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5.7 Differentiating between the shock states

Mar 8, 2025

Types of Shock: Comparative Analysis

This lecture provides an advanced overview of different types of shock, focusing on key physiological parameters to differentiate them. These include:

  • Cardiac Output (CO): Volume of blood pumped by the heart per minute.
  • Systemic Vascular Resistance (SVR): Resistance of the blood vessels.
  • Pulmonary Capillary Wedge Pressure (PCWP): Indicates heart's ability to pump fluid forward.
  • Left Ventricular End Diastolic Volume (LVEDV): Blood volume in the left ventricle at relaxation end.
  • Mixed Venous Oxygen Saturation (MVO2): Measures oxygen content in blood, indicating oxygen extraction by tissues.

Types of Shock

1. Cardiogenic Shock

  • Cause: Heart's inability to pump.
  • Effects:
    • Decreased cardiac output.
    • Elevated systemic vascular resistance.
    • Increased PCWP and LVEDV (fluid backup).
    • Lower MVO2 (due to increased tissue oxygen extraction).

2. Obstructive Shock

  • Cause: Obstruction preventing blood flow.
  • Similar to Cardiogenic Shock:
    • Increased PCWP (fluid backup).
    • Elevated SVR (compensatory mechanism).
    • Lower MVO2 due to high oxygen extraction.
  • Differentiation: Patient history and symptom onset.

3. Hypovolemic Shock

  • Cause: Low blood volume.
  • Effects:
    • Low cardiac output due to reduced fluid return.
    • Elevated SVR as compensation.
    • Low MVO2 (intense tissue oxygen extraction).
    • Decreased ventricular volume.

4. Neurogenic Shock

  • Cause: Impaired sympathetic response.
  • Effects:
    • Decreased sympathetic tone to heart and vessels.
    • Bradycardia (unique feature).
    • Decrease in pressure and mixed venous oxygen.

5. Septic Shock

  • Cause: Immune response to infection.
  • Effects:
    • Systemic vasodilation (reduced SVR).
    • Variable cardiac output (initially elevated, reduced later).
    • Oxygen extraction affected (elevated or decreased MVO2).

6. Anaphylactic Shock

  • Cause: Allergic reactions causing swelling.
  • Effects:
    • Decreased SVR due to dilated vessels.
    • Elevated cardiac output.
    • Variable PCWP.

7. Dissociative Shock

  • Cause: Oxygen not dissociating from red blood cells.
  • Effects:
    • Increased cardiac output and SVR.
    • Lowered MVO2 due to poor oxygen delivery to tissues.
  • Characteristic: Tissue starvation despite increased circulation.

Conclusion

  • Review the chart provided in the lecture to reinforce understanding.
  • Understand the physiological mechanisms leading to decreased oxygen perfusion in each type of shock.

Full transcript