Week 101: Diarrhoea Flashcards
What are the signs of clinical dehydration?
⇒ Appears to be unwell/deteriorating ⇒ Altered responsiveness (e.g. irritable/lethargic) ⇒ Sunken eyes ⇒ Tachycardia ⇒ Tachypnoea ⇒ Reduced skin turgor
- Decreased urine output
- Dry mucous membranes
⇒ Symptoms of the hand indicate shock
What are the signs of clinical shock?
- Decreased level of consciousness
- Pale or mottled skin
- Cold extremities
- Tachycardia
- Tachypnoea
- Weak peripheral pulses
- Prolonged capillary refill time
- Hypotension (decompensated shock)
⇒ Symptoms of the hand indicate shock
How is diarrhoea caused in severe acute malnutrition (SAM)?
Higher levels of potassium are excreted from the cells than normal which leads to diarrhoea
What fluid management would you use for shock?
- 20ml/kg in 30 minutes
- Repeat if still in shock
- Then move to maintenance fluid
Maintenance fluid post shock?
- 0.9% saline
- 100ml/kg/day
Maintenance fluid (not post shock)?
- 0.9% saline
- 50ml/kg/day
Maintenance fluid in children?
⇒ 4-2-1 rule
- 4: first 10kg, 4ml/kg/hour
- 2: next 10kg, 2ml/kg/hour
- 1: more weight, 1ml/kg/hour
What is the calculation to work out electrolytes in the stool?
290 - 2(concentration (Na+K))
- 290 is the normal osmolality of blood
How does osmotic diarrhoea work?
- Electrolytes are absorbed normally
- Other things malabsorbed
- Little Na and K excretion
- Normal osmolality
⇒ Caused by malabsorption (coeliac disease)
How does secretory diarrhoea work?
- Damage to membrane leads to a loss of Na and K
- Low answer to calculation, low osmolality
⇒ Mainly caused by infection
How to tell the difference between osmotic and secretory diarrhoea?
- Osmotic diarrhoea stops when eating stops
- Secretory diarrhoea continues regardless
What are the drugs that can cause diarrhoea?
- Antibiotics
- NSAIDs
- Digoxin
- Lipase inhibitor
- Magnesium
What is the leading cause of gastroenteritis worldwide?
Rotavirus
What causes infant diarrhoea?
Rotavirus
What causes an outbreak of diarrhoea in a hospital amongst staff?
Norovirus
What is the most likely cause of diarrhoea amongst patients in a hospital?
Clostridium difficile
What is the most likely cause of diarrhoea after a barbecue?
Campylobacter
What is the most likely cause of diarrhoea after raw eggs?
Salmonella
What is the most likely cause of diarrhoea after working on a farm in the US?
EHEC
What is the most likely cause of diarrhoea after working on a farm in a developing country?
ETEC
What is the most likely cause of diarrhoea due to war or water?
Cholera
What are the most likely causes of diarrhoea after travelling?
Giardiasis
ETEC
What is the most likely cause of diarrhoea amongst elderly/hospitalised/antibiotic using?
Clostridium difficile
What is the main sign of giardiasis?
Cysts in the faeces
- It is spread by cysts in faeces
- Cysts are not always present
What are the pharmacological treatments of diarrhoea?
⇒ Loperamide
- Opioid antagonist
- Receptors in bowel
- Gives gut more time to absorb fluid
⇒ Oral rehydration solution
- Dioralyte
- WHO oral rehydration spoon
What is the difficulty with tachypneic patients?
- Getting rid of too much CO2
- Leads to respiratory alkalosis
- Body can’t compensate
How would you treat respiratory alkalosis?
- iv Ringer’s Lactate
- iv Hartman’s Lactate
What are the differences between crystalloids and colloids?
⇒ Crystalloid
- Small molecules
- Can cross semi-permeable membranes
- E.g. sodium chloride
⇒ Colloid
- Large molecules
- Can expand fluid in blood cells
- Increase blood pressure
- E.g. albumin
What is the main organism that colonises the duodenum?
⇒ Giardia
- Won’t find giardia anywhere else
What is the main function of the jejunum?
Food absorbed
What is absorbed in the distal ileum?
- Bile acids
- Vitamin B12 with intrinsic factor
What are the main immune cells in the ileum?
Payer’s Patches
What are goblet cells?
Goblet cells contain clear mucin granules, mucous secretion serves a protective role
Denser in proximal intestine, sparser on villus tip
What are absorptive cells?
Have well adapted microvilli, found in small intestine
What are crypt cells?
Smaller with fewer less developed microvilli than absorptive cells, have narrow apices
Found in the small intestine
What are paneth cells?
Found at the base of the crypt villi
Contain eosinophilic secretory granules
More common in the ileum than the jejunum
Probably involved in intestinal barrier function
What are m cells?
M cells are found over Peyer’s Patches
Rapidly transport luminal macromolecules and some microorganisms by transcytosis
Probably important for processing and presenting antigens to the mucosal immune system
Where is food absorbed?
In the jejunum
What are Peyer’s Patches?
Immune cells found in the ileum
What is submucosa?
Contains blood vessels, connective tissue lymphatics, and lymphoid aggregations
What is the main organism that colonies the duodenum?
Giardiasis
Embryologically, what divisions of the embryo form the gastrointestinal system?
Foregut, midgut, hindgut, mesenteries
What does ectoderm make?
Hair Retina Outer layer of skin Central nervous system Outer lining of everything Enteric nervous system (neural tube) Extrinsic innervation
What does the mesoderm make?
Muscle Bone Organs Mesentery Connective tissues Blood vessels
What does endoderm make?
Lining of the gut Secretory cells of the GI tract Inner linings (including respiratory tract) Epithelium Glands
What is diarrhoea?
3 or more loose or watery stools in a 24-hour period
