<prompt> Pulmonary wedge pressure is indirectlyLeft atrial pressureRight atrial pressureRight ventricular pressureLeft ventricular pressure  <response>: A Left atrial pressure Pulmonary capillary pressure is about 10 mm Hg. Whereas the oncotic pressure is 25 mm Hg, which keeps the alveoli free of fluid. When pulmonary capillary pressure is more than 25 mm Hg - as it may be, for example, when there is backward failure of the left ventricle-pulmonary congestion and edema result. Pulmonary capillary wedge pressure or PCWP also called the pulmonary wedge pressure or PWP, or pulmonary artery occlusion pressure or PAOP is the pressure measured by wedging a pulmonary catheter with an inflated balloon into a small pulmonary arlerial branch. Because of the large compliance of the pulmonary circulation, it provides an indirect measure of the left atrial pressure. For example, it is considered the gold standard for determining the cause of acute pulmonary edema; this is likely to be present at a PCWP of 20mmHg. It has also been used to diagnose severity of left ventricular failure and mitral stenosisCalculating PCWP is also important in diagnosis of acute respiratory distress syndrome ARDS.Physiological pressure: 6-12 mm Hg. 