Continuous estimation of blood concentration of substances using photo-technology

这个项目的目的是利用光纤导管和先进的光技术相结合来估计各种物质的血液浓度。1.制造光学仪器这种光学仪器可以提供和接收八种波长的光，是为雅培光纤导管设计的。这一多波长光学仪器能够测量血液中物质的光吸收和荧光。2.血液内物质的研究1)光吸光度研究吲哚青绿(ICG)、靛红、磺酸盐卡巴克罗姆和葡萄糖作为光吸光剂。其中，ICG最适合于这一测量。虽然葡萄糖不吸收任何波长的可见光，但其吸收光谱与水在近红外荧光中的吸收光谱略有不同。2)我们研究了核黄素和异丙酚作为荧光剂。荧光强度与核黄素浓度相关。异丙酚在血浆中由于蛋白结合而不发出荧光。3.体外研究试管中ICG浓度与荧光强度的关系。ICG浓度与荧光强度的线性关系最高可达3μg/ml，在三种不同血红蛋白浓度的血样中，这种关系几乎相同。4.活体实验：新西兰大白兔。经右颈静脉置入5.5Fr Abbott光导纤维导管。导管尖端分别置于上腔静脉、右心房和下腔静脉3个位置，记录每个位置830 nm的信号输出。在噪声最小的位置注射ICG 5 mg。静脉注射5 mg的ICG可提供足够强度的830 nm荧光信号。

The purpose of this project was to estimate blood concentrations of various substances using fibre-optic catheter in combination with advanced photo-technology.1.Producing an optical instrumentThis optical instrument that is able to supply and receive eight kinds of wavelengths of light, was designed for the Abbott fibre-optic catheters. This multi wavelengths optical instrument enabled to measure light absorption and fluorescence of intra-blood substances.2.Searching intra-blood substancesWe investigated several intravenous agents and native substances in vitro as candidates of the subjects in this project.1)Light absorbentWe studied indocyanin green (ICG), indigo carmine, sulphonate carbachrom, and glucose as light absorbents. Among them ICG was the most suitable for this measurement. Although glucose did not absorb any wavelength of visible light, its absorption spectrum was slightly different from that of water in near infrared.2)FluorescentWe studied riboflavin and propofol as fluorescents. Intensity of the fluorescence correlated to the concentration of riboflavin. Propofol in plasma did not emit fluorescence because of protein binding.3.In vitro studyRelationship between ICG concentration and the fluorescence intensity was studied in blood samples in a tube. The relationship between ICG concentration and the fluorescence intensity was linear up to 3 μg/ml, and this relationship was almost same in the three blood samples of different haemoglobin concentrations.4.In vivo studyNew Zealand White rabbits were studied. A 5.5 Fr Abbott fibre-optic catheter was inserted from right jugular vein. The tip of catheter was placed at three positions ; superior vena cava, right atrium and inferior vena cava, and recorded 830 nm signal output at each position. At the position of the minimum noise 5 mg of ICG was injected. The 5 mg of ICG injected intravenously provided sufficient intensity of 830 nm fluorescence signal.