Effect of Prolonged Pressure on Hemodynamics of Sacral Tissues Assessed by Diffuse Optical Imaging: A Pilot Study.

Pressure injuries (PIs) are wounds resulting from prolonged pressure exerting on the skin and underlying tissues over bony prominences (e.g., lower back, heels, shoulders) in bed-bound patients and wheelchair users. Minimizing pressure has long been considered the most effective preventative method, and current guidelines require visual skin inspection and repositioning every two hours. However, these strategies are often applied deficiently and do not adequately prevent PIs from becoming penetrating wounds. Recent studies attribute the development of PIs to cell deformation, inflammatory, and ischemic damages that cumulatively propagate from the microscale (death of few cells) to the macroscale (tissue necrosis) within one to several hours. Although the nature of the PI pathogenesis is complex and multifactorial, measuring tissue alterations in real-time may elucidate the origination mechanism and ultimately allow detecting PIs at the earliest stage. In this pilot study, we evaluated the ability of diffuse optical imaging (DOI) to assess hemodynamic changes resulting from prolonged pressure on the sacral tissues in five healthy volunteers laying immobile in a supine position for 2 hours. A thin, body-conforming optical imaging probe encompassing 256 optodes arranged in a regularly spaced grid over a 160 × 160 mm area was used to construct DOI volumetric images representing changes of oxyhemoglobin (HbO