Gangrene

Etiology and early symptoms

The development of gangrene is always associated with critical impairment of blood flow. The factors leading to this condition are divided into two groups:

• External factors: extensive tissue crushing, trauma and vascular injury, as well as prolonged compression (e.g., due to improperly applied casts or a tourniquet left on for too long).
• Internal factors: conditions that occlude the vessel lumen from within or compress it externally. These include thrombosis, embolism, intestinal volvulus, and chronic vascular pathologies such as atherosclerosis obliterans and thromboangiitis obliterans (endarteritis obliterans).

With acute cessation of blood flow, a characteristic clinical picture of ischemia develops. The first sign is severe ischemic pain localized distal to the site of vascular occlusion. Visually, the limb turns pale and then acquires a mottled bluish hue. On palpation, it is cold to the touch. Skin sensitivity in the affected area disappears completely.

Types of gangrene: dry and wet

The clinical presentation and course of the pathology depend on whether infection joins the necrosis.

Dry gangrene

Occurs when dead tissues dry out rapidly (mummification) without the development of infection.

• Local manifestations: the affected area dries and turns black. A clear boundary—the line of demarcation—forms between healthy and dead tissue.
• General condition: systemic intoxication is absent or very mild because breakdown products are not absorbed.

Wet gangrene

Develops as liquefactive (wet) necrosis with mandatory involvement of a putrefactive infection. Most commonly affects the foot and lower third of the leg.

• Local manifestations: the skin becomes bluish, then dirty green or black. The limb increases significantly in volume due to edema. Blisters with dark red (hemorrhagic) fluid appear. The tissues look dirty gray and emit a foul odor.
• General condition: extremely severe from the first hours due to the absorption of toxic breakdown products. Marked intoxication is observed: high body temperature, chills, tachycardia, severe thirst, and characteristic dry tongue (dryness of mucous membranes and skin).

First aid and principles of surgical treatment

Upon detecting the first signs of ischemia or necrosis, it is necessary to immediately immobilize the affected limb and apply an aseptic dressing.

Further tactics depend on the etiology but are based on the general principles of surgical debridement of the focus:

1. Necrotomy (tissue incision). The surgeon makes several parallel incisions into the dead tissue. Since sensitivity is lost, anesthesia is not required. The main goal is to ensure the outflow of liquefied masses and reduce the level of intoxication. After the procedure, alcohol-soaked dressings or physical antiseptic agents are applied.
2. Necrosectomy (removal of dead tissue). Can be performed mechanically (using a scalpel and scissors), chemically (using proteolytic enzymes), or physically (laser, ultrasound).

Surgical tactics for limb gangrene:

• In progressing wet gangrene, prompt high-level amputation within healthy tissue is indicated. Waiting for the demarcation line to form is prohibited due to escalating, fatal intoxication.
• In dry gangrene, an expectant management approach is used. Physicians wait for the formation of a clear line of demarcation, after which amputation is performed slightly proximal to this boundary (within healthy tissue).

Class and exam questions

What else to study on this topic

• Mechanisms of liquefactive necrosis formation
• Atherosclerosis obliterans as a cause of circulatory disorders
• Endarteritis obliterans: pathogenesis and differences
• Proteolytic enzymes in the treatment of necrosis
• Technique of high-level limb amputation

Other topics of 'CHAPTER 13. VASCULAR AND LYMPHATIC INSUFFICIENCY OF THE EXTREMITIES'

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.