Pat Pressure Injury Staging Model™Pat Pressure Injury Staging Model In the past, healthcare providers have been taught wound care through high quality photographs and video. Pat Pressure Injury Staging Model brings wound care alive in a way that even the best of photographs cannot. The model displays the following pressure injuries (per NPUAP 2016 National Pressure Ulcer Advisory Panel): Stage 1 (in both darkly and lightly pigmented skin), Stage 2, Stage 3 with undermining, tunneling