Abstract
A pressure injury is a localized damage to the skin or underlying tissue associated with pressure, or a combination of pressure and shear, in both apparently intact and open skin areas. Pressure injuries were previously known as pressure ulcers or decubitus ulcers. They are common complications in persons with limited mobility, such as those with a spinal cord injury. Pressure injury development significantly impacts the morbidity and even mortality of affected persons, limiting activities of daily living and decreasing quality of life. They are also associated with high healthcare utilization and costs. Pressure injury is considered a patient safety issue. Prevention of pressure injuries is a key indicator of the quality of care. Although many pressure injuries are probably preventable, expert consensus indicates that some are unavoidable. The complex and multi-factorial nature of pressure injury development emphasizes the need to consider intrinsic and extrinsic risk factors associated with the patient and the environment. These factors include: mobility, urinary and bowel incontinence, malnourishment, anemia, diabetes status, and the use of appropriate pressure redistribution strategies. If a pressure injury develops, a patient-centered, interdisciplinary management plan is essential. Treating pressure injuries involves minimizing and correcting systemic and local factors impeding healing. Systemic factors are similar to those that lead to pressure injury formation. Local factors include biofilm and necrotic tissue development. In addition to standard conservative and surgical management, technologies such as electrical stimulation may be beneficial to the healing of pressure injuries.
Keywords
Bed sore, Decubitus ulcer, Pressure injury, Pressure sore, Pressure ulcer
| Synonyms | |
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| ICD-10 Codes | |
| L89009 | Pressure ulcer of unspecified elbow, unspecified stage |
| L89119 | Pressure ulcer of right upper back, unspecified stage |
| L89129 | Pressure ulcer of left upper back, unspecified stage |
| L89139 | Pressure ulcer of right lower back, unspecified stage |
| L89149 | Pressure ulcer of left lower back, unspecified stage |
| L89159 | Pressure ulcer of sacral region, unspecified stage |
| L89209 | Pressure ulcer of unspecified hip, unspecified stage |
| L89309 | Pressure ulcer of unspecified buttock, unspecified stage |
| L89509 | Pressure ulcer of unspecified ankle, unspecified stage |
| L89609 | Pressure ulcer of unspecified heel, unspecified stage |
| L89819 | Pressure ulcer of head, unspecified stage |
| L89899 | Pressure ulcer of other site, unspecified stage |
| L8990 | Pressure ulcer of unspecified site, unspecified stage |
Definition
A pressure injury is a localized wound to the skin or underlying tissue usually over a bony prominence, as a result of pressure or pressure in combination with shear. The development of pressure injuries due to tissue breakdown and cell necrosis is a significant problem for many patients, including the elderly, and those with impaired mobility or paralysis. Pressure injuries are associated with significant morbidity and even mortality—they can cause pain as well as decreased activities of daily living and quality of life. Therefore, this is a pertinent issue for many patients in rehabilitation. Furthermore, they are extremely costly—the burden on the United States healthcare system was estimated at $6 to $15 billion per year in 2012.
Tissue breakdown is referred to by many terms, including decubitus ulcers, pressure sores, bedsores, and pressure ulcers. The term pressure injuries (PrIs) is currently defined by the National Pressure Ulcer Advisory Panel (NPUAP) to be the accurate nomenclature to describe localized skin damage, whether the skin appeared to be intact or ulcerated, due primarily to excessive applied pressure. This term is used throughout the chapter.
The incidence of pressure injuries among patients in acute care hospitals ranges from 1% to 33%, with prevalence rates of 3% to 69%. Higher rates have been associated with increasing age and duration of hospital stay in the elderly. In those with spinal cord injury, individuals with paraplegia are more likely to be re-hospitalized because of pressure injuries. The prevalence of pressure injuries on admission to skilled nursing facilities ranges between 10% and 26%.
A consideration of the risk factors in pressure injury development is of vital importance because they contribute to the development of treatment and rehabilitation strategies. There are many factors that can lead to the development of pressure injuries. These can be generally classified as intrinsic factors, which are related to the clinical and physiologic profile of the individual, and extrinsic factors, which are primarily attributed to the external environment ( Table 149.1 ). These intrinsic and extrinsic factors can overlap. They highlight the complex nature of pressure injury development and are indicative of the need for a holistic and systematic approach to prevent their formation. Another approach to describe the risk factors is through a conceptual framework illustrated by Coleman et al., in which factors are described in terms of physiological susceptibility, tissue tolerance, and the biomechanical determinants of pressure injury development.
| Extrinsic Factors | Intrinsic Factors |
|---|---|
| Applied pressure | Reduced or absent sensation |
| Surface shear | Impaired mobility |
| Local microenvironment | Decreased blood flow |
| Muscle atrophy | |
| Poor nutrition | |
| Systemic diseases (e.g., diabetes) | |
| Altered mental status |
Intrinsic Risk Factors
Intrinsic risk factors in pressure injury development are related to the conditions of the individual patient. Decreased muscle activity and paralysis lead to loss of muscle bulk, thus reducing soft tissue coverage over the bony prominences of the pelvic and other anatomic regions. As muscle bulk decreases, regional vascularity diminishes and the proportion of avascular fatty tissue increases, resulting in an increased risk of pressure injury. Loss of normal muscle tone leads to abnormal responses to environmental stimuli, such as applied pressure, thus increasing the risk for blood flow to become compromised.
Furthermore, motor paralysis will directly affect a person’s ability to respond unconsciously to potential noxious stimuli (e.g., fidgeting while sitting or turning while asleep). Reduced mobility also profoundly alters the individual’s ability to consciously perform postural maneuvers necessary to relieve prolonged applied pressure, from weight shifting while sitting to walking. The loss or reduction of mobility may be further complicated by sensory impairment, leading to the absence or alteration of normal perception of environmental stimuli, such as pain or temperature. Patients with impaired sensation or proprioception are at increased risk for pressure injury development because they cannot sense the warning signals that precede tissue damage.
The malnourished patient is at increased risk for pressure injury development and will also have an impaired response to healing. Normal tissue integrity depends on correct nitrogen balance and vitamin intake. Protein depletion will lead to decreased perfusion and impaired immune response. The presence of an exuding pressure injury will cause massive protein loss, and the patient will move into increasingly negative nitrogen balance. The severity of a pressure injury may be directly related to the degree of hypoalbuminemia. Fluid balance must also be considered in conjunction with nutritional status because dehydration will decrease cellular nutrient delivery.
Patients with systemic diseases may be at higher risk of pressure injuries. For instance, those with renal disease and diabetes may be more prone to pressure injury formation due to their peripheral vascular status. The cognitive and mental status of an individual may also affect the ability to perform pressure relief for at-risk body areas, hence potentially increasing the risk of pressure injury formation.
Bowel (see Chapter 139 ) and bladder (see Chapter 138 ) incontinence causing excessive local moisture may alter the microenvironment of the skin surface, making it more susceptible to maceration and skin breakdown.
Extrinsic Risk Factors
The primary extrinsic risk factor is external applied pressure. Body tissues can support high levels of hydrostatic pressure, such as in deep sea diving. When pressure is the same in all directions, there is no resulting tissue damage. However, nonuniform applied pressure causes tissue distortion, leading to localized tissue damage. This will occur when a patient is in contact with an external load-supporting device, such as a bed or wheelchair. The pressure at the interface between the patient and the support surface must be maintained at a level such that the local blood supply and lymphatic circulation are not impaired. This threshold varies between individuals. A specialized support system is often required for high-risk individuals, such as acute spinal cord injured patients.
Any external load that can cause tissue distortion is also likely to cause shear stresses. When only shear forces are present, slipping occurs, and tissue damage will be minimized. However, shear and normal applied loads generally tend to occur together. The normal applied load required to occlude blood flow can be halved when shear forces are also present. Significant clinical problems can arise from propping patients up in bed at angles of less than 90 degrees. In contrast, in the side-lying position, it has been found that blood flow is severely impaired by fully lying on the trochanteric region, but at a partial 30-degree side-lying position, blood flow is maintained.
Biofilm
All pressure injuries are associated with some degree of bacterial colonization, which may or may not lead to local wound infection. The presence of bacterial biofilms in the wound bed is dependent on intrinsic and extrinsic risk factors and may be both a cause and effect of delayed healing. Biofilms are aggregated communities of slow-growing bacterial cells surrounded by a dense matrix of both bacterial and host material (i.e., polysaccharides, proteins, glycolipids, and extracellular DNA). They can contribute to the difficulty of treating chronic infections solely with antimicrobial agents. Consequently, it is postulated that the infected wound bed remains in an inflammatory state with elevated levels of matrix metalloproteinase and reactive oxygen that damage the proteins vital for wound healing. Biofilms are typically polymicrobial and are not detected by routine clinical microbiology. They may inhibit healing even in the absence of clinical signs of infection. The possible clinical signs and symptoms of local infection include increasing pain in the wound; erythema, edema, and heat of the peri-wound area; foul odor; and purulent drainage. Frequent removal of biofilms through débridement followed by the use of antimicrobial agents may facilitate healing and prevent biofilm reformation. Individuals with spinal cord injury may not have intact sensation; in such cases, infected wounds are painless but can cause systemic responses, such as autonomic dysreflexia.
Unavoidable Pressure Injuries
With the complexity and severity of intrinsic and extrinsic risk factors in mind, some cases of pressure injuries may be considered “unavoidable.” At times, efforts to minimize pressure injury risk factors may be ineffective or counterproductive, given the complexity of the patient’s medical conditions or care required. Factors including individual behaviors, comorbidities, medical related treatments, and medications may be non-modifiable and can contribute to the development of unavoidable pressure injuries. Common conditions that are related to the development of unavoidable pressure injuries include: forced immobilization due to life support and acute illness, use of vasopressors for cardiovascular support, hypotension, severe congestive heart failure, chronic kidney disease, end-stage dementia, and metastatic cancer.
Symptoms
The primary symptoms of a pressure injury are due to an area of persistent tissue breakdown involving the skin and underlying tissues. The patient may complain of an open area in the skin, drainage, bleeding, odor, fever, and pain. The severity of pressure injuries has traditionally been characterized by the extent of breakdown, as described by a staging system.
Physical Examination
Physical examination for a pressure injury starts with an overall assessment of the risk factors of the individual and his or her environment. During general examination, evaluation of overall strength, muscle tone, spasticity, range of motion, and presence of contractures is important. Abnormalities in these areas can contribute to both the development and the persistence of pressure injuries. In addition, it is important to note whether the individual is malnourished, anemic, incontinent of feces or urine, cognitively impaired, or immobile from medical conditions such as stroke or spinal cord injury as well as whether appropriate pressure-relieving surfaces for seating and sleeping have been used. The Braden Scale is a commonly used nursing risk assessment tool to determine whether an individual is at risk for pressure injury development. An individual with a score of 18 or lower is found to be at risk. It is important to note that contributing factors, such as frequency in training on pressure injury risk and electronic adaptations of the Braden Scale, can affect the usability of the scale in clinical practice. A systematic approach to the examination of the pressure injury is necessary to provide accurate assessment and monitoring of the pressure injury. The following parameters are to be noted:
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Location of the injury
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Size of the pressure injury (length to be measured as the maximum measurement craniocaudally; width as the maximum measurement from side to side; depth to be measured at the deepest part of the wound perpendicular to the skin surface)
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Staging of the injury
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Presence of undermining or tunneling
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Wound bed appearance
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Presence of necrotic materials, slough, eschar, fibrous tissues
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Presence of rolled wound edges
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Presence and amount of drainage (exudate vs transudate)
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Presence of foul odor
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Tissue health of the periulcer tissues, including any surrounding erythema, maceration, edema, or associated fungal infection
Staging of pressure injuries describes the extent of tissue breakdown at initial examination. There have been multiple staging systems for pressure injuries. The NPUAP has developed the follow staging system to stage pressure injuries.
Stage 1 Pressure Injury: Non-Blanchable Erythema of Intact Skin
Intact skin with a localized area of non-blanchable erythema, which may appear differently in darkly pigmented skin. Darkly pigmented skin may not have visible blanching; its color may differ from the surrounding area. Presence of blanchable erythema or changes in sensation, temperature, or firmness may precede visual changes. Color changes do not include purple or maroon discoloration. These may indicate deep tissue pressure injury
Stage 2 Pressure Injury: Partial-Thickness Skin Loss With Exposed Dermis
Partial-thickness loss of skin with exposed dermis. The wound bed is viable, pink or red, moist, and may also present as an intact or open/ruptured serum-filled or serosanguinous-filled blister. Adipose fat and deeper tissues are not visible. Granulation tissue, slough, and eschar are not present. Commonly results from adverse microclimate and shear in the skin over the pelvis and shear in the heel. This stage should not be used to describe moisture-associated skin damage, including incontinence-associated dermatitis, intertriginous dermatitis, medical adhesive- related skin injury, or traumatic wounds (skin tears, burns, abrasions).
Stage 3 Pressure Injury: Full-Thickness Skin Loss
Full-thickness tissue loss. Adipose tissue is visible in the ulcer and granulation tissue and epibole (rolled wound edges) are often present. Slough and/or eschar may be visible. May include undermining and tunneling. The depth of a Stage 3 pressure injury varies by anatomic location. Areas of significant adiposity can develop extremely deep wounds. Fascia, muscle, tendon, ligament, cartilage, and/or bone are not exposed. If slough or eschar obscures the extent of tissue loss, this is an unstageable pressure injury.
Stage 4 Pressure Injury: Full-thickness Skin and Tissue Loss
Full-thickness tissue loss with exposed or directly palpable fascia, ligament, cartilage, bone, tendon, or muscle in the wound. Slough and/or eschar may be present. Often includes epibole (rolled edges), undermining, and tunneling. The depth of a Stage 4 pressure injury varies by anatomic location. If slough or eschar obscures the extent of tissue loss, this is an unstageable pressure injury.
Unstageable Pressure Injury: Obscured Full-Thickness Skin and Tissue Loss
Full-thickness tissue loss in which actual depth of the injury is completely obscured by slough (yellow, tan, gray, green, or brown) or eschar (tan, brown, or black) in the wound bed. Until enough slough or eschar are removed to expose the base of the wound, the true depth cannot be determined, but it will be either a Stage 3 or 4. Stable (dry, adherent, intact without erythema or fluctuance) eschar on the heel or ischemic limb serves as “the body’s natural (biological) cover” and should not be softened or removed.
Deep Tissue Pressure Injury: Persistent Non-Blanchable Deep Red, Maroon, or Purple Discoloration
Intact or non-intact skin with localized area of persistent non-blanchable deep red, purple, or maroon discoloration or epidermal separation revealing a dark wound or blood-filled blister due to damage of underlying soft tissue from prolonged pressure or shear at the bone-muscle interface . Pain and temperature changes often precede skin color changes. Deep tissue injury may be difficult to detect in individuals with dark skin tones. Evolution of wound may evolve rapidly to reveal the actual extent of tissue injury or may resolve without tissue loss. If necrotic tissue, subcutaneous tissue, granulation tissue, fascia, muscle, or other underlying structures are visible, this indicates a full-thickness pressure injury (Unstageable, Stage 3, or Stage 4). Do not use deep tissue pressure injury to describe vascular, traumatic, neuropathic, or dermatologic conditions.
Medical Device–Related Pressure Injury
Pressure injuries related to prolonged pressure applied on medical devices used for diagnostic or therapeutic purposes. The pressure injury generally conforms to the pattern or shape of the device. Use the staging system to stage the injury as described above.
Mucosal Membrane Pressure Injury
Pressure injuries found on the mucous membranes as a result of prolonged use of a medical device at the location of the injury. Staging for these injuries cannot be determined due to anatomy of tissue.
This staging system can be used only for initial description of the skin damage. It cannot be used for repeated assessments or reverse staging, primarily because it is not a physiologic description and cannot characterize what is happening in a healing wound. Re-epithelialization will occur before lost muscle, subcutaneous fat, or dermis is replaced, resulting in mistakes when healed wounds are staged again.
Care must also be taken in the evaluation of the skin of patients with darkly pigmented skin. Sprigle and colleagues found that erythema in subjects with dark skin is more likely to be non-blanching and to have poor resilience. This indicates that clinicians should use persistence of erythema rather than blanching status to judge incipient pressure injuries. The staging system defined here includes both visual and nonvisual indicators in the definition of a Stage 1 injury, in part to address this issue.
Pressure injuries also frequently exhibit wound drainage. However, this drainage is not necessarily due to wound infection, and unless it is clinically indicated, routine wound swab culture may not be warranted because this would give a false-positive result. On the other hand, in some cases, increased volumes of exudate may indicate wound infection. Systemic infection may develop if the initial local wound infection is not adequately treated. In such cases, patients may exhibit fever, malaise, and chills. Cellulitis, osteomyelitis, and bacteremia may also develop.
Manual measurement of the wounds by length, width, and depth is the conventional method, but there is poor interrater reliability. Furthermore, manual measurement does not reveal the actual surface area of the wound nor wound depth. Electronic technologies allow more accurate documentation and measurements of the surface areas. Digital stereophotogrammetry systems, such as the 3D LifeViz (Quantificare, San Mateo, CA) ( Fig. 149.1 ) and Silhouette (ARANZ Medical Ltd, New Zealand), can also provide 3D wound geometry. These techniques allow remote wound monitoring and have been shown to minimize differences in wound measurement between expert and non-expert observers.
