Research Centre for Biomedical Engineering, School of Mathematics, Computer Science & Engineering, City, University of London, London, United Kingdom. Author to whom any correspondence should be addressed.
Physiol Meas. 2018 Jul 3;39(7):075001. doi: 10.1088/1361-6579/aacc1d.
Intestinal anastomotic failure that occurs mainly due to ischaemia is a serious risk in colorectal cancer patients undergoing surgery. Surgeons continue to rely on subjective methods such as visual inspection to assess intestinal viability during surgery and there are no clinical tools to directly monitor viability postoperatively. A dual-wavelength reflectance optical sensor has been developed for continuous and dynamic monitoring of intestinal viability via the intestinal lumen. Maintaining direct contact between the sensor and the inner intestinal wall can be difficult in an intraluminal design, therefore impacting on signal acquisition and quality. This paper investigates the effect of direct contact versus variable distances between the sensor and the tissue surface of the buccal mucosa as a surrogate.
The in vivo study involved 20 healthy volunteers to measure the effect of optical sensor-tissue distances on the ability to acquire photoplethysmography signals and their quality. Signals were acquired from the buccal mucosa at five optical sensor-tissue distances.
Distances between 0 mm (contact) to 5 mm were the most optimal, producing signals of high quality and signal-to-noise ratio, resulting in reliable estimations of the blood oxygen saturation. Distances exceeding 5 mm compromised the acquired signals, and were of poor quality, thereby unreliably estimating the blood oxygen saturation.
The developed optical sensor proved to be reliable for acquiring photoplethysmography signals for cases where distances between the optical sensor-tissue may arise during the assessment of intraluminal intestinal viability.
结直肠肿瘤患者术后吻合口失败主要是由于缺血所致，这是一个严重的风险。外科医生在手术过程中仍然依赖于视觉检查等主观方法来评估肠的活力，目前还没有临床工具可以直接监测术后的活力。一种双波长反射式光学传感器已经被开发出来，用于通过肠腔对肠活力进行连续和动态监测。在腔内设计中，传感器与肠内壁保持直接接触可能很困难，这会影响信号的获取和质量。本文研究了传感器与颊黏膜组织表面之间直接接触与可变距离对获取光体积描记信号及其质量的影响。
这项体内研究涉及 20 名健康志愿者，以测量光学传感器-组织距离对获取光体积描记信号及其质量的能力的影响。在五个光学传感器-组织距离处从颊黏膜获取信号。
0 毫米（接触）到 5 毫米之间的距离是最理想的，产生高质量和高信噪比的信号，从而能够可靠地估计血氧饱和度。超过 5 毫米的距离会影响信号的获取，并且信号质量较差，从而无法可靠地估计血氧饱和度。
所开发的光学传感器被证明在评估腔内肠活力时，在光学传感器-组织之间可能出现距离的情况下，能够可靠地获取光体积描记信号。
