Shock Classifications and Pathogenesis

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Questions and Answers

What are the different categories of shock?

Hypovolemic (correct)

Cardiogenic (correct)

Distributive (correct)

Metabolic/regulatory (correct)

Obstructive (correct)

What is shock?

Shock is a state in which diminished cardiac output or reduced effective circulating blood volume impairs tissue perfusion and leads to cellular hypoxia.

What is hypovolemic shock and its subcategories?

Hypovolemic shock is cellular hypoxia caused by decreased cardiac output secondary to an insufficient blood volume. It has two subcategories: hemorrhagic and non-hemorrhagic.

What etiologies of shock are classified as distributive?

Distributive shock includes septic, anaphylactic, and neurogenic causes. Signup and view all the answers

What is distributive shock?

Distributive shock is the redistribution of circulating volume into tissues or accumulation of circulating volume within the vasculature where it's able to pool. Signup and view all the answers

What is obstructive shock?

Obstructive shock is caused by physical blockage of blood flow or external compression of the heart which reduces cardiac output. Signup and view all the answers

What is cardiogenic shock?

Cardiogenic shock is caused by insufficient cardiac output due to a primary defect within the heart itself, leading to a lack of tissue perfusion and cellular hypoxia. Signup and view all the answers

What is metabolic/respiratory shock?

Metabolic/respiratory shock is cellular hypoxia caused by defects in oxygen transport, delivery, or utilization by tissues even with normal cardiac function. Signup and view all the answers

How does cardiogenic shock affect cardiac output, systemic vascular resistance, and wedge pressure?

Cardiac output decreases, systemic vascular resistance increases, and wedge pressure increases. Signup and view all the answers

How does hypovolemic shock affect cardiac output, systemic vascular resistance, and wedge pressure?

Cardiac output decreases, systemic vascular resistance increases, and wedge pressure decreases. Signup and view all the answers

What changes occur to the cardiac output, systemic vascular resistance, and wedge pressure during distributive shock?

Cardiac output is increased or normal, systemic vascular resistance is decreased, and wedge pressure is normal or decreased. Signup and view all the answers

What is the difference between shock categories, shock stages, and shock classifications?

Shock classifications refer to the organization of etiologies and pathogenesis leading to shock. Shock stages describe the progression of clinical symptoms and the body's compensatory ability. Shock categories relate to a patient's hemodynamic profile. Signup and view all the answers

What are the three stages of shock?

Irreversible Shock Signup and view all the answers

What organelle damage is associated with the transition from progressive to irreversible shock?

Damage to mitochondria is associated with the transition from progressive to irreversible shock. Signup and view all the answers

What are the major compensatory mechanisms active in compensated shock?

CNS Ischemic Reflex, Baroreceptor Reflex, RAAS, ADH, and Sympathetics are major compensatory mechanisms during compensated shock. Signup and view all the answers

How does the transition from aerobic to anaerobic metabolism affect shock progression?

Anaerobic metabolism lowers pH and cannot produce enough energy to regenerate cellular stores, causing vasodilation and decreasing cardiac output, worsening hypoxia. Signup and view all the answers

What is the only class of shock where the patient's skin temperature is normal or elevated?

Distributive shock is the only class of shock where the skin temperature may be normal or elevated. Signup and view all the answers

Study Notes

Categories of Shock

Five categories based on etiology: Hypovolemic, Distributive, Obstructive, Cardiogenic, and Metabolic/Regulatory.
Each type impairs tissue perfusion leading to cellular hypoxia.

Definition of Shock

Characterized by diminished cardiac output or reduced circulating blood volume, impacting tissue perfusion.

Hypovolemic Shock

Results from decreased cardiac output caused by insufficient blood volume.
Subcategories:
- Hemorrhagic Shock: Due to whole blood loss from bleeding.
- Non-Hemorrhagic Shock: Due to plasma volume loss without significant RBC loss.

Distributive Shock

Includes septic, anaphylactic, and neurogenic shock.
Causes decreased tissue perfusion through fluid redistribution due to increased vessel permeability (septic and anaphylactic) or massive vasodilation (neurogenic).

Neurogenic Shock

Results from loss of sympathetic tone and massive vasodilation, pulling volume away from the heart.

Obstructive Shock

Caused by physical blockage or external compression of blood flow, reducing cardiac output.
Common etiologies include: Pulmonary Embolism, Cardiac Tamponade, and Tension Pneumothorax.

Cardiogenic Shock

Insufficient cardiac output due to primary heart defects; leads to tissue hypoxia.

Metabolic/Respiratory Shock

Occurs despite normal cardiac function; results from defects in oxygen transport, delivery, or utilization by tissues.

Hemodynamic Changes in Shock Types

Cardiogenic Shock: Decreased CO, increased SVR, and increased Wedge Pressure.
Hypovolemic Shock: Decreased CO, increased SVR, and decreased Wedge Pressure.
Distributive Shock: Increased or normal CO, decreased SVR, and decreased or normal Wedge Pressure.
Obstructive Shock: Decreased CO, increased SVR, and normal or decreased Wedge Pressure (especially in pulmonary embolism).

Transition and Progression in Shock

Shift from aerobic to anaerobic metabolism leads to lactic acid production and intracellular ion imbalances.
Major compensatory mechanisms in compensated shock include: CNS Ischemic Reflex, Baroreceptor Reflex, RAAS, ADH, and Sympathetics.

Stages of Shock

Compensated Shock: Normal functional state maintained through reflex mechanisms.
Progressive Shock: Compensatory mechanisms fail; hypoperfusion causes metabolic and circulatory disturbances.
Irreversible Shock: Permanent damage occurs due to lack of tissue perfusion.

Mitochondrial Dysfunction

Transition from progressive to irreversible shock associated with mitochondrial damage due to persistent hypoxia.

Cutaneous Manifestations

Normal or elevated skin temperature observed in distributive shock due to systemic vasodilation, unlike other shock types where blood is shunted away from the skin.

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Description

This quiz explores the various classifications of shock, including hypovolemic, distributive, obstructive, cardiogenic, and metabolic/regulatory. It also covers the definition of shock and its impact on tissue perfusion and cellular hypoxia. Perfect for medical students and healthcare professionals.