Coagulation pet clinical application knowledge
What is coagulation?
Blood coagulation, referred to as coagulation, refers to the process in which blood changes from a flowing liquid state to a non-flowable gel state. The essence of blood coagulation is the process by which soluble fibrinogen in plasma becomes insoluble fibrin.
The coagulation system includes both coagulation and anticoagulation. The dynamic balance between the two is the key to maintaining the body's blood fluid flow and preventing blood loss.
Coagulation mechanism
Endogenous coagulation pathway
It refers to the participation of all coagulation factors from blood (endogenous), from factor XII activation to factor X activation.
Exogenous coagulation pathway
It means that not all of the participating clotting factors are present in the blood, and there are foreign clotting factors involved in stopping bleeding. This process is initiated by exposure of tissue factor to blood and to the activation of factor X.
Common pathway of coagulation
Activation from factor X to fibrin formation is a common coagulation pathway for endogenous and exogenous coagulation. It mainly includes two stages of thrombin generation and fibrin formation.
As a screening tool for abnormal blood coagulation, the coagulation analyzer is an indispensable testing device in hospitals. It plays an important role in preoperative examination and intraoperative risk diagnosis, anticoagulation and thrombolytic therapy monitoring, and physical examination of middle-aged and elderly animals. . The application of the coagulation analyzer makes the hemostasis and thrombus examinations simple, accurate and reliable, and greatly meets the needs of clinical diagnosis and treatment.
1. Screening for endogenous and exogenous coagulation functions, such as preoperative screening, to reduce the risk of surgery.
2. Medication monitoring for oral or injection of anticoagulant drugs, such as monitoring of drug use for thrombosis.
3. Investigation of the activity, defects and function of related coagulation factors, such as canine Werber disease.
4, monitoring of intravascular coagulation, thrombosis and thrombolytic therapy to determine the prognosis of animals.
5. Monitoring of various diseases such as tumors, burns, infections and hepatitis.
Second, the test project
Prothrombin time (PT)
Refers to the time required for prothrombin to be converted to thrombin after the addition of excess tissue factor in plasma lacking platelets, resulting in plasma coagulation.
As a screening test for exogenous coagulation system, it is also an important means of clinical oral anticoagulant therapy dose control.
PT primarily tests the function of pre-activation of the coagulation cascade (coagulation factors II, V, VII, X) and the final common pathway. Since factor VII is the vitamin K-dependent coagulation factor with the shortest half-life, PT is also considered to be an early indicator of vitamin K deficiency.
PT extension
More common in severe liver disease, vitamin K deficiency, DIC and so on.
PT shortening
More common in early DIC, after ether anesthesia.
Activated partial thromboplastin time (APTT)
It refers to the artificial addition of special substances to activate the endogenous coagulation pathway to coagulate blood.
It mainly tests the integrity of the endogenous pathway and the final common pathway of the coagulation cascade, and reflects the levels of blood coagulation factors VIII, IX, XI, and XII in the blood plasma. It is a screening test for the endogenous coagulation system.
Heparin anticoagulant therapy is monitored by APTT.
APTT extension
More common in the lack of blood coagulation factors XII, XI, IX, and VIII or long-term vitamin K deficiency, severe liver disease, rodenticide poisoning, DIC and so on.
APTT shortened
More common in cerebral thrombosis, myocardial infarction, DIC hypercoagulable period.
Thrombin time (TT)
Refers to the time of blood coagulation after the addition of standardized thrombin to plasma. In the common coagulation pathway, the produced thrombin converts fibrinogen to fibrin, which can be reflected by TT.
TT extension
More common in hereditary fibrinogen deficiency; severe coagulation (shock, severe infection, tumor) in the body leads to excessive consumption of fibrinogen; DIC; severe liver disease; when the activity of AT-III in circulating blood is significantly increased.
Shortening has no clinical significance.
Activated clotting time (ACT)
It is commonly used as an indicator for monitoring the anticoagulant efficacy of heparin in extracorporeal circulation It is sometimes used in conjunction with the PT trial to determine if bleeding is due to an excess of anticoagulant or due to clotting factor consumption.
ACT extension
Commonly, platelets are significantly reduced, blood coagulation factors are severely deficient, and anticoagulant drugs are taken.
Fibrinogen (FIB)
An acutely reactive protein that is synthesized by the liver and has a coagulation function.
FIB increase
Stress, acute infection, burns, atherosclerosis, acute myocardial infarction, autoimmune diseases, multiple myeloma, diabetes, uremia, etc.
FIB reduction
DIC, congenital fibrinogen abnormalities, severe hepatitis, cirrhosis, and thrombolytic therapy.
