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Pulmonary Medicine
Volume 2012, Article ID 657180, 7 pages
http://dx.doi.org/10.1155/2012/657180
Clinical Study

Do We Need Exercise Tests to Detect Gas Exchange Impairment in Fibrotic Idiopathic Interstitial Pneumonias?

1Clinique des Maladies Respiratoires, Centre de Compétence des Maladies Pulmonaires Rares, Hopital Calmette, Lille 2 University Boulevard Leclercq, CHRU, 59037 Lille, France
2Unité de Biostatistiques, CHRU, 59037 Lille, France
3Service d'Explorations Fonctionnelles Respiratoires, Hopital Calmette, CHRU, 59037 Lille, France

Received 24 March 2012; Accepted 14 May 2012

Academic Editor: Marc A. Judson

Copyright © 2012 Benoit Wallaert et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

In patients with fibrotic idiopathic interstitial pneumonia (f-IIP), the diffusing capacity for carbon monoxide (DLCO) has been used to predict abnormal gas exchange in the lung. However, abnormal values for arterial blood gases during exercise are likely to be the most sensitive manifestations of lung disease. The aim of this study was to compare DLCO, resting PaO2, P(A-a)O2 at cardiopulmonary exercise testing peak, and oxygen desaturation during a 6-min walk test (6MWT). Results were obtained in 121 patients with idiopathic pulmonary fibrosis (IPF, ) and fibrotic nonspecific interstitial pneumonias (NSIP, ). All but 3 patients (97.5%) had low DLCO values (<LLN) whereas only 66.6% had low KCO; 42 patients (65%) exhibited resting hypoxemia (<75 mmHg); 112 patients (92.5%) exhibited a high P[(A-a)O2], peak (>35 mmHg) and 100 (83%) demonstrated significant oxygen desaturation during 6MWT (>4%). Interestingly 27 patients had low DLCO and normal P(A-a)O2, peak and/or no desaturation during the 6MWT. The 3 patients with normal DLCO also had normal PaO2, normal P(A-a)O2, peak, and normal oxygen saturation during 6MWT. Our results demonstrate that in fibrotic IIP, DLCO better defines impairment of pulmonary gas exchange than resting PaO2, exercise P(A-a)O2, peak, or 6MWT SpO2.