Pulmonary wedge pressure is indirectly

(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.