Which hemodynamic finding is consistent with cardiogenic shock: elevated pulmonary capillary wedge pressure (>15 mm Hg), low cardiac index (<1.8 L/min/m²) without support, normal systolic blood pressure, or sustained hypotension (systolic <90 mm Hg for >30 minutes)?

Hemodynamic Findings Consistent with Cardiogenic Shock

All four options listed contain elements that appear in cardiogenic shock definitions, but only sustained systolic BP <90 mm Hg for >30 minutes and cardiac index <1.8 L/min/m² without support are independently diagnostic criteria, while PCWP >15 mm Hg is required to confirm the diagnosis and differentiate from other shock types. 1, 2

Core Hemodynamic Criteria for Cardiogenic Shock

The diagnosis of cardiogenic shock requires simultaneous presence of multiple hemodynamic abnormalities, not isolated findings 1, 2:

Blood Pressure Criteria

• Systolic BP <90 mm Hg sustained for >30 minutes is a defining clinical criterion for cardiogenic shock 1, 2
• Alternatively, the need for vasopressors or inotropes to maintain SBP ≥90 mm Hg also meets the hypotension threshold 1, 2
• A systolic BP of 130 mm Hg categorically excludes cardiogenic shock regardless of other findings, placing the patient at most in SCAI Stage A (at-risk) 2, 3

Cardiac Output Criteria

• Cardiac index <2.2 L/min/m² is the standard hemodynamic threshold used in major clinical trials (SHOCK, IABP-SHOCK II, CULPRIT-SHOCK) 1
• Cardiac index <1.8 L/min/m² without vasopressor or inotropic support defines severe cardiogenic shock and is the more stringent contemporary criterion 1, 2
• Cardiac power output <0.6 W identifies refractory shock requiring mechanical circulatory support 1, 2

Filling Pressure Criteria

• PCWP >15 mm Hg is mandatory to confirm cardiogenic shock and differentiate it from hypovolemic shock (which shows low PCWP) 1, 2
• Classic cardiogenic shock typically shows PCWP >18–20 mm Hg, reflecting left ventricular failure and pulmonary congestion 1, 4
• Central venous pressure >15 mm Hg suggests right ventricular involvement or biventricular failure 2, 3

Why Each Option Is or Is Not Diagnostic

PCWP >15 mm Hg

• Consistent with cardiogenic shock but not sufficient alone 1, 2
• This finding distinguishes cardiogenic from hypovolemic shock but must be accompanied by low cardiac index and hypotension to meet diagnostic criteria 1, 2
• PCWP elevation reflects backward failure and pulmonary congestion characteristic of left ventricular dysfunction 1, 3

Cardiac Index <1.8 L/min/m² Without Support

• This is a core hemodynamic criterion that defines severe cardiogenic shock 1, 2
• The "without support" qualifier is critical—it indicates profound pump failure before any pharmacologic intervention 1, 2
• Major trials used the slightly higher threshold of <2.2 L/min/m², but contemporary guidelines emphasize <1.8 L/min/m² without inotropes as the severe shock threshold 1, 2

Systolic BP of 130 mm Hg

• This finding excludes cardiogenic shock entirely 2, 3
• Normal or near-normal blood pressure places the patient in SCAI Stage A (at-risk) at most, even if other abnormalities exist 2, 3
• Rare cases of "nonhypotensive shock" with peripheral hypoperfusion despite SBP >90 mm Hg carry 43% mortality but do not meet standard shock definitions 5

Systolic BP <90 mm Hg for >30 Minutes

• This is a defining clinical criterion for cardiogenic shock 1, 2
• Sustained hypotension distinguishes shock from transient hypotensive episodes 1, 2
• This threshold appears consistently across all major guidelines and clinical trials 1, 6

Complete Diagnostic Algorithm

To diagnose cardiogenic shock, the American College of Cardiology requires all three components simultaneously 1, 2:

1. Confirm sustained hypotension: SBP <90 mm Hg for >30 minutes OR need for vasopressors to maintain SBP ≥90 mm Hg 1, 2

2. Document end-organ hypoperfusion (at least one): altered mental status, cold/clammy extremities, urine output <30 mL/h, lactate >2 mmol/L 1, 2

3. Obtain invasive hemodynamics via pulmonary artery catheter 1, 2:

   • Cardiac index <2.2 L/min/m² (or <1.8 L/min/m² without support for severe shock) 1, 2
   • PCWP >15 mm Hg (typically >18–20 mm Hg) 1, 2
   • Calculate cardiac power output: (CO × MAP) ÷ 451; if <0.6 W, consider mechanical circulatory support 1, 2

Critical Pitfall to Avoid

Hypotension alone is insufficient for diagnosis—you must document both low blood pressure AND objective evidence of end-organ hypoperfusion 1, 2. Similarly, isolated hemodynamic abnormalities (low cardiac index or elevated PCWP alone) without hypotension and hypoperfusion do not constitute cardiogenic shock 1, 2. The diagnosis requires the complete triad of hypotension, hypoperfusion, and confirmatory invasive hemodynamics showing low cardiac output with elevated filling pressures 1, 2.