Pressure Injury Staging

A pressure injury is localized damage to the skin and/or underlying tissue caused by pressure or pressure combined with shear. It usually occurs over a bony prominence, but it can also follow the contact pattern of a medical or therapeutic device. Mechanical loading deforms tissue; sustained loading can reduce perfusion, and the resulting injury may involve localized ischaemia, reperfusion injury, impaired lymphatic drainage, and direct cell deformation. Direct deformation can damage muscle quickly, whereas perfusion-related damage may take longer. Muscle and other deep tissues can therefore be injured before the surface change appears. The size of a visible skin lesion may underestimate the damage beneath it. There is no universal pressure-time threshold: tissue geometry, load, duration, microclimate, perfusion, and individual tolerance alter when injury occurs. Staging describes the deepest level of tissue loss that can be seen or directly assessed. It does not grade pain, infection, wound dimensions, healing speed, or the person's overall risk. A wide Stage 2 injury does not become Stage 3 because of its surface area, and an anatomically shallow injury can still be Stage 4...