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Gangrene

Medicine > Infection

Background knowledge 🧠

Definition

  • Gangrene refers to the death of body tissue due to a lack of blood flow or a severe bacterial infection.
  • It can affect any part of the body but commonly occurs in the extremities.
  • Classified into dry, wet, and gas gangrene based on the underlying cause and characteristics.
  • Requires urgent medical attention to prevent further tissue death and complications.

Epidemiology

  • Incidence higher in populations with peripheral vascular disease, diabetes, or immunosuppression.
  • More common in older adults due to higher prevalence of comorbid conditions.
  • Occurs equally in both genders.
  • Higher rates in lower socioeconomic groups due to delayed healthcare access.
  • More prevalent in regions with poorsanitation and healthcare infrastructure.

Aetiology

  • Dry gangrene: caused by chronic ischemia, typically due to peripheral arterial disease.
  • Wet gangrene: results from an untreated infected wound leading to tissue necrosis.
  • Gas gangrene: caused by Clostridium bacteria producing gas within tissues, often following trauma.
  • Underlying conditions: diabetes, severe burns, frostbite, arterial occlusion, trauma.

Pathophysiology

  •  Interruption of blood supply leading to tissue ischemia, necrosis, and subsequent infection.

Types

  • Dry gangrene: characterised by dry, shriveled skin ranging in colour from brown to purplish-blue to black.
  • Wet gangrene: characterised by swelling, blistering, and a wet appearance due to bacterial infection.
  • Gas gangrene: marked by pale skin that quickly turns grey, dark red, or purple, and the presence of gas bubbles under the skin.
  • Internal gangrene: affects internal organs, commonly the intestines, gallbladder, or appendix.
  • Fournier’s gangrene: a rare type affecting the genital organs.

Clinical Features 🌡️

Symptoms

  • Severe pain followed by numbness in the affected area.
  • Skin discolouration: red to black in dry gangrene; swollen, red, and blistering in wet gangrene.
  • Foul-smelling discharge in cases of wet and gas gangrene.
  • Crepitus: crackling sound under the skin in gas gangrene due to gas production by bacteria.
  • Fever and general malaise indicating systemic infection.
  • Tachycardia and hypotension in severe cases.

Signs

  • Visible necrosis and tissue death.
  • Skin changes: colour, texture, and temperature variations.
  • Loss of pulse in the affected area.
  • Swelling and oedema surrounding the gangrenous tissue.
  • Signs of sepsis: fever, tachycardia, hypotension, altered mental state.
  • Laboratory signs: elevated WBC, CRP, and other inflammatory markers.

Investigations 🧪

Tests

  • Blood tests: FBC, CRP, ESR, blood cultures.
  • Imaging: X-ray, CT scan, MRI to assess extent and presence of gas in tissues.
  • Doppler ultrasound: to evaluate blood flow in the affected area.
  • Tissue biopsy: for histopathological examination and culture.
  • Angiography: in cases of suspected arterial occlusion.
  • Microbiology: wound swabs for bacterial identification and sensitivity.

Management 🥼

Management

  • Surgical debridement or amputation of necrotic tissue.
  • Broad-spectrum intravenous antibiotics initially, tailored based on culture results.
  • Hyperbaric oxygen therapy: particularly useful in gas gangrene.
  • Vascular surgery: to restore blood flow in cases of ischemia.
  • Supportive care: fluid resuscitation, pain management, nutritional support.
  • Regular wound care and monitoring for signs of infection or recurrence.

Complications

  • Sepsis and septic shock
  • Systemic inflammatory response syndrome (SIRS)
  • Multi-organ failure
  • Chronic pain and disability following tissue loss or amputation
  • Psychological impact: anxiety, depression
  • Recurrent infections and chronic wounds

Prognosis

  • Varies depending on the type and severity of gangrene.
  • Dry gangrene: better prognosis if treated early.
  • Wet and gas gangrene: poorer prognosis due to rapid spread and risk of sepsis.
  • Early intervention and aggressive treatment improve outcomes.
  • Close monitoring and follow-up essential for preventing complications.
  • Mortality higher in patients with significant comorbidities.

Key points

  • Prompt recognition and treatment are crucial for survival.
  • Multidisciplinary approach involving surgeons, infectious disease specialists, and critical care teams.
  • Patient education on risk factors and early signs of gangrene.
  • Regular follow-up for high-risk patients (e.g., diabetics, those with peripheral vascular disease).
  • Ongoing research into advanced therapies and preventative measures.

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Infection