What can cause increased central venous pressure (CVP)/right atrial pressure (RAP)?

Increased central venous pressure (CVP) or right atrial pressure (RAP) reflects a rise in the volume or pressure of blood within the central venous system, which can be influenced by various factors. One key cause of increased CVP/RAP is impedance to right atrial emptying. This can happen when there's an obstruction or restriction in the pathways that allow blood to flow from the right atrium into the right ventricle.

Conditions such as severe tricuspid valve stenosis, pulmonary hypertension, or increased pressure in the thoracic cavity can impede this flow, leading to blood backing up into the right atrium and subsequently increasing pressure readings in the CVP/RAP. Therefore, any obstruction that limits the efficiency of blood drainage from the right atrium can significantly elevate these pressures.

The other options relate to situations that do not typically result in increased CVP/RAP. Dehydration would generally decrease fluid volume and, thereby, CVP/RAP. Decreased intrapleural pressure usually aids venous return and can lead to lower pressures. While pericardial effusion can increase pressures in some cases, it's primarily due to compression of the heart rather than direct impedance to right atrial emptying.