Diarrhoea Flashcards
Which types of stools are categorised as diarrhoea on the bristol stool chart?
Type 5
Type 6
Type 7
What is diarrhoea?
A change in normal bowel habits that causes an increased frequency of bowel movements that produce soft and watery stool.
What is the difference between acute and chronic diarrhoea?
ACUTE:
- Abrupt onset of >3 stools per day
- Lasts no longer than 14 days
- often dietary causes
- Can be a result of bacterial or viral infection
- Usually restores in 2-3 days without treatment- just hydration and maybe hydration salts
CHRONIC:
- Has a pathological cause
- Lasts longer than 14 days
- Can be a flare up of a diagnosed condition e.g. IBS
- Requires further investigations
How many stools a day is classified as diarrhoea?
> 3
How long does acute diarrhoea typically last?
Usually restores within 2-3 days
but diarrhoea lasting less than 14 days is classified as acute diarrhoea
What age group is very common to get diarrhoea?
Under 5s
- often have 1-3 bouts per year
How many bouts of diarrhoea does the typical adult have per year?
1
- 22% is food related
- May be travellers diarrhoea
What is diarrhoea the second highest cause of?
Child mortality globally
What is the pathophysiology of diarrrhoea?
This is due to the changes in the balance between water and electrolytes absorption and secretion:
- Osmotic force drives water into the gut lumen e.g. after eating non-absorbable sugars e.g. mannitol or xylitol- if these sugars are avoided, diarrhoea stops
- Enterocytes (gut cells that line the gi tract) secrete fluid e.g. enterotoxin- induced diarrhoea- unlike above, this cant be avoided by stopping substance eating as it is caused by a pathogen
- Ion transporters are activated by bacteria pathogens- they invade enterocytes, causing the production of enterotoxins that damage cells, this increases cytokine secretion + increased prostaglandins = secretions
What is the difference between invasive bacteria, non-invasive bacteria and virus caused diarrhoea?
INVASIVE BACTERIA:
- cause a direct attack on the mucosal cells in the GIT
- The stools may contain blood and pus
- Often also causes a fever
- e.g. salmonella from badly cooked chicken, shigella, E.coli
NON-INVASIVE BACTERIA:
- These don’t directly damage the gut but instead produce enterotoxins that disrupt secretions the GIT causing watery stools
- e.g. saureus, enterotxigenic e.coli
Enterotoxin = a toxin produced in or affecting the intestines, such as those causing food poisoning or cholera
VIRALLY-INDUCED DIARRHOEA:
- The mechanism of action is not fully known
- The enterocytes become secretory = watery diarrhoea
What are the common causes of diarrhoea in the different age groups (infants, school children, adults, elders)?
INFANTS:
Infectious gasteroenteritis
Toddlers diarrhoea- hands in mouth, objects in mouth
Food intolerance
Coeliac disease
SCHOOL CHILDREN:
Infectious gasteroenteritis
Drugs e.g. antibiotics
ADULTS:
Infectious gastroenteritis
IBS, IBD
Drugs
Alcohol
Spicy foods
coeliac disease
ELDERLY:
Large bowel cancer
Faecal impaction
Drugs
Pseudo diarrhoea- watery stools spill over hard stools
Ischemic collitis
What are some microorganisms that cause diarrhoea with how long onset is?
Rotavirus- 12-48 hours
E.coli- 1-6 days
Shigella - 1-7 days
Salmonella - 12-24 hours
What are some drugs that can cause diarrhoea?
Antibiotics
laxatives
metformin
ferrous sulphate
NSAIDs
Cholestyramine
antacids
beta-blockers
digoxin
misoprolol
What are the treatment options for diarrhoea?
- Mostly oral rehydration therapy e.g. Dioralyte
- Rapid control = loperamide (opioid agonist that decreases gut motility)
What is the OTC dose of loperamide?
Initially, 4mg, followed by 2mg after each loose stool.
Usual daily dose = 6-8 mg and max daily dose = 12mg
Up to 48 hours only
What is the prescribed dose of loperamide?
initial 4mg, then 2mg after each loose stool.
Usual daily dose = 6-8mg and max daily dose = 16mg
Up to 5 days use max
Would you give loperamide in severe cases of diarrhoea e.g. dysentery or gastroenteritis?
NO- as loperamide can prolong the infection. Would use oral rehydration therapy only.
What non-pharmaceutical advice should be given to patients with diarrhoea?
- Eat as soon as able to - this should be bland and starchy foods such as bread, pasta, rice
- Avoid caffeine, alcohol, and carbonated drinks- as these all act as diuretics and we want to avoid dehydration
- wash hands and clean the home
- Dont return to work or school till symptom-free for 48 hours
- Other medications may not be absorbed- follow sick day rules
What age can oral rehydration therapy- dioralyte be used otc?
OTC dioralyte can be used in 2 years +
For under 2, it must be prescribed
How is Dioralyte used?
Mix one sachet with 200ml of water until it turns cloudy.
Adults = 1-2 sachets after each loose stool
Children = 1 sachet after each loose stool
What is the treatment in severe cases of diarrhoea?
Admission to hospital for IV fluids
What are the some of the possible causes for chronic diarrhoea (>4 weeks)?
Traveller’s diarrhoea
laxative abuse
medications e.g PPIs or antibiotics
lactose intolerance
Is immunocompromised
Family history of IBS, coeliac disease etc
Can Loperamide be used in pregnancy and breastfeeding?
Avoid loperamide in pregnancy- refer out of a community pharmacy
Loperamide appears in breastmilk in small amounts but is not recommended
use oral rehydration therapies and fluids - essential!
Can children be given Loperamide?
Do not give loperamide to children under 12 years old unless their doctor prescribes it
What other medications can be used for diarrhoea, aside from loperamide?
- Co-phenetrope
- Kaolin + morphine
- Bismuth subsalicyclate (peptobismol)
- Probiotics
These are not all used very often and have little evidence for efficiency
How does loperamide work?
- Loperamide is a synthetic opioid analogue that is based on the chemical structure of pethidine
- Loperamide binds to mu-opioid receptors in the gut wall and inhibits the release of acetylcholine and prostaglandins- both of which normally stimulate defecation
- Acetylcholine is the main excitatory neurotransmitter in the GIT. When it binds to nicotinic or muscarinic acetylcholine receptors, it increases parasympathetic activity.
- So if, acetylcholine is inhibited by loperamide, propulsion and peristalsis are decreased. Sensitivity to rectal distension is also decreased and there is an increase in the sphincter tone of the ileocaecal valve and anal sphincter (circular muscles that can open and close to control the passage of food through the gi tract) (Ileocaecal valve is found between the ileum and colon- separating the small and large intestine)
- If prostaglandin release is inhibited, especially prostaglandin E2 there is a decrease in gut secretions and gut motility.
- This all increases intestinal transit time and therefore enhances water and electrolyte reabsorption to harden the stool
Does loperamide cross the blood brain barrier?
NO- it has peripheral effects
Does morphine and codeine cross the blood brain barries and how do they worK?
They have the same moa as loperamide apart from the fact that they can cross the BBB
What is the role of the ileocaecal valve in diarrhoea?
It limits the rate of food passage into the caecum (from the small to large intestine).
- If there is an increase in muscle tone, there is a limit rate of food passage + decreased gut motility and therefore there is more opportunity for water and electrolytes to be reabsorbed = decreased diarrhoea
Therefore, if muscle tone is increased = it aids diarrhoea treatment
What is the role of the anal sphincter in diarrhoea?
Keeps the anus closed as stool collects in the rectum until pressure increases and causes the sphincter to relax = allowing
defecation
What are the red-flag symptoms of diarrhoea (refer)?
- Recent travel abroad
- Blood or mucus in stool
- severe vomiting or fever
- Abdominal pain
- Pregnant or breastfeeding
- Signs of dehydration
Refer to GP if the duration exceeds
1 day for infants, over 2 days if children under 3 or the elderly and over 3 days in children over 3 nd healthy adults.
What causes travellers diarrhoea?
This is usually due to comparatively lower food hygiene and sanitisation leading to infection with bacteria e.g. e.coli or virus
How can travellers reduce their risk of getting diarrhoea?
- Be cautious with the food and drinks consumed
- Drink bottled water]-
- Avoid ice, salads, unpasteurized milk, uncooked veg fish or meat
- Avoid street vendors
- B e vaccinated - hepatitis A, Typhoid and cholera
What is the treatment for traveller’s diarrhoea?
- Maintain hydration
- Loperamide
- May have antibiotic treatment depending on the pathogen e.g. broad-spectrum antibiotic such as ciprofloxacin
What drugs are recommended to stop when having D+V and why?
Stop taking until well + have had 24-48 hours of eating and drinking normally - as they can lead to acute kidney injury when dehydrated:
Ace inhibitors
ARBs
NSAIDs
diuretics
Metformin- dehydration can increase risk of lactic acidosis
Why should you temporarily stop metformin when dehydrated/ have D+V?
- Dehydration can increase the risk of lactic acidosis which is a severe side effect of metformin
What can lead to a c.difficile infection?
Repeat use of broad-spectrum antibiotics can upset the microbiome and the healthy bacteria in the gut and therefore c.diff can enter and damage the colon causing diarrhoea. This can be very fatal and can cause sepsis.
What are the risk factors for developing a c.diff infection?
- Use of broadspectrum antibiotics
- Over 65 years old
- prolonged hospital stay
- Immunocompromised
What is the treatment for a c.diff infection?
- Vancomycin 125-500mg every 6 hours for 10 days
