1: Acute Limb Ischaemia

Question 1

define acute limb ischaemia

Answer 1

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

Question 2

what are the causes of acute limb ischaemia (3)

Answer 2

1. embolisation: thrombus from proximal source travels distally to occlude artery
   - original thrombus source may be from AF, post-MI, AAA, prosthetic heart valves
2. thrombosis in situ: atheroma plaque in artery ruptures and thrombus forms on plaque’s cap
3. trauma: compartment syndrome

Question 3

what are the clinical features of acute limb ischaemia

Answer 3

6 Ps
* Pain
* Pallor
* Pulselessness
* Paresthesia
* Perishingly cold
* Paralysis

Question 4

what is a sensitive sign of embolic occlusion

Answer 4

normal pulsatile contralateral limb

Question 5

what are the clinical categories of acute limb ischaemia

Answer 5

Rutherford classification

Question 6

what are ddx for acute limb ischaemia

Answer 6

• CLTI
• acute DVT
• spinal cord/peripheral nerve compression

Question 7

what are appropriate investigations for acute limb ischaemia

Answer 7

• routine bloods: serum lactate (level of ischaemia), thrombophilia screen (<50 w no known risk factors), G&S
• ECG

suspected cases initially investigated w bedside Doppler USS of both limbs + potential CT angiography

Question 8

what investigation can be performed if the limb is considered to be salvageable

Answer 8

CT arteriogram - provides more info regarding anatomical location of occlusion
- also helps decide the operative approache.g. femoral vs popliteal incision

Question 9

why is acute limb ischaemia a surgical emergency

Answer 9

complete arterial occlusion will lead to irreversible tissue damage within 6 hours

Question 10

what is the initial management of acute limb ischaemia

Answer 10

• start pt on high flow oxygen and ensure adequate IV access
• therpaeutic dose heparin or IV hep infusion initated asap

Question 11

when can conservative management be considered in patients with acute limb ischaemia

Answer 11

Rutherford 1 and 2a
- prolonged course of heparin

Question 12

what will patients who are started on heparin require

Answer 12

regular assessment to determine effectiveness through monitoring APPT ratio blood tests and clinical review

Question 13

when is surgical intervention considered in patients with acute limb ischaemia

Answer 13

Rutherford 2b

Question 14

what is the surgical intervention for acute limb ischaemia due to embolic causes

Answer 14

• embolectomy via Fogarty catheter
• local intra-arterial thrombolysis
• bypass surgery

Question 15

what is the surgical intervention for acute limb ischaemia due to thrombotic disease

Answer 15

• local intra-arterial thrombolysis
• angioplasty likely combined with thrombolysis
• bypass surgery

Question 16

how does irreversible limb ischaemia present

Answer 16

mottled non-blanching appearance with hard woody muscles

Question 17

how is irreversible limb ischaemia managed

Answer 17

urgent amputation or palliative approach

Question 18

why do most post-op cases of limb ischaemia require a high level of care

Answer 18

ischaemia reperfusion syndrome

Question 19

what is the long term management of acute limb ischaemia

Answer 19

• reduction of CVS mortality risk by promoting exercise, smoking cessation and weight loss
• most cases started on anti-platelet e.g. low dose aspirin/clopidogrel or anticoag e.g. warfarin or DOAC
• treat any underlying predisposing conditions e.g. uncontrolled AF
• if amputation, will require occupational therapy and physio

Question 20

what is an important complication of acute limb ischaemia

Answer 20

reperfusion injury where the sudden increase in cap permeability can lead to:
- compartment syndrome
- release of substances from damaged muscle cells e.g. K+, H+, myoglobin (AKI)

Question 21

for patients with critical limb ischaemia, when is Endovascular surgery used vs Open surgery

Answer 21

• high-risk patients with short segment stenosis (<10cm) are more suited to endovascular revascularization
• invasive surgery and so would be reserved for more diffuse disease, or with stenosis >10cm

Question 22

what are the different types of gangrene

Answer 22

• dry: blood flow to an area is blocked
• wet: combo of injury and bac infection
• gas: infection develops deep inside the body and bacteria responsible start releasing gas