A 3-year-old child presents with shock. On examination, the child has warm extremities, bounding pulses, and a wide pulse pressure. Capillary refill is brisk. Which feature best distinguishes septic shock from hypovolemic shock in this presentation?

Explanation

## Distinguishing Septic from Hypovolemic Shock ### Key Clinical Feature **Key Point:** Warm peripheries with bounding pulses and wide pulse pressure are hallmark signs of **distributive shock (septic shock)**, whereas hypovolemic shock presents with cold, clammy extremities, weak pulses, and narrow pulse pressure. ### Pathophysiology **High-Yield:** In septic shock, peripheral vasodilation caused by inflammatory mediators (TNF-α, IL-1, nitric oxide) leads to: - Warm skin and mucous membranes - Bounding pulses (due to high cardiac output and low SVR) - Wide pulse pressure - Brisk capillary refill In hypovolemic shock, reduced circulating volume causes: - Compensatory vasoconstriction → cold extremities - Weak, thready pulses - Narrow pulse pressure - Delayed capillary refill (>2 seconds) ### Comparison Table | Feature | Septic Shock | Hypovolemic Shock | | --- | --- | --- | | **Skin temperature** | Warm | Cold, clammy | | **Pulse quality** | Bounding, full | Weak, thready | | **Pulse pressure** | Wide | Narrow | | **Capillary refill** | Brisk (<2 sec) | Delayed (>2 sec) | | **SVR** | Low | High | | **Cardiac output (early)** | High | Low | | **Urine output** | May be preserved initially | Oliguria | ### Clinical Pearl **Clinical Pearl:** The presence of warm shock (warm peripheries) in a febrile child with signs of systemic inflammation is virtually pathognomonic for septic shock and is the single best discriminator from hypovolemic shock at the bedside. ### Why Other Features Are Non-Discriminatory Elevated lactate, tachycardia, and metabolic acidosis occur in **both** septic and hypovolemic shock as markers of tissue hypoperfusion and anaerobic metabolism. These are not discriminating features. [cite:Nelson Textbook of Pediatrics 21e Ch 180]