Diarrhoea / constipation Flashcards
Causes of diarrhoea/constipation?
Diarrhoea: increased secretion of fluid and electrolytes (si) or decreased absorption of fluid (li)
Constipation: develops if too much water absorbed or muscular contraction sluggish
How is decreased absorption of fluids occur?
- LOSS OF VILLI - can be transient due to infection, if coeliac then ongoing process
- Gut removed will also have lower surface area for absorption
- Via rapid proliferation of cells from crypts –> disorganised gut wall cells or loss of epithelial layer
disorganisation means cells don’t act efficiently- (and cells that are there don’t do their job or don’t do it very efficiently)
Infection with salmonella (enteritidis in this case) - can lead to lack of absorption
- release of TOXINS - lose EPITHELIAL cells - lose finger-like PROJECTIONS - like a drainpipe - occurs in CROHN'S (so not just acute setting - chronic important as well)
Loss of finger-like projections
- nutrient intake can be an issue - not just in acute setting - also in chronic
What happens when after infection / disorganisation of gut wall
Sodium, water, glucose, amino acids uptake - usually happens at the top end - in the organised area
BICARBONATE, CHLORIDE and WATER are lost from the bottom - in kind of crypts
Only bit of cell you have left after infection is crypt area - so begin to LOSE:
- BICARBONATE so pH CHANGES
- CHLORIDE loss - important because it is counterpoints with things like sodium
- WATER loss
- Massive amount of water in wrong area - absorption later down in lower intestine NOT SUFFICIENT to OFFSET what you lose at UPPER end
- Mucosal surface area decrease - nutrient and water uptake decreased - essentially diarrhoea
Causes of diarrhoea?
Infection: bacteria, virus, parasite
- food borne diarrhoeal disease not actually the most common, fungus if really unlucky!
most infectious diarrhoea relatively acute - should be self-limiting as long as otherwise healthy
Medications: ~7% of all adverse reactions
- ‘diarrhoea and constipation’ - young children with impaction - get seepage, more on acute side - in most cases if take away medicine should absorb itself
Chronic bowel disorders
- Removal of part of bowel - resection of bowel can be curative in some diseases (ulcerative colitis) as can live without parts of colon - can have colostomy or gain enough absorption from whats left
Crohn’s disease - not much you can cut out but can have surgery to open bowel to rest in-between time?
Causes of infective diarrhoea?
Bacteria:
E. coli Salmonella enteritidis/typhi Vibrio cholera Campylobacter jejuni - very high in stool sample tests - but not most common as lots of stools for simple infection wouldn’t get sent off C. difficile - amoxicillin can cause C. diff - - C. diff treated by metronidazole this hospital uses tetracycline as less associated with C. diff Shigella
Parasites:
Cryptosporidium parvum
Entamoeba histolytica
- some parasites notifiable diseases
- trekking abroad - diarrhoea can still be there after 21 days
Virus Norwalk virus Rota virus - affects babies and adults - most common cause - rotavix vaccine - rotavirus can kill - but usually self-limiting
Adenovirus
Most common causes of infective diarrhoea?
Less than 2 years
- Rotavirus 22%
- Bacteria 14%
Adult:
Viral - high
Bacteria 33%
- cooking
- catering for people than you otherwise normally do - e.g. harder to cook through eggs in bulk
- so see outbreaks in groups/parties
Campylobacter 15%
- Malabsoprtion of water and nutrients leads to dehydration and malnutrition
- Major cause of death in children under 5
- Spread through water, food, utensils, hands, flies
Drugs that cause diarrhoea?
~700
Cholinergics: increased ACh
- neostigmine
- stimulating muscarinic receptors
Cytotoxic agents: loss of gut epithelia
- target cells that are turning over quickly
- high turnover in gut epithelia
- then patient feels unwell and may not finish course which is really important in cancer treatment
Broad spectrum antibiotics: change in gut flora
- C diff associated with amoxicillin and others (those associated with resistant bacteria)
- clear out good bacteria - bad ones take over
- rarely get fungal infections causing diarrhoea
Chronic bowel diseases causing diarrhoea?
Endocrine diseases
- diabetes
- thyroid disease
Inflammatory bowel disease
- ulcerative colitis
- Crohns
- some people get IBS after they’ve been treated for their Crohn’s/UC
Diverticular disease
Self induced - laxative abuse
Psychological - stress
Malabsorption
- coeliac disease
- pancreatic insufficiency
- controls a range of things to do with absorption
- cystic fibrosis
- chloride transporter lost or changed in any way - gut habits may change (chloride, bicarbonate, water absorption)
Antibiotic associated colitis
Chemotherapy GI irradiation
Irritable bowel syndrome
Problems/pathophysiology associated with diarrhoea?
Infection/drug/malabsorption –> diarrhoea
Dehydration (H2O, Na loss) Metabolic acidosis (HCO3 loss) Potassium depletion (K loss) Hypovolaemia CV collapse Death
Isotonic dehydration signs?
95% hydration
- thirst
- skin turgor
- tachycardia
- dry mucous membranes
- sunken eyes
- lack of tears
- sunken anterior fontanelle - babies
- oliguria
90% hydration is life threatening
- anuria
- hypotension
- feeble and very rapid radial pulse
- cool and moist extremities
- diminished consciousness
- signs of hypovolaemic shock (so can happen very rapidly)
Effect of alcohol?
Diuresis:
- Every 200ml alcohol = 300ml urine
- Stasis in gut - gut transit slowed down
Treatment of acute diarrhoea?
ORT: prevention or reversal of dehydration
Antimotility drugs: relieve symptoms (not recommended in children)
immodium = loperamide (opioid)
- specific to gut mucosa - not affecting brain
Antispasmodics: reduce cramping and pain
- IBS when in remission from Crohn’s
Antibacterials: usually not required in simple episodes
- unless sepsis risk
- or travellers diarrhoea
Normal stool contents?
Na, K, Cl, Bicarbonate, Water
Infection - sodium control deranged
ORT?
Oral rehydration therapy
Clean water:
- Isotonic (usually) or slightly hypotonic when rehydrated
- Priority in acute diarrhoea is prevention or reversal of dehydration particularly in infants and the elderly (those that would otherwise succumb to these diseases- most adults would be alright unless comorbidity)
Try control sodium (where sodium goes water goes):
- Only way to get it back in is by countercurrent system with glucose- really only reason glucose is there is to help the sodium get across
- But benefit of extra energy
GLUCOSE-SODIUM COTRANSPORTER
- Only one that seems to survive during an attack of diarrhoea / diarrhoea infection- only have ability to bring sodium in but requires glucose
- Sodium increases in blood - water comes in
- Can have problems if osmolarity is a bit different - can get hypernatraemia, or hyponatraemia (woozy)- sodium balance incredibly important
Anti-motility drugs?
Symptomatic relief (so may not be best thing)
- Increase muscle tone but diminish propulsive activity
- Reduced awareness of the urge
- Opiates - CODEINE, MORPHINE, LOPERAMIDE, COPHENOTROPHE (loperamide = over counter)
- Loperamide - relatively selective in GI tract - reduced BBB, central activity
- Binding of µ opioid receptor in the SUBMUCOSAL plexus (MYENTERIC plexus) of the intestinal wall
- no euphoria etc
- can get gas but not diarrhoea as propulsive force is lost
Side effects - nausea, vomiting, cramps, paralytic ileum
- paralytic ileus; part of ileum cramping up
