CLASE TEÓRICA 9 - TRASTORNOS HIDRODINÁMICOS Y HEMODINÁMICOS PARTE 1

Introduction to Hydro and Hemodynamic Disorders

Definition of Edema

• Dr. Carolina Luque introduces the topic of hydro and hemodynamic disorders, specifically focusing on edema as the accumulation of fluid in interstitial spaces or body cavities.

• The discussion includes potential locations for edema, such as pleural, pericardial, or peritoneal cavities.

Mechanisms of Fluid Movement

• Normal fluid movement is explained through hydrostatic pressure gradients; intravascular fluid exits into interstitial space and returns via oncotic pressure primarily influenced by plasma proteins.

• Lymphatic vessels also play a role in returning excess fluid to the bloodstream.

Pathophysiological Mechanisms Leading to Edema

Increased Hydrostatic Pressure

• Elevated hydrostatic pressure results in increased fluid outflow from arteriolar capillaries, which can overwhelm return mechanisms leading to edema.

• Conditions like heart failure or venous return alterations are highlighted as primary causes of increased hydrostatic pressure.

Decreased Oncotic Pressure

• A reduction in plasma oncotic pressure prevents adequate reabsorption of fluids back into venules, contributing to edema formation.

• Causes include nephrotic syndrome (protein loss), malabsorption syndromes (poor protein absorption), and liver dysfunction affecting protein metabolism.

Other Contributing Factors to Edema

Increased Permeability

• Inflammatory processes lead to vasodilation and increased capillary permeability, resulting in greater fluid leakage into interstitial spaces.

Lymphatic Obstruction

• Obstruction of lymphatic drainage due to tumors or other conditions can cause localized edema due to impaired fluid clearance.

Summary of Edema Causes

Key Pathophysiological Mechanisms

• Increased Hydrostatic Pressure: Often due to congestive heart failure or venous obstruction.

• Decreased Oncotic Pressure: Seen in conditions like cirrhosis or nephrotic syndrome where protein levels drop significantly.

• Lymphatic Obstruction: Can be caused by inflammation, neoplasia, surgical interventions, or radiation therapy.

Clinical Presentation of Cardiac Edema

Characteristics of Cardiac Edema

• Acute pulmonary edema shows alveolar spaces filled with eosinophilic material due to vascular congestion leading to high pressures within blood vessels.

• Postural characteristics are noted; for instance, when standing patients may exhibit swelling in lower extremities while lying down may shift this accumulation based on position.

Clinical Examination of Edema and Its Implications

Understanding Edema in Clinical Context

• The temperature may be decreased due to poor regulation from altered blood flow. The clinical examination reveals the "fobia" sign, where soft tissues are compressed against the tibia, leaving characteristic impressions indicative of edema.

• Renal-origin edema presents distinct clinical features, with loose connective tissue accumulating fluid in areas like the face and external genitalia, leading to a specific appearance associated with renal issues.

Observations on Edema Locations

• Bone color remains unchanged during compression; however, significant edema can be observed in external genitalia and facial areas due to renal function alterations.

• Cerebral edema is illustrated by comparing a normal brain (left) with one exhibiting marked edema (right), emphasizing potential severe complications if untreated, such as death from cerebral edema.

Mechanisms Behind Edema Development

• Compression of rigid structures like the skull can lead to brain displacement towards critical areas affecting vital respiratory centers, potentially resulting in fatal outcomes.

Hiperemia vs. Congestion: Key Differences

Definitions and Processes

• Both hiperemia and congestion involve increased blood volume in tissues but differ fundamentally: hiperemia is an active process while congestion is passive.

Visual Representation of Blood Flow Changes

• Diagrams illustrate capillary beds showing arterioles supplying blood actively during hiperemia (e.g., exercise or inflammation).

• Congestion results from impaired venous outflow leading to increased resistance; conditions like congestive heart failure exemplify this phenomenon.

Chronic Passive Congestion Effects on Liver

Macroscopic and Microscopic Findings

• Images depict liver sections showing dark brown punctate patterns alongside pale yellowish areas; histological views reveal hepatocyte changes surrounding necrotic zones due to inter-hepatic congestion.

Consequences of Right Heart Failure

• Chronic passive congestion often stems from right heart failure, causing difficulties for blood flow through inferior vena cava into right chambers.

Hemorrhage Types and Their Clinical Significance

Classification of Hemorrhages

• Hemorrhage refers to blood exiting the intravascular space into interstitial spaces or body cavities. Various types include:

• Petechiae: small spots (<2mm), often seen on skin/mucosa linked to vascular issues.

• Purpura: larger spots (up to 2cm), associated with trauma or vascular disorders.

• Ecchymosis: large hemorrhages (>2cm), forming subcutaneous hematomas that change color over time.

Importance of Location in Hemorrhage Assessment

Classification of Hemorrhages

Types of Blood Loss

• Blood loss can be classified based on timing; for instance, significant blood loss from a right colon carcinoma differs from sudden blood loss due to an accident.

• Different types of hemorrhages are identified by their location, such as petechiae in extremities and specific patterns observed in the hard and soft palate.

Manifestations and Sizes of Hemorrhages

• Various manifestations include subcutaneous hemorrhages appearing as linear streaks, Osler's nodes at fingertip extremities, and conjunctival petechiae visible on the eyelids.

• Larger lesions like Hanaway lesions are noted on the soles of feet, indicating more extensive bleeding compared to smaller petechiae.

Causes of Major Hemorrhage

• Large hemorrhages may arise from complications such as aortic aneurysms characterized by wall erosion and thinning that can lead to rupture.

• Ruptured aortic aneurysms often result in hemoperitoneum, which is typically fatal due to hypovolemic shock.

Cardiac Implications