What are the causes of Pulse Paradoxus (Pulsus Paradoxus)?

From the Guidelines

Pulsus paradoxus is defined as a drop in systolic blood pressure >10 mmHg during inspiration whereas diastolic blood pressure remains unchanged, and it is easily detected by feeling the pulse 1.

Diagnosis and Evaluation

To determine pulsus paradoxus, the magnitude is evaluated by sphygmomanometry, where the first Korotkoff sound is heard only during expiration, and the blood pressure cuff is inflated above the patient’s systolic pressure 1.

• The diagnosis of pulsus paradoxus is crucial in identifying conditions such as cardiac tamponade, which is characterized by elevated systemic venous pressure, hypotension, and tachycardia 1.
• The clinical presentation of cardiac tamponade includes dyspnea or tachypnea with clear lungs, and precipitating factors such as drugs, recent cardiac surgery, and malignancies 1.

Clinical Significance

Pulsus paradoxus is a significant clinical finding that can indicate severe cardiac or respiratory disease, and its presence should prompt further evaluation and management 1.

• The absence of pulsus paradoxus in tamponade complicating atrial septal defect or in patients with significant aortic regurgitation should be noted 1.
• The diagnosis of cardiac tamponade can be confirmed by echocardiogram, which shows diastolic collapse of the right ventricular free wall, and cardiac catheterization, which confirms the diagnosis and quantifies the hemodynamic compromise 1.

Management

The management of pulsus paradoxus depends on the underlying cause, and in the case of cardiac tamponade, pericardial aspiration is necessary to relieve the hemodynamic compromise 1.

• Patients with pulsus paradoxus should be monitored closely for potential complications and managed accordingly 1.
• The presence of pulsus paradoxus is a critical finding that requires prompt attention and management to prevent morbidity and mortality 1.

From the Research

Definition and Mechanism of Pulsus Paradoxus

• Pulsus paradoxus is defined as an exaggerated fall in systolic blood pressure with inspiration, typically greater than 10 mmHg 2, 3, 4, 5.
• The mechanism underlying pulsus paradoxus involves inspiratory increases in right heart filling and output, which lead to decreases in left ventricular dimensions and aortic and mitral velocities 2.
• Doppler studies have confirmed that an inspiratory fall in left atrial filling is necessary for pulsus paradoxus to occur 2.

Clinical Conditions Associated with Pulsus Paradoxus

• Pulsus paradoxus can be observed in cardiac tamponade, constrictive pericarditis, asthma, and several other clinical conditions 3, 4, 5.
• It can also occur in conditions where intrathoracic pressure swings are exaggerated or the right ventricle is distended, such as severe acute asthma or exacerbations of chronic obstructive pulmonary disease 5.
• Pulsus paradoxus has been reported in cases of pulmonary embolization, where echocardiography demonstrated inspiratory failure of the aortic valve to open and decreases in left ventricular cavity size 6.

Diagnostic and Clinical Significance of Pulsus Paradoxus

• Early recognition of pulsus paradoxus in the emergency room can help diagnose cardiac tamponade rapidly 5.
• Measurement of pulsus paradoxus is useful in assessing the severity of acute asthma and its response to therapy 5.
• The predictive value of a present or absent pulsus paradoxus is rather limited in certain clinical situations, such as inflow obstruction into the heart or extreme respiratory variations in intrathoracal pressure 3.