Episode Details

1. The Continuum: Perfusion Failures

• Shock: Decreased tissue perfusion causing a life-threatening cellular O2 supply/demand imbalance.
• SIRS: Systemic inflammation from infection, trauma, or ischemia, causing capillary leak and endothelial damage.
• Sepsis & Septic Shock: Sepsis is infection + dysregulated host response + organ dysfunction (altered mentation, SBP ≤100, RR ≥22, lactate >1 mmol/L). Septic shock is a subset with persistent hypotension requiring vasopressors to maintain MAP ≥65 mmHg despite aggressive fluid resuscitation.
• MODS: Failure of ≥2 organ systems. Lungs (ARDS) are usually the first to fail.

2. The 4 Main Shock Types

• Cardiogenic: Pump failure (commonly MI). Low CO (<4 L/min), high preload (PAWP, CVP), and high afterload (SVR). Shows pulmonary crackles, cool/clammy skin.
• Hypovolemic: Volume deficit (absolute: hemorrhage, GI loss; relative: burns, third-spacing). Low preload (CVP, PAWP), low CO, high compensatory SVR.
• Distributive: Vasodilation & relative hypovolemia.
  • Neurogenic: Spinal injury ≥T5; loss of SNS tone causes massive vasodilation. Sign: hypotension with bradycardia, dry/warm skin.
  • Anaphylactic: Allergic reaction causing bronchospasm, laryngeal edema, and capillary leak. First line: Epinephrine (IM/IV).
  • Septic: Cytokine-mediated endothelial damage, microthrombi (DIC risk), and hypermetabolism. Early phase: high CO, low SVR (warm, flushed skin).
• Obstructive: Physical block to flow (PE, tamponade, tension pneumothorax). Shows JVD, pulsus paradoxus, low CO, high SVR.

3. Stages of Shock

• Initial: Cellular anaerobic metabolism, lactic acid buildup; clinically silent.
• Compensatory: SNS activation shunts blood to heart/brain. Tachypnea, tachycardia, cool skin (except early sepsis), activated RAAS, decreased bowel sounds.
• Progressive: Compensatory failure. Capillary leak (anasarca), profound hypotension (MAP <60), dysrhythmias, ARDS, ischemic gut, AKI (high creatinine, oliguria), and DIC.
• Refractory: Multi-organ failure, profound hypoxia, unresponsive to therapy.

4. Priority Nursing & Intensivist Actions

• Hour-1 Sepsis Bundle: 1) Measure/remeasure lactate if >2; 2) Blood cultures before antibiotics; 3) Broad-spectrum antibiotics; 4) 30 mL/kg crystalloid for hypotension/lactate ≥2; 5) Vasopressors (Norepinephrine is 1st choice) for MAP ≥65.
• Evaluation: Passive leg raise (PLR) challenge checks fluid responsiveness. Monitor urine output (goal >0.5 mL/kg/hr).
• Nutrition: Start trophic enteral nutrition (10 mL/hr) within 24h to protect gut mucosa.