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ANKI GI > [5] Acute Mesenteric Ischaemia > Flashcards

[5] Acute Mesenteric Ischaemia Flashcards

1
Q

What is acute mesenteric ischaemia?

A

A sudden decrease in blood supply to the bowel, resulting in bowel ischaemia and if not promptly treated, rapid gangrene

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2
Q

What can the common causes of mesenteric ischaemia be classified into?

A
  • Thrombus-in-situ
  • Embolism
  • Non-occlusive cause
  • Venous occulsion and congestion
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3
Q

What is it called when acute mesenteric ischaemia is caused by a thrombus-in-situ?

A

Acute mesenteric arterial thrombosis (AMAT)

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4
Q

What is it called when acute mesenteric ischaemia is caused by an embolism?

A

Acute mesenteric arterial embolism (AMAE)

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5
Q

What is it called when acute mesenteric ischaemia is caused by a non-occlusive cause?

A

Non-occlusive mesenteric ischaemia (NOMI)

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6
Q

What is it called when acute mesenteric ischaemia is caused by venous occulsion and congestion?

A

Mesenteric venous thrombosis

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7
Q

What proportion of cases of acute mesenteric ischaemia are caused by acute mesenteric arterial thrombosis?

A

25%

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8
Q

What proportion of cases of acute mesenteric ishaemia are acute mesenteric arterial embolism?

A

50%

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9
Q

What proportion of cases of acute mesenteric ischaemia are non-occlusive mesenteric ischaemia?

A

20%

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10
Q

What proportion of cases of acute mesenteric ischaemia are caused by venous occlusion and congestion?

A

<10%

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11
Q

What is the underlying cause of acute mesenteric arterial thrombosis?

A

Atherosclerosis

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12
Q

What is the underlying cause of acute mesenteric arterial embolism?

A
  • Cardiac causes, e.g. arrhythmias, post-MI mural thrombus, or prosthetic heart valves
  • Abdominal/thoracic aneurysm
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13
Q

What is the underlying cause of non-occulusive mesenteric ischaemia?

A
  • Hypovolaemic shock
  • Cardiogenic shock
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14
Q

What are the underying causes of mesenteric venous thrombosis?

A
  • Coagulopathy
  • Malignancy
  • Inflammatory disorders
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15
Q

What are some rarer causes of acute mesenteric ischaemia?

A
  • Takayasu’s arteritis
  • Fibromnuscular dysplasia
  • Polyarteritis nodosa
  • Thoracic aorta dissections
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16
Q

What do the risk factors of acute mesenteric ischaemia depend on?

A

The underlying cause

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17
Q

What are the main reversible risk factors for acute mesenteric arterial embolism?

A
  • Smoking
  • Hyperlipidaemia
  • Hypertension
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18
Q

How does mesenteric ischaemia present?

A

Generalised abdominal pain, out of proportion to the clinical findings

May be associated nausea and vomiting

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19
Q

Describe the pain in acute mesenteric ischaemia?

A

Typically a diffuse and constant pain

The patient may find it difficult to localise the pain

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20
Q

What % of cases of acute mesenteric ischaemia have associated nausea and vomiting?

A

Around 75% of cases

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21
Q

What is found on examination in acute mesenteric ischaemia?

A

The abdomen is often unremarkable

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22
Q

What can late stage bowel ischaemia and necrosis present as?

A

Bowel perforation

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23
Q

What is it important to take note of when examining for suspected mesenteric ischaemia?

A

Any potential embolic sources, such as AF, heart murmurs, or signs of previous valvular replacement surgery

24
Q

What points in the history should be considered in suspected acute mesenteric ischaemia?

A
  • A history of AF or cardiovascular disease
  • Previous DVT or PE
  • Hypercoaguable states, e.g. active neoplasia or anti-phospholipid syndrome
25
Q

When should mesenteric ischaemia be considered as a differential?

A

In all cases of severe acute abdomen, especially where there is no other obvious cause

26
Q

What other causes of the acute abdomen may have similar presentations to acute mesenteric ischaemia?

A
  • Peptic ulcer disease
  • Bowel obstruction
  • Symptomatic AAA
27
Q

What investigations should be done in suspected acute mesenteric ischaemia?

A
  • Arterial blood gas
  • Routine blood tests
  • Imaging
28
Q

Why should an urgent ABG be performed in acute mesenteric ischaemia?

A

To assess the degree of acidosis and serum lactate, secondary to the severity of bowel infarction

29
Q

What blood tests should be performed in acute mesenteric ischaemia?

A
  • FBC
  • U&Es
  • Clotting
  • Amylase
  • LFTs
  • Group and save
30
Q

What conditions can cause an increase in amylase?

A
  • Pancreatitis
  • Mesenteric ischaemia
  • Ectopic pregnancy
  • Bowel perforation
  • Diabetic ketoacidosis
31
Q

Why may LFTs be affected in acute mesenteric ischaemia?

A

If the coeliac trunk is affected, ischaemia of the liver may cause derangement

32
Q

What does the definitive diagnosis of acute mesenteric ischaemia require?

A

A CT scan with IV contrast (as a triple phase scan, with thin slices taken in the arterial phase)

33
Q

How will arterial bowel ischaemia initially show on CT imaging?

A

As oedematous bowel

34
Q

What causes the oedematous bowel in acute mesenteric ischaemia?

A

Secondary to ischaemia and vasodilation

35
Q

What does the CT imaging progress too in acute mesenteric ischaemia?

A

A loss of bowel wall enhancement, and then to pneumatosis

36
Q

Why should oral contrast be avoided in cases of mesenteric ischaemia?

A

Due to difficulty in assessing for bowel wall enhancement

37
Q

What investigations are done if there is any suspicion of a bowel perforation?

A

An inital AXR and erect CXR, then CT abdomen with contrast if there is significant suspicion

38
Q

Is acute mesenteric ischaemia a surgical emergency?

A

Yes

39
Q

What does acute mesenteric ischaemia require for its management?

A

Urgent resuscitation with early senior involvement

40
Q

What jobs can a junior doctor do in the management of acute mesenteric ischaemia?

A
  • Give IV fluids
  • Insert catheter
  • Start fluid balance chart
41
Q

What should be given in confirmed cases of acute mesenteric ischaemia?

A

Broad-spectrum antibiotics

42
Q

Why should broad spectrum antibiotics be given in confirmed cases of acute mesenteric ischaemia?

A

Due to the risk of faecal contamination in case of perforation of the ischaemic (and potentially necrotic) bowel

43
Q

Why is early ITU input to optimise the patient necessary in acute mesenteric ischaemia?

A

Because the patient will have significant acidosis, and is at high risk of developing multi-organ failure.

Taking the patient to theatre for potential bowel resection without the support of ITU is likely to be futile

44
Q

What determines the surgical intervention performed in acute mesenteric ischaemia?

A
  • Location
  • Timing
  • Severity

Amongst other factors

45
Q

What are the surgical options in acute mesenteric ischaemia?

A
  • Excision of necrotic or non-viable bowel
  • Revascularisation of bowel
46
Q

When is excision of necrotic or non-viable bowel performed in acute mesenteric ischaemia?

A

It not suitable for, or unable to access, revascularisation

47
Q

How should the patient be managed post-operatively following an excision of necrotic or non-viable bowel?

A

They should be on the intensive care unit under sedation, planned for potential relook laparotomy in 24-48 hours

48
Q

What will the majority of patients end up with following the excision of necrotic or non-viable bowel in acute mesenteric ischaemia?

A

Either a covering loop or end stoma

49
Q

What condition is there a high chance of after the excision of necrotic or non-viable bowel in acute mesenteric ischaemia?

A

Short gut syndrome

50
Q

What does revascularisation of the bowel involve in acute mesenteric ischaemia?

A

Removal or any thrombus or embolism via radiological intervention

51
Q

What is the decision for revascularisation in acute mesenteric ischaemia made based on?

A
  • The state of the patient
  • The state of the bowel
  • The angiographic appearance of the mesenteric vessels
52
Q

How is revascularisation of the bowel preferabl done in acute mesenteric ischaemia?

A

Through angioplasty

53
Q

Why is it preferable to perform revascularisation of the bowel through angioplasty in acute mesenteric ischaemia?

A

Due to the risk of aortic contamination in open surgery

54
Q

Other than angioplasty, what procedure can be used to revascularise the bowel in acute mesenteric ischaemia?

A

Open embolectomy through the CT, SMA, IMA, or aorta

55
Q

What are the main risks of mesenteric ischaemia?

A

Bowel necrosis and perforation

56
Q

What is the mortality rate of acute meseteric ischaemia?

A

50-80%, even if the diagnosis is made and treatment is performed

ANKI GI (43 decks)

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