Shock: Classification and Management

Shock Fundamentals - The Lowdown Low Flow

• Definition: Critical, life-threatening state of circulatory failure. Results in inadequate oxygen delivery ($DO_2$) to meet cellular oxygen consumption ($VO_2$) and metabolic demands.
• Core Issue: Global tissue hypoperfusion leading to cellular dysoxia (impaired oxygen use).
• Pathophysiology: ↓Perfusion → cellular hypoxia → anaerobic metabolism → ↑lactic acid → metabolic acidosis → cellular injury, organ dysfunction, and ultimately death if uncorrected.

⭐ Lactate is a key marker of tissue hypoperfusion and shock severity.

Shock Types - The Nasty Quartet

Meet the 'Nasty Quartet' of shock: four primary types, each defined by unique underlying causes and distinct hemodynamic profiles. Quick differentiation is absolutely vital.

Shock Sleuthing - Spotting the Signs

Prompt recognition is key. Look for:

• Core Indicators: Hypotension (SBP <90 mmHg or MAP <65 mmHg), tachycardia (>100 bpm), tachypnea (>20/min).
• Perfusion Deficits: Altered mental status, oliguria (<0.5 mL/kg/hr), cool/clammy skin (warm in distributive), delayed capillary refill (>2s), ↑lactate (>2 mmol/L).

⭐ Pulsus paradoxus >10 mmHg is a key finding in cardiac tamponade (obstructive shock).

Shock Solutions - The Rescue Mission

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High‑Yield Points - ⚡ Biggest Takeaways

• Shock is inadequate tissue perfusion; key signs: hypotension, tachycardia, oliguria, altered mental status.
• Initial management: ABCDEs, IV crystalloids, oxygen; target MAP ≥65 mmHg.
• Hypovolemic shock: Aggressive fluid resuscitation and source control.
• Cardiogenic shock: Inotropes (dobutamine) and vasopressors (norepinephrine) for pump failure.
• Septic shock: Early antibiotics, fluids, and norepinephrine. Anaphylactic shock: IM epinephrine.
• Obstructive shock: Relieve obstruction. Monitor lactate clearance and urine output.