GI - SA acute vomiting/diarrhoea Flashcards
Where is the vomiting centre located?
In the brainstem
What parts of the body act on the vomiting centre?
Cerebral cortex
Vestibular system
GI tract
Peripheral sensory receptors
Chemical stimuli in blood
What are the 4 stages of vomiting?
Prodromal - signs of nausea
Retching
Expulsion
Relaxation
What are the signs of nausea?
Restlessness
Lip smacking
Salivating
What occurs during retching?
Duodenal retroperistalsis
What occurs during expulsion of vomit?
Pyloric contraction
Lower oesophageal sphincter relaxation
Protect the airway - breathing inhibition, closed glottis
Abdominal contraction
Diaphragm descent - squashes stomach
What are some bad consequences of vomiting?
Fluid loss - dehydration
Acid base disturbance
Aspiration pneumonia
What make up normal stomach electrolytes?
Hydrochloric acid and potassium
(HCl only produced during feeding though)
What makes up normal duodenum electrolytes?
Bicarbonate
What electrolytes are primarily lost during vomiting with a patent pylorus? What does this cause?
Primarily lose bicarbonate and potassium
Causes a metabolic acidosis
Why does vomiting with a patent pylorus cause a metabolic acidosis?
Because the only thing left is the HCl making it acidic
What electrolytes are primarily lost during vomiting with an obstructed pylorus? What does this cause?
Primarily lose hydrochloric acid and potassium (the stomach contents)
Causes a metabolic alkalosis
What are the main two anti-emetic drugs?
Maropitant
Metoclopramide
What action does maropitant have to act as an anti-emetic?
NK1 receptor antagonist
What are the actions of metoclopramide?
Anti-emetic
Pro-kinetic - stimulates gastric and duodenal motility
When should you not use metoclopramide?
If there is a GI tract blockage - increased motility doesnt help
In cats - poor efficacy, maropitant is better
What are the 4 disease types of diarrhoea?
Osmotic
Secretory
Permeability
Motility
What causes osmotic diarrhoea?
Food not being digested properly
Net water movement into gut lumen due to the unabsorbed solute
What causes secretory diarrhoea?
Intestines secrete too much GI fluid and cant absorb it back
What causes permeability diarrhoea?
Disease in the lining of the intestines
Increases the leakiness and impairs fluid absorption, villus atrophy
What causes motility diarrhoea?
Increased GI transit rate - pass through too quickly for fluid to be absorbed
What is motility diarrhoea usually secondary to?
Bacterial toxins
Intestinal distention (laxatives)
High T4
What can be used/done as therapy for diarrhoea?
Appropriate fluid intake
Buscopan - antimuscarinic
Opioids
What should you do to treat acute diarrhoea?
Usually self limiting so doesnt need treating itself, just treat symptoms eg. fluid balance