On the Origin of Intraoperative Pressure Injury: An Angiosomal Theory of Pressure Injury Formation.

We review a case of a 22-year-old healthy man who underwent a 5-h maxillofacial surgery while continuously supine with foam pads placed prophylactically over elevated heels. Immediately after surgery, Stage 1 pressure injuries appeared on the left lateral heel and right lateral ankle, despite the absence of local pressure to these areas. Both lesions eventually resolved. Eight months later, a Doppler evaluation was performed of the patient's lower extremities, the peroneal artery and its tributaries were marked, and the intraoperative positioning was simulated to determine if a wedge at the back of the calf could have obstructed blood flow in these vessels. In this position, the feet naturally abducted so that the lateral calcaneal and posterior malleolar arteries became positioned immediately underneath the wedge. We propose a vascular mechanism of pressure injury development, postulating that some heel pressure injuries are not the result of localized pressure but rather angiosomal ischemia, based on the observation that the anatomical pattern of these lesions frequently follow the distribution of a named vessel. We hypothesize that in this case, intraoperative positioning along with permissive hypotension may have occluded arterial or venous flow to the relevant angiosomes, causing an ischemia reperfusion injury to the downstream tissues.