Pulsus

Pulsus paradoxus (or paradoxical pulse) is an exaggerated decrease in pulse amplitude during inspiration. It is a clinical sign that can be indicative of several medical conditions, such as cardiac tamponade, constrictive pericarditis, and severe bronchospasm.

Definition

Pulsus paradoxus is defined as a decrease in systolic blood pressure of more than 10 mm Hg during inspiration. This phenomenon is normally present to a small degree in healthy individuals, but becomes pronounced in certain disease states.

Mechanism

The mechanism of pulsus paradoxus involves changes in intrathoracic pressure during the respiratory cycle. During inspiration, the decrease in intrathoracic pressure increases venous return to the right side of the heart. In conditions such as cardiac tamponade or constrictive pericarditis, the heart's ability to accommodate this increased venous return is impaired, leading to a decrease in left ventricular stroke volume and a consequent decrease in pulse amplitude.

Clinical significance

Pulsus paradoxus can be a useful clinical sign in the diagnosis of several conditions. It is most commonly associated with cardiac tamponade, but can also be seen in constrictive pericarditis, severe bronchospasm (as in asthma or COPD), and obstructive sleep apnea. In addition, it can be seen in some patients with hypertrophic cardiomyopathy.

Measurement

Pulsus paradoxus is typically measured using a sphygmomanometer. The blood pressure is measured during both inspiration and expiration, and the difference between these two measurements is the degree of pulsus paradoxus.

See also

• Blood pressure
• Cardiac tamponade
• Constrictive pericarditis
• Bronchospasm

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