Right Atrial Pressure (RAP) Calculator

Right Atrial Pressure Estimation Using IVC Diameter and Collapse Estimating right atrial pressure is an essential part of echocardiographic assessment because it directly influences the calculation of pulmonary artery systolic pressure and provides insight into right sided cardiac filling. The widely adopted method is based on the diameter of the inferior vena cava and its collapsibility with inspiration. A small vena cava with preserved inspiratory collapse indicates normal right atrial filling while a dilated vena cava with minimal collapse suggests elevated right atrial pressure.

The collapse index is calculated using the ratio between expiration and inspiration diameters. A high collapse index reflects good venous compliance and normal filling pressure while a low collapse index reflects high intrathoracic pressure transmission or impaired venous return. Normal right atrial pressure values are generally three to eight millimeters of mercury.

A severely dilated IVC with reduced collapse usually corresponds to a pressure around fifteen millimeters of mercury which suggests right sided pressure overload or impaired right ventricular compliance. Factors such as volume status, mechanical ventilation, intra abdominal pressure, and patient respiratory effort can influence measurements. Therefore clinical interpretation should incorporate the entire hemodynamic context including jugular venous examination and right ventricular function.