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3: Surgery Y3 - Vascular [20] > [8] Acute Limb Ischaemia > Flashcards

[8] Acute Limb Ischaemia Flashcards

1
Q

What is acute limb ischaemia defined as?

A

A sudden decrease in limb perfusion that threatens the viability of the limb

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2
Q

What can complete or partial occlusion of the arterial supply to a limb lead to?

A

Rapid ischaemia and poor functional outcomes within hours

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3
Q

What can the causes of acute limb ischaemia be classified into?

A

Thrombosis in situ
Embolisation
Trauma

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4
Q

What % of cases of acute limb ischaemia are caused by thrombus in situ?

A

60%

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5
Q

How does a thrombosis in situ form?

A

An atheromatous plaque in the artery ruptures and a thrombus forms on the plaques cap

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6
Q

What kind of presentation can acute limb ischaemia caused by a thrombosis in situ?

A

Acute, or acute-on-chronic (on a background of peripheral arterial disease)

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7
Q

What % of cases of acute limb ischaemia are caused by embolisation?

A

30%

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8
Q

How does embolisation cause acute limb ischaemia?

A

A thrombus from a proximal source travels distally to occlude the artery

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9
Q

Where may the original thrombus result from in embolism causing acute limb ischaemia?

A

AF
Post-MI mural thrombus
Abdominal aortic aneurysm
Prosthetic heart valves

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10
Q

What % of cases of acute limb ischaemia are caused by trauma?

A

10%

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11
Q

Give an example of a traumatic cause of acute limb ischaemia

A

Compartment syndrome

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12
Q

What are the classical signs and symptoms of acute limb ischaemia?

A 
Pain
Pallor
Pulselessness
Paresthesia
Perishingly cold
Paralysis
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13
Q

What is acute limb ischaemia often characterised by?

A

The sudden onset of symptoms

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14
Q

What is a normal, pulsatile contralateral limb a sensitive sign of in acute limb ischaemia?

A

Embolic occlusion

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15
Q

What should be explored in the history of an acute limb ischaemia?

A

Causes of potential embolism

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16
Q

What are the potential causes of embolisation in acute limb ischaemia?

A 
Chronic limb ischaemia
Atrial fibrillation
Recent MI resulting in mural thrombus
Symptomatic AAA 
Peripheral aneurysms
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17
Q

What is the result of a later presentation to hospital with acute limb ischaemia?

A

The later a patient presents to hospital, the more likely that irreversible damage to the neuromuscular structures will have occurred, which will ultimately result in a paralysed limb

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18
Q

When does irreversible damage to neurovascular structures become more common in acute limb ischaemia?

A

> 6 hours post-symptom onset

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19
Q

What are the categories of acute limb ischaemia?

A

I - Viable
IIA - Marginally threatened
IIB - Immediately threatened
III - Irreversible

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20
Q

What is the prognosis of category I acute limb ischaemia?

A

No immediate threat

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21
Q

What degree of sensory loss is there in category I acute limb ischaemia?

A

None

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22
Q

What degree of motor deficit is there in category I acute limb ischaemia?

A

None

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23
Q

Is the arterial doppler audible in category I acute limb ischaemia?

A

Yes

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24
Q

Is the venous doppler audible in category I acute limb ischaemia?

A

Yes

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25
Q

What is the prognosis in category II acute limb ischaemia?

A

Salvageable, if promptly treated

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26
Q

What degree of sensory loss is there in category II acute limb ischaemia?

A

Minimal (toes) or none

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27
Q

What degree of motor loss is there in category II acute limb ischaemia?

A

None

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28
Q

Is the arterial doppler audible in category II acute limb ischaemia?

A

No

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29
Q

Is the venous doppler audible in category II acute limb ischaemia?

A

Yes

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30
Q

What is the prognosis of category III acute limb ischaemia?

A

Salvageable if immediately revascularised

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31
Q

What degree of sensory loss is there in category III acute limb ischaemia?

A

More than toes

Rest pain

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32
Q

What degree of motor deficit is there in category IIb acute limb ischaemia?

A

Mild/moderate

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33
Q

Is the arterial doppler audible in category III acute limb ischaemia?

A

No

34
Q

Is the venous doppler audible in category III acute limb ischaemia?

A

Yes

35
Q

What is the prognosis of category III acute limb ischaemia?

A

Major tissue loss with permanent nerve damage inevitable

36
Q

What degree of sensory loss is there in category III acute limb ischaemia?

A

Profound

37
Q

What degree of motor loss is there in category III acute limb ischaemia?

A

Profound, paralysis

38
Q

Is the arterial doppler audible in category IV acute limb ischaemia?

A

No

39
Q

Is the venous doppler audible in category IV acute limb ischaemia?

A

No

40
Q

What are the differential diagnoses of acute limb ischaemia?

A

Critical chronic limb ischaemia
Acute DVT
Spinal cord or peripheral nerve compresison

41
Q

What forms of DVT can present like acute limb ischaemia?

A

Phlegmasia cerulea dolens and Phlegmasia alba dolens

42
Q

What investigations into acute limb ischaemia should be done?

A

Routine bloods
ECG
Doppler ultrasound scan
CT angiography

43
Q

What should routine bloods include in acute limb ischaemia?

A

Serum lactate
Thrombophilia screen
Group and save

44
Q

Why is serum lactate important in acute limb ischaemia?

A

Assess the level of ischaemia

45
Q

When should a thrombophilia screen be done in acute limb ischaemia?

A

If <50 years old without known risk factors

46
Q

What investigation can be done if the limb is considered to be salvageable?

A

CT arteriogram

47
Q

Why is a CT arteriogram done when the limb is considered to be salvageable in acute limb ischaemia?

A

It can provide more information regarding the anatomical location of the occlusion, and can help decide the operative approach

48
Q

How long will it take for acute limb ischaemia to cause irreversible tissue damage?

A

6 hours

49
Q

What is the result of acute limb ischaemia causing irreversible tissue damage within 6 hours?

A

It is a surgical emergency, and early senior surgical support is vital

50
Q

How should a patient with acute limb ischaemia be managed initially?

A

Start patient on high-flow oxygen and ensure adequate IV access
A therapeutic dose of heparin or preferably a bolus dose then heparin infusion should be initiated as soon as practical

51
Q

When can conservative management be considered in acute limb ischaemia?

A

In category I and IIa cases

52
Q

What is the most effective non-operative management of acute limb ischaemia?

A

Prolonged course of heparin

53
Q

What is required in any patient started on conservative management of acute limb ischaemia via heparin?

A

They will need regular assessment to determine its effectiveness through monitoring APPT and clinical review

54
Q

What may be warranted in a patient recieving conservative management for acute limb ischaemia if no significant improvement is seen?

A

Surgical interventions

55
Q

When is surgical intervention mandatory for acute limb ischaemia?

A

Category 2b cases and above

56
Q

What are the options for surgical management of acute limb ischaemia when the cause is embolic?

A

Embolectomy
Local intra-arterial thrombolysis
Bypass surgery

57
Q

How is an embolectomy performed in acute limb ischaemia?

A

Via a Fogarty catheter

58
Q

What is the problem with the use of intra-arterial thrombolysis in acute limb ischaemia?

A

It is often difficult to conduct within 6 hours

59
Q

What is intra-arterial thrombolysis often used for as a result of it being difficult to conduct within 6 hours?

A

Category 2a cases

60
Q

When is bypass surgery used to treat embolic acute limb ischaemia?

A

When there is insufficient flow back

61
Q

What are the options for surgical management of acute limb ischaemia when caused by thrombotic disease?

A

Local intra-arterial thrombosis
Angioplasty
Bypass surgery

62
Q

What are the clinical signs of irreversible limb ischaemia?

A

Mottled, non-blanching appearance with hard woody muscles

63
Q

What management does irreversible limb ischaemia require?

A

Urgent amputation or palliative approach

64
Q

How are patients with acute limb ischaemia managed post-operatively?

A

Most require a high level of care, typically at the surgical high dependancey unit

65
Q

Why do acute limb ischaemia patients need to be managed with a high level of care after acute limb ischaemia?

A

Due to the ischaemia reperfusion syndrome

66
Q

What is involved in the long term management of acute limb ischaemia?

A

Reduction of the cardiovascular mortality risk
Anti-platelet therapy
Treatment of underlying predisposing conditions, e.g. uncontrolled AF
Occupational therapy and physiotherapy

67
Q

How is the cardiovascular mortality risk reduced following acute limb ischaemia?

A

Promotion of regular exercise
Smoking cessation
Weight loss

68
Q

What anti-platelet therapy is given after acute limb ischaemia?

A

Low-dose aspirin or clopidogrel

69
Q

What can be given as an alternative to anti-platelet therapy in acute limb ischaemia?

A

Anticoagulation with warfarin or a DOAC

70
Q

When will occupational therapy and physiotherapy be required in the long-term management of acute limb ischaemia?

A

In cases resulting in amputation

71
Q

How is rehabilitation conducted after amputation due to acute limb ischaemia?

A

A long term rehabilitation plan is discussed, with transfer to an intermediate rehabilitation centre

72
Q

What is the mortality rate of acute limb ischaemia?

A

20%

73
Q

What is the 30-day mortality rate following the surgical treatment of acute limb ischaemia?

A

15%

74
Q

What is an important complication of acute limb ischaemia?

A

Reperfusion injury

75
Q

What happens in reperfusion injury?

A

There is a sudden increase in capillary permeability

76
Q

What can a sudden increase in capillary permeability result in?

A

Compartment syndrome

Release of substances from damaged muscle cells, such as potassium ions, hydrogen ions, and myoglobin

77
Q

What can potassium ions released from damaged muscle cells lead to?

A

Hyperkalaemia

78
Q

What can hydrogen ions released from damaged muscle cells lead to?

A

Acidosis

79
Q

What can myoglobin released from damaged muscle cells lead to?

A

Significant AKI

80
Q

What does electrolyte imbalance due to reperfusion injury require?

A

Close monitoring and potentially haemofiltration

3: Surgery Y3 - Vascular [20] (10 decks)

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