Volume Correction For Diffusion Capacity: Use Of Total Lung Capacity By Either Nitrogen Washout Or Body Plethymography Instead Of Alveolar Volume By Single Breath Methane Dilution

Abstract

1 2 3 the brooklyn hospital center, brooklyn, NY, United States of America Corresponding author's email: auvieghara@yahoo.co.uk Rationale: It is a standard practice to report absolute Diffusion Capacity (DLCO) and also Volume corrected DLCO i.e. Transfer coefficient Kco = (DLCO/VA) in Pulmonary Function test (PFT) reports. However, alveolar volume (VA) measurement done concurrently during DLCO measurement by single breath holding can be considerably lower than the true lung volume i.e. total lung capacity (TLC) measurement done by either N2 washout or Body plethysmography. Transfer coefficient Kco to separate patients with and without parenchymal lung disease. However use of volume correction is controversial. We tested the hypothesis that in patients with reduced absolute DLCO, whether Volume correction with TLC would accurately diagnose underlying disease.: Retrospective review of all PFTs done between 1/1/9 and 9/1/9. PFTs of 230 male and female patients between the ages of 18 Methods and 75 yrs with reduced DLCO were analyzed. The interpretive strategy of ATS/ERS 2005 standards was used to classify the nature and severity of underlying defect. Absolute reduction in DLCO was correlated with DLCO/VA and DLCO/TLC for concordance and discordance. Also the correlation coefficient between VA and TLC was calculated.The correlation coefficient between VA and TLC was .59 in patients with severe obstructive lung disease. In the other groups of Results patients the correlation coefficient between VA and TLC ranges from .78 to .95. There was a high degree of discordance between DLCO and DLCO/VA in all groups of patients. However 69% of patients with severe obstructive lung disease show concordance between low DLCO and DLCO/TLC, Disease