Cardiogenic shock management

Cardiogenic shock management

Cardiogenic shock management

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Pathophysiology & Diagnosis - The Failing Pump

  • Vicious Cycle: A primary cardiac insult (e.g., large MI) drastically reduces contractility, leading to a sharp ↓ in Cardiac Output (CO) and subsequent hypotension.
  • Maladaptive Compensation: The body's response-↑ sympathetic tone and ↑ Systemic Vascular Resistance (SVR)-paradoxically increases cardiac afterload and myocardial oxygen demand, which further impairs pump function and worsens ischemia.
  • Diagnosis: Based on clinical signs of hypoperfusion (cool, clammy skin; altered mental status; oliguria) and congestion (JVD, rales).
    • Hemodynamic Criteria (Invasive Monitoring):
      • Systolic BP < 90 mmHg
      • Pulmonary Capillary Wedge Pressure (PCWP) > 18 mmHg
      • Cardiac Index (CI) < 2.2 L/min/m²

⭐ The classic hemodynamic signature is a low Cardiac Index (< 2.2) with a high PCWP (> 18), differentiating it from hypovolemic or distributive shock.

Cardiogenic Shock Classification and Hemodynamic Profile

Initial Management - First-Response ABCs

  • A - Airway: Assess patency. Low threshold for endotracheal intubation in patients with altered mental status or impending respiratory collapse to reduce the work of breathing.
  • B - Breathing:
    • Administer supplemental O₂ to maintain SpO₂ > 90%.
    • Consider Non-Invasive Positive Pressure Ventilation (NIPPV) for acute pulmonary edema if the patient is alert and hemodynamically stable.
    • Proceed to mechanical ventilation if NIPPV fails or is contraindicated.
  • C - Circulation:
    • Secure 2 large-bore peripheral IVs.
    • Treat unstable arrhythmias (tachycardia/bradycardia) per ACLS.
    • ⚠️ Judicious fluid challenge: 250-500 mL isotonic crystalloid only if no signs of fluid overload (e.g., pulmonary rales).

⭐ Unlike other shock types, large-volume fluid resuscitation is harmful in cardiogenic shock as it exacerbates pulmonary edema and cardiac strain.

Chest X-ray and CT: Cardiogenic Pulmonary Edema

Pharmacotherapy - Potent Potion Push

  • Goal: Improve cardiac output (CO) & maintain mean arterial pressure (MAP) > 65 mmHg.

  • First-line therapy depends on blood pressure.

  • Key Agents:

    • Norepinephrine: α1 > β1 agonist. ↑SVR, ↑MAP. First choice in hypotension.
    • Dobutamine: β1 > β2 agonist. ↑CO, ↓SVR. Can cause hypotension. Use when BP is stable or with a pressor.
    • Milrinone: PDE-3 inhibitor. Inodilator (↑CO, ↓SVR). Useful if patient is on beta-blockers.
    • Diuretics (Furosemide): Use cautiously for pulmonary congestion if BP allows.

⭐ In cardiogenic shock with profound hypotension, norepinephrine is the initial vasopressor of choice. Dobutamine can be added once MAP is stabilized (>65 mmHg) to specifically improve cardiac contractility and output.

Common Inotropes and Vasopressors: Dosing and Half-life

Mechanical Support - The Big Guns

  • Intra-Aortic Balloon Pump (IABP):
    • Mechanism: Counter-pulsation. Inflates in diastole (↑coronary perfusion), deflates in systole (↓afterload).
    • Provides modest hemodynamic support.
    • ⚠️ CI: Significant aortic regurgitation, aortic dissection.
  • Percutaneous VADs (e.g., Impella):
    • Mechanism: Axial flow pump actively pulls blood from the left ventricle to the aorta.
    • Directly unloads the LV, providing superior support to IABP.
  • VA-ECMO (Veno-Arterial ECMO):
    • Provides full cardiopulmonary support; highest level of support.

    VA-ECMO increases LV afterload, which can worsen pulmonary edema. May require LV venting (e.g., with an Impella).

VA-ECMO with LV Venting Strategies for Cardiogenic Shock

High‑Yield Points - ⚡ Biggest Takeaways

  • Cardiogenic shock is defined by low cardiac output and high PCWP (>18 mmHg).
  • Initial stabilization may require inotropes (dobutamine) and vasopressors (norepinephrine).
  • Use IV fluids cautiously or not at all, as they can worsen pulmonary edema.
  • Definitive treatment targets the underlying cause, most commonly urgent revascularization for acute MI.
  • Intra-aortic balloon pump (IABP) can serve as a bridge to definitive therapy.
  • Avoid beta-blockers and nitrates during the acute hypotensive phase.

Practice Questions: Cardiogenic shock management

Test your understanding with these related questions

A 40-year-old Caucasian male presents to the emergency room after being shot in the arm in a hunting accident. His shirt is soaked through with blood. He has a blood pressure of 65/40, a heart rate of 122, and his skin is pale, cool to the touch, and moist. This patient is most likely experiencing all of the following EXCEPT:

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Flashcards: Cardiogenic shock management

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Which major medical insurance plan limits patients to a network of doctors, specialists, and hospitals without requirement of referrals?_____

TAP TO REVEAL ANSWER

Which major medical insurance plan limits patients to a network of doctors, specialists, and hospitals without requirement of referrals?_____

Exclusive provider organization (EPO)

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