Shock is a state of circulatory failure resulting in inadequate tissue perfusion and oxygen delivery, leading to cellular hypoxia and organ dysfunction.
| Type of shock | Mechanism | Causes | Suggestive features |
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| Hypovolaemic | ↓ Circulating volume → ↓ preload → ↓ cardiac output |
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| Cardiogenic | Pump failure → ↓ cardiac output |
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| Obstructive | Mechanical obstruction to cardiac output |
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| Distributive | Vasodilation → ↓ systemic vascular resistance |
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Disclaimer: Neurogenic shock may be considered a distinct fifth type of shock or grouped under distributive shock due to its underlying vasodilatory mechanism. Both approaches are used in clinical practice.
Unlike other forms of distributive shock, neurogenic shock presents with bradycardia (rather than tachycardia), typically in the context of spinal cord injury.