diarrhoea Flashcards
what is defecation?
Defecation is the term given for the act of expelling faces from the digestive tract via the anus.
what systems does defecation involve?
GI system
nervous system
musculoskeletal system
what happens in defecation?
- expel undigested portions of food
- expel metabolic waste from the body in the form of stool
- stools containing bacteria and cellular debris from GIT
how frequent is defecation?
- varies on age and diet
usual normal bowel:1-3 times a day
what role does the colon have in defecation?
right- mixes and stores contents
left- conduit
what does rectum and anal canal do in defecation?
it enables defecation and maintains faecal continence
what is the colon responsible for?
- delay passage of luminal contents to allow for water absorption
- allow for segmentation and mixing luminal contents with the mucosa
- store faecal matter before defecation
- propel faeces towards the rectum
- begins the urge to defecate
what controls the act of defecation?
two sphincters
internal anal sphincter- smooth muscle cells- involuntary control
external anal sphincter- striated muscle cells- voluntary control
what is the mechanism of defecation?
the pudendal nevre provides the voluntary motor control of faecal and urinary continence
- the pelvic nerve regulate the emptying of the urinary bladder
- the hypogastric nerve is responsible for proprioception and proper functioning or the urethral and anal sphincters
what is the pre-defecatory phase?
1 hour before actual defecation
majority of the colon exhibits an increase in propulsive peristalsis waves
-colonic mass improvements and peristalsis move intentional contents distally into the rectum
- sensation to poo is not evident till 15 min before hand
what happens when stools reaches the rectum?
There is activation of recto-anal inhibitor reflex
process of determining if the rectal contents are of the gas solid or liquid
what happens when stool comes in contact with the receptors in the upper anal canal?
this can affect relaxation of the inner anal sphincter
what happens if the external anal sphincter does not relax?
- retrograde passage of stool into the rectum
- diminished proximal peristaltic propagative waves
- maintained continence when immediate defecation is not desirable or convenient
what do you do when you are revaluating the rectum and defecation?
-squatting position
-contraction of the abdominal musculature of the diaphragm
relaxed pelvic floor facilities defecation
what is the process of expulsion of feces?
- contraction of the abdominal muscles
- performing the valsalva manoeuvre
- relaxing the external anal sphincter and puborectalis muscle
what happens after faecal expulsion?
the external anal sphincter regains its tone to maintain continence at rest
what does the size and the consistency of the stool as well as bacterial content vary with?
- vary based on diet and water intake
- determined by transit time
what would changes in defecation habits be a sign of?
- common symptom of the defecation process
- is a common side effects to many therapies
- may indicate alarming condition such as colorectal malignancy
what would stool form alteration be indicative of?
disease:
-steatorrhea results from lack of adequate amounts of pancreatic enzymes and/or bile acids and intestinal malabsorption
how can a stool content provide diagnostic information?
e.g. c. difficle : watery diarrhea, fever, nausea and abdominal pain
what are the 3 pathophysiology associated with defecation?
diarrhea
constipation
faecal incontienence
what is diarrhoea?
it is defined as an increase passage of loose or watery stools relative to usual habit
it is not a disease
what is the usual cause of diarrhoea?
usually caused by a viral or bacterial infection
also associated with other conditions such as IBS/IBD
What are the subcategories of diarrhoea?
osmotic, secretory, inflammatory, functional
define osmotic diarrhoea
it is characterised by the presence of unabsorbed solutes
it is caused by either decreased absorption or increased secretion of electrolytes and water by the intestinal epithelium
define secretory diarrhoea
is caused by addisons disease, simulant laxatives, small intestine bacterial overgrowth or electrolyte transport disorders
define chronic and inflammatory diarrhoea
it is characterised by persisting (more than 4 weeks) diarrhea stools of watery or loose consistency
define dysfunctional in intestinal molitility diarrhoea
alterations in intestinal motility (usually increased propulsions) are observed in many types of diarrhoea
what does osmotic diarrhoea occur as a result of?
- bacterial enterotoxins- cholera or e.coli
- reduced absorptive surface area caused by disease or resection
- luminal secretaggues
- medical problems that compromise regulation of intestinal function
what is the main reason for osmotic diarrhoea?
- occurs when too much water is drawn into the bowels
- frequently present in malabsorption syndromes such as lactose intolerance or celiac disease
- result from the indigestion of of osmotically active substances like magnesium or sulfate
how are osmotic and secretory diarrhoea distinguishable from one another?
by calculating the decal osmotic gap
when does chronic inflammatory diarrhoea occur?
when inflammation of the bowel musosa causes decreased fluid resorption
present in diesease such as DC/UC/
invasive intestinal infections: c.difficle or shigella
what is a common presentation of stool in inflammatory diarrhoea
stool will contain blood, white blood cells along with mucus
What is functional diarrhoea charazterised by?
it is a GI disorder characterised by a chronic or recurrent diarrhoea not explained by structural or chemical abnormalities
most common form is IBS
may be due to alterations in the microbiome of the intestine in addition to the rapid transit time of contents through the digestive tract
what is diarrhoea due to impaired intestinal motility?
abnormal intestinal motility that accelerate transit mouth to anus transit time can decrease absorption resulting in diarrhoea
what are the other possible causes of diarrhoea?
exudative
malabsorption or maldigesting of fat or carbs
microscopic colitis
what is the most common cause of gastroenteritis in adults? and children?
campylobacyer-adults
rotavirus- children
what are some bacterial causes of diarrhoea?
e.coli, salmonella, shigella, closyridum
what are some viral causes of diarrhoea?
norovirus
adenovirus
what are some protozoal causes of diarrhoea?
cryptsporidium
giardia
what is travelers diarrhoea?
it is caused by gastroenteritis in 80% of cases due to contaminated food or water
typcially undercooked poultry or reheated meat: ecoli/ shigella/ salmonella/ campylpbacter jejuni/ virus ,protoza and helminthis
giardia lambia/ entamoeba
how quickly does travelers diarrhoea occur?
within 72 hours
onset within 6 hours of meal indicative of bacterial toxins being produced
what is the usual duration of travelers diarrhoea?
normally short duration- typically 4 days to a max 7 days
what are some of the main drugs that cause diarrhoea?
alpha blockers, ACEI, ang receptor blockers, antacids, antibacterial, antidepressant, antiepileptic, antiviral, bb, PPIs, all NSAIDS
what are the questions you would look out for when patient comes in with diarrhoea/ signs and symptoms of diarrhoea?
loose watery stools history of onset important duration family members recent travel abroad food eated drug use dehydratin problem in young and elderly
when would you refer a person with diarrhoea?
symptoms over 72 hours and 48 hours in elderly and 24 hours in people with diabetes.
what are the accompaning symptoms of diarrhoea?
it is associated with severe fever and vomiting
history of change of bowel habit
presence of blood or mucus in stools
suspected adverse drug reaction
alternating constipation and diarrhoea in elderly patients
how do you treat diarrhoea?
self limiting if acute infective diarrhoea and travlers diarrhoea
- good hygeine should be followed to prevent spreading
- electrolyte loss -its is important to maintain fluid intake, particularly fruit juice as thet contain glucose,k+ and na+
young and elderly- oral rehydration solution
when do you use antibiotics to treat diarrhoea?
in moderate to severe travelers diarrhoea- it depends on what kind of bacteria has caused the infection
what antibiotics treat 1) giardua lambli 2) cryptosporidium 3) cyclospora cayetanenis
4) amoebae?
1- metronidazole, tinidazile or nitazocanide
2-nitazoxanide
3-trimethoprim-sulfamethoxazole
4-metronidazole or tinidazole, followed by a luminal agent such as paraomycin
what is an antimotility agent used for?
symptomatic relief of diarrhoea
what are the most commonly used antimotility agents?
codeine, phosphate, loperamide, diphenoxylate and kaolin/opiate preparations
when are antimotility agents not recommended?
in children with acute diarrhoea as there is a risk of precipitating respiratory depression or paralytic ileus
what is another use/ therapy for an antimotility agent?
-adjunctive therapy to antibiotics in travlers diarrhoea
is severe diarrhoea and dysentery- antimotility agent in conjunction with antimicrobial therapy
what is loperamide and what does it do?
it is an opioid receptor agonist and acts on the mu-opioid receptors in the myenteric plexus of the large intestine
what effects does medication like loperamide have by binding to mu opioid receptors in gut?
- reduces peristalsis
- increases transit time
- enchances water and electrolyte reabsorption
- reduces gut secretions
- has an effect within 1 hour after oral administration
- relatively free of CNS s/e but can cause cns depression in overdose
what does diphenoxylate do?
it is a mu opiate receptor agonists
it is used combination with atropine in atopine in adults and children under 13 years
what is the MOA of diphenoxylate?
rapidly metabolised to difenoxin
acts primarily on the intestine slowing down contraction
crosses the BBB
induces euphoria-can be abused
what can bulking agents be used to treat? give an example?
they are used to treat acute/diarrhoea
they can help to control faecal consistancy in IBS where diarrhoea is predominant or for older people with an ileostomy or colostomy
give an examples of bulking agents?
wheat bran, ispaghula husk, methylcellulose and sterculia
what is the advice and recommendations that you would give a patient on diarrhoea?
nb-some antidiarrhoea drugs can reduce the absorption of some drugs- antidiabetics/ coagulants/ malarials/ oral contraceptives
- drink lots of clear fluids
- avoid drinks high in sugar
- avoid milk and milky drinks
