Septic shock vs Cardiogenic shock
How to tell Septic shock and Cardiogenic shock apart when a board question makes them look alike.
Septic shock is low-SVR vasodilation; cardiogenic shock is pump failure with high filling pressures.
Side by side
Infection-driven distributive shock with low SVR, high/normal cardiac output early, fever, and warm extremities early.
Pump-failure shock with low cardiac output, pulmonary edema, cool extremities, elevated JVP, and high filling pressures.
Inflammatory vasodilation and capillary leak lower systemic vascular resistance.
Myocardial pump failure reduces forward flow and backs pressure into the lungs.
High lactate with suspected infection and low SVR supports septic shock.
High PCWP, pulmonary edema, and low cardiac output favor cardiogenic shock.
The trap
Skin temperature does not decide shock type. Late septic shock can drop cardiac output and present with cold, mottled extremities that mimic cardiogenic. The deciding combination is SVR and PCWP: low SVR with normal-or-high cardiac output and low-to-normal PCWP is septic; high SVR with low cardiac output and high PCWP is cardiogenic. When a Swan-Ganz is not available, an early bedside echo (poor LV function = cardiogenic) plus lactate and infection workup carries the decision.
Watch it explained
The repair move
Classify shock by SVR, cardiac output, and filling pressures before naming the cause.
Try a free question
CoreA patient with pneumonia has hypotension, fever, warm extremities, bounding pulses, elevated lactate, high cardiac output, and low systemic vascular resistance. Which shock state is most likely?
Show answer and explanation
Answer: A. Septic shock. Early septic shock is distributive: low SVR with warm extremities and high/normal cardiac output.
Why the other choices are tempting
- B. Cardiogenic shock is pump failure with low cardiac output and high filling pressures.
- C. Hypovolemic shock has low preload and usually cool extremities.
- D. Obstructive shock needs a mechanical block such as tamponade or tension pneumothorax.
- E. Neurogenic shock has loss of sympathetic tone, often with bradycardia.
Flashcards
Tap a card to flip it.
What hemodynamic variable separates septic from cardiogenic shock fastest?
Septic shock is low-SVR distributive physiology; cardiogenic shock has pump failure with high filling pressures.
Why can early septic shock have warm extremities?
Inflammatory vasodilation lowers vascular resistance, so extremities may be warm before late cold shock develops.
Quick answers
What is the fastest way to tell Septic shock from Cardiogenic shock?
Septic shock is low-SVR vasodilation; cardiogenic shock is pump failure with high filling pressures.
What is the key clue for Septic shock?
Infection-driven distributive shock with low SVR, high/normal cardiac output early, fever, and warm extremities early.
What is the key clue for Cardiogenic shock?
Pump-failure shock with low cardiac output, pulmonary edema, cool extremities, elevated JVP, and high filling pressures.
What is the common trap with Septic shock vs Cardiogenic shock?
Skin temperature does not decide shock type. Late septic shock can drop cardiac output and present with cold, mottled extremities that mimic cardiogenic. The deciding combination is SVR and PCWP: low SVR with normal-or-high cardiac output and low-to-normal PCWP is septic; high SVR with low cardiac output and high PCWP is cardiogenic. When a Swan-Ganz is not available, an early bedside echo (poor LV function = cardiogenic) plus lactate and infection workup carries the decision.