Gangrene

The Concept

Gangrene is death (necrosis) of tissue with putrefaction, usually resulting from a loss of blood supply, often complicated by infection. Its clinical types are distinguished by whether infection is present and how the tissue looks, and this distinction determines urgency and treatment.

DRY Gangrene

Dry gangrene follows a gradual arterial occlusion (chronic ischaemia, as in peripheral arterial disease or diabetes). The tissue slowly dries out, becoming shrivelled, mummified and black, with a clear line of demarcation between dead and living tissue and no significant infection. It progresses slowly and is comparatively less dangerous.

Wet Gangrene

Wet gangrene is necrosis complicated by infection (often with venous as well as arterial obstruction). The tissue is swollen, boggy, blistered, discoloured and foul-smelling, with no clear line of demarcation and rapid, spreading progression, causing systemic toxicity (sepsis). It is a surgical emergency.

Gas Gangrene & Management

Gas gangrene is a life-threatening necrotising infection caused by Clostridium perfringens, producing crepitus (gas in the tissues), rapid myonecrosis and severe toxaemia. Management across the types involves treating the cause (revascularisation where possible), antibiotics, and surgical debridement or amputation — urgently for wet and gas gangrene — with a clean amputation through viable tissue.

A Note on the Line of Demarcation

The line of demarcation between dead and living tissue is a useful concept: in dry gangrene a clear line forms, and a stable, demarcated dry gangrene of a toe may be allowed to auto-amputate or be removed electively once demarcation is complete. In wet gangrene there is no clear line and the process spreads, so urgent debridement or amputation through healthy proximal tissue is required to control sepsis — the presence or absence of demarcation thus guides the urgency of surgery.

The Bottom Line

Gangrene is tissue necrosis with putrefaction: dry (chronic ischaemia, demarcated, may be watched), wet (necrosis + infection, spreading, an emergency), and gas gangrene (Clostridium, crepitus, life-threatening) — treated by revascularisation, antibiotics and debridement/amputation.

A Note on Pressure Sores & Decubitus

Related to gangrene is the pressure sore (decubitus ulcer) — localised tissue necrosis over a bony prominence (sacrum, heel, ischium) from sustained pressure occluding the blood supply in an immobile patient. Like gangrene it reflects tissue death from ischaemia, and prevention (regular repositioning, pressure-relieving mattresses, good nutrition and skin care) is far better than treatment, which requires pressure relief, wound care and sometimes debridement — an important nursing and surgical concern in the bedbound patient.

Wet and gas gangrene are emergencies requiring urgent debridement.

• Gangrene = tissue necrosis with putrefaction, usually from loss of blood supply ± infection.
• Dry gangrene: gradual arterial occlusion (chronic ischaemia); dry, mummified, black, clear line of demarcation, no infection.
• Wet gangrene: necrosis + infection; swollen, boggy, foul, spreading, no demarcation, systemic toxicity — emergency.
• Gas gangrene: Clostridium perfringens; crepitus, myonecrosis, toxaemia — life-threatening.
• Treat: revascularise the cause, antibiotics, urgent debridement/amputation (esp. Wet and gas gangrene).