Hemodynamic Disorders and Thrombosis

Hemodynamic Disorders, Thrombosis, and Shock

• Proper circulation is essential for delivering oxygen and removing waste from cells and tissues.
• Fluid homeostasis ensures blood remains liquid until clotting is necessary.

Hemostasis and Thrombosis

• Normal hemostasis involves regulated processes to keep blood fluid in vessels and quickly form clots at injury sites.
• Key components include the vascular wall, platelets, and the coagulation cascade.

Endothelial Cells

• Endothelial cells balance anti- and prothrombotic activities influencing thrombus formation.
• Under normal conditions, they exhibit antiplatelet, anticoagulant, and fibrinolytic properties.
• Endothelial injury leads to prothrombotic changes, facilitating platelet adhesion via von Willebrand factor (vWF).

Antithrombotic Properties

• Antiplatelet Effects: Inhibits platelet aggregation through prostacyclin (PGI2), nitric oxide, and adenosine diphosphatase.
• Anticoagulant Effects: Utilizes heparin-like molecules and thrombomodulin to prevent clotting.
• Fibrinolytic Effects: Involves tissue plasminogen activator (t-PA) to dissolve clots.

Prothrombotic Properties

• Endothelial injury increases platelet adhesion and activates the coagulation cascade, generating tissue factor in response to cytokines.
• Endothelial cells can also secrete plasminogen activator inhibitors (PAIs), limiting fibrinolysis.

Platelet Function

• Platelets are crucial in hemostasis, adhering to extracellular matrix through vWF.
• After adhesion, they release contents that increase surface expression of phospholipid complexes, promoting aggregation.
• Thrombin plays a key role in converting fibrinogen to fibrin, stabilizing the secondary hemostatic plug.

Coagulation Cascade

• Comprised of sequential proteolytic activations, culminating in thrombin production.
• Antithrombins, proteins C and S, and tissue factor pathway inhibitor (TFPI) control clot formation.
• Fibrinolysis is mediated by plasmin, which breaks down fibrin and is regulated to prevent excessive clot dissolution.

Thrombosis Types

• Venous Thrombosis: Especially prevalent in the legs; superficial thrombosis rarely embolizes, while deep vein thrombosis (DVT) poses serious risks of embolization.
• Cardiac and Arterial Thrombosis: Often associated with atherosclerosis and myocardial infarction, leading to mural thrombi.

Embolism

• An embolus is a mass that travels through blood vessels; most are thromboemboli.
• Can also include fat droplets, air bubbles, or foreign bodies, leading to ischemia in downstream tissues.

Pulmonary Thromboembolism

• Occurs in 20 to 25 of 100,000 hospitalized patients annually; causes around 200,000 deaths in the US.
• Originates predominantly from DVTs in the legs; can be asymptomatic or lead to sudden death if significant obstruction occurs.

Systemic Thromboembolism

• Refers to emboli in arterial circulation, mainly from cardiac sources, with common sites including lower extremities and brain.

Risk Factors for Deep Vein Thrombosis

• Immobility, pregnancy, post-surgical state, severe burns, heart failure, and disseminated cancer increase risk.
• High-risk patients need prophylaxis measures like heparin and mechanical leg compression.

Treatment of DVT

• Intravenous heparin and warfarin are standard treatment options.

Fat Embolism

• Occurs after long bone fractures or tissue trauma, leading to the entry of fat globules into circulation.
• Characterized by pulmonary insufficiency, neurological symptoms, and thrombocytopenia, with a fatality rate of about 10%.

Explore the crucial aspects of hemodynamic disorders, thrombosis, and shock in this comprehensive quiz. Understand how normal fluid homeostasis and hemostasis processes contribute to the health of cells and tissues. Test your knowledge on the mechanisms involved in maintaining blood's liquid state until clot formation is necessary.