Hemostasis is the natural process that stops blood loss when an injury occurs.It involves three steps: (1) vascular spasm (vasoconstriction); (2) platelet plug formation; and (3) coagulation. Vasoconstriction is a reflex in which blood vessels narrow to increase blood pressure. Next, platelet plug formation involves the activation, aggregation, and adherence of platelets into a plug that serves as a barrier against blood flow.
Study 25 Chapter 8 Hemostasis flashcards from Mayra D. On StudyBlue. Difficulty breathing, chest pain, changes in skin color or temperature. Changes in vital signs & open bleeding wounds.
Coagulation involves a complex cascade in which a fibrin mesh is cleaved from fibrinogen. Fibrin acts as a 'molecular glue' during clot formation, holding the platelet plug together. Coagulometers are automated or semiautomated.
Semiautomated coagulometers require the operator to deliver test plasma and reagents manually to the reaction cuvette and limit testing to one or two specimens at a time. They are relatively inexpensive, but their use requires considerable operator expertise. Fully automated analyzers provide pipetting systems that automatically transfer reagents and test plasma to reaction vessels and measure the end point without operator intervention (Table 47-1). Multiple specimens can be tested simultaneously. Automated coagulometers are expensive, and laboratory staff require specialized training to operate and maintain them.
Regardless of technology, all semiautomated and automated analyzers offer better coagulation testing accuracy and precision than visual methods.