Orthopnea occurs in response to an increase in what?

Orthopnea is a specific type of dyspnea that occurs when a person is lying flat, often relieved by sitting or standing up. This condition is primarily associated with heart failure and is caused by increased pressure in the pulmonary circulation. The correct answer highlights the role of pulmonary capillary wedge pressure, which serves as an estimate of left atrial pressure.

In heart failure, the heart's ability to pump blood effectively is compromised, leading to congestion in the pulmonary circulation. When a patient lies down, blood that was previously pooling in the lower extremities returns to the central circulation, increasing the volume of blood in the heart and subsequently raising the pulmonary capillary wedge pressure. This increased pressure can lead to fluid leakage into the alveoli of the lungs, causing pulmonary congestion and resulting in orthopnea.

Understanding the role of pulmonary capillary wedge pressure is crucial for managing patients with heart failure, as it directly relates to their symptoms and helps guide treatment decisions. Proper assessment and management of congestion can lead to significant improvements in a patient's quality of life and symptom relief.