Cardiogenic Shock
Based on the hemodynamic profile presented—tachycardia (HR 120), low cardiac output, high systemic vascular resistance, hypotension, and metabolic acidosis (low base deficit)—this clinical picture is most consistent with cardiogenic shock (Answer C).
Hemodynamic Rationale
The combination of low cardiac output with high SVR distinguishes cardiogenic shock from other shock types 1. In cardiogenic shock, the body attempts to compensate for inadequate cardiac output by increasing systemic vascular resistance (vasoconstriction) to maintain perfusion pressure 1. This compensatory mechanism differentiates it from:
Hypovolemic shock: While also presenting with low cardiac output and high SVR, hypovolemic shock typically responds to fluid resuscitation, whereas cardiogenic shock results from primary myocardial dysfunction 1
Obstructive shock: Shares similar hemodynamics (low CO, high SVR) but results from mechanical obstruction to cardiac filling or emptying rather than intrinsic myocardial failure 1
Anaphylactic/Distributive shock: Characterized by low SVR (vasodilation), not high SVR, making this incompatible with the presented hemodynamics 1
Clinical Presentation Details
The tachycardia represents a compensatory mechanism attempting to maintain cardiac output despite reduced stroke volume 1. The metabolic acidosis (low base deficit) reflects tissue hypoperfusion and anaerobic metabolism from inadequate oxygen delivery 1, 2. Hypotension occurs when compensatory mechanisms fail, representing decompensated shock 1.
Key Distinguishing Features
Cardiogenic shock is defined as sustained hypotension (SBP <90 mmHg) with signs of hypoperfusion and reduced cardiac index <2.2 L/min/m² despite adequate filling status 1. The high SVR in this scenario indicates the body is attempting vasoconstriction to maintain blood pressure in the face of pump failure 1.
Common Pitfall to Avoid
Do not confuse cardiogenic shock with obstructive shock—both present with low cardiac output and high SVR 1. The distinction requires echocardiography to identify mechanical causes (tamponade, massive PE, tension pneumothorax) versus intrinsic myocardial dysfunction 1.
Management Implications
In cardiogenic shock with tachycardia and hypotension, norepinephrine is the recommended vasopressor, with inotropes (dobutamine or milrinone) added to improve cardiac output 1. The high SVR indicates afterload is already elevated, so pure vasopressors must be balanced against the risk of further increasing myocardial work 1.