Ramirez Francisco C, Padda Sukhdeep, Medlin Susan, Tarbell Helen, Leung Felix W
Research Service, Carl T. Hayden VA Medical Center, Phoenix, Arizona 85012, USA.
Am J Gastroenterol. 2002 Nov;97(11):2780-4. doi: 10.1111/j.1572-0241.2002.07022.x.
Reflectance spectrophotometry (RS) assesses blood flow changes by measuring an index of Hb concentration (IHB) and index of Hb oxygen saturation (ISO2). We tested the following hypotheses: 1) endoscopic RS measurements obtained by two observers and with the aid of fiber optic and video endoscopes are similar, and 2) the method is suitable for documenting mesenteric venoconstriction associated with systemic hypoxia and blood flow autoregulation associated with hemorrhagic hypotension.
Study 1: two investigators obtained baseline gastric mucosal RS measurements in anesthetized rats (n = 3) before and after stepwise reduction of blood pressure induced by arterial hemorrhage. Study 2: subjects were examined by both fiber optic and video endoscopes. Endoscopic RS measurements were obtained at 20 cm from the anal verge. Study 3: video endoscope was used to obtain RS measurements in oxygen-dependent patients on and off oxygen treatment. Study 4: the procedures in study 1 were repeated in five additional rats by one of the investigators.
Study 1: there was good agreement between the measurements of IHB and ISO2 between the two investigators. Study 2: video endoscope-assisted measurements were consistently lower. Study 3: cessation of oxygen treatment produced a significant drop in oxygen saturation (pulse oximetry), decline in ISO2, and rise in IHB. Study 4: when blood pressure varied between 90% and 40% of baseline, gastric mucosal blood flow (IHB) was maintained at approximately 70% of baseline level.
We confirmed that reproducible measurement can be obtained by different investigators using standardized techniques. Standardization of endoscopic equipment is also necessary to overcome the significant limitation of endoscopic equipment on RS measurements. RS measurements can document mesenteric venoconstriction associated with systemic hypoxia and blood flow autoregulation associated with hemorrhagic hypotension.
反射分光光度法（RS）通过测量血红蛋白浓度指数（IHB）和血红蛋白氧饱和度指数（ISO2）来评估血流变化。我们检验了以下假设：1）由两名观察者借助纤维光学和视频内窥镜获得的内镜RS测量结果相似；2）该方法适用于记录与全身缺氧相关的肠系膜静脉收缩以及与出血性低血压相关的血流自动调节。
研究1：两名研究者在麻醉大鼠（n = 3）中，通过动脉出血逐步降低血压前后，获取胃黏膜RS基线测量值。研究2：受试者同时接受纤维光学和视频内窥镜检查。在内镜距离肛门边缘20 cm处进行RS测量。研究3：使用视频内窥镜对接受和未接受氧疗的氧依赖患者进行RS测量。研究4：其中一名研究者在另外五只大鼠中重复研究1的操作。
研究1：两名研究者对IHB和ISO2的测量结果具有良好的一致性。研究2：视频内窥镜辅助测量结果始终较低。研究3：停止氧疗导致氧饱和度（脉搏血氧饱和度）显著下降、ISO2降低以及IHB升高。研究4：当血压在基线的90%至40%之间变化时，胃黏膜血流（IHB）维持在基线水平的约70%。
我们证实不同研究者使用标准化技术可获得可重复的测量结果。为克服内镜设备对RS测量的显著限制，内镜设备的标准化也很有必要。RS测量可记录与全身缺氧相关的肠系膜静脉收缩以及与出血性低血压相关的血流自动调节。
