The contribution of pressure gradients to advancing understanding of deep tissue injury to sacral regions

Aims: To explore correlations between peak pressure and pressure gradient at 1.5 cm and 2.5 cm, and selected risk factors for pressure injury including Waterlow risk assessment score and body mass index. Background: Accurately predicting pressure injury formation remains elusive. Exploring pressure gradients through pressure mapping systems may increase understanding of suspected deep pressure injury development. Methods: A nested prospective correlational exploratory study recruited 120 medical and surgical patients with convenience sampling. Patients were positioned supine with a 30-degree head elevation, on a computer-linked pressure sensor mapping mat. Mean peak interface pressure and pressure gradients were calculated. Results: Large correlation coefficients were identified between peak interface pressure and pressure gradients at distances of 1.5 cm and 2.5 cm, indicating that the area at the base of the 'cone-like' pressure damaged area remained essentially constant, rather than increasing with peak interface pressure. Conclusions: Pressure is experienced in a 'V' shape rather than a 'U' shape. Additionally, the area subjected to the highest pressure gradient is restricted in size and the impact of pressure reduces with distance from the point of peak interface pressure. The results suggest that with increasing peak interface pressure, the surrounding area becomes subject to higher gradients and shearing forces. Relevance to clinical practice: Increased use of pressure mapping systems in the clinical setting shows educational promise through visualisation of factors affecting deep tissue injury.