Bodipletizmografiya: theoretical and clinical aspects
Whole-body plethysmography - the lung function test that allows to measure of thoracic gas volume (TGV), vital capacity, total lung capacity (TLC), residual volume and airway resistance. The method is based on the relationship between pressure (P) and volume (V) at constant temperature of a fixed quantity of gas: P*V = constant under isothermal conditions (Boyle-Mariotte’s Law). Clinical benefit of body plethysmography is the definition of restrictive lung disease at the presence of a reduced TLC and obstructive lung disease at the presence of abnormally increased lung volumes: RV, RV/TLC and TGV. Interpretation of lung volumes is based on comparisons of data measured in individual patient with reference (predicted) values based on healthy subjects. Normative values for lung volumes in adults have been reported by American Thoracic Society and European Respiratory Society in 2005 (ATS/ERS, 2005). Whole-body plethysmography provides the unique clinically relevant information, allows to estimate pulmonary mechanical parameters, carry out the differential diagnosis, control the course of the disease.