Lawrence J. Gottlieb
A pressure injury is a soft tissue injury due to the complex interplay of tissue deformation, stress, strain and ischemia from unrelieved pressure, shear, and friction typically overlying bony prominence.1
The standard for classifying pressure injuries is based on the four grades originally described by Shea in 1975.2
Grades I and II have potentially reversible acute inflammatory reactions involving all soft tissue layers; grade III has full-thickness tissue loss, extending to fascia; and grade IV extends through the deep fascia to bone.
Skin loss in grades I and II is thought to be more likely due to shear, friction, and maceration rather than pressure per se.
Over time, refinements have been made to this classification with the most recent being a six-stage classification by The National Pressure Ulcer Advisory Panel during their 2016 Staging Consensus Conference.3
Pressure injuries typically occur over bony prominences and are dependent on patient positioning.
Supine: greatest pressure overlying heels, sacrum, occiput, and scapula
Sitting: greatest pressure at ischial tuberosities, elbows
Lateral decubitus: greatest pressure over greater trochanters (often accompanied by hip flexion contractures), fibular head, and malleoli
Pressure injuries also occur due to inadvertent pressure from external objects pressing on the skin (ie, IV connectors, side rail of bed pressing on the skin or small object in shoe of the patient with neuropathy) or securing devices too tight (ie, nasal tubes, CPAP devices).
Extrusion of internal objects (ie, hardware or internal prosthetic or tubing) is generally caused by the same pathophysiology of classic pressure injuries over bony prominences.
External pressure greater than capillary pressure leads to decreased blood flow and tissue ischemia, eventually causing tissue necrosis.
Pounds-per-square-inch pressure highest in thin patients over bony prominences. Obese patients are able to distribute pressure better.4
Tissue loss after restoration of blood flow and generation of oxygen free radicals after relief of pressure
Deformation injury of cells
Local cell damage and death
Tissue breakdown may also occur due to
Tissue breakdown is more likely with circulatory disturbances.
The presence of infection and edema can influence the wound environment and ultimately the extent of necrosis.
Pressure injuries are “inside-out” injuries caused by soft tissue damage from unrelieved pressure on the skin, typically overlying bony prominences.
Tissues most sensitive to pressure die first.
Nerve and muscle are the most sensitive to ischemia from pressure, which is why there is no muscle or major nerves between the skin and bony prominences in any area of the body.
Subcutaneous fat dies first in the typical pressure injury occurring over bony prominences.
Skin is one of the most resistant tissues to pressure. The earliest changes seen in the skin (ie, swelling and erythema of stage 1 pressure injuries) generally reflect injury to the tissues beneath.
Skin breakdown without underlying tissue loss (stage II) is generally due to shearing, friction, and maceration and not pressure per se.
The tissue type most resistant to pressure is fascia, which has very low metabolic demands.
“Iceberg effect”: by the time that there is any evidence of pressure injury in the skin, there is significant tissue destruction beneath; the skin findings are only the “tip of the iceberg.”
Although pressure injuries are typical in debilitated, immobile, and/or insensate patients, they are not inevitable and indeed should be preventable in most situations.
Prevention is directly related to educating and motivating patients and or caregivers in
Recognizing risks in various situations
Relieving pressure every 15 minutes when seated or for 5 minutes every 2 hours when in decubitus position will generally prevent pressure injuries.
Providing resources (eg, cushions for seats)
Change in caregivers and/or intermittent psychological disturbance (such as depression) correlate with pressure injury development and recurrence.
PATIENT HISTORY AND PHYSICAL FINDINGS
Patients at risk
Patients with diminished mobility
Spinal cord injury, disease, or dysfunction
Patients under anesthesia or deep sedation during surgery or undergoing procedure or treatment requiring prolonged immobilization (eg, ECMO)
Patients requiring others to move them
Patients with quadriplegia
Patients who are debilitated due to cerebral dysfunction (stroke, intoxication, infection)
Debilitated patients in acute care and long-term care facilities
Patients with diminished sensation
Spinal cord injury, disease, or dysfunction
Assess for muscle spasticity, which increases the risk of shearing forces and friction and postoperative healing issues if not controlled.
Assess for joint contractures, which make avoiding pressure on bony prominences very difficult for health care providers.
Assess for tunneling and pseudobursa formation.
Assess for involvement of joint spaces and other adjacent structures.
Assess for bone exposure.
Assess for infection: soft tissue and bone.
Assess for urinary tract infections, in patients with spinal cord dysfunction.
Assess patient and caregiver knowledge, home resources, likelihood of being compliant, and potential social/psychological issues, all of which can affect incidence of recurrence.
X-rays are helpful for assessment of osteoporosis, fractures, and heterotopic ossification.
Radionuclide bone scans are helpful in assessing activity of heterotopic ossification.
MRI is the best diagnostic imaging to evaluate for acute osteomyelitis; however, bone biopsy remains gold standard for the diagnosis of osteomyelitis.
CT scan or MRI and sinograms are helpful to evaluate for sinus tracts, fluid collections, and tunneling in the pelvis or possible involvement of rectum.
Nonoperative management of pressure injuries is appropriate in patients who
Are prohibitive surgical risk due to comorbidities
Demonstrate that they would not be compliant with postoperative regimens
Need to be prepared for possible operative management in the future
Optimize nutrition (sufficient protein, vitamins/minerals).
Monitor prealbumin levels.
Check vitamin D levels.
Promote optimization of general medical care.
Evaluate cardiovascular, pulmonary, and genitourinary systems.
Promote smoking, alcohol, and drug cessation.
Promote treatment of depression.
Optimize wound conditions.
Quantitative bacteriologic assessment of wound with wound tissue biopsy
Pathologic assessment of long-standing (more than 5 years) wounds with wound tissue biopsy
Offloading/frequent turning for pressure relief
Provide patient and caregiver education.
Medical management: baclofen, dantrolene, diazepam, botulinum toxin
Surgical management: rhizotomy, baclofen pump, peripheral nerve blocks
Assess colonization vs infection of wound using quantitative cultures.
If quantitative culture shows greater than 105 organisms per gram, use a topical antimicrobial (eg, silver sulfadiazine, mafenide acetate, dilute hypochlorite solution).
If unable to control bacteria with topical, it may need surgical debridement.
Systemic antibiotics used for treatment of cellulitis, osteomyelitis, or joint space infections as well as for any distant infection of genitourinary or respiratory tracts
If repeat quantitative culture shows greater than 105 organisms per gram, consider additional debridement and/or change in topical antibiotic treatment prior to definitive closure.