Department of Engineering Technology, University of Houston, Houston, TX, USA.
Electrical and Computer Engineering, University of Houston, Houston, TX, USA.
Adv Exp Med Biol. 2021;1269:335-339. doi: 10.1007/978-3-030-48238-1_53.
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) and deoxyhemoglobin (HHb) concentration from a zeroed baseline. After 2 hours of continuous body weight pressure, hemodynamic images in all subjects were substantially dissimilar from their individual baseline. We also found that hemodynamic similarity computed pairwise across subjects exhibited a high value and limited variability around the mean, thus denoting a consistent level of image similarity across subjects. These preliminary results indicate that prolonged pressure causes distinctive hemodynamic patterns that can be effectively investigated with DOI and that monitoring functional changes over time holds potential for clarifying the development mechanisms of PIs.
压力性损伤（PI）是由于卧床患者和轮椅使用者身体的骨隆突部位（如腰部、脚跟、肩部）长时间受到压力，导致皮肤和下面的组织受伤。长期以来，人们一直认为减轻压力是最有效的预防方法，目前的指南要求每两小时进行一次皮肤目视检查和重新定位。然而，这些策略经常执行不到位，无法充分防止 PI 发展成穿透性伤口。最近的研究将 PI 的发展归因于细胞变形、炎症和缺血损伤，这些损伤在一个到几个小时内从微观尺度（少数细胞死亡）累积传播到宏观尺度（组织坏死）。尽管 PI 发病机制的性质复杂且多因素，但实时测量组织变化可能阐明发病机制，并最终允许在最早阶段检测到 PI。在这项初步研究中，我们评估了漫射光学成像（DOI）评估 5 名健康志愿者在仰卧位平躺 2 小时后，骶骨组织长时间受压导致的血流动力学变化的能力。使用薄的、与身体贴合的光学成像探头，探头包含 256 个光导，以规则的间隔网格排列在 160×160mm 的区域上，构建了表示从零点基线变化的氧合血红蛋白（HbO）和脱氧血红蛋白（HHb）浓度的 DOI 体积图像。在连续 2 小时的体重压力后，所有受试者的血流动力学图像与各自的基线明显不同。我们还发现，受试者之间的成对血流动力学相似性计算值很高，平均值周围的变异性有限，这表示受试者之间的图像相似性具有一致的水平。这些初步结果表明，长时间的压力会导致独特的血流动力学模式，可以用 DOI 有效地进行研究，并且随着时间的推移监测功能变化有可能阐明 PI 的发展机制。
