Ischaemia & the bowel Flashcards
What is ischaemia?
Inadequate blood supply to an organ or part of the body
The cells do not receive enough oxygen or glucose to keep them alive
What causes bowel ischaemia?
Thrombus or embolus
Aortic dissection
Trauma
Vasculitis
Radiotherapy
Strangulation eg. volvulus or hernia
Name the 2 types of bowel ischaemia?
Briefly what are the differences?
Mesenteric ischaemia: affects small bowel
Ischaemic colitis: affects large bowel
Which arteries commonly become occluded?
Splanchnic arteries:
- Superior mesenteric
- Coeliac arteries
- Renal arteries
Bifurcation of the aorta
What does the superior mesenteric artery supply?
From lower duodenum to 2/3 across transverse colon
What does the inferior mesenteric artery supply?
Distal 1/3 of transverse colon down to rectum
There are two types of mesenteric ischaemia. What are they?
Acute + chronic
What causes acute mesenteric ischaemia?
A thrombus or embolus usually
Other causes: trauma, infection, tumour
Clinical features of acute mesenteric ischaemia?
Acute, severe abdominal pain
Pain is diffuse
Rectal bleeding
Vomiting + diarrhoea
Shock
Why does acute mesenteric ischaemia lead to shock?
Because of the loss of blood you get hypovolaemia
Also, in severe cases bowel perforation can occur which leads to shock
What happens to the bowel when it is ischaemic?
It become starved of blood and therefore oxygen + glucose
Cells can’t respire, necrosis
Inflammation which escalates damage
Widespread necrosis leading to perforation of bowel wall
Investigations of acute mesenteric ischaemia?
From history: often patients appear far more unwell than the results of examination would
suggest
Bloods:
- raised lactic acid
- raised white cells
- metabolic acidosis
AXR:
- Gasless abdomen
Angiography using CT/MRI: use contrast dye to see blockages
What complications can occur from acute mesenteric ischaemia?
Perforation of bowel causing peritonitis leading to sepsis
Systemic inflammatory response syndrome (SIRS)
Which can lead to Multi-organ dysfunction syndrome (MODS)
What is SIRS?
Systemic inflammatory response syndrome
Body’s immune system goes into overdrive as a response to sepsis or similar
Causing damage to the body
What is MODS?
Multi-organ dysfunction syndrome
Dysfunction of two or more organs so that homeostasis can’t be maintained without intervention
Treatment of acute mesenteric ischaemia?
Resuscitate: fluids
Analgesia
Treat sepsis: antibiotics, heparin to prevent DIC
Surgical revascularisation: stent, embolectomy
Surgery to remove damaged/necrotic bowel
What is DIC?
Disseminated intravascular coagulation
What causes chronic mesenteric ischaemia?
Low blood flow due to atherosclerosis
Similar to angina
What are the clinical features of chronic mesenteric ischaemia?
Abdominal pain after eating
Unintentional weight loss
Vomiting
Anorexia: due to pain caused by eating
Rectal bleeding
Why does chronic mesenteric ischaemia cause weight loss?
Less blood supply to bowel
Less ability to absorb nutrients from food
Malabsorption leading to weight loss
Why do you need to be concerned by chronic mesenteric ischaemia?
Because acute mesenteric ischaemia is highly likely to occur
You want to prevent this
Investigation of chronic mesenteric ischaemia?
CT or MRI angiography: contrast dye shows up blockages in blood vessels
USS could help show abnormal blood flow
Treatment of chronic mesenteric ischaemia?
Surgical revascularisation: insert stent
Treat symptoms: analgesia
What is ischaemic colitis?
Ischaemia affecting the colon!
Inflammation occurs because of the damage caused by ischaemia
Which artery is mostly affected in ischaemic colitis?
Inferior mesenteric artery
Clinical features of ischaemic colitis?
Lower left sided abdominal pain
Bloody diarrhoea
Pyrexia
Shock
How severe is ischaemic colitis?
It’s very variable
Some are mildly affected and some develop sepsis and become fatally ill
Investigations of ischaemic colitis?
CT scan maybe
Colonoscopy: look for evidence of ischaemic damage
Biopsy: lots of white cells, damaged necrotic cells
Treatment of ischaemic colitis?
In mild to moderate cases supportive care is sufficient
- fluids
- antibiotics
In cases where peritonitis and sepsis have developed, resuscitation and resection of damaged bowel
What often occurs in patients who recover from ischaemic colitis?
Strictures develop in the bowel
