Functional disorders in patients with COPD assessed by spirometry DL CO transfer characteristics, and plethysmography

Rational. Post-bronchodilator fixed ratio of FEV 1 /FVC and FEV 1 are widely accepted as primary parameter representing airflow limitation and,CO-transfer characteristics serves as additional severity parameters in COPD. Less is known to what extend plethysmography additionally offers information regarding obstruction, pulmonary hyperinflation (PH) and trapped gases (V TG ). Aim. Assessment of functional disorders by body plethysmography in addition to spirometry and single-breath DLCO in COPD patients. Methods. We evaluated 174 patients (84 males; 90 females; aged 29.4 to 89.4 ys) with COPD, (GOLD I to IV). All lung function data were expressed as gender- age- and height-specific standard deviations scores (SDS) obtained by z-transformation from newest prediction equations, taking also into consideration lower and upper limits of normal, defined as ±1.645*SDS. Target parameters were FEV 1 /FVC, FEV 1 , TLC He , FRC He , RV He , TLC, FRC pleth , RV, V TG =FRC pleth -FRC He , sG eff , sG tot . Results. Post-bronchodilator fixed ratio of FEV 1 /FVC was lower than LLN in 66.1%, FEV 1 in 75.3% (combined in 90.2%) of cases. In contrast, bronchial obstruction was recognized by sG eff in 98.9%. Gas transfer disturbances were recognised by DL CO in 73.6% of cases. In 14.9% PH, in 39.7% V TG and in 29.3% PH and V TG were found. Moreover, DL CO transfer characteristics significantly correlated with the amount of V TG (p< 0.001). Conclusion. The patter of different functional derangements in patients with COPD can comprehensively only be assessed by plethysmography, feathering together with DL CO and K CO insights into the interacting processes of lung physiology in COPD.