Gangrene Flashcards
What is gangrene?
Tissue necrosis, either wet, dry or gas gangrene
Due to poor vascular supply (Infection, vascular, trauma)
What is the difference between dry and wet gangrene?
Dry: necrosis in absence of infection (ischaemic gangrene- arterial/ venous obstruction)
Wet: necrosis + infection (infectious gangrene- inc. nec fasciitis + gas)
What is gas gangrene?
subset of necrotising myositis caused by spore-forming Clostridial species
Clostridia perfringens
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 apparent physical signs
Predisposing event (e.g. trauma, ulcer, surgery)
Give 2 signs of gangrene
Erythematous/ oedematous region around gangrenous tissue
Gangrenous tissue = BLACK due to Hb breakdown products
How does gas gangrene present?
Rapid onset severe pain (initially no skin changes)
Systemic Sx
Overlying oedema, discolouration + crepitus (due to gas formation by the infection)
Cellulitis progressing to dark purple with vesicle/bullae formation
4 signs of dry gangrene
Diminished pedal pulses + ankle-brachial index
Coldness + palor in area
No discharge
Numbness
Give 3 signs of wet gangrene
Boggy/ pus discharge
Strong odour caused by activity of anaerobes
Low-grade fever + chills
List 3 signs of necrotising fasciitis
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)
LDH: elevated with haemolytic anaemia (common in gas gangrene)
Glucose
CRP: elevated
Cultures
What other investigations may be performed in gangrene?
Wound Swab, Pus/Fluid Aspirate: MC+S
X-ray: underlying osteomyelitis/ gas produced in gas gangrene
CT/MRI: abscess formation, oedema or thickening of fascia
Doppler US: presence + severity of arterial/ venous obstruction
Give 3 categories of risk factors for developing ischaemic gangrene
Atherosclerosis: Diabetes, Peripheral vascular disease, Smoking
Thrombosis: vasculitis, IVDU, trauma, anti-phospholipid syndrome, malignancy
Vasospasm: Raynauds, Cocaine
In which 5 patient groups is there increased risk of developing infectious gangrene post-surgery
Diabetes IVDU Alcoholics PVD Immunosuppression
