Serum is one of the main samples for clinical biochemical, immune and other tests. At present, the method of obtaining serum samples in medical institutions is mainly by collecting venous blood and centrifuging it after the blood is completely coagulated. Under normal circumstances, it takes more than 60 minutes for blood samples to be completely coagulated after isolation, which is difficult to meet the needs of rapid laboratory testing. The containers used for collecting venous blood samples in medical institutions mainly include blood collection tubes with coagulant or blood samples collected with disposable syringes and then injected into non-vacuum containers. The materials of the containers are glass or plastic.
The coagulation process needs to include at least three basic biochemical reactions:
① Formation of prothrombin activator;
②Prothrombin activator converts prothrombin into active thrombin with the participation of calcium ions;
③ Soluble fibrinogen is converted into insoluble fibrin under the action of thrombin. Macroscopic clot formation is both a physical phenomenon of fibrin formation and the final point of a series of enzymatic biochemical reactions.
There are many clotting factors involved in the whole process. Under physiological conditions, coagulation factors are generally in an inactive state. When these coagulation factors are activated, a series of enzymatic reactions that are still recognized as the "waterfall theory of coagulation mechanism" will occur and lead to blood coagulation. Tissue factor, namely tissue thromboplastin or coagulation factor III, is the only coagulation factor that does not exist in animal blood. It is a lipoprotein, and its main component is phospholipid. Tissue factor lipoprotein is widely present in animal tissues such as brain, lung and placenta. It is released after tissue damage, acts on the extrinsic coagulation system, and promotes coagulation with the endogenous coagulation system products under the catalysis of thrombin. Coagulation pathway to achieve coagulation effect.
The main function of blood coagulants is to accelerate blood coagulation, that is, to shorten the blood coagulation time in vitro without affecting the necessary components of blood, and to promote serum separation.
The performance evaluation of blood coagulants should be considered from the following aspects:
1) Coagulation time: the time required for blood to fully coagulate after contacting with the coagulant.
2) Procoagulation efficiency: the relative amount of coagulant added to make the blood achieve the best coagulation effect.
3) Coagulation effect: the amount of serum exudation after blood coagulation.
4) Separation effect: whether the blood after coagulation can achieve complete and clear separation of serum after centrifugation, and whether hemolysis occurs.
5) Effects on essential components of blood: The use of coagulants cannot have a harmful effect on the clinical test results of blood and the performance and quality of blood products.
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