Acute limb threat

Question 1

What are the 3 acute limb threats?

Answer 1

Acute limb ischaemia, acute on chronic limb ischaemia and diabetic foot sepsis.

Question 2

What is acute limb ischaemia?

Answer 2

Sudden loss of blood supply to limb due to occlusion of native artery or bypass graft.

Question 3

What are the causes of sudden occlusion?

Answer 3

Embolism, atheroembolism, arterial dissection, trauma, extrinsic compression e.g. tumours.

Question 4

What are the clinical features of acute limb ischaemia?

Answer 4

Pain, pallor, pulseless, perishingly cold, paraethesia (numbness, pins and needles), paralysis (non-salvable).

Question 5

How do you know if acute limb ischaemia is not actually acute on chronic limb ischaemia?

Answer 5

No prior history of claudication, if there is a known cause for embolism, if there is a full complement of contra-lateral pulses (suggests embolism).

Question 6

What is the pain like in acute limb ischaemia?

Answer 6

Severe, sudden onset, resistant to analgesia.

Question 7

What can indicate muscle necrosis (often irreversible)?

Answer 7

Calf/muscle tenderness with right woody compartment.

Question 8

Describe the changes in pallor that occur in acute limb ischaemia.

Answer 8

1. Limb white with empty veins.
2. Capillaries fill with stagnated deoxygenated blood giving mottle appearance (blanching mottling, salvageable if prompt revascularisation).
3. Arteries distal to occlusion fill with propagated thrombus with rupture of capillaries (non-blanching mottling - irreversible ischaemia).

Question 9

What is sensorimotor (paraesthesia and paralysis) deficit indicative of and is it salvageable?

Answer 9

Muscle and nerve ischaemia, yes if prompt revascularisation.

Question 10

Describe the development of acute limb ischaemia at 0-4 hours, 4-12 hours and >12 hours.

Answer 10

0-4: white foot, painful, sensorimotor deficit - salvageable.
4-12 hours: mottled, blanches on pressure - partly reversible.
>12 hours: fixed mottling, non-blanching, compartments tender/red, paralysis - non-salvageable.

Question 11

Why is it bad to revascularise someone who has fixed mottling and paralysis?

Answer 11

The toxins from the dead tissue could kill them.

Question 12

What blood tests would you order to manage acute limb ischaemia?

Answer 12

FBC, U/Es, CK, coag and maybe troponin.

Question 13

What would you look for in an ECG for suspected acute limb ischaemia?

Answer 13

MI, dysrhythmia.

Question 14

What would you look for in a CXR for suspected acute limb ischaemia?

Answer 14

Underlying malignancy.

Question 15

What are the benefits of anticoagulation in acute limb ischaemia?

Answer 15

Stops propagation of thrombus, may improve perfusion.

Question 16

When would you do and not do an angiogram in suspected acute limb ischaemia?

Answer 16

Don’t do: no prior history of claudication, cause for embolism known, full complement of contra-lateral pulses.
Do: if doubts as to history.

Question 17

What procedures would you do if the limb was salvageable?

Answer 17

Embolectomy (remove embolus), fasciotomies (remove fluid from fascia), thrombolysis.

Question 18

What would you do if the limb was not salvageable?

Answer 18

Amputation or palliation.

Question 19

When would you do an intra-operative angiogram during an embolectomy?

Answer 19

If concerns about inflow or run-off i.e. Fogarty embolectomy catheter not passing up/down artery.

Question 20

Describe an embolectomy.

Answer 20

Use balloon catheter, fix arteries and pull embolism back.

Question 21

What is the diabetic foot sepsis triad?

Answer 21

Diabetic neuropathy, peripheral vascular disease, infection.

Question 22

What does the diabetic foot sepsis triad lead to and what may it result in?

Answer 22

Tissue ulceration, necrosis and gangrene. Limb amputation.

Question 23

What may sepsis result from?

Answer 23

Simple puncture wound, infection from nail plate or inter-digital space, or from a neuro-ischaemia ulcer.

Question 24

Where do neuro-ischaemic ulcers occur?

Answer 24

On areas of increased pressure i.e. under metatarsal heads.

Question 25

Describe the pathogenesis of diabetic foot sepsis.

Answer 25

Infection tracks into soft tissues of rigid compartment, buildup of pus cannot escape, pressure builds leading to impairment of capillary blood flow, further ischaemia and tissue damage, can rapidly progress to sepsis and limb loss.

Question 26

What assumes first priority in the management of any diabetic foot problem and why?

Answer 26

The evaluation and treatment of infection as diabetic foot sepsis is a vascular surgical emergency.

Question 27

What are the systemic clinical findings of diabetic foot sepsis?

Answer 27

Pyrexia, tachycardia, tachypnoea, confused, Kussmauls breathing (deep, repetitive, gasping breathing).

Question 28

What are the local clinical findings of diabetic foot sepsis?

Answer 28

Swollen affected digit (sausage like), swollen forefoot (boggy feeling to swelling), tenderness, ulcer with pus extruding, erythema (may track up limb), patches of rapidly developing necrosis, crepitus in the soft tissues of foot (gas from gas forming organisms).

Question 29

When should you call the vascular surgeons and administer antibiotics in diabetic foot sepsis?

Answer 29

At the earliest opportunity.

Question 30

What sort of microbes may be infecting a diabetic foot?

Answer 30

Lots of different types: gram +ve cocci, gram -ve bacilli, anaerobes.

Question 31

What surgical procedures are used in diabetic foot sepsis?

Answer 31

Rapid surgical debridement of infected tissue, if performed at early stages the foot and limb may be salvaged. Remove all infected tissue and leave wound open to encourage drainage.

Question 32

If there is too much infection, what is done?

Answer 32

Cut the foot off and come back later to form a stump.

Question 33

How can you prevent diabetic foot problems?

Answer 33

Adequate education, foot assessment (diabetic foot clinic, podiatrist) and pressure offloading footwear.

Question 34

Describe in simple terms the process of diabetic foot sepsis.

Answer 34

Compartment pressure -> vascular compromise -> necrotic tissue -> limb loss.