Mesenteric ischaemia Flashcards
What are the clinical sequelae of mesenteric ischaemia dependent upon?
- number of vessels affected
- adequacy of collateral circulation
- duration of the insult
Incidence of acute mesenteric ischaemia?
12.9/100 000
What are the four principle causes of acute mesenteric ischaemia
- arterial embolism
- arterial thrombosis (coeliac axis/ SMA)
- venous thrombosis
- non- occlusive mesenteric ischaemia
Rare causes: aortic dissection, aneurysmal disease and vasculitides
Which three main arteries supply the bowel
- coeliac axis: foregut
- superior mesenteric artery: midgut
- inferior mesenteric artery: hindgut
At what pressure does the gut become ischaemic? What changes occur once the gut becomes ischaemic
- gut becomes ischaemic at pressures less than 40 mmHg
- after 15 minutes: changes in villi
- 3 hours: mucosa sloughs off
- 6hours: Trans mural necrosis –> perforation, sepsis and death
Describe the abdominal pain associated with acute mesenteric ischaemia?
- pain disproportionate to clinical abdominal findings
- sudden onset pain
- located centrally or in the epigastrium
- pain initially collicky –> constant
What are symptoms of acute mesenteric ischaemia
- severe abdominal pain
- nausea and vomiting
- diarrhea which may contain blood (late sign)
Findings on examination in acute mesenteric ischaemia
- acutely ill patient with hypotension and tachycardia
- abdominal distension
- bowel sounds may be normal or absent
- peritonitis is a late sign suggesting bowel infarction or perforation
What lab investigations should be done for acute mesenteric ischaemia? What do they usually show
- WCC, CRP and serum amylase may be raised but are non specific
- metabolic acidosis with high serum lactate
Plain abdominal X-ray and CTA should be done in acute mesenteric ischaemia, what can a CTA show
- filling defect in coeliac axis or SMA
- pneumatosis intestinalis
- portal vein gas
- bowel wall thickening
- solid organ infarction
- CTA can also assess vascular anatomy and other pathology
General management of AMI
- aggressive fluid resus, correction or electrolyte imbalance, urinary catheter, broad spectrum antibiotics
- heparin IVI, bolus 5000 u followed by continuous infusion to maintain aPTT 2 x normal
Explorative laparotomy is part of surgical management, what is one looking for?
- is there ischaemic bowel
- how much bowel is salvageable
- is revascularisation an option
What is the minimum amount of small bowel required to maintain life?
50- 70 cm
If bowel does appear salvageable on explorative laparotomy, what are treatment options?
- SMA embolectomy if embolic cause
- SMA bypass if thrombotic cause
Endovascular management options for AMI?
- aspiration thrombectomy
- thrombolysis
- angioplasty and stenting
Mean thirty day mortality for AMI
68% (32 - 81%)
Factors associated with poor outcome in AMI?
Age
Extensive bowel necrosis
Peritonitis and bowel perforation
Co Morbities
Common underlying causes associated with a risk for mesenteric vein thrombosis
- thrombophilia
- portal hypertension
- intra abdominal malignancies
- pancreatitis
- pregnancy
What is the mainstay of diagnosis of mesenteric vein thrombosis
CT
Treatment of mesenteric vein thrombosis
Systemic anti coagulation
Which patients does non occlusive mesenteric ischaemia (NOMI) develop?
- develops in patients with severe systemic illness associated with shock and multi organ failure
- Typically in patients in ICU with cardiac dysfunction on inotrope support causing severe intestinal vasospasm
Management of NOMI
- optimize patient haemodynamics
- Eliminate inotrope therapy
- correct systemic factors contributing to shock
- intra mesenteric infusion of papaverine
Aetiology of chronic mesenteric ischaemia
- due to artherosclerosis and affects origins of the mesenteric vessels
Clinical presentation of chronic mesenteric ischaemia
- mesenteric angina: peri umbilical pain occurring 30 minutes after a meal
- weight loss due to fear of food
- nausea and vomiting
- abdominal bruit
