What type of shock is characterized by tachycardia, decreased cardiac output, increased systemic vascular resistance (SVR), increased or normal ventricular pressure, decreased pulse pressure, and decreased venous oxygen saturation (SvO2)?

Cardiogenic or Hypovolemic Shock

The hemodynamic profile described—tachycardia, decreased cardiac output, increased SVR, increased or normal ventricular pressure, decreased pulse pressure, and decreased SvO2—is most consistent with either cardiogenic or hypovolemic shock, with the key distinguishing feature being ventricular/filling pressure: elevated in cardiogenic shock versus decreased in hypovolemic shock. 1

Hemodynamic Pattern Analysis

The constellation of findings points to a compensated low-output shock state where the body is attempting to maintain perfusion pressure through systemic vasoconstriction:

• Decreased cardiac output (<2.2 L/min/m²) indicates inadequate forward flow from either pump failure (cardiogenic) or insufficient preload (hypovolemic) 1
• Increased SVR represents compensatory vasoconstriction attempting to maintain blood pressure despite falling cardiac output 1
• Tachycardia is the body's attempt to maintain cardiac output when stroke volume is reduced 2
• Decreased pulse pressure reflects the combination of reduced stroke volume and increased arterial stiffness from vasoconstriction 2
• Decreased SvO2 (<70%) indicates inadequate oxygen delivery to tissues with increased oxygen extraction 2

Critical Distinguishing Feature: Ventricular Pressure

The ventricular/filling pressure is the definitive discriminator between these two shock types:

If Ventricular Pressure is ELEVATED (>15 mmHg):

This is cardiogenic shock. 1

• Pulmonary capillary wedge pressure (PCWP) >15 mmHg reflects left ventricular failure and backward congestion 1
• Central venous pressure (CVP) >15 mmHg indicates right-sided failure or biventricular involvement 1
• The failing myocardium cannot generate adequate output despite elevated filling pressures 2
• Clinical signs include pulmonary edema, jugular venous distension, and signs of organ hypoperfusion 2

If Ventricular Pressure is NORMAL or LOW:

This is hypovolemic shock. 2

• Low CVP and PCWP reflect inadequate intravascular volume 2
• The heart is structurally normal but lacks sufficient preload to generate adequate output 2
• Clinical signs include flat neck veins, poor skin turgor, and history of fluid losses 3

Why NOT the Other Options

Distributive shock (including septic and anaphylactic) demonstrates decreased SVR as the primary pathophysiologic mechanism, which is the opposite of this case 2, 1

Neurogenic shock presents with bradycardia (not tachycardia) due to unopposed parasympathetic tone, along with decreased SVR and low CVP 4

Obstructive shock (e.g., pulmonary embolism, cardiac tamponade) would show elevated CVP with specific findings like pulsus paradoxus in tamponade or right ventricular strain patterns in massive PE, but the hemodynamic profile can overlap with cardiogenic shock 2

Clinical Approach to Differentiation

Immediate bedside assessment should include: 1

• Physical examination: Look for jugular venous distension (elevated in cardiogenic, flat in hypovolemic), pulmonary rales (present in cardiogenic), and peripheral perfusion 2
• Point-of-care ultrasound: Assess left ventricular function (depressed in cardiogenic, hyperdynamic in hypovolemic), inferior vena cava size (dilated in cardiogenic, collapsed in hypovolemic) 5
• Invasive hemodynamic monitoring: Pulmonary artery catheter provides definitive measurements of cardiac output, SVR, and filling pressures when diagnosis remains unclear 2

Common Pitfall

Do not confuse late-stage septic shock with cardiogenic shock. Septic shock can develop myocardial depression ("septic cardiomyopathy"), but the primary hemodynamic pattern remains distributive with decreased SVR, not the increased SVR seen in cardiogenic shock 1, 4