**Question:** Pulsus paradoxus is present in all except

A. Pulmonary embolism
B. Bronchial asthma
C. Congenital heart disease
D. Congestive heart failure

**Correct Answer:** .

**Core Concept:**
Pulsus paradoxus is a clinical sign that describes a decrease in systolic blood pressure by more than 10 mmHg during each expiration. It is commonly observed in conditions causing increased intrathoracic pressure, such as fluid overload or pulmonary embolism.

**Why the Correct Answer is Right:**
Pulsus paradoxus is not typically observed in bronchial asthma, congenital heart diseases, and congestive heart failure (CHF). In asthma, the increased respiratory effort does not result in significant alterations in intrathoracic pressure. In congenital heart diseases, the pathophysiology is usually more complex, and the changes in intrathoracic pressure may not be as pronounced as in conditions with increased intrathoracic pressure like pulmonary embolism. In CHF, the elevated left atrial pressure does not lead to such a significant decrease in systolic blood pressure during expiration.

**Why Each Wrong Option is Incorrect:**
In bronchial asthma, the increased respiratory effort may not cause a significant decrease in systolic blood pressure due to a lack of significant changes in intrathoracic pressure.

In congenital heart diseases, the pathophysiology may be more complex, as the condition can involve multiple structures and mechanisms, which may not result in a consistent and pronounced decrease in systolic blood pressure during expiration.

In congestive heart failure (CHF), the elevated left atrial pressure is usually not associated with a significant decrease in systolic blood pressure during expiration due to the various compensatory mechanisms that the body employs to maintain cardiac output.

**Clinical Pearl:**
Pulsus paradoxus is a valuable clinical sign to consider in the diagnosis of pulmonary embolism, as it is typically absent or mild in other conditions. A significant decrease in systolic blood pressure during expiration should prompt further evaluation for pulmonary embolism, as it is a consistent finding in this condition.