Etiology and pathogenesis
The formation of pressure ulcers (decubitus) is based on local ischemia. During prolonged forced body positioning, soft tissues are compressed between a hard surface and prominent skeletal areas. This leads to the compression of blood vessels, cellular oxygen starvation, and subsequent necrosis. In severe, neglected cases, tissue death affects not only the skin and subcutaneous tissue, but also the periosteum and superficial layers of bone tissue.
Key factors accelerating this process:
- Prolonged bed rest (in severely ill and depleted patients).
- Impaired normal innervation (e.g., in spinal cord injuries).
- Pelvic organ dysfunction (constant contact with urine or feces causes maceration, irritation, and infection).
Classification by localization
Pressure ulcers occur not only on the skin. Several localization variants are distinguished:
- Typical (over bony prominences): sacrum (the most frequent site of lesion), heels, occipital region, scapulae, elbows, and the greater trochanter of the femur.
- Internal organs (from pressure of foreign bodies):
- Gallbladder: prolonged pressure of a calculus on the wall can cause local necrosis with subsequent organ perforation.
- Intestines: due to prolonged pressure from a rigid drainage tube.
- Trachea: forms from the pressure of the cuff or the endotracheal tube itself during prolonged mechanical ventilation.
- Iatrogenic (external compression): tissue necrosis under improperly applied plaster casts or rigid transport splints.
Clinical picture and stages of development
The pathology develops gradually, passing through four sequential stages of development:
- Stage of ischemia: the skin at the compression site turns pale, followed by pronounced cyanosis.
- Stage of superficial necrosis: tissues become edematous, and the epidermis begins to peel off. Small or large bullae filled with reddish-brown contents form on the surface.
- Stage of ulceration: the bullae rupture, and reddish-purple wound surfaces—excoriations—appear in their place.
- Stage of deep necrosis: tissue death penetrates the entire depth of the soft tissues and actively spreads laterally, involving surrounding areas. The size of the defect can be significant (palm-sized or larger).
Most commonly, the process proceeds as dry gangrene; however, when microbial flora joins in, the clinical course changes and wet gangrene develops.
Principles of treatment
Treatment of established defects is a difficult and comprehensive task.
Local surgical treatment: The main method in the presence of necrosis is necrectomy (removal of dead tissue). It can be performed mechanically, physically, or chemically. Repeated surgical debridements are often required. After cleansing the wound bed, treatment continues as for a standard purulent wound, with the main goal of stimulating reparative regeneration.
General therapy: Aims to eliminate the root cause. Includes combating patient depletion, treating sepsis or the underlying severe disease, and attempting to restore tissue innervation.
Preventive measures
The basis of successful prevention is constant and meticulous care of the immobilized patient.
General measures:
- Early patient mobilization and regular position changes in bed.
- Use of anti-decubitus mattresses and inflatable or rubber ring cushions.
- Elimination of any wrinkles on bed linen, keeping it clean and dry.
- Daily skin care: wiping risk areas twice a day with camphor alcohol, talcum powder, or eau de cologne.
- In the initial stages, a 5% potassium permanganate solution may be used.
Specific measures:
- If pain occurs under a plaster cast or splint, immediate replacement of immobilization is required.
- Timely removal of drains from body cavities.
- If prolonged mechanical ventilation is necessary, tracheostomy is indicated to prevent the formation of a tracheal pressure ulcer from the endotracheal tube.
Briefly: answers to topical questions
What necrectomy methods are used to cleanse pressure ulcers of dead tissue?
To cleanse wounds of devitalized tissue and remove necrotic tissue, necrectomy is performed using several main methods. These include mechanical necrectomy performed surgically using a scalpel and scissors. Physical methods, including the use of laser and ultrasound, are also employed. Chemical necrectomy is performed using proteolytic enzymes that accelerate eschar separation.
For quick memorization of pressure ulcer stages, use the acronym "IPOZ": Ischemia (pallor and cyanosis) → Superficial necrosis (edema and bullae) → Open ulcer (rupture of bullae, excoriations) → Deep necrosis (involvement of all layers inward and outward).
Class and exam questions
Can a pressure ulcer form inside the body?
Yes, internal pressure ulcers arise from prolonged pressure of foreign bodies or medical devices. Typical examples: a gallstone in the gallbladder, a rigid drain in the intestine, or an endotracheal tube in the trachea.
What to do if a patient complains of pain under a plaster cast?
The cast must be immediately removed or replaced. The onset of pain indicates progressive tissue ischemia, which is the first stage in the development of an iatrogenic pressure ulcer.
Which form of gangrene is most characteristic of pressure ulcers?
A typical variant is dry gangrene. However, if infection enters the necrotic area (e.g., through contact with excrement), the process transforms into wet gangrene.
What else to study on this topic
- Methods of performing necrectomy: mechanical, physical, and chemical debridement.
- Features of wound management after necrectomy (phases of the wound healing process).
- Prevention of airway pressure ulcers: strict indications for tracheostomy during mechanical ventilation.
- Impact of concomitant depletion on the rate of necrosis formation and healing.
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