In the classification of shock, which of the following is characterized by inadequate oxygen delivery due to reduced cardiac output despite normal or elevated systemic vascular resistance?

Explanation

## Shock Classification by Pathophysiology **Key Point:** Cardiogenic shock results from primary cardiac dysfunction leading to reduced cardiac output (CO), which is the defining feature that distinguishes it from other shock states. ### Cardiogenic Shock Characteristics | Parameter | Cardiogenic Shock | | --- | --- | | **Cardiac Output** | ↓ (< 2.2 L/min/m²) | | **Systemic Vascular Resistance (SVR)** | ↑ Normal or elevated | | **Central Venous Pressure (CVP)** | ↑ Elevated | | **Pulmonary Capillary Wedge Pressure (PCWP)** | ↑ Elevated | | **Oxygen Delivery (DO₂)** | ↓ Inadequate | **High-Yield:** The hallmark of cardiogenic shock is the combination of: - Low cardiac output - High filling pressures (elevated CVP and PCWP) - Elevated SVR (compensatory vasoconstriction) - Inadequate tissue oxygen delivery ### Comparison with Other Shock Types | Shock Type | CO | SVR | CVP/PCWP | Mechanism | | --- | --- | --- | --- | --- | | **Cardiogenic** | ↓ | ↑ | ↑ | Pump failure | | **Hypovolemic** | ↓ | ↑ | ↓ | Volume loss | | **Septic (early)** | ↑ | ↓ | ↓ | Vasodilation | | **Anaphylactic** | ↓ | ↓ | ↓ | Vasodilation + myocardial depression | **Clinical Pearl:** In cardiogenic shock, the body attempts compensatory vasoconstriction to maintain blood pressure, but this increases cardiac afterload and worsens the situation—a vicious cycle that distinguishes it from distributive shocks where SVR is low. **Mnemonic:** **PUMP** = Cardiogenic shock - **P**ressures elevated (CVP, PCWP) - **U**tput reduced (CO) - **M**yocardial dysfunction - **P**erfusion inadequate [cite:Harrison 21e Ch 330]