Gangrene Flashcards
What is gangrene?
Tissue necrosis, either wet, dry or gas gangrene
Due to poor vascular supply
What is necrotising fasciitis?
Life-threatening infection of deep fascia causing necrosis of subcutaneous tissue.
What is the difference between dry and wet gangrene?
Dry: necrosis in absence of infection (ischaemic gangrene)
Wet gangrene: tissue death + infection (infectious gangrene)
What is gas gangrene?
subset of necrotising myositis caused by spore-forming Clostridial species
What may cause gangrene?
Tissue ischaemia + infarction (critical limb ischaemia)
Physical trauma
Thermal injury
Gas gangrene is caused by Clostridia perfringens
Describe the aetiology of necrotising fasciitis
Usually polymicrobial involving streptococci, staphylococci, bacterioides + coliforms
List 8 risk factors for gangrene and necrotising fasciitis
Diabetes Peripheral vascular disease Renal disease Leg ulcers Malignancy Immunosuppression Drug/alcohol abuse Steroid use
Describe the epidiemiology of gangrene and necrotising fasciitis
Gangrene: relatively COMMON
Necrotising fasciitis + gas gangrene: RARE
List 3 features of gangrene
Pain
Black discolouration of affected area
Often affects extremities/ areas subject to high pressure
List 3 features of necrotising fasciitis
Pain
Often seems SEVERE + out of proportion to the apparent physical signs
Predisposing event (e.g. trauma, ulcer, surgery)
Give 2 signs of gangrene
Painful area = erythematous region around gangrenous tissue
Gangrenous tissue = BLACK due to Hb breakdown products
How does gas gangrene present?
Rapid onset of myonecrosis, muscle swelling, gas production, sepsis, severe pain
Spreading infection + destruction of tissues causes overlying oedema, discolouration + crepitus (due to gas formation by the infection)
Give a sign of dry gangrene
Diminished pedal pulses + ankle-brachial index
Give 3 signs of wet gangrene
Tissue becomes boggy with associated pus
Strong odour caused by activity of anaerobes
Low-grade fever + chills
List 3 signs of necrotising fasciitis
Area of erythema + oedema
Haemorrhagic blisters may be present
Signs of SIRS + sepsis (high/low temperature, tachypnoea, hypotension)
What bloods are taken in gangrene?
FBC (leukocytosis + anaemia)
Met panel (may have met acidosis, liver derangement + renal fail)
U+Es
LDH: elevated with haemolytic anaemia (common in gas gangrene)
Glucose
CRP: elevated
Blood culture
What other investigations may be performed in gangrene?
Wound Swab, Pus/Fluid Aspirate: MC+S
X-ray: gas produced in gas gangrene or indicate underlying osteomyelitis
CT/MRI: abscess formation, oedema or thickening of fascia
Doppler US: presence + severity of arterial/ venous obstruction
Give 2 additional risk factors for developing ischaemic gangrene
Atherosclerosis
Smoking
Give 2 additional risk factors for developing infectious gangrene
Puncture/ surgical wounds
Trauma
