUGS LIBERATE 5-HT FROM ENTEROCHROMAFFIN CELLS LINING THE UPPER GI TRACT
- this causes vomitting
what do 5-HT3 receptor antagonist do
Prevent chemotherapy-induced emesis, acting mostly at GI vagal nerve endings
describe the anti-emetic activity of corticosteroids such as dexamethasone
Anti-inflammatory
Enhances anti-emetic efficacy of several other anti-emetics
Anti-emetic when give alone (eg.chemotherapy, post-operative nausea & vomiting)
Anti-nausea effects
May increase appetite
what is given for moderately sever forms of emesis
5-HT3 receptor antagonist + dexamethasone given in combination
what does 5-HT3 receptor antagonist + dexamethasone given in combination do
Substantial reduction in number & duration of hospital admissions + other costs associated with prevention/ management of nausea & vomiting
Reduced medical costs
Rare for patients to refuse chemotherapy because they can not tolerate the nausea or vomiting, or visiting the emergency room because of CINV-induced dehydration
name some examples of 5-HT3 receptor antagonist + dexamethasone
Granisetron Ondansetron Tropisetron Dolasetron Palonosetron: Long-Acting Ramosetron (Japan) High-dose Metoclopramide
what do NK1 receptors do
- blocks the action of substance P ( this is a neurotransmitter used y the vagus and some brainstem nerves)
what is given for sever forms of emesis
5-HT3 receptor antagonist + NK1 receptor antagonist + dexamethasone given in combination
why are large dose opiates sometimes unavoidable
- for pain
- these are a prophylactic of anti-emetic medication
what should e used to treat opiates
Choose an anti-emetic that also enhances analgesic efficacy
eg. Dexamethasone
if you have bowel obstructor what would you use
Metoclopramide (D2 antagonist, 5-HT4 agonist),
prucalopride (5-HT4 agonist)
- these stimulate gastrointestinal propulsion
if there is pain retropulsion and emesis caused y distention motor activity secretion in bowel obstruction what would you use
Reduce inflammation
- Dexamethasone
Reduce build-up of fluid in the lumen
- Octreotide, a somatostatin antagonist, which may also reduce pain
- Nasogastric tube, venting, gastrostomy tube
what is olanzapine
Atypical antipsychotic (thiobenzodiazepine class)
May be used in breakthrough vomiting
Antagonises at D1, D2, D3, D4, 5-HT2A, 5-HT2C, 5-HT3, 5-HT6, α1 adrenergic, H1 and m1, m2, m3, m4 receptors
Some improvement in nausea when given with 5-HT3 and NK1 receptor antagonists and dexamethasone
what are interceptive brain regions and how are they linked to vomitting
process stress, fear
there is sustained activation in subjects reporting “severe nausea & strong stomach awareness”
How does diabetes lead to vomitting and nausea
- diabetic keotacidis may somehow turn on D2 receptors
- diabetic gastroparesis - stimulates the vagus nerve, might also end up with destruction of 5HT pacemaker cells in the stomach and this creates an abnormal movement in the stomach
