Optical Coherence Tomography To Investigate Optical Properties Of Blood During Coagulation Under Various Flow Conditions

Blood coagulation，which contains a series of biochemistry reactions, is a very complexprocess that was important to maintain the balance of physiological conditions. But abnormalcoagulating process may cause some serious related disease, such as the disordered formation ofembolism and thrombosis. Therefore, to develop high-efficiency techniques to monitoring bloodcoagulation process in early stage in clinical diagnosis become more and more imperative. Opticalcoherence tomography (OCT) realized the real time and non-invasive monitoring in the live body.The OCT technology use low-coherence light, which is different from traditional test methods,such as optical and acoustic techniques. This paper based on OCT technology to explore thevariation of optical property of blood during coagulation under various flow conditions.1/e light penetration depth (d1/e) was developed to reflect the changes of optical properties ofblood during coagulation. The OCT system was used to enhance the accuracy and sensitivity ofthe detection due to the center wavelength of840nm and the light source bandwidth of95nm.The process of blood coagulation was triggered and begin to time when adding the calciumchloride solution (Ca2+).Experimental results indicated that d1/ewas able to differentiate the different sections ofcoagulation course. The refractive index mismatching between the blood cells and blood plasmawas decreased and then remained invariable in the entire process of blood coagulation due to theincreasing refractive index of plasma and the unchanged refractive index of red blood cells. d1/evs.time were obtained from the profiles of reflectance against depth. Results showed that1) theconcentration of Ca2+(c, mmol/L) was an important factor of the blood coagulation, thecoagulation time (Tc) decreased with the increasing concentration ranging from5mmol/L to25mmol/L while increased in the range of25mmol/L to50mmol/L;2) the flow velocity (ν,mm/sec) also have remarkable influence on the process of coagulation. The d1/eincreased by0.0201mm,0.0498mm,0.0647mm and0.0771mm and the clotting time was685±44.5,990±33.7, 1147±104.9and1472±127.1sec for the blood samples at velocity of5,15,20, and25mm/sec,respectively;3) tubing sizes(d, mm) from0.9-mm to2-mm lead to the Tc increased from577.5±97s to1635±47.8s and the Sr descended from6.2997±0.342to3.882±0.068;4) After40min clotting, d1/e increased by27.62%,12.21%,25.13%and28.98%and the clotting time was607±57,963±83,1098±72and1229±69sec for the blood samples at HCT of25,35,45, and55%,respectively. The optical parameters vs time curve was abnormal during the blood clotting processat the samples HCT of55%. In a word, the four factors studied in this paper all have obviousinfluence on the course of blood coagulation. The calcium chloride with final concentration of25mmol/L was optimum, the increasing of flowing velocity and tubing size lead to the increase ofcoagulation time. In the normal range of the HCT, the lower of the HCT, the shorter time of bloodclotting.