What is Kussmaul sign?

• A. Decreased central venous pressure with inspiration
• B. Increased central venous pressure with inspiration
• C. No change in central venous pressure with inspiration
• D. Pulsus paradoxus

Answer: (B)

Kussmaul sign is an inspiratory rise in central venous (jugular) pressure. Normally, inspiration makes the intrathoracic pressure more negative and reduces venous return pressure, so the jugular venous pressure would fall slightly. But when the right ventricle fills poorly due to stiff pericardium or reduced RV compliance (as in constrictive pericarditis or restrictive cardiomyopathy, and in some cases of right‑sided heart failure or RV infarction), the increased venous return during inspiration cannot be accommodated. The result is a paradoxical or inspiratory rise in central venous pressure.

Pulsus paradoxus, by contrast, is an exaggerated fall in systolic blood pressure during inspiration, not a change in central venous pressure, and is classically seen in tamponade and some obstructive lung diseases.