Lower GI Flashcards
What causes food to move from SI to caecum, colon and then into rectum?
Peristalsis
What do bacteria in large intestine produce
Vit. K and biotin (vit B7)
What is constipation
difficulty in opening bowel
going less than 3 times a weeks
straining more than 25% shits
Hard or pellet stools
What dietary factors can cause constipation
Low fibre
high fats
Alcohol
Caffeine
Low fluid intake
Name a bulking agent
Ispaghula husk
methylcellulose
Name a stimulant laxative
Bisacodyl
Senna
Dantron
Sodium picosulphate
Name a faecal softeners
Docusate
Glycerol
Arachis oil (enema)
Name a Osmotic Laxatives
Lactulose
Macrogols
Magnesium hydroxide and sulphate
Phosphate
Sodium citrate
What should you give a patient who has hard stools with faecal loading/ impaction?
High dose oral macrogol or stimulant
if not work- glycerol and/ or Bisacodyl supps
What should you give a patient who has soft stools with faecal loading/ impaction?
stimulant
then docusate or sodium citrate enema
What should you give a patient who has acute constipation?
lifestyle advice
bulk forming
(and/ or) osmotic: macrogol
stimulant
What can you give opioid induced constipation?
Osmotic and stimulant
Naloxegol (PAMORA drug)
AVOID BULK FORMING
What are lifestyle advice points for constipation?
30g a day fibre
good fluids
wholemeal bread
increase exercise
What can you give a pregnant woman who has constipation?
Bulk forming lax.
Can add/ switch to osmotic lax
SENNA NOT OTC FOR PREGNANCY
glycerol supp.
What can you give a child who has constipation
Macrogols and interventions
Can use stimulant lax.
Add lactulose if macrogol not tolerated
Name some osmotic laxatives
Macrogol
lactulose
Mg Hydroxide
Docusate (and a stim)
What is prucalopride
selective serotonin 5HT4 receptor agonist for constipation
What is linaclotide
drug used for constipation with IBS
How do Bulk-forming lax work?
Polysaccharides increase osmolality in gut when broken down therefore retention of water
Causes a bulkier stool
This distends colon
Promotes peristalsis
How do osmotic laxatives work?
Osmotic agents increase water retention as poorly absorbed
Absorbed into stool making softer
How do stimulant laxatives work?
Stimulates local reflexes of myenteric nerve plexus of guy
Irritate nerve endings in intestine
Motor effect-> increase propulsion/ motility
What does senna do? How does it work?
anthraquinone laxative
Combines with sugars- forms glycosides
Bond hydrolysed by colonic bacteria to release an irritant- sennosides A and B
Absorbed and has action on myenteric nerve plexus
Assumption that incr. PGE
Also decreases colonic water absorption
How do stool softeners work?
Surface wetting agents/ surfactants
Decrease surface tension allowing water to penetrate
Soften stool
Has some stim action
Arachis oil creates barrier between stool and intestine wall
How does a PAMORA work?
Competitive antagonist at intestinal mu-opioid receptors
Prevents opioid activation of intestinal mu-opioid receptors
Targets opioid induced side effects
How does prucalopride work?
5HT4 receptor agonist
activation increases ACh increases parasympathetic drive (rest and digest)
Increases peristalsis
What is acute diarrhoea?
more than 3 loose stools a day for no more than 14 days
What causes diarrhoea
change in balance of absorption and secretion of water due to osmotic force
or
enterocytes secreting fluid causes activation of ion transporters- can cause cytokine secretion to produce prostaglandins which stim. secretion
explain the differences between invasive and non-invasive bacteria causing diarrhoea
invasive- attacks mucosal cells
may contain blood and pus
fever
non-invasive-
Bacteria produce enterotoxins that disrupt secretion
watery
How do you diagnose diarrhoea
Accompanying symptoms
Rapid set
no stool formation
Faecal studies
Serum albumin
intestinal biopsy
What drugs may cause diarrhoea
Antibiotics
laxatives
metformin
antacids
digoxin
ferrous sulphate
NSAIDs
Beta blockers
cholestyramine (for high lipids-bile salts)
What is the treatment for acute diarrhoea
Loperamide- PRESCRIBED = 4mg, 2mg after each loose stool- 5 days max. Max 16mg
- GSL/OTC = 48 hrs max. Max 12g a day
Bland foods- soup, bread, pasta, rice
What is oral rehydration therapy
Dioralytes
Corrects dehydration
What can you give someone who is breastfeeding or pregnant for diarrhoea?
ORT and fluids
Loperamide for breastfeeding AVOID IN PREG.
How does loperamide work?
Synthetic opioid analogue- doesn’t pass BBB
Binds to mu-receptors in gut wall
Inhibits ACh and prostaglandin release therefore decreasing parasympathetic activity
What medicines should be stopped during vomiting, diarrhoea, fever, sweats etc: (sick day)
STOP
ACE inhibitors (prils)
ARBs (sartans)
NSAIDs
Diuretics
Metformin
C. Diff infection risk factors
broad spec. antibiotic use
Stay in hospital
over 65
Treatment for c. diff
Vancomycin 125-500mg every 6hrs for 10 days
Symptoms of IBS
Abdominal cramps
Diarrhoea/ constipation etc
Flatulence
acid indigestion
Eating may worsen symptoms
How do you diagnose IBS
abdominal pain for 6 months
Relief by defecation
Bloating
Mucus
Worsened by eating etc
What is IBS-C
more than 25% type 1/2
less than 25% type 6/7
What is IBS-D
more than 25% type 6/7
less than 25% type 1/2
What is IBS-M
more than 25% type 1/2 and more than 25% type 6/7
What is IBS-U
IBS but cant be categorised
What is an antispasmodic? what’s it used for?
IBS
Smooth muscle relaxants
Mebevrine / peppermint / hyoscine butyl bromide (more antimuscarinic side effects)
What is used to treat IBS-c
laxatives
(not lactulose tho as can increase gas and worsen symptoms)
What is used to treat IBS-d
Loperamide but must be over 18 for GSL and diagnosed with IBS
2 weeks max
What is linaclotide used for
Moderate/severe IBS-C if had for over a year and other laxatives not work
How do antispasmodics work
Block voltage gated sodium channels
Prevents build up of calcium
Decreases smooth muscle cell contraction
How does linaclotide work
guanylate cyclase-c agonist
leads to increased production of cGMP
causing CTFR ion channel causing increased secretion of chloride and bicarbonate into intestine causing increased GI transit
GC-C-> cGMP -> CFTR action -> increase intestinal chloride and bicarb
Red flags for IBS
weight loss
rectal bleeding
loose stools for more than 6 weeks when over 60yrs old
What causes diverticulosis
muscular hypertrophy causing narrowing of lumen and forms small chamber with high pressure
What causes diverticulitis
Faecal material collects in diverticula and causes obstruction
bacterial overgrowth and vascular compromise
causes increase in luminal pressure resulting in inflammation
Management of diverticulosis
Weight loss, smoking cessation, high fibre, bulk-forming laxatives
what is diverticular disease
intermittent pain in LLQ
worsened by eating- relieved by shitting
tender on palpitation LLQ
What is the management for diverticular disease
high fibre
bran and bulk forming laxative
lifestyle advice
avoid NSAIDS and anti-motility drugs like codeine
What is the management for diverticulitis
co-amoxiclav or trimethoprim and metronidazole 5x a day
What is exocrine pancreatic insufficiency
Lack of pancreatic digestive enzymes being secreted into duodenum
Lack of amylase, lipase, protease
What can exocrine pancreatic insufficiency be cause by
pancreatitis
diabetes
coeliac disease
tumours
cystic fibrosis
Symptoms of exocrine pancreatic insufficiency
malnutrition
lack of growth in children
low zinc conc and selenium so lowered immune function and healing
muscle loss
diarrhoea
cramping/bloating
fatty stools- steatorrhea
treatments of exocrine pancreatic insufficiency
creon
pancrex v
Pancreatic enzyme replacement
