Diarrhoea and constipation Flashcards
Day 5
Define diarrhoea
Three or more loose or liquid stools per day; or more frequently than is normal for the individual
Define constipation
Bowel movements that are infrequent, or hard to pass, often associated with being hard and dry.
What are the 3 different types of diarrhoea ?
Osmotic - non absorbable substances and excess water are drawn into bowel which increases weight and volume of stool. Caused by decreased transit time, excessive use of antacids, osmotic laxatives and lactose intolerance.
Secretory - increased secretion or decreased absorption in normal mucosa. Cholera, food poisoning.
Motility - decreased transit time means that fluid reabsorption in the bowel is decreased.
Caused by short bowel (post op), fistula formation, IBS or overuse of laxatives.
What are some common diarrhoeal infections ?
Bacterial - campylobacter, E coli, salmonella, shigella
Viral - norovirus, rotavirus (viral gastroenteritis)
What is the difference between large and small volume diarrhoea ?
Large - Volume increased
Watery, non-bloody
Periumbilical cramps
Bloating
Nausea and vomiting
Caused by toxin producing bacteria (eg: E. Coli)
Potential for hypokalaemia and metabolic acidosis
No tissue invasion or inflammation
Small - Volume not increased
Bloody stools
Lower abdominal pain
Urgent desire to defecate
No nausea and vomiting
Caused by bacterial invasion of intestinal cells (eg: salmonella)
What are the types of constipation ?
Normal transit - known as functional constipation; involves regular passing stools but evacuation is difficulty.
Associated with a sedentary lifestyle, low residue (low fibre) diet and low fluid intake
Slow transit - involves infrequent bowel movement, straining to pass stool and mild abdominal distention by impaired colon activity
Pelvic floor / outlet dysfunction - poor action of the pelvic floor muscles or anal sphincter leading to difficulty or inability to defaecate.
What are the classifications of obstructions ?
Small bowel - acute, partial extent
Large bowel - chronic, complete extent
What are the effect of obstructions on the intestinal wall ?
Simple: Obstruction of lumen does not affect blood supply
Strangulated: Obstruction of lumen causes decreased blood supply
Closed Loop: Obstruction occurs at the end of each segment of intestine
What is pseudo obstruction ?
(Ogilvie syndrome) dilation of colon due to adynamic bowel, in absence of mechanical obstruction. Thought to be due to interruption of autonomic nervous supply to colon resulting in absence of smooth muscle action in bowel wall. Untreated lead to high risk of toxic megacolon, bowel ischaemia, perforation.
What are the causes of pseudo obstruction ?
Electrolyte imbalanceorendocrine disorders
Including hypercalcaemia, hypothyroidism, or hypomagnesaemia
Medication
Including opioids, calcium channel blockers, or anti-depressants
Recent surgery,severe illness, ortrauma
Includes cardiac ischaemia
Neurological disease
Includes Parkinson’s disease, Multiple Sclerosis, andHirschsprung’s disease
What can obstruction can cause ?
Gas and fluid to gather above the obstruction resulting in intestinal distention. Water and electrolytes unable to be absorbed in the intestine so fluid and electrolytes increased within lumen. Vomiting will result in loss of fluid and electrolytes.
Extracellular fluid and plasma volume decreases resulting in tachycardia, hypotension, dehydration and electrolyte imbalance
Loss of hydrogen ions from vomiting and inability to absorb electrolytes results in metabolic alkalosis and eventually metabolic acidosis as bicarbonate won’t be absorbed. This may result in hypokalaemia. Poor absorption of carbohydrates and increasing amount of lactate from anaerobic respiration may cause ketosis
What is bowel perforation ?
Bowel perforation is a hole in the wall of the colon..
A perforation may be a puncture, cut, or tear. The opening allows air and colon material (chyme/faeces) material to leak into the abdominal cavity.
This will cause the condition peritonitis – an infection of the peritoneum (the protective) membrane over the abdominal organs
A severe or prolonged infection may result in Sepsis.
What is aversion illness ?
Foods eaten before sickness cause a psychological association with nausea, leading to food aversion. Example of classical conditioning, neutral stimulus (food) paired with unconditioned stimulus (illness) leads to unconditioned response (feel sick)
