A pressure ulcer, also known as pressure sore, is a cutaneous and subcutaneous local injury, following long-term pressure of soft tissues under bony prominences.
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Epidemiology
Pressure ulcer incidence differs considerably by the clinical setting and the quality of care.
Incidence rates varies between 3.3%-39.3% in intensive care units, 2.2% - 23.9% for long term care settings and between 0% and 17% for home care 1-2.
Risk factors
More than 100 risk factors are identified in the literature, and the most important ones to assess are impaired mobility and sensory perception, moisture, malnutrition, low activity, friction, and shear 3.
Clinical presentation
Pressure ulcers evolve through time and present in the early stages as non-blanching skin erythema. Conscious patients may complain of pain or paresthesia. In later stages, a wound will develop, skin and soft tissue erosions will expose subcutaneous fat with possible muscular or bone exposure.
Pathology
Pressure ulcer results from sustained hypoperfusion and ischemia, associated with a local inflammatory reaction and bacterial colonization of the upper layers of the skin, extending progressively to the deeper layers leading to skin erosions, loss of all skin layers, necrosis of the subcutaneous tissue, and eventually necrosis of muscles, tendons, and bone.
Pressure ulcers are classified into four grades, according to the ICD-11 (2018 version) 4:
- grade 1: precursor state to cutaneous ulceration with skin erythema that does not blanch under fingertip pressure.
- grade 2: partial-thickness erosion of dermis presenting as a superficial pink wound.
- grade 3: full-thickness skin erosion with possible extension to subcutaneous fat or fascias.
- grade 4: full-thickness tissue necrosis with exposure of bone, muscle, tendons, or joint capsules.
The most affected sites by pressure ulcers are regions where sustained pressure is applied on bony prominence such as the 5:
- sacrum: sacral pressure ulcer
- ischial tuberosity: ischial pressure ulcer
- scapula: scapular pressure ulcer
- occiput: occipital pressure ulcer
- greater trochanter: trochanteric pressure ulcer
- calcaneal tuberosity
- lateral malleolus
- elbow
- ears
Radiographic features
Plain radiographs
The performance of plain radiographs and fistulography is low for the evaluation of fistulous tracts and bone involvement of pressure ulcers 6.
Ultrasound
Ultrasound is hard to perform on pressure ulcers because of gas, paraosteopathy changes, and skin thickness that does not allow ultrasound beam penetration 6.
It may show fluid collections or abscess, but does not visualize fistulous tracts, bone, or joint involvement 6.
CT
CT is the modality of choice for assessment of bone involvement in pressure ulcers 6. It demonstrates:
- ulcer cavity with loss of soft tissue thickness
- soft tissue gas, fluid collection, or abscess
- paraosteopathy with bone erosion and sclerosis
- periarticular calcifications
- gas in the joint
CT fistulography with contrast introduction in the fistula may show contrast diffusion in the fistulous tract, allowing the evaluation of necrosis extension to the joints or bone surface 6.
Treatment and prognosis
The treatment depends on the stage of the pressure ulcer, and may include 7:
- medical treatment with antibiotics
- surgical treatment with debridement and cleaning of the wound
- pressure irrigation using high-pressure water jets.
- hydrocolloid dressings
- negative pressure wound therapy
Prevention
Patients at high risk of pressure injury should get special care to control risk factors with:
- static or dynamic surfaces like cushions, foam, air or fluid-filled mattresses, air fluidized beds, pneumatic ripple beds
- daily skin inspection for any signs of pressure ulcers
- nutrition improvement
Complications
Differential diagnosis
Pressure ulcer differentials include all causes of cutaneous erythema and chronic wounds such as venous or diabetic ulcers. Still, the site and clinical presentation of the lesion usually make it easy to diagnose.