Hemodynamic Disorders and Edema Quiz

Hemodynamic Disorders, Thromboembolic Disease and Shock

• The presentation covers hemodynamic disorders, thromboembolic diseases, and shock.
• Objectives include recognizing different types of hemodynamic disorders, understanding thromboembolism and its complications, and distinguishing various types of shock.
• A disclosure indicates most images are from Elsevier Inc.

Edema and Effusions

• Edema and effusions are fluid accumulation in tissues (edema) or body cavities (effusions).
• Hydrostatic pressure pushes fluid out of capillaries into interstitial space, while colloid osmotic pressure pulls it back.
• Imbalance due to high hydrostatic pressure or low colloid osmotic pressure leads to fluid accumulation.
• Fluid accumulates if fluid movement out of vessels exceeds lymphatic drainage.
• Edema is fluid in tissues; effusion is fluid in body cavities

Edema

• About 60% of lean body weight is water.
• Two-thirds of body water is intracellular.
• Most of the remainder is found in the extracellular space as interstitial fluid.
• About 5% of total body water is in blood plasma.

Types of Edema

• Increased hydrostatic pressure: impaired venous return; congestive heart failure; constrictive pericarditis; ascites; venous obstruction/compression; thrombosis; external pressure; inactivity/prolonged dependency; heat.
• Reduced plasma osmotic pressure: protein-losing glomerulopathies; liver cirrhosis; malnutrition; protein-losing gastroenteropathy; lymphatic obstruction; inflammatory conditions; neoplastic conditions; post-surgical; post-irradiation.
• Sodium retention: excessive salt intake; renal insufficiency; increased tubular reabsorption of sodium; renal hypoperfusion; increased renin-angiotensin-aldosterone secretion.
• Inflammation: acute inflammation; chronic inflammation; angiogenesis.

Morphology of Edema

• Edema fluid is typically subtle cell swelling with separation of extracellular matrix elements.
• Edema distribution varies depending on the cause and hydrostatic pressure points (dependent parts of the body like legs, sacrum).
• Pulmonary edema is characterized by increased lung weight and blood-tinged frothy fluid upon sectioning.
• Brain edema is characterized by grossly swollen brain, narrowed sulci, and flattened against the skull.

Hyperemia and Congestion

• Hyperemia and congestion both involve increased blood volume in a tissue.
• Hyperemia is active (arteriolar dilation) driven by increased tissue inflow.
• Congestion is passive (impaired outflow) leading to reduced blood flow.
• Congestion often results in cyanosis due to deoxygenated hemoglobin buildup.
• Congestion and edema frequently occur together.
• Capillary rupture can happen with chronic congestion, leading to small clusters of hemosiderin-laden macrophages.

Hemorrhage

• Hemorrhage refers to blood extravasation due to vessel rupture.
• Capillary bleeding can result from chronic congestion and increased tendency to injury.
• Large vessel rupture often results from vascular injury.
• Hemorrhage manifests as various patterns.
• Hematoma: enclosed blood in tissue (can range from minor bruises to fatal).
• Petechiae: minute (1-2mm) hemorrhages in skin or mucosal membranes, often associated with low platelets or clotting factor deficits.
• Purpura: slightly larger (>3mm) hemorrhages, potentially related to similar conditions as petechiae, trauma, inflammation, or increased vascular fragility.
• Ecchymoses: large (>1-2cm) subcutaneous hematomas, often associated with trauma.
• Degraded erythrocytes lead to hemoglobin conversion to bilirubin and eventually hemosiderin, influencing hematoma color.
• Large blood accumulation in body cavities is called hemothorax, hemopericardium, hemoperitoneum, or hemarthrosis.

Hemostasis and Thrombosis

• Normal hemostasis involves maintaining a clot-free blood state in healthy vessels and inducing a rapid localized hemostatic plug at a site of injury.
• It is the opposite of thrombosis, a pathological condition of blood clotting.
• Regulation of hemostasis/thrombosis involves the vascular wall, platelets, and the coagulation cascade.

Normal Hemostasis

• Primary hemostasis: involves vasoconstriction, platelet adhesion, shape change, granule release, and aggregation to form an initial hemostatic plug.
• Secondary hemostasis: involves tissue factor exposure, thrombin activation, fibrin polymerization, formation of a stable fibrin and platelet aggregate plug to prevent further bleeding.
• Clot stabilization and resorption: stabilized fibrin and platelet aggregates undergo contraction which is followed by clot resorption and tissue repair.

Inhibit Thrombosis vs. Favor Thrombosis

• Inhibititing thrombosis mechanisms are factors that regulate the coagulation cascade to prevent over-activation of platelets and clotting.
• Favoring thrombosis mechanisms typically increase blood coagulation, damage blood vessels, disrupt blood flow (stasis).

Platelets

• Platelets contain alpha and dense bodies which are specific types of granules containing various substances with roles in mediating normal hemostasis responses.
• Platelets play key roles in adhesion and secretion as well as in aggregation processes which allow them to form a stable plug to prevent further bleeding.

Fate of the Thrombus

• Thrombi, if they survive the immediate effects of obstruction of vascular flow, may undergo various processes like progression (increase in thrombus size by accumulation of fibrin and platelets), embolization (dislodgement and travel to other parts of the circulatory system), dissolution (removal by fibrinolysis which is the process of dissolving or breaking down fibrin in an organism), or organization/recanalization (induction of inflammation and fibrosis that may lead to reestablishment of vessel function or being incorporated into the vessel wall).

Disseminated Intravascular Coagulation (DIC)

• DIC is a sudden or insidious condition characterized by widespread fibrin thrombi in microcirculation.
• It can cause considerable circulatory issues in organs such as the brain, lungs, heart, and kidneys.
• A rapid consumption of clotting factors and platelets leads to a consumption coagulopathy which is characterized by an initially thrombotic disorder that can subsequently evolve into a serious bleeding disorder.

Embolism

• An embolus is a detached mass (solid, liquid, or gaseous) carried by the blood stream to a distant site.
• Most emboli originate from dislodged thrombi.
• Embolism is categorized as thromboembolic, fat, air, or amniotic fluid emboli depending on the source.

Pulmonary Thromboembolism

• Pulmonary thromboembolism is a common and potentially fatal event where a thromboembolism (blood clot) lodges in the pulmonary artery, frequently originating from deep vein thrombi (DVTs) of the leg.
• Symptoms, depending on size/location of the embolic event can range from silent, to sudden death or right heart failure.
• Diagnosis and treatment can vary depending on a number of risk factors.

Systemic Thromboembolism

• Systemic thromboembolism results from emboli traveling through the arterial circulation.
• Emboli frequently develop from thrombi within the heart's chambers or large arteries.
• The body's response to a systemic embolus, depends on the extent of collateral vascular supply to affected tissue, the tissue's vulnerability to ischemia, and caliber of the occluded vessel.

Fat Embolism

• Fat embolism results from fat release due to marrow or adipose tissue injury and is typically seen in individuals with severe skeletal injuries.
• Fat emboli circulate in the bloodstream often causing neurologic, pulmonary problems, and anemia.
• Clinical presentation can vary but is typically seen within 1 to 3 days after injury due to a rapid set of symptoms and progression to potentially fatal outcome.

Air Embolism

• Air embolism is a complication of procedures that can introduce excess air into the circulatory system (e.g. some obstetric procedures, or chest wall injuries).
• Symptoms and clinical presentation depend on volume of air introduced, affected vessels location, and presence or absence of other complications.
• Treatment of air embolism may involve inducing pressure changes to push air bubbles into solution.

Amniotic Fluid Embolism

• Amniotic fluid embolism (AFE) is a rare but serious complication of pregnancy typically occurring during labor or shortly after delivery.
• It can present as sudden respiratory distress, cyanosis, and/or hemorrhagic shock.
• Pathophysiology includes amniotic fluid infusion with contents into the maternal circulation leading to activation of coagulation pathways and resulting in pulmonary complications, widespread coagulation (DIC), and potential death.

Infarction

• An infarct is an area of ischemic necrosis due to occlusion in either arterial supply and/or venous drainage.
• Infarcts are primarily caused by thromboembolic/embolic events. Infarcts can also be caused by other issues like vessel vasospasm, expansion of atherosclerotic plaque or extrinsic compression.
• Infarct morphology classifies infarcts based on the degree of hemorrhage and presence of infection.
• Red infarcts are hemorrhagic, and white infarcts are anemic. Septate infarcts are those that include infection.

Shock

• Shock is a life-threatening condition with inadequate tissue perfusion, causing cellular hypoxia and dysfunction, culminating in potential death if not managed appropriately.
• Types of shock: cardiogenic, hypovolemic, neurogenic, anaphylactic, and septic.
• Clinical presentation and pathophysiology of different shock types vary.
• Stages of shock: Non-progressive, progressive, and irreversible.

Questions?

• The presentation concludes with a prompt for questions.