A 62-year-old man with an extensive anterior myocardial infarction is hypotensive (BP 78/50 mmHg), oliguric, and has cold clammy peripheries. Pulmonary artery catheter shows cardiac index 1.6 L/min/m2, pulmonary capillary wedge pressure 26 mmHg, and systemic vascular resistance 1800 dynes.s/cm5. Which category of shock does this represent?

• A Distributive shock with low SVR and high output
• B Hypovolaemic shock with low filling pressures
• C Obstructive shock from pulmonary embolism
• D Cardiogenic shock with low output and high filling pressures ✓

Explanation

The combination of low cardiac index, elevated PCWP, and elevated SVR defines cardiogenic shock: the failing pump raises left-sided filling pressures while compensatory vasoconstriction raises SVR. Hypovolaemic shock would show a low PCWP, and distributive shock a low SVR with warm peripheries, so both are excluded by this profile. In massive pulmonary embolism the wedge pressure is characteristically normal because the obstruction lies upstream of the left atrium.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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