| Blood coagulation,which contains a series of biochemistry reactions, plays significant roles in maintaining the normal function of physiological system. Effective coagulation can protect humans from the blood loss while abnormal coagulating process may cause some serious diseases such as thrombosis and coagulopathy. Fibrinogen is an important blood coagulation factor which has an important effect on the normal function of coagulation. Therefore, it is essential to propose an in vitro method for analysis of the interaction of fibrinogen concentration with blood coagulation. Optical coherence tomography can realize longitudinal and cross-sectional assessment of tissue structure which based on the classical Michelson interferometer and has advantages in realizing the real time and non- invasive dection. Besides, our previous studies have made great progress in monitoring the blood coagulation by OCT technique.In this study, 1/e light penetration depth(d1/e) was developed to reflect the changes of optical properties of blood during coagulation under static and flow ing condition. It took the dynamic study of d1/e to characterize the whole blood coagulation process. The effect of various concentrations on coagulation was completed under static and flowing condition. Furthermore, effect of calcium concentration, hematocrits(HCT) and blood flow rate on the clotting time under various fibrinogen concentrations were studied.Experimental results indicated that the variation of d1/e was feasible to detect the coagulation of the blood sample with various fibrinogen concentrations. Time-course changes in d1/e of the blood samples increased markedly then changed to a small extent with an approximate horizontal asymptote.After the blood sample with HCT of 35% was studied under static condition, t he IV clotting time of 588±13.86, 448.7±13.61, 364±2.65, 314.3±8.14 and 266±10.44 s was fibrinogen-concentration dependent and decreased with the increase of additional concentrations in 2, 4, 6, 8 and 10 g/L, respectively. At the HCT of 45%, the tc derived from d1/e – time plot was approximately 665.3±12.66, 564±7.21, 513.3±7.23, 453±8.89 and 395±5s for the clotted blood with additional fibrinogen of 2, 4, 6, and 8 g/L, respectively. As to the results deriving from the porcine native blood at HCT of 55%, they were readily obtained from d1/e – time plot corresponding to the commercial fibrinogen concentration of 0, 2, 4, 6, and 8 g/L with the t decreased from 901±6.56, 812.3±26.31, 592±14.42, 536±32.14 to 506.7±4.73 s. These results demonstrated that the coagulation time was inversely proportional to the concentration of fibrinogen at any HCTs in our experiment i.e. the blood samples with higher concentration of fibrinogen prefer to coagulate spending less time. Similar results can be obtained from the reconstituted samples with the freeze-thawing treated plasma of various fibrinogen concentrations. The concentration of Ca2+ was an important factor of the blood coagulation, t decreased from, 714.7±6.03, 559.3±15.14 s to 419.7±14.67 s with the increasing concentration ranging from 0.05, 0.15 to 0.25mol/L. At the same time, this study demonstrated that the clotting time was proportional to the HCT, t ranged from 743.7±11s, 811.7±11.6s, to 901±6.56 s corresponding with the HCT of 35%, 45%, 55%. Effects of HCT on clotting time of the blood under various fibrinogen concentrations were also similar.In order to better simulate the process of coagulation, we made the experiments on the flowing blood, then, drew the conclusion that the fibrinogen takes the same effects to accelerate the coagulation of the flowing blood. The coagulation time under different flowing velocity were derived from the d1/e-time course corresponding with the additional fibrinogen concentration of 0, 2, 4, 6, and 8 g/L. According with the experiment operation, it was easily to discriminate the coagulation time decreased from 714±11.93 s to 621.7±19.86 s, 508±11.53 s, 468±8.02 s and 411.7±7.51 s under static condition. Next, the coagulation time ranged from 863.7±12.1s to 751±19.52 s,629±11.36 s, 544.7±7.09 s, 503.7±14.5s and 440.7±8.62 s when the flowing velocity was 5mm/s. After this, the flowing velocity was set as 10mm/s, then the coagulation time were changing to 1050.7±13.5s, 988±9.64 s, 887.7±11.5s, 831.7±5.51 s, and 751±5.03 s. Finally, the coagulation time decreased according to the order of 1153.7±6.11 s, 1045±8.33 s, 967.3±7.02 s, 898±10.14 s, 830.3±9.29 s when the flowing velocity was set as 15mm/s. Meanwhile, the coagulation corresponding with the experimental concentrations order ra nged from 735±10s, 634.7±4.16 s, 538.7±18.5s, 439.3±16.04 s, 389±5s, 339.3±5.69 s when the HC T was 35%. Besides, the coagulation time decreased following the sequence of 967.3±19.1s, 848.7±9.61 s, 743.7±15.18 s, 640.3±14.74 s, 601±3s, 521±10.54 s at the HCT of 55%. All experimental results indicated that the coagulation time was inversely proportional to the concentration of fibrinogen under the flowing condition. the coagulation time was decreased by the increasing amount of fibrinogen. Moreover, the flow velocity and HCT also made great influences on the process of coagulation. It took more time to complete the coagulation when the HCT and flow velocity were increasing. Thus, it is feasible to detect the fibrinogen effect on coagulation. Meanwhile, we carefully concluded that OCT should be a useful and promising tool of clinical test. |
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