CARDIOGENIC SHOCK IN THE ICU

Cardiogenic shock = pump failure → ↓ CO/CI → ↓ tissue perfusion → ↑ filling pressures.

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1. Definition 

Cardiogenic shock =

• SBP < 90 mmHg (or MAP < 65)

• Signs of hypoperfusion (lactate ↑, cold extremities, low UOP, AMS)

• Reduced cardiac index (CI < 2.2 L/min/m²)

• Elevated PCWP (> 15 mmHg) if measured

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2. Causes

• Acute MI (MOST common)

• Decompensated HFrEF

• Arrhythmias (VT/VF, AF RVR, bradycardia)

• Mechanical complications (papillary rupture, VSD, free wall rupture)

• Myocarditis

• Severe valvular disease (AS, AR, MR)

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3. Clinical Clues

Findings:

• Cool, pale, clammy skin

• Narrow pulse pressure

• JVD (if RV failure)

• Pulmonary edema

• Weak pulses

• Oliguria

• Elevated lactate

Labs:

• Troponin

• BNP

• Lactate

• ABG: metabolic acidosis

• Renal dysfunction

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4. Echocardiography Findings 

Look for:

• LVEF ↓

• Small LV with poor contractility

• RV strain (if RV-predominant)

• Valvular pathology

• Tamponade physiology

• IVC: plethoric, poor collapse

Echo helps differentiate:

• Cardiogenic vs obstructive vs hypovolemic vs septic shock

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5. Hemodynamics (Swan-Ganz if needed)

Parameter	Cardiogenic Shock
CO / CI	Low (CI < 2.2)
PCWP	High (>15–18)
CVP	High (if RV failure)
SVR	High (compensatory vasoconstriction)
SvO₂	Low (< 60%)

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6. Management Algorithm (ICU)

Step 1 — Stabilize airway & breathing

• Oxygen

• Avoid intubation early if possible (intubation can worsen hypotension!)

• If intubation needed → use ketamine + small tidal volumes + low PEEP

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Step 2 — Support blood pressure

First-line vasopressor:

Norepinephrine

• Best choice: raises MAP without increasing HR too much

If additional support needed:

Vasopressin

• Catecholamine-sparing

Avoid pure alpha agents like phenylephrine (worsens afterload).

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Step 3 — Improve cardiac output (Inotropes)

Preferred:

✔ Dobutamine 2.5–20 mcg/kg/min

• ↑ contractility

• ↑ CO

• May ↓ BP (combine with norepi)

Alternative:

✔ Milrinone 0.125–0.75 mcg/kg/min

• Good in RV failure

• Avoid in renal failure

• More hypotension

If severe hypotension:

• Norepi + dobutamine combination is common

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Step 4 — Diuresis if congested

• Loop diuretics (IV furosemide)

• Goal: negative fluid balance

• Reduce PCWP to 15–18 mmHg

• Improves pulmonary edema

But avoid aggressive fluids unless clearly hypovolemic.

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Step 5 — Revascularization (if MI)

• Intervention: PCI is REQUIRED

• Cardiogenic shock due to MI → emergent cath

• Mortality decreases with early PCI

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Step 6 — Correct Arrhythmias

• VT/VF: defibrillate

• Afib RVR: cardioversion or amiodarone

• Bradycardia: dopamine or pacing

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7. Mechanical Circulatory Support

Used when medications aren’t enough.

1. IABP – Intra-aortic balloon pump

• Reduces afterload

• Improves coronary perfusion

• Not super strong support

• Used in MI-related shock

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2. Impella

• Direct LV unloading

• Improves CO

• Stronger than IABP

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3. VA-ECMO

• For refractory cardiogenic shock

• Provides full cardiac + respiratory support

• Bridge to recovery, PCI, transplant, LVAD

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4. TandemHeart

• Left atrium to aorta bypass pump

• For profound LV failure

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8. Ventilator Management (ICU Must Know)

For cardiogenic shock with pulmonary edema:

• Use low PEEP (5–8)

• Avoid high plateau pressure

• Small tidal volumes if intubated

• Avoid hypercapnia (↑ RV afterload)

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9. Lactate Trends

• #1 indicator of perfusion

• Failure to clear lactate predicts mortality

• Goal: lactate ↓ by ≥ 10% per 2–4 hours

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10. ICU Pearls

• Don’t give large fluid boluses—worsens pulmonary edema

• CI < 2.2 → cardiogenic shock

• PCWP > 18 → pulmonary congestion

• Norepi + dobutamine is a classic combination

• Consider early echocardiography

• Revascularization (PCI) is life-saving in MI

• Start inotropes early for cold/wet profile

• Consider ECMO early if crashing despite meds