The automatic coagulation analysis instrument, also known as the coagulation instrument, is primarily utilized in laboratory examinations to analyze blood clot formation and hemostasis. It provides crucial information for diagnosing and differentiating hemorrhagic and thrombotic diseases, as well as monitoring thrombolysis and anticoagulation treatments. Various types of coagulation instruments employ distinct principles in their operation. Presently, the primary detection methods used include the coagulation method, substrate chromogenic method, immune method, and latex agglutination method. Now, let's delve into the detection method employed by the automatic coagulation analysis instrument, specifically, the coagulation method.
The coagulation technique involves analyzing variations in several physical parameters such as light, electricity, mechanical movement, and others to detect changes. This approach employs the laws governing these physical phenomena to determine the outcome.
There are three main categories of coagulation methods utilized in automatic coagulation analysis instruments: the current method, optical method, and magnetic bead method. These methods are employed to effectively analyze and detect coagulation processes.
1. Current method
The existing approach relies on the fact that fibrinogen lacks conductivity, while fibrin possesses conductivity. In this method, the sample being tested is incorporated into a circuit, and the formation of fibrin is determined by monitoring the change in circuit current throughout the coagulation process. However, due to its limited reliability and narrow scope, this current method was swiftly replaced by the more sensitive and versatile optical method.
2. Optical method (nephelometric method)
The optical analysis instrument for coagulation measurement is designed to assess the coagulation function by monitoring changes in turbidity during the coagulation process. It determines the endpoint of detection by analyzing the light variations in the tested sample as coagulation occurs. With the addition of a coagulation activator, the light intensity gradually increases as fibrin clot formation takes place. This evolving optical change is represented as a coagulation curve. Once the sample is fully coagulated, the light intensity stabilizes. The key advantages of optical coagulation detection include its high sensitivity, simple instrument structure, and ease of automation. However, it is worth noting that optical abnormalities in the sample, smoothness of the detection cup, and presence of air bubbles can all pose interference factors during measurement. By rearranging the provided information, we retain the essential details of the original content while presenting it in a slightly different manner.
3. Magnetic bead method
The initial magnetic bead method automated coagulation analysis instrument operates by placing a magnetic bead in the detection cup, which is in close proximity to a ferromagnetic metal rod outside the cup in a straight line. As soon as the sample solidifies, the magnetic bead will shift due to the formation of fibrin. This deviation from the metal rod serves as the endpoint detection for the instrument. This technique is also known as the planar magnetic bead method. The early planar magnetic bead approach was successful in overcoming the sample background interference issue encountered in the optical method, but it lacked sensitivity as a drawback.
In the late 1980s, an innovative method using magnetic beads emerged, which soon transitioned into commercial use in the early 1990s. This method, known as the dual magnetic circuit magnetic bead method, revolutionized the field. It operates on the principle of detection, wherein a pair of driving coils are positioned on both sides of a detection cup. These coils generate a constant alternating electromagnetic field, resulting in continuous and consistent oscillation of specialized demagnetized small steel balls within the cup.
To analyze the process further, once a coagulation activator is introduced, the production of fibrin increases, causing the plasma viscosity to rise. Consequently, the movement amplitude of the small steel balls gradually diminishes. This critical change in motion is detected by another set of measuring coils incorporated in the automatic coagulation analysis instrument. The instrument detects the decrease in movement amplitude and determines the endpoint of coagulation when the decay reaches 50%.
This highly efficient dual magnetic circuit magnetic bead method has significantly advanced coagulation analysis by accurately monitoring and evaluating the coagulation process. Its ability to sense subtle changes in small steel ball movement enables precise determination of the endpoint of coagulation, offering valuable insights for medical diagnostics and treatments.
