A bed sore, also known as a pressure ulcer or decubitus ulcer, is an injury to the skin and underlying tissue that is caused by prolonged pressure on the skin. Bed sores most often develop on skin that covers bony areas of the body, such as the heels, ankles, hips and tailbone.
People who are bedridden, use a wheelchair or are unable to change positions are most at risk of developing bed sores. Elderly people, people with medical conditions that limit mobility and people who have suffered a spinal cord injury also are at risk.
Bed sores are classified into stages based on severity, from stage 1 (earliest signs) to stage 4 (worst). A black eschar is dead tissue that can be a sign of a stage 3 or 4 pressure ulcer. When a bed sore turns black, it indicates the skin and tissue (muscle, fat and tendons) are dying. This is a serious complication that needs prompt medical care.
What causes bed sores?
Bed sores are caused by constant pressure on an area of skin. Bony areas of the body can withstand the least amount of pressure before skin and tissue are damaged.
Pressure on the skin squeezes tiny blood vessels that supply the skin with nutrients and oxygen. When skin goes without blood flow for too long, the tissue dies.
Common causes of constant pressure include:
– Lying or sitting in one position without shifting weight
– Sliding down in the bed or chair so pressure is placed on the tailbone
– Wrinkles in the bedding or clothes rubbing against skin
– Immobility due to illness, injury or condition
– Devices such as catheters, braces or feeding tubes pressing into skin
– Moisture from sweat, urine or feces irritating skin
What are the stages of bed sores?
Bed sores are categorized into four stages based on severity:
Stage 1
The earliest sign is reddened skin that doesn’t turn white when pressure is relieved. The area may be painful, firm, soft, warmer or cooler compared to surrounding skin. Stage 1 indicates the skin is at risk for ulceration.
Stage 2
Partial loss of the skin’s outer layer leads to shallow, pink or red sores. The wound may look like an abrasion, blister or shallow crater.
Stage 3
The sore worsens to entirely destroy the skin, causing a deep crater that can damage tissue, fat, muscles and tendons. Black, brown or yellow dead tissue and fluid-filled blisters are visible.
Stage 4
The open wound exposes bone, tendon and muscle. Slough and eschar (dead tissue) may be present. Pockets of pus and deep tunnels that undermine healthy tissue also can form. This stage causes extensive destruction and is life-threatening.
What does a black bed sore indicate?
A black bed sore indicates the skin and underlying soft tissue (fat, muscle, tendons) are dying. When skin tissue dies, it changes color and begins to decay.
As blood supply is cut off and the sore penetrates deeper layers, the wound bed turns black, brown or yellow. This dead, devitalized tissue is called eschar or slough.
Seeing black, dead tissue in the wound bed signifies the pressure ulcer has become serious (stage 3 or 4). It means the sore extends beneath the skin surface, damaging and killing the tissue.
What causes eschar to form?
Eschar is thick, leathery dead tissue that forms as skin and soft tissue die from prolonged lack of blood flow. Bony areas under constant pressure develop eschar as the sore worsens from the inside out.
Causes and risk factors for eschar developing include:
– Unrelieved pressure on the skin
– Poor blood circulation
– Chronic illnesses such as diabetes, vascular disease or kidney failure
– Advanced age
– Poor nutrition and hydration
– Skin conditions that cause fragility
– Nerve damage that prevents positional changes
Is black eschar different from scab?
Black eschar is different than a normal scab or crust that forms over a minor wound while healing. Key differences include:
Eschar
– Thick, leathery, black or brown dead tissue
– Firmly attached to the wound bed
– Devascularized tissue that won’t recover
– Caused by external injury or internal damage
– Associated with nonhealing wounds
Scab
– Dry crust of dried blood/plasma/skin cells
– Loosely attached to surface of wound
– Temporary protective barrier while healing
– Formed from wound exudate/clotting
– Associated with healing wounds
While scabs flake off as a minor wound heals, eschar must be removed for wounds to heal. Leaving dead tissue in place delays healing.
Is eschar painful?
Eschar itself has no nerve supply and cannot sense pain. But the wound beneath eschar may still contain nerve endings that can cause pain.
Removing dead tissue also exposes nerve endings that can make debriding painful. Signs a black bed sore is painful include:
– Discomfort, stinging or throbbing around the wound site
– Sensitivity, soreness when touched
– Grimacing when wound is cleaned or dressed
– Reluctance to move the body part with the sore
– Increased anxiety, irritability, distress
– Withdrawal from care during dressing changes
How is eschar removed from a pressure ulcer?
Several methods may be used to remove thick, hardened eschar from a pressure wound:
Autolytic debridement
Special dressings that lock in moisture against the eschar to help it soften. Can take several weeks.
Enzymatic debridement
Applying topical agents containing enzymes that break down dead tissue.
Biological debridement
Maggots are allowed to feed on dead tissue.
Mechanical debridement
Using a scalpel, forceps or whirlpool irrigation to scrape away dead tissue. Usually done by a skilled wound care specialist.
Surgical debridement
Cutting away necrotic tissue and cleansing the wound bed under general anesthesia. May be needed if eschar is thick.
Removing dead tissue relieves pressure on healthy tissue and helps reveal the extent of tissue damage to determine best treatment.
What happens if eschar is not removed?
Leaving black, dead tissue (eschar or slough) in place can harm the wound and delay healing. Risks if eschar is not removed include:
– Buildup of bacteria under eschar can cause infection
– Dead tissue blocks wound drainage, causing abscess
– Dry eschar sticks to wound bed, further damaging tissue
– Undermined edges prevent assessing wound margins
– Hard eschar rubs off healthy skin and new growth
– Toxins from necrotic tissue irritate wound and skin
– Healing is stalled with dead tissue present
Regular wound debridement is key for preventing further deterioration and promoting healing in pressure ulcers.
What is the outlook for stage 3 or 4 pressure ulcers?
The prognosis depends on factors like the person’s health, wound cause and characteristics, and how quickly treatment begins. Possible outcomes include:
– Smaller ulcers may heal in a month with proper wound care. Larger ulcers may take months.
– With deep wounds, surgery may be needed to remove dead tissue and close the hole.
– Bony infections are possible when wounds reach bone. This requires long-term antibiotic therapy.
– When wounds tunnel and undermine tissue, extensive surgery is needed to remove the damaged tissue. Skin grafting may be required.
– Severe wounds may never fully heal, requiring long-term wound care to control odor and drainage.
– If vital organs become infected through the bloodstream, it can be life-threatening.
– Extended bedrest, poor nutrition and uncontrolled medical conditions slow healing.
Elderly or disabled individuals are at highest risk of complications and death from late-stage pressure sores. In some cases, the person’s health is too poor to recover from such a large, deep wound.
Can black eschar turn back to healthy tissue?
Unfortunately, dead black tissue cannot revive itself and turn healthy again. Eschar and necrotic tissue have to be removed by debridement.
Cellular changes that occur in ischemic, dead tissue are not reversible. The affected skin and underlying structures are permanently damaged.
However, removing all eschar and slough allows healthy granulation tissue to form at the wound base. New pink or red tissue with a bumpy texture indicates healing.
Proper wound care provides a moist, non-toxic environment to help fresh tissue grow inward from the ulcer edges. As the gap fills in, new skin forms over the wound bed through the process of epithelialization.
What is healthy granulation tissue?
Healthy granulation tissue is the goal during the proliferative phase of healing in a pressure ulcer. Signs include:
– Shiny, moist, pink or red tissue
– Smooth, even texture with a bumpy, cobblestone appearance
– Bleeds easily when injured
– No dead tissue or drainage present
This fresh tissue is fragile and highly vascular. It contains new blood vessels, collagen and cells needed to fill wound defects.
As granulation tissue matures at the base and edges, the sore gradually fills in. Epithelial cells then migrate across the moist surface to close the wound.
Conclusion
A black eschar on a pressure ulcer indicates the skin and underlying tissue are devitalized and have died. Dead, black tissue won’t recover and has to be removed by debridement for healing to progress.
Leaving necrotic tissue delays healing and raises infection risk. Removing eschar allows healthy granulation tissue to develop and fill wound defects. With proper treatment, even stage 3 and 4 ulcers can gradually mend as fresh skin forms across the open crater.