Development of a system to measure circulating blood volume using infra-red laser.

研制了一种可植入血管床的光纤探头，用于红细胞压积的原位连续测定。该系统由柔性导管型光纤、激光源和激光光电探测器组成。导管由双腔塑料管（外径1.5 mm ;内径0.7 mm）构成，其中安装了发送器和接收器塑料光纤。在顶部形成1 mm的狭缝，连续监测流过狭缝的血液的血细胞比容值。作为光源，用二极管（KLS-810- 3 W，Kette）获得805 nm波长（氧合血红蛋白和脱氧血红蛋白的等吸光波长）的光。用硅光电二极管（S2386- 18 K，Hamamatsu）监测来自接收器光纤的光强度。光强度经光放大器（C2719，Hamamatsu）放大，A/D转换后由PC-386微机（EPSON）记录，用不同红细胞压积的洗涤红细胞悬液对该系统进行了体外评价，结果与Loewinger公式的理论值符合较好。动物实验在麻醉家兔上进行。将光纤探头插入家兔右心房。在体内连续监测红细胞压积值，并将该值与离心法获得的血样红细胞压积值进行比较。在常规方法和本方法获得的值之间观察到高度显著的相关性，尽管在输注盐水后观察到约1%的偏差。这一发现表明，输注的盐水在血管系统中存在不均匀分布。在本实验过程中，我们成功地发展了一种显示组织中氧气分布的方法。通过结合这两种方法，将有可能更详细地分析氧气输送。

Optical fiber probe implantable into vascular bed was developed for in situ determination of hematocrit continuously. This system consists of a flexible catheter-type optical fiber, a laser source, and a laser photo-detector. The catheter was constructed from double-lumen plastic tube(outer diameter, 1.5 mm ; inner diameter, 0.7 mm) in which transmitter and receiver plastic optical fibers were installed. At the top portion, a slit of 1 mm was made, and the hematocrit value of blood flowing through the slit was monitored continuously. As the light source, light with 805-nm wave length (an isosbestic wave length for oxy- and deoxy-hemoglobin) was obtained with diode (KLS-810-3W, Kette). Light intensity from the receiver fiber was monitored with a silicone photo diode (S2386-18K, Hamamatsu). The light intensity was amplified with a photosensor amplifier (C2719, Hamamatsu), and recorded with micro-computer (PC-386, EPSON) after A/D conversion.This system was evaluated in vitro, using suspension solution of washed erythrocyte with varied hemotocrit, which showed high coincidence with the theoretical value by Loewinger's formula. Animal experiments were performed on anesthetized rabbits. The fiber probe was inserted into the right atrium of rabbit. The hematocrit value was monitored continuously in vivo, and the value was compared the hematocrit value obtained with centrifugation method on sampled blood. Highly significant correlation was observed between the values obtained with conventional method and the present method, although about 1% of deviation was observed after infusion of saline. This finding suggests that the existence of uneven distribution of infused saline in blood vessel system.During the course of this experiment, we succeeded to develop a method to visualize oxygen distribution in tissue. By combining these two methods, it will be possible to analyze oxygen delivery in more detail.