A 35-year-old woman with severe sepsis from urinary tract infection presents with hypotension, warm skin, and bounding pulses. Her systemic vascular resistance (SVR) is markedly reduced. Which hemodynamic finding best distinguishes septic shock from cardiogenic shock?

Question

Accepted Answer

D. Low SVR with normal or elevated cardiac output in early phase. ## Distinguishing Septic from Cardiogenic Shock

### Pathophysiologic Contrast
Septic and cardiogenic shock represent opposite hemodynamic extremes: septic shock is characterized by **vasodilation and distributive failure**, while cardiogenic shock is characterized by **pump failure with vasoconstriction**.

### Hemodynamic Profile Comparison

| Parameter | Septic Shock (Early) | Cardiogenic Shock |
|-----------|----------------------|-------------------|
| **SVR** | ↓↓ Markedly reduced | ↑ Elevated |
| **Cardiac Output** | ↑ Normal or elevated | ↓ Decreased |
| **PCWP** | ↓ Low or normal | ↑ Elevated (>18 mmHg) |
| **CVP** | Variable | ↑ Elevated |
| **Skin perfusion** | Warm, flushed | Cold, clammy |
| **Lactate** | Elevated | Elevated |
| **Mechanism** | Vasodilation + maldistribution | Myocardial pump failure |

**Key Point:** The **hallmark of septic shock is low SVR with maintained or elevated cardiac output** in the early (warm) phase. This is due to endotoxin-mediated vasodilation, loss of autoregulation, and AV shunting. In cardiogenic shock, the heart cannot pump effectively, so cardiac output falls and SVR rises as a compensatory mechanism.

### Clinical Pearl
Septic shock patients have **warm extremities and bounding pulses** (high cardiac output state) despite hypotension, whereas cardiogenic shock patients have **cold extremities and weak pulses** (low cardiac output state). This clinical distinction mirrors the hemodynamic difference.

**High-Yield:** Early septic shock = **warm shock** (vasodilation); late septic shock may progress to **cold shock** (refractory hypotension with reduced cardiac output). Cardiogenic shock = **cold shock** from the outset.

**Mnemonic:** **WARM vs COLD**
- **W**arm = septic (vasodilation, high CO, low SVR)
- **C**old = cardiogenic (pump failure, low CO, high SVR)

![Shock — Types and Mechanisms diagram](https://mmcphlazjonnzmdysowq.supabase.co/storage/v1/object/public/blog-images/explanation/21205.webp)

Answer

A. Elevated pulmonary capillary wedge pressure

Answer

B. Elevated central venous pressure with pulmonary edema

Answer

C. Severe reduction in cardiac output

A 35-year-old woman with severe sepsis from urinary tract infection presents with hypotension, warm skin, and bounding pulses. Her systemic vascular resistance (SVR) is markedly reduced. Which hemodynamic finding best distinguishes septic shock from cardiogenic shock?

Explanation

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