Gangrene and Necrotising Fasciitis Flashcards
What is the definition of gangrene and necrotising fasciitis?
Gangrene - tissue necrosis, either wet with superimposed infection, dry or gas gangrene
Necrotising Fasciitis - a life-threatening infection that spreads rapidly across fascial planes
What is the aetiology of gangrene and necrotising fasciitis?
Gangrene
- Tissue ischaemia and infarction
- Physical trauma
- Thermal injury
- Gas gangrene is caused by Clostridia perfringens
Necrotising Fasciitis
- Usually polymicrobial involving streptococci, staphylococci, bacterioides and coliforms
Risk Factors
- Diabetes
- Peripheral vascular disease
- Leg ulcers
- Malignancy
- Immunosuppression
- Steroid use
- Puncture/surgical wounds
What is the epidemiology of gangrene and necrotising fasciitis?
Gangrene - relatively COMMON
Necrotising fasciitis and gas gangrene - RARE
What are the presenting sumptoms of gangrene and necrotising fasciitis?
Gangrene
- Pain
- Discolouration of affected area
- Often affects extremities or areas subject to high pressure
Necrotising Fasciitis
- Pain = Often seems SEVERE and out of proportion to the apparent physical signs
- Predisposing event (e.g. trauma, ulcer, surgery)
What are the signs of gangrene and necrotising fasciitis?
Gangrene
- Painful area = erythematous region around gangrenous tissue
- Gangrenous tissue = BLACK because of haemoglobin break down products
- Wet Gangrene - tissue becomes boggy with associated pus and a strong odour caused by the activity of anaerobes
- Gas Gangrene - spreading infection and destruction of tissues causes overlying oedema, discolouration and crepitus (due to gas formation by the infection)
Necrotising Fasciitis
- Area of erythema and oedema
- Haemorrhagic blisters may be present
- Signs of systemic inflammatory response and sepsis (high/low temperature, tachypnoea, hypotension)
What are the appropriate investigations for gangrene and necrotising fasciitis?
Bloods - FBC, U&Es, glucose, CRP and blood culture
Wound Swab, Pus/Fluid Aspirate - MC&S
X-ray of affected area - may show gas produced in gas gangrene
