Mesenteric ischaemia

Question 1

What are the clinical sequelae of mesenteric ischaemia dependent upon?

Answer 1

• number of vessels affected
• adequacy of collateral circulation
• duration of the insult

Question 2

Incidence of acute mesenteric ischaemia?

Answer 2

12.9/100 000

Question 3

What are the four principle causes of acute mesenteric ischaemia

Answer 3

• arterial embolism
• arterial thrombosis (coeliac axis/ SMA)
• venous thrombosis
• non- occlusive mesenteric ischaemia

Rare causes: aortic dissection, aneurysmal disease and vasculitides

Question 4

Which three main arteries supply the bowel

Answer 4

• coeliac axis: foregut
• superior mesenteric artery: midgut
• inferior mesenteric artery: hindgut

Question 5

At what pressure does the gut become ischaemic? What changes occur once the gut becomes ischaemic

Answer 5

• 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

Question 6

Describe the abdominal pain associated with acute mesenteric ischaemia?

Answer 6

• pain disproportionate to clinical abdominal findings
• sudden onset pain
• located centrally or in the epigastrium
• pain initially collicky –> constant

Question 7

What are symptoms of acute mesenteric ischaemia

Answer 7

• severe abdominal pain
• nausea and vomiting
• diarrhea which may contain blood (late sign)

Question 8

Findings on examination in acute mesenteric ischaemia

Answer 8

• 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

Question 9

What lab investigations should be done for acute mesenteric ischaemia? What do they usually show

Answer 9

• WCC, CRP and serum amylase may be raised but are non specific
• metabolic acidosis with high serum lactate

Question 10

Plain abdominal X-ray and CTA should be done in acute mesenteric ischaemia, what can a CTA show

Answer 10

• 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

Question 11

General management of AMI

Answer 11

• 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

Question 12

Explorative laparotomy is part of surgical management, what is one looking for?

Answer 12

• is there ischaemic bowel
• how much bowel is salvageable
• is revascularisation an option

Question 13

What is the minimum amount of small bowel required to maintain life?

Answer 13

50- 70 cm

Question 14

If bowel does appear salvageable on explorative laparotomy, what are treatment options?

Answer 14

• SMA embolectomy if embolic cause

- SMA bypass if thrombotic cause

Question 15

Endovascular management options for AMI?

Answer 15

• aspiration thrombectomy
• thrombolysis
• angioplasty and stenting

Question 16

Mean thirty day mortality for AMI

Answer 16

68% (32 - 81%)

Question 17

Factors associated with poor outcome in AMI?

Answer 17

Age
Extensive bowel necrosis
Peritonitis and bowel perforation
Co Morbities

Question 18

Common underlying causes associated with a risk for mesenteric vein thrombosis

Answer 18

• thrombophilia
• portal hypertension
• intra abdominal malignancies
• pancreatitis
• pregnancy

Question 19

What is the mainstay of diagnosis of mesenteric vein thrombosis

Answer 19

CT

Question 20

Treatment of mesenteric vein thrombosis

Answer 20

Systemic anti coagulation

Question 21

Which patients does non occlusive mesenteric ischaemia (NOMI) develop?

Answer 21

• 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

Question 22

Management of NOMI

Answer 22

• optimize patient haemodynamics
• Eliminate inotrope therapy
• correct systemic factors contributing to shock
• intra mesenteric infusion of papaverine

Question 23

Aetiology of chronic mesenteric ischaemia

Answer 23

• due to artherosclerosis and affects origins of the mesenteric vessels

Question 24

Clinical presentation of chronic mesenteric ischaemia

Answer 24

• mesenteric angina: peri umbilical pain occurring 30 minutes after a meal
• weight loss due to fear of food
• nausea and vomiting
• abdominal bruit

Question 25

What other disorders should be excluded before chronic mesenteric ischaemia is diagnosed?

Answer 25

Intra abdominal malignancy
Pancreatitis
Gastric ulcer

Question 26

Imaging investigations for chronic mesenteric ischaemia

Answer 26

• duplex ultrasound
• CTA/ MRA
• digital subtraction angiogram

Question 27

Endovascular management of chronic mesenteric ischaemia

Answer 27

• balloon angioplasty and stenting

Question 28

Open surgery options for chronic mesenteric ischaemia?

Answer 28

• re- implantation technique
• endarterectomy
• bypass from the infra renal or supra renal aorta or iliac artery