Postural Changes in Pleural Fluid Constituents

Measurement of pleural fluid constituents (pH, PCO 2 , protein, lactic dehydrogenase [LDH], glucose, red blood cells [RBC], and white blood cells [WBC]) are of value in the diagnosis of pleural effusions and in the separation of exudates from transudates. The position of the patient (sitting or lying) prior to thoracentesis may result in differences in the measurement of these constituents. We found significant postural changes (p