City, University of London, Research Centre for Biomedical Engineering, London, United Kingdom.
Queen Mary, University of London, National Bowel Research Centre, Blizard Institute, Barts and the L, United Kingdom.
J Biomed Opt. 2020 Feb;25(2):1-16. doi: 10.1117/1.JBO.25.2.027001.
Colorectal cancer is one of the major causes of cancer-related deaths worldwide. Surgical removal of the cancerous growth is the primary treatment for this disease. A colorectal cancer surgery, however, is often unsuccessful due to the anastomotic failure that may occur following the surgical incision. Prevention of an anastomotic failure requires continuous monitoring of intestinal tissue viability during and after colorectal surgery. To date, no clinical technology exists for the dynamic and continuous monitoring of the intestinal perfusion.
A dual-wavelength indwelling bowel photoplethysmography (PPG) sensor for the continuous monitoring of intestinal viability was proposed and characterized through a set of in silico and in vivo investigations.
The in silico investigation was based on a Monte Carlo model that was executed to quantify the variables such as penetration depth and detected intensity with respect to the sensor-tissue separations and tissue perfusion. Utilizing the simulated information, an indwelling reflectance PPG sensor was designed and tested on 20 healthy volunteers. Two sets of in vivo studies were performed using the driving current intensities 20 and 40 mA for a comparative analysis, using buccal tissue as a proxy tissue-site.
Both simulated and experimental results showed the efficacy of the sensor to acquire good signals through the "contact" to a "noncontact" separation of 5 mm. A very slow wavelength-dependent variation was shown in the detected intensity at the normal and hypoxic states of the tissue, whereas a decay in the intensity was found with the increasing submucosal-blood volume. The simulated detected-to-incident-photon-ratio and the experimental signal-to-noise ratio exhibited strong positive correlations, with the Pearson product-moment correlation coefficient R ranging between 0.65 and 0.87.
The detailed feasibility analysis presented will lead to clinical trials utilizing the proposed sensor.
结直肠癌是全球癌症相关死亡的主要原因之一。手术切除癌性生长是这种疾病的主要治疗方法。然而，由于手术后可能发生吻合口失败，结直肠手术后的手术往往不成功。预防吻合口失败需要在结直肠手术后持续监测肠组织活力。迄今为止，没有临床技术用于动态和连续监测肠道灌注。
提出了一种用于连续监测肠活力的双波长留置式肠光体积描记术 (PPG) 传感器，并通过一系列体内外研究对其进行了特征描述。
体内外研究基于蒙特卡罗模型，该模型用于量化传感器与组织分离和组织灌注的穿透深度和检测强度等变量。利用模拟信息，设计了一种留置反射式 PPG 传感器，并在 20 名健康志愿者身上进行了测试。使用 20 和 40 mA 两种电流强度进行了两组体内研究，以颊组织为替代组织部位进行了比较分析。
模拟和实验结果均表明，该传感器能够通过“接触”到 5 毫米的“非接触”分离来获取良好的信号。在组织的正常和缺氧状态下，检测强度表现出非常缓慢的波长依赖性变化，而随着黏膜下血液体积的增加，强度衰减。模拟的检测到的与入射光子比和实验的信噪比表现出很强的正相关，皮尔逊积矩相关系数 R 介于 0.65 到 0.87 之间。
提出的传感器的详细可行性分析将导致临床试验的开展。
