Shock Syndromes and Management

Shock Syndromes and Management

Shock Syndromes and Management

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Shock: Definition & Classification - Perfusion Plunge

  • Shock: Critical state of ↓ tissue perfusion & O₂ delivery → cellular hypoxia & organ dysfunction.
  • Classification & Primary Defect:
    • Hypovolemic: ↓ Intravascular volume (e.g., hemorrhage, dehydration).
    • Cardiogenic: Pump failure (e.g., MI, severe arrhythmia).
    • Distributive: Vasodilation, ↓SVR (e.g., Sepsis, Anaphylaxis). 📌 SANe (Septic, Anaphylactic, Neurogenic).
    • Obstructive: Extracardiac flow obstruction (e.g., PE, Tamponade, tension pneumothorax).
  • Key Markers:
    • MAP < 65 mmHg (resuscitation target).
    • Lactate > 2 mmol/L (tissue hypoxia).
    • Oliguria (< 0.5 mL/kg/hr).

⭐ In early septic shock (hyperdynamic phase), cardiac output may be normal or ↑, but tissue oxygen extraction is impaired, often reflected by a normal or ↑ ScvO₂/SvO₂.

Shock: Pathophysiology - Cellular Mayhem

  • Initiating Event: Systemic hypoperfusion → ↓$O_2$ delivery → cellular hypoxia.
  • Energy Depletion: ↓ATP production → shift to anaerobic glycolysis → ↑lactic acid (Lactate >2 mmol/L, pH <7.35).
  • Membrane Dysfunction: $Na^+$ / $K^+$ pump failure → $Na^+$ & $H_2O$ influx → cellular swelling, organelle damage.
  • Calcium Overload: ↑Intracellular $Ca^{2+}$ → activates proteases, phospholipases → further cell injury.
  • Mitochondrial Breakdown: Critical point of no return → triggers apoptosis/necrosis.
  • Inflammatory Response: Release of damaging mediators (cytokines, ROS, NO).

⭐ Mitochondrial dysfunction is a key irreversible step in shock-induced cellular injury, leading to ATP depletion and cell death.

Shock: Diagnosis - Code Red Clues

  • Core Vital Signs & Mental Status:
    • Hypotension: SBP < 90 mmHg or MAP < 65 mmHg.
    • Tachycardia: HR > 100 bpm (Shock Index: $HR/SBP > \textbf{0.9}$ indicates stress).
    • Tachypnea: RR > 22/min.
    • Altered Mental Status: New confusion, lethargy (GCS < 15).
  • Peripheral Hypoperfusion Markers:
    • Skin: Cool, clammy, pale/mottled (warm in early distributive shock).
    • Capillary Refill Time (CRT): > 3 sec.
    • Oliguria: Urine Output < 0.5 mL/kg/hr.
  • Key Lab Indicators:
    • Serum Lactate: > 2 mmol/L.
    • Base Deficit: < -4 mEq/L (or worsening).

⭐ > Elevated serum lactate (> 2 mmol/L) is a critical marker of tissue hypoperfusion and strongly correlates with increased mortality in shock.

Shock: Management - Lifeline Tactics

Immediate Goals: Restore tissue perfusion, prevent organ damage. Optimize oxygen delivery ($DO_2$) and reduce oxygen consumption ($VO_2$). 📌 Mnemonic (VIP): Ventilate, Infuse, Pump.

  • Airway & Breathing:
    • Oxygen: High flow, target SpO₂ > 94%.
    • Intubate if GCS < 8 or respiratory failure.
  • Circulation:
    • Access: Two large-bore (16-18G) IV lines.
    • Fluids: Crystalloids (NS/RL) 20-30 mL/kg bolus. Reassess.
      • Caution: Cardiogenic shock.
    • Vasopressors (if MAP < 65 mmHg post-fluids):
      • Norepinephrine: 0.01-3 mcg/kg/min (1st line septic/undifferentiated).
    • Inotropes (e.g., Dobutamine 2-20 mcg/kg/min) if myocardial dysfunction.
  • Monitoring:
    • Vitals, Urine Output (> 0.5 mL/kg/hr), Lactate clearance.
    • Target MAP ≥ 65 mmHg.

⭐ For septic shock, Surviving Sepsis Campaign guidelines recommend initiating vasopressors if MAP remains < 65 mmHg during or after fluid resuscitation to maintain perfusion.

Shock Management Algorithm

High‑Yield Points - ⚡ Biggest Takeaways

  • Septic shock: Norepinephrine first-line; target MAP ≥65 mmHg.
  • Distributive shock (septic, anaphylactic): Key feature is ↓SVR, often warm peripheries.
  • Cardiogenic shock: Presents with ↓CO, ↑PCWP, ↑SVR; treat cardiac cause.
  • Hypovolemic shock: Priority is rapid crystalloid infusion & controlling loss.
  • Obstructive shock (tamponade, tension pneumothorax, PE): Requires urgent specific intervention.
  • Lactate elevation indicates tissue hypoperfusion; guides resuscitation.
  • Recognize compensated shock (normal BP, ↑HR, cool skin) early for better outcomes.

Practice Questions: Shock Syndromes and Management

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What is the treatment for class I hypovolemic shock?

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Flashcards: Shock Syndromes and Management

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The Systemic Inflammatory Response Syndrome (SIRS) is defined by e2 of the following:Temp: >_____ or 90 bpmWBC: >12,000 or 10%RR: >20 breaths/min or PaCO2 <32 mmHg

TAP TO REVEAL ANSWER

The Systemic Inflammatory Response Syndrome (SIRS) is defined by e2 of the following:Temp: >_____ or 90 bpmWBC: >12,000 or 10%RR: >20 breaths/min or PaCO2 <32 mmHg

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