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Physiology · Cardiovascular system: distributive shock haemodynamics
Sample itemA 45-year-old woman with pneumonia has bounding pulses, warm flushed extremities, blood pressure 80/35 mmHg and a high cardiac output on echocardiography. Which haemodynamic pattern explains her hypotension?
Original practice item, not a recalled exam question. Nothing here is recorded.
The answer and the reasoning
D. Low systemic vascular resistance with raised cardiac output
In septic (distributive) shock, mediator-driven vasodilatation lowers systemic vascular resistance and the diastolic pressure, so the pulse pressure widens and the extremities stay warm. Cardiac output is raised to compensate but cannot restore pressure. Cold, clammy skin with a low output is the pattern of cardiogenic and hypovolaemic shock.
Option by option
A. High systemic vascular resistance with low cardiac output
High resistance with low output is the picture of hypovolaemic or cardiogenic shock, with cold peripheries.
B. Obstruction to ventricular outflow with a high afterload
Outflow obstruction would give a low output and a narrow, not wide, pulse pressure.
C. Raised preload with falling contractility from pump failure
Pump failure gives a low cardiac output, which does not fit the echocardiographic finding.
D. Low systemic vascular resistance with raised cardiac output (correct)
Correct. Pressure falls because vascular resistance collapses despite a high output.
Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.
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