Gangrene

Question 1

Define gangrene

Answer 1

Death of tissue from poor vascular supply, a sign of critical ischaemia. A complication of necrosis characterised by decay of body tissues

Classified as:
Wet / infectious
Dry / ischaemic
Gas

Question 2

Aetiology of dry gangrene

Answer 2

Atherosclerosis
Diabetes microangiopathy
Thrombosis
Hypercoagulable states, APLS
IVDU
Vasculitis
Malignancy
Autoimmune diseases
Phlegmasia cerulea dolens

Question 3

Aetiology of wet gangrene

Answer 3

Tissue death and infection (associated with discharge) occurring together

Group A strep
Staphylococcus
Enterobacteriaceae
Anaerobes (clostridium, bacteroides)

Question 4

Aetiology of gas gangrene

Answer 4

Subset of necrotising myositis caused by spore-forming, gram +ve, anaerobic clostridial species.
Clostridium perfringens

Question 5

Symptoms and signs of gangrene

Answer 5

Severe pain
Muscle swelling oedema
Skin discoloration
Hypotension, tachycardia
Cold extremities

Question 6

Clinical features that distinguish the types of gangrene

Answer 6

Gas: crepitus

Ischaemic:
- well-demarcated necrotic area without signs of infection
- diminished pedal pulses and ABPI
- Auto-amputation

Infective:
- necrotic area is poorly demarcated from the surrounding tissue,
- Low-grade fever and chills (infectious)

Question 7

Investigations for gangrene

Answer 7

FBC: leucocytosis/haemochromatosis/anaemia
CRP/ESR: raised
U&Es
VBG
LDH
Clotting
Blood cultures
Glucose

Plain X-ray: ?gas
CT/MRI: ?abscess/oedema
Doppler US: ?vessel obstruction
Tissue biopsy: Confirm diagnosis and identify causative organism

Question 8

Management for gangrene

Answer 8

Wet
Awaiting culture / sensitivity results → surgical debridement + ITU + broad-spectrum ABx
Confirmed: ± amputation
- Type I → local irrigation
- Type II → IVIG (toxic shock)

Dry
IV heparin +/- surgical revascularisation +/- amputation +/- percutaneous transluminal angioplasty

Gas gangrene → ITU + surgical debridement +/- amputation + broad-spectrum IV ABx + Hyperbaric oxygen therapy

Question 9

Complications of gangrene

Answer 9

Sepsis
Shock
Acute renal failure
Haemolysis
Amputation
Disseminated intravascular coagulation

Question 10

Prognosis of gangrene

Answer 10

Potentially life- and limb-threatening condition
Better prognosis if early recognition and aggressive management Necrotising fasciitis properly treated with surgery + Abx → 10-40% mortality
Patients who develop shock and end-organ damage → 30-70% mortality
Recurrence of necrotising fasciitis is rare