Diarrhoea - 101 Flashcards
What is secretory diarrhoea? How can you tell it is secretory not osmotic?
In secretory diarrhoea there is active secretion of fluid and electrolytes from the gut wall. It can be due to irritants e.g. E.coli. Stool has normal osmolality. Diarrhoea continues with fasting so if patient stops eating and diarrhoea continues it must be secretory diarrhoea.
What is osmotic diarrhoea? How can you tell it is osmotic not secretory?
When there are large amounts hypertonic substances in the lumen. The stool will have a high osmolality and diarrhoea will stop with fasting so you can get patient to stop eating and see if diarrhoea stops.
How do you treat diarrhoea?
1) Assess hydration - treat dehydration, e.g. ORS (Dioralyte), IV fluids.
2) Treat the cause of diarrhoea (antibiotics)
3) Stop diarrhoea - loperamide
Name 3 viruses that can cause diarrhoea and how you would recognise them.
Rotavirus - common in infants, infectious for 21 days, leading worldwide cause of gastroenteritis.
Norovirus - common in children, outbreaks, closed communities, winter.
Astrovirus - Institutions, sporadic acute diarrhoea, mainly children.
Name 3 bacteria that can cause diarrhoea and how you would recognise them.
Campylobacter - bird faeces source of infection, contaminated poultry, water, unpasteurised milk etc. 2nd most common cause of travellers diarrhoea. Patient has watery/bloody stool with cramps and fever.
Salmonella - contaminated animal foods
E.coli - ETEC (travellers), EHEC (contaminated food, 0157), EPEC, EIEC, EAEC
Cholera - if patient lives/travels abroad. Severe white watery stool.
C. difficile - Recent antibiotic use, cramps, foul smelling stool.
Shigellosis - severe dysentry, mainly children.
Name 2 parasites that can cause diarrhoea
Giardiasis - excretion in cysts.
C. parvum - transmission from livestock/zoos.
Name some signs of dehydration
- Tachycardia
- Tachypnoea
- Skin turgor
- Dry mucus membranes
Name some signs of shock
- Slow capillary refill
- Low bp
- Tachycardia
What is severe acute malnutrition? How can SAM cause diarrhoea?
SAM is classed as a very low weight for height. It can be seen clinically by severe wasting or nutritional oedema. In SAM there is not enough energy to maintain ion balance (keep Na out and K in cells). This means that [K] in blood builds up, it also ends up in faeces and causes diarrhoea (using mechanism of osmotic diarrhoea).
What fluid would you give to treat shock?
20ml/kg given in a bolus over ~30 minutes.
If someone is dehydrated and is being treated for shock give 100ml/kg/day. If they are not being treated for shock give 50ml/kg/day as maintenance fluid.
What is the 4-2-1 rule regarding fluids for dehydrated infants?
For the first 10kg of baby’s weight give 4ml/kg/hr.
For the next 10kg of baby’s weight give 2ml/kg/hr.
For any further weight give 1ml/kg/hr.
E.g. if a baby weighs 14kgs give: 10x4 = 40ml. 4x2=8ml. Give 48ml.
What is happening to someone’s blood pH if they are tachypnoeic?
They are getting rid of too much CO2 and with therefore get alkalitic blood. This is called respiratory alkalosis.
What happens to someone’s blood pH is they are hypoventilation? (Bradypnoea)
The blood will become more acidic due to the increased blood [CO2], this is called respiratory acidosis and can be treated with Hartmann’s or Ringer’s solution in dehydration.
What is the difference between crystalloids and colloids?
Colloids, e.g. albumin, have large molecules that are insoluble.
Crystalloids, e.g. NaCl, contain small molecules that can cross semi-permeable membranes.
What pathogenic organism mainly colonises the duodenum?
Giardia.
