Upper and lower GI bleeding Flashcards
what types of muscle is the oesophagus comprised of (3)
- striated, voluntary muscle in the upper 1/3
- smooth, involuntary muscle in the lower 1/3
- mixture of both in the middle third
at what vertebral level is the cervicle oesophagus at
C6
what are the 2 sphincters that are at either end of the oesphagus
- upper oesophageal sphincter
- lower oesophageal sphincter
what is the arterial and venous supply of the cervical oesphagus
inferior thyroid artery/vein
what is there arterial and venous supply of the thoracic oesophagus
arterial - oesophageal branches of the thoracic artery
venous - azygous system
what is there arterial and venous supply of the abdominal oesophagus
arterial - left gastric artery
venous - portal system
what ligament does the lesser curvature give rise to
hepatogastric ligament
what is the arterial supply of the fundusand upper body of the stomach
the short and posterior gastric branches of the splenic artery
what is the arterial supply of the pylorus of the stomach
the gastroduodenal artery (branch of the common hepatic)
what is the cardia of the stomach
the opening of the oesophagus into the stomach
what areas does the small bowel develop from (2)
- the distal foregut
- midgut
what are the 3 main structures of the small bowel
- distal duodenum
- jejenum
- ileum
what is the main artery that supplied the small bowel
superior mesenteric artery
what do pancreatic secretions and bile do in the duodenum
break down chyme into sugars, amino acids and fatty acids
what does the jejenum primarily absorb (2)
- water
- micronutrients
what does the terminal ileum absorb (2)
- vit B12
- bile acids
what is the ampulla of vater
the spot where the pancreatic and bile ducts release their secretions into the intestines
what is the etymology of jejenum
from the latin jejenus meaning ‘fasting’as it was often found empty
what is different about he proximal 40% of the jejenum
the lumen is wider and thicker than the rest with more prominent mucosal folds
what are the names of the mucosal folds in the jejenum
valvulae conniventes
is there a clear demarcation between thee ileum and jejenum
no
what does the ileum have more of compared to the jejenum (2)
- lymph nodes
- peyer’s patches
what are peyers patches
clusters of subepithelial, lymphoid follicles found in the intestine
what is the average length of the ileum
2m
what is the main venous drainage of the small bowel
portal vein
where doe the colon extend from and to
extends from the cecum to the anal canal
what is absorbed in the colon (2)
water and electrolytes
what are the 4 parts of the colon
- ascending
- transverse
- descending
- sigmoid
what artery supplies the hind gut
inferior mesenteric artery
which artery supply the ascending colon
ileocolic - branch of the sma
what arteries supply the transverse colon
the SMA (right and middle colic arteries) and IMA (left colic artery) - it is both mid and hind gut
what artery supplies the descending colon
left colic artery (branch of the IMA)
what does the superior mesenteric vein drain (4)
- small intestine
- cecum
- asending colon
- transverse colon
what does the inferior mesenteric vein drain (3)
- descending colon
- sigmoid
- rectum
which 3 veins join together to make the portal vein
SMV, IMV, splenic
what anatomical marker is sued to differentiate between an upper and lower GI bleed
the ligament of treitz - supports and anchors the duodenum, without it intestinal twisting can occur
causes of an upper GI bleed (6)
- peptic ulcer
- oesophagus varices
- oesophagitis
- mallory weiss tear
- AV malformation
- upper GI cancers
causes of a lower GI bleed (5)
- diverticulosis
- haemorrhoids
- colorectal cancer
- mesenteric ischaemia
- AV malformations
what is haematemesis
vomiting fresh or altered blood
what is haematochezia
bright red rectal bleeding
what is occult bleeding
blood in the feces that is not visibly apparent
where is the disease site if haematemesis is seen
proximal to the ligament of treitz (upper GI)
where is the disease site if
melaena is seen
upper GI - jejenal usually; can be ileal and right colon also
where is the disease site if
bright red rectal bleeding is seen
usually ileo-colonic; rarely - rapid upper tract bleeding
what pumps are responsible for gastric acid secretion
- Acid secretion occurs through gastric proton pumps located in parietal cells;
- These are hydrogen-potassium ATPase pumps (H+ into gastric lumen and K+ out), At rest, these pumps are located intracellularly;
what can stimulate parietal cells and what does this stimulation cause to happen
Simulation of parietal cells by a combination of Ach (vagus nerve) gastrin (antral G cells) and histamine (enterochromaffin like cells) translocate the proton pumps to the apical secretory canalicular (luminal) membrane;
what happens in the cephalic phase of a meal
During the cephalic phase of meal stimulated acid secretion; vagal activity stimulates ECL cells, G cells and parietal cells
what happens in the gastric phase of the meal
During the gastric phase, gastric distention of the stomach augments vagal output and short peptides, amino acids and calcium, as well as alkaline pH stimulate gastrin release by G cells. Gastrin release is inhibited by a gastric pH <3
what are the normal mucosal defense mechanisms against gastric acid (4)
- the secretion of bicarbonate mucus and phospholipid by gastroduodenal epithelial surface mucous cells;
- the epithelial barriers,
- mucosal blood flow
- epithelial cell renewal
Many of these defense mechanisms are prostaglandin dependent
what are the 2 most common causes of peptic ulcer disease
- H.pylori
- NSAIDs
less common causes of peptic ulcer disease
- hypersecretory states
- viral infection (CMV, HSV1)
- drugs - cocaine
- ischaemia
- radiation
- infiltrative disorders e.g. sarcoidosis
how does H.pylori survive in stomach acid (4)
- urease activity (convert urea to ammonia)
- motility
- microaerophilic properties
- proteases (digest protective mucus)
how does H.pylroi damage gastric mucosa
- production of ammonia
- proteases
- lipases
- mucinates
6 physiological changes with hypovolaemia
- tachycardia
- peripheral shut down
- hypotension
- postural drop may be evident (BP)
- confusion
- oliguria
nb. BP may be well preserved in young and fit
what is the Glasgow blatchford score
stratifies upper GI bleeding patients who are ‘low-risk’ and candidates for outpatient management
what is portal hypertensive bleeding
a spectrum of conditions encompassing oesophageal, gastric and ectopic varies, and portal hypertensive gastropathy
what value is portal venous pressure normally
5-10mmHg
how do oesophageal varices arise
the gradients between portal venous pressure and ICV pressure is >10mmHg (normally 3-7mmHg) due to a rise in portal venous pressure -> blood flowing through the hepatic portal system is redirected from the liver into areas with lower venous pressures -> collateral circulation develops in the lower esophagus, abdominal wall, stomach, and rectum -> The small blood vessels in these areas become distended, becoming more thin-walled, and appear as varicosities
variceal haemorrhage mgx (7)
- resusitation and supportive care;
- blood transfusion
- terlipressin or somatostatin analogue - give at presentation if suspected bleed
- prophylactic abx - intravenous ceftriaxone given immediately
- endoscopic variceal band ligation
- balloon tamponade (emergency holding measure) or Danis stent
- transjugular intrahepatic portosystemic shunt (TIPSS)
what does splanchnic circulation refer to
blood flow tot he abdominal GI organs, including stomach, liver, spleen, pancreas, small intestimes, large intestines - comprises of the coeliac artery, SMA and IMA
why must abx be given for variceal haemorrhages
bacteraemia and subsequent sepsis is very common
secondary prevention of variceal haemorrhages
- treat liver disease
- variceal obliteration
- drugs - BBs (carvediol)
- determine cause of portal hypertension
complications of balloon tamponade for variceal haemorrhages (2)
- aspiration
- mucosal necrosis
what is transjugular intrahepatic portosystemic shunt (TIPSS)
a mgx for variceal hamorrhages that shunts blood from the portal vein to the hepatic vein - definative treatment for bleeding gastric varices
transjugular intrahepatic portosystemic shunt complications (6)
- procedural/technical fault
- infection
- stent occlusion
- rebleeding
- portal systemic shunting
- encephalopathy
