Diarrhoea Flashcards
What is the definition of diarrhoea?
A change in normal bowel habit resulting in increased frequency of bowel movements and the passage of soft or watery stools.
May be accompanied by colicky pain due to increased contraction of smooth muscle and additional production of gas which can cause discomfort.
Its a SYMPTOM not a disease
What is acute diarrhoea?
Abrupt onset of >3 loose stools a day and lasts no longer that 14 days
Can have dietary causes e.g. alcohol or spicy foods
Can be a bacterial or viral infection
Majority resolve within 2-3 days without specific treatment
What is chronic diarrhoea?
Pathological cause
Lasts over 14 days
Possibly flare up of previously diagnosed condition e.g. IBS
Needs further investigation to identify the underlying the cause.
What are the morbidity factors for diarrhoea?
Age and nutritional status are most important host factors in determining severity and duration
The younger the child, the higher risk for severe, life-threatening dehydration as their immune system is not as strong and they can’t physically consume enough water to rehydrate themselves.
What is the pathophysiology of diarrhoea?
Essentially the change in balance between the absorption and secretion of water and electrolytes.
It can be due to 2 reasons:
- An osmotic force that drives water into the gut lumen, e.g. after ingestion of non absorbable sugars
- Proportional to the intake and responsive to fasting - meaning if the patient is un able to digest a certain type of sugar, then more severe symptoms would occur, hence if they stop consuming that sugar they’re condition will better.
OR 2. Enterocytes (cells lining the GI tract) actively secreting fluid e.g. enterotoxin-induced diarrhoea
- Not responsive to fasting (so even if they avoid that substance it will make no difference as its caused by a pathogen)
- Ion transporters are activated by the bacteria by e.g. bacteria resulting in pathogens:
-> Invading enterocytes or
-> Producing enterotoxins which damage cells or
-> Inducing cytokine secretion to produce prostaglandins which stimulate secretion (hence extra secretion of fluids and electrolytes promoting the loss of water through diarrhoea)
What is the mechanism of how bacteria can cause bacteria?
- Invasive mechanism:
- Specific types of microorganism can directly attach mucosal cells which causes diarrhoea
- Stools may contain blood and pus
- Develop a fever
- E.g. Shigella, Salmonella, Yersinia, Enteroinvasive E Coli
- Non-invasive mechanism:
- They do not directly damage the gut
- But the bacteria produce enterotoxins that disrupt secretion
- Watery diarrhoea
- E.g. S aureus, B cereus, C perfinngens, Enterotoxigenic E coli
How do we diagnose diarrhoea? What factors do we look at?
- Symptoms
- Any associated symptoms? e.g. temp, fever, blood etc
- How quickly was the onset?
- Is there an absence of stool formation? - Trigger factors?
- “Bad”/unusual food, alcohol, drugs, contaminated water etc - Time/intensity
- Dehydration in major risk groups
- How long and severe are the symptoms - Fecal studies
- To identify the pathogen - Serum albumin (to identify if theres any loss of protein hence suggesting theres damage taking place in the GI tract)
- Fecal alpha 1 antitrypsin (to identify if theres any loss of protein hence suggesting theres damage taking place in the GI tract)
- Intestinal biopsy (VERY SEVERE CASES)
What is gastroenteritis?
Inflammation of the stomach and intestines, typically resulting from bacterial toxins or viral infections causing vomiting and diarrhoea.
What are the common causes of diarrhoea in infants?
- Infectious gastroenteritis
- Toddlers diarrhoea
- Food intolerance
- Coeliac disease
What are the common causes of diarrhoea in school age children?
- Infectious gastroenteritis
- Drugs (Antibiotics)
What are the common causes of diarrhoea in adults?
- Infectious gastroenteritis
- IBS
- IBD
- Drugs
- Excess alcohol
- Spicy food
- Coeliac disease
What are the common causes of diarrhoea in older people (elderly)?
- Infectious gastroenteritis
- Large bowel cancer
- Faecal impaction
- Drugs
- Ischaemic colitis
How can we prevent diarrhoea?
Good hygiene: Wash hands regularly
- After visiting the toilet
- Before touching food
- After gardening
- After playing with pets
- Between handling raw and cooked food
What are the treatment aims of treating acute diarrhoea in adults?
- Prevention and reversal of fluid and electrolyte depletion
- Management of dehydration (if present)
- Most acute diarrhoea settle spontaneously (at around 3 days)
- Oral rehydration therapy provided if needed
For rapid control of symptoms:
LOPERAMIDE:
Prescribed dose > 12 years: Initially 4mg, followed by 2mg after each loose stool (for up to 5 days max); Usual dose 6-8mg daily ; maximum 16mg per day (8 caps)
GSL/P dose > 12 years: Initially 4mg followed by 2mg after each loose stool (for up to 48hrs max); usual dose 6-8mg daily; maximum 12mg per day (6 caps)
- We get the patient to eat as soon as possible/able (bland) - soups, bread, pasta, rice, potatoes
- Avoid caffeine, alcohol, carbonated drinks (diuretics)
Why should anti-motility drugs be avoided in severe gastroenteritis or dysentery?
As these conditions are more serious - consisting of blood/music In stools and fever
The concern is that Loperamide can prolong the infection.
- Prevention and treatment of fluid and electrolyte depletion is primary importance - Oral rehydration therapy*
What is oral rehydration therapy?
- Most common brand is Dioralyte (if under 2yrs only under medical supervision)
- Mainstay of treatment for acute diarrhoea
- To prevent or correct dehydration
- Maintain appropriate fluid intake once rehydration established
- Mix sachet with 200ml water!!!
- Severe cases require hospitalisation for IV fluids - refer
What are the treatment steps for chronic treatment?
- Determine underlying cause and treat as appropriate
- Ask about any foreign travel
- Ask about any Laxative abuse
- Other medications? e.g. PPIs, antibiotics
(ORT and loperamide whole investigations ongoing) - Is the patient immunocompromised
- Is there any family history of IBS/Coeliac disease?
- Lactose intolerance? (if symptoms worsened by dairy), excess caffeine/sorbitol
- Refer for specialist investigations
What are the treatments options for diarrhoea in pregnant and breastfeeding patients?
Loperamide manufacturers advice to AVOID in pregnancy
- Weigh up risks to both baby and mum (if severe enough- refer)
Loperamide appears in breast milk
- Amount probably too small to be harmful but not convincing for a breast feeding mother
Oral rehydration therapy (ORT)and fluids essential - to avoid dehydration
If symptoms warrant Loperamide, refer in both instances from community pharmacy - Loperamide is not licensed OTC for pregnancy or breastfeeding
What are the treatments options for diarrhoea in children?
- Feeding babies: continue with normal milk feeds (breast milk will contain antibodies it needs to fight infection)
- Older children: encourage plenty of fluid
- Use ORT
- ANTI-DIARRHOEALS NOT RECOMMENDED BY NICE
How can spread of diarrhoea be prevented in children?
- Careful washing and drying of hands after using toilet, nappy changing and before meals
- Don’t share towels
- 47hr exclusion from school following cessation of symptoms
- Avoid swimming for 2 weeks following last episode of diarrhoea
What is the pharmacology of loperamide?
Loperamide is a synthetic opioid analogue - Pethidine congener which doesn’t readily pass the blood brain barrier
- Loperamide binds to mu-opioid receptors in the gut wall
- This binding inhibits Acetylcholine (ACh) and Prostaglandin release
- ACh is the main excitatory neurotransmitter in the GI tract
- ACh binds to muscarinic/nicotinic ACh receptors, increasing parasympathetic activity
ACh inhibition leads to:
- Decreased propulsive peristalsis
- Decreased sensitivity to rectal distension
- Increased sphincter tone of the ileocaecal valve (located between the small intestine and large intestine- so food is passed through the ileocaecal valve - rate limiting and also helps prevent reflex of digested material back into the small intestine) and anal sphincter (it is a ring of muscles at the opening of the anus- the anal sphincter keeps the anus closed as its collecting stool in the rectum)
Prostaglandin inhibition leads to:
- Reduced gut secretions
- Reduced gut motility
Therefore Loperamide increases intestinal transit time enhancing water and electrolyte reabsorption,
What is the problem with using morphine and codeine to treat diarrhoea?
Morphine and codeine are also sometimes used to treat diarrhoea.
As they are opioids they have the same mechanism of action as Loperamide.
However as they do readily cross the blood brain barrier, there are problems with abuse and dependence of these medications.
What is the pharmacology of Co-Phenotrope? (opioid + anti-muscarine)
Diphenoxylate (opioid)
- Synthetic opioid - pethidine congener; dose NOT readily pass the blood brain barrier
- Does not usually have CNS activity; large doses lead to typical opioid effects
- Insoluble salts mean that there is no potential misuse by injectors
Atropine (anti-muscarinic)
- Muscarinic ACh receptor antagonist
- Reduction in ACh reduced parasympathetic drive
- GI motility is inhibited
- Effect not marked as several excitatory transmitters, including ACh are important in the function
What are the key red flags to refer in diarrhoea?
- Recent travel abroad
- Blood or mucus in stools
- Associated with severe vomiting and fever
- Severe or persistent abdominal pain
- Pregnancy or breastfeeding
- Signs of dehydration
