Pressure Injury (Pressure Ulcer)

Pressure times time, and under anesthesia you own the clock - The injury is ischemia from external pressure exceeding capillary closing pressure, compounded by reperfusion when flow returns. The ward answer for a patient who cannot move themselves is repositioning every 2 hours so ischemic areas can recover. An anesthetized patient never repositions, so a long case is one uninterrupted pressure exposure — case duration is the variable that matters most, and on a long case it is reasonable to ask for a pressure check or a shift in position.

Anesthesia removes the feedback that protects everyone else - Patients with sensory deficits develop pressure injuries because the pressure-feedback response is absent and pressure goes unrelieved. General anesthesia and a dense neuraxial block do exactly that to a patient who had normal sensation an hour ago. That is the reason the operating room generates these injuries at all.

Sites, mapped onto your position - The sacrum is the most common site, followed by the heels, greater trochanter, and ischial tuberosity; the hip and buttock region accounts for roughly two-thirds of pressure ulcers. The other named sites are the back of the head, ears, shoulders, elbows, inner knees, and malleoli. Supine loads the sacrum, heels, occiput, elbows, and shoulders; lateral loads the dependent greater trochanter, malleolus, and ear; a seated or beach-chair position loads the ischial tuberosities. Float the heels off the surface rather than resting them on foam.

Your equipment causes them too - Pressure injuries are defined to include damage related to medical devices, and the skin under nasogastric and endotracheal tubes is a documented site. That list is yours: the tube and its tie or fastener, the NG tube, the oximeter probe, the blood pressure cuff, and any tubing or connector that ends up trapped under a limb. Look under the things you put on.

Who has a short safe window - Immobility, reduced perfusion, malnutrition, and sensory loss are the core risk factors. Add cerebrovascular or cardiovascular disease, a recent lower-extremity fracture, diabetes, and incontinence. Older patients are at higher risk because thinning of the dermis and epidermis lowers resistance to shear. Vitamin C deficiency, chronic steroid therapy, hypoxia, and a cold patient all impair healing once an injury has formed.

Name the score, do not eyeball it - Use the Braden or Norton scale rather than an impression. Braden runs 6 to 23 across six categories, one of which is friction and shear, and lower is worse; a Braden of 12 or less is the threshold for a pressure-relieving air mattress. Norton runs 5 to 20, with onset of risk at 16 or below and high risk at 12 or below. The admission Braden score is usually already in the chart — read it in your preop and let it set how much padding effort this case gets.

Stage it by name and document it before induction - Use the National Pressure Injury Advisory Panel staging system; there is no universal classification, but NPIAP is the one in wide use and it grades by depth of tissue injury. Document any pre-existing injury and its stage before the patient goes to sleep. Pressure injuries are treated as an indicator of a facility's quality of care and inadequate prevention or treatment leads to litigation, so an injury that first appears in the PACU note with nothing preoperative to compare it against is the version of this that becomes a claim.

Shear is a separate mechanism from pressure - When the skeleton moves one way and the skin the other, the layer between them tears and perfusion to the dermis and epidermis is lost. Every slide-board transfer, every steep Trendelenburg, and every unplanned slump down the table is a shear event. Lift, do not drag.

What actually reduces risk - Redistribute pressure with support surfaces and reposition; both reduce friction and shear force. ACP 2015 guidance is to select advanced static mattresses or overlays made of foam, sheepskin, or gel for patients at increased susceptibility, and advises against alternating-air mattresses and overlays in that same group, both on moderate-quality evidence. Keep skin dry, because excess moisture breaks skin down — pooled prep solution, irrigation runoff, and a soaked drape under the patient are pressure-injury problems, not housekeeping. And since the threshold is pressure against perfusion pressure, a long hypotensive stretch shortens the safe window at every loaded point.

What goes wrong afterwards - Infection is the significant complication and runs from local wound infection through soft tissue infection to osteomyelitis and bacteremia; osteomyelitis can present only as a wound that will not heal, without sepsis or leukocytosis. The presence of a pressure injury also marks a worse overall prognosis, with increased mortality in both elderly and intensive care patients.

A pressure injury is localized damage to skin and underlying soft tissue, usually over a bony prominence or under a medical device, caused by prolonged or severe pressure with contributions from shear and friction. When external pressure exceeds capillary closing pressure the tissue goes ischemic and eventually necroses; restoring flow adds a second insult, because reperfusion generates reactive oxygen species and triggers an inflammatory response.

In a patient positioned at an incline, bone and muscle are displaced downward by gravity and distort or flatten the vessels feeding the dermis above, producing tissue hypoxia. Shear injures differently: when the skeleton slides one way and the skin the other, the capillary bed between them tears and the dermis and epidermis lose perfusion. Aging skin has a thinner dermis and epidermis and less resistance to shear.