8 minute read
Pressure = flow × resistance
MAP ≈ CO × SVR. Shock is inadequate flow, and its four families are the ways that equation fails: the pump (cardiogenic), the tank's fill (hypovolemic), the pipes' tone (distributive), and the circuit's plumbing (obstructive). The bedside sorts them fast: warm or cold periphery, JVP high or low, and the story.
The exam still works
Warm, bounding, low-pressure: distributive. Cold and clamped with a high JVP: cardiogenic or obstructive. Cold with a flat JVP: empty. Lactate then quantifies what the skin suggested, and its clearance is the resuscitation end point.
Pearls
- Blood pressure is the last thing to fall in the young; tachycardia and lactate are earlier witnesses.
- Fluid is a drug with a dose and a stop-rule, decided at ordering time.
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