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Year 3 > Gangrene (CV) > Flashcards

Gangrene (CV) Flashcards

1
Q

Define gangrene.

A

Complication of necrosis characterised by decay of body tissues.

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2
Q

What are the two major types of gangrene? (2)

A
  • infectious gangrene (wet):
    • necrotising fasciitis
    • gas gangrene - Clostridium perfringes
  • ischaemic gangrene (dry) - arterial or venous obstruction (PAD)
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3
Q

What is ischaemic gangrene (dry) caused by?

A

Peripheral artery disease (critical limb ischaemia) due to atherosclerosis (arterial obstruction) or venous obstruction

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4
Q

Compare peripheral artery disease (PAD) with Buerger’s disease (thromboangiitis obliterans). (2)

A
  • PAD - leg pain with strenuous exercise, but not commonly associated with Raynaud’s phenomenon
  • Buerger’s is a small and medium vessel vasculitis strongly associated with smoking and causes Raynaud’s phenomenon
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5
Q

What do we see on angiogram for Buerger’s disease (gangrene)?

A

Corkscrew-shaped collateral blood vessels

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6
Q

What are the types of infective gangrene? (2)

A
  • necrotising fasciitis
  • gas gangrene
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7
Q

Describe dry (ischaemic) gangrene.

A

Necrosis in absence of infection with atherosclerosis, thrombosis or vasospasm

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8
Q

Describe wet gangrene.

A

Tissue death and infection

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9
Q

Describe gas gangrene.

A

Susbet of necrotising myositis caused by spore-forming Clostridial species

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10
Q

Describe progressive bacterial (Meleney’s) synergistic gangrene.

A

Synergistic interaction between Staphylococcus aureus and microaerophilic streptococci (ileostomy/colostomy)

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11
Q

What is necrotising fasciitis (type of infective gangrene)

A

Life-threatening infection of deep fascia causing necrosis of subcutaneous tissue

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12
Q

What is Fournier’s gangrene?

A

Necrotising fasciitis of the scrotum/vulva

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13
Q

What might gangrene result from?

A

Ischaemia, infection or trauma (or a combination of these processes)

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14
Q

What is the most common cause of gangrene?

A

Critically insufficient blood supply - often associated with diabetes and long-term smoking

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15
Q

What are the general clinical features of gangrene? (4)

A
  • pain
  • oedema/swelling
  • skin discolouration (e.g. painful black tissue)
  • feeling of heaviness in affected area
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16
Q

What are some clinical features specific to wet gangrene?

A
  • sudden onset of pain
  • low grade fever and chills
  • poorly demarcated necrotic area
17
Q

What are some clinical features specific to ischaemic (dry) gangrene? (3)

A
  • diminished pedal pulses and ABPI
  • well demarcated necrotic area
  • Hx of chronic claudication (pain in arms/legs when moving)
18
Q

What are some clinical features specific to gas gangrene? (8)

A
  • darkened skin
  • crepitus - due to escaping gas
  • infective area gives off distinct and potent smell
  • may be able to visualise on radiograph
  • rapid onset myonecrosis
  • muscle swelling
  • sepsis
  • severe pain
19
Q

What might you find on examination in gangrene? (4 + 3)

A
  • painful area
  • gangrenous tissue - black to due Hb breakdown products
  • haemorrhagic blisters
  • signs of systemic inflammatory response + sepsis
  • wet gangrene - tissue boggy with pus and strong odour caused by anaerobe activity
  • gas gangrene - spreading infection, destruction of tissues causing overlying oedema, discolouration, crepitus
  • ischaemic gangrene - diminished pedal pulses and ABPI
20
Q

What are some risk factors for gangrene? (8)

A
  • diabetes mellitus
  • atherosclerosis (ischaemic gangrene)
  • smoking (ischaemic gangrene)
  • drug and alcohol use
  • renal disease
  • malignancy
  • trauma/abdominal surgery (infectious gangrene)
  • contaminated wounds (infectious gangrene)
21
Q

What are the first-line investigations for gangrene? (6)

A
  • FBC
  • comprehensive metabolic panel
  • serum LDH - elevated if haemolytic anaemia
  • coagulation panel - normal
  • blood cultures - positive for infective organism
  • serum CRP - elevated in necrotising fasciitis
22
Q

What might FBC show in gangrene? (3)

A

Leukocytosis, haemoconcentration or anaemia

23
Q

What might comprehensive metabolic panel show in gangrene? (4)

A
  • low sodium
  • metabolic acidosis
  • liver derangement
  • renal failure
24
Q

What investigation would you do if infectious gangrene is suspected?

A

Blood cultures

25
Q

How can you detect the presence and severity of arterial or venous obstruction in gangrene?

A

Doppler ultrasonography

26
Q

What might plain x-ray show in gas gangrene?

A

May demonstrate gas in the soft tissues and/or indicate underlying osteomyelitis

27
Q

How can you make a definitive diagnosis of gangrene? (2)

A
  • surgical exploration
  • skin biopsy
28
Q

What are some differential diagnoses for gangrene? (7)

A
  • Staphylococcal skin lesions (distinct pustules, blood cultures)
  • erysipelas (recurrent pharyngitis, prodrome of pruritus and burning)
  • cellulitis
  • insect bites
  • DVT
  • polymyositis
  • pyoderma gangrenosum
29
Q

What is the 1st-line treatment for necrotising fasciitis awaiting MC&S?

A
  • surgical debridement
  • intensive supportive care
  • empirical broad-spectrum Abx (vancomycin, tazobactam)
30
Q

What is the 1st-line treatment for polymicrobial necrotising fasciitis? (5)

A
  • intensive supportive care
  • surgical debridement
  • local irrigation with bacitracin-infused normal saline
  • broad-spectrum IV Abx
  • consider amputation
31
Q

What is the 1st-line treatment for monomicrobial necrotising fasciitis? (6)

A
  • intensive supportive care
  • surgical debridement
  • IV Abx
  • IVIg (Streptococcal toxic shock)
  • consider hyperbaric oxygen therapy
  • consider amputation
32
Q

What is the 1st-line treatment for gas gangrene? (4)

A
  • intensive supportive care
  • surgical debridement
  • IV Abx (benzylpenicillin sodium, clindamycin)
  • consider amputation
33
Q

What is the 1st-line treatment for ischaemic gangrene? (5)

A
  • IV heparin
  • surgical revascularisation
  • life expectancy <2y: percutaneous transluminal angioplasty
  • viable extremity or phlegmasia cerulea dolens: thrombolytic therapy
  • non-viable limb: amputation
34
Q

In summary, how do you manage wet gangrene (necrotising fasciitis & gas gangrene)? (2)

A
  • surgical debridement
  • broad-spectrum Abx
35
Q

In summary, how do you manage dry/ischaemic gangrene? (3)

A
  • IV heparin
  • surgical revascularisation
  • amputation if non-viable
36
Q

What are some complications of gangrene? (6)

A
  • sepsis
  • shock
  • acute renal failure
  • haemolysis
  • loss of limb
  • DIC
37
Q

What are two key factors for improving outcomes in gangrene (life and limb-threatening)?

A
  • early recognition
  • aggressive Abx and surgical management
38
Q

What is dry gangrene linked to?

A

Critical limb ischaemia & PAD

Year 3 (80 decks)

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