How Do Bedsores Happen? Causes, Stages & Complications
The Mechanics of Tissue Breakdown
Bedsores occur when prolonged mechanical forces exceed capillary blood pressure (typically 32 mmHg). When an immobile patient remains in one position, blood vessels collapse, depriving epidermal and muscular cells of essential oxygen and nutrients.
Direct downward force between bone and support surfaces shuts down micro-circulation, initiating cellular asphyxiation in as little as two hours.
Skin sliding against coarse linens or mattresses scrapes away delicate superficial epithelial cells, weakening dermal resilience.
When a patient slides down in an inclined bed, skeletal bones move downward while skin adheres to bedding, twisting and tearing underlying capillaries.
The 4 Clinical Stages of Pressure Ulcers
Non-Blanchable Erythema
Skin remains intact with localized redness that does not turn white when gently pressed. Skin may feel warmer, firmer, or tender.
Partial Thickness Loss
The outer epidermis breaks open, presenting as a shallow open sore or intact/ruptured serum-filled blister with a pinkish red wound bed.
Full Thickness Skin Loss
Deep crater-like ulcer extending down into subcutaneous adipose tissue. Slough or dead yellow tissue may be present.
Deep Tissue Destruction
Severe extensive necrosis exposing underlying muscle tissue, tendons, joints, or bone. High risk of osteomyelitis and systemic infection.
Severe Complications of Untreated Bedsores
- Cellulitis: Acute spreading bacterial infection of skin and subcutaneous tissues causing swelling, redness, and excruciating local pain.
- Bone & Joint Infections (Osteomyelitis): Deep Stage 4 ulcers allow bacterial penetration into joints and bones, severely restricting limb function.
- Sepsis: A life-threatening medical emergency where bacteria enter the bloodstream, potentially leading to organ failure.