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This Article Full Text (PDF) All Versions of this Article: chest.07-2388v1 133/5/1149    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to My Personal Article Archive Download to citation manager Google Scholar Articles by Dressel, H. Articles by Jörres, R. A. PubMed PubMed Citation Articles by Dressel, H. Articles by Jörres, R. A.

Lung diffusing capacity for nitric oxide and carbon monoxide: Dependence on breath-hold time

¹ Institute and Outpatient Clinic for Occupational, Social and Environmental Medicine, Ludwig-Maximilians-University, Munich, Germany ² Department of Pneumology, Medizinische Klinik Innenstadt, Ludwig-Maximilians-University, Munich, Germany ³ Viasys Healthcare GmbH, Würzburg, Germany

holger.dressel{at}med.uni-muenchen.de

Abstract

Background: The lung diffusing capacity for nitric oxide (DL_NO) and carbon monoxide (DL_CO) is a simple, non-invasive tool but methodological factors might influence the results and reproducibility. We thus quantified the influence of breath-hold time on DL_CO and DL_NO in subjects with or without airway disease.

Methods: Simultaneous single-breath measurements of DL_CO and DL_NO were performed in 10 patients with cystic fibrosis (CF, mean±SD age 33±9 years, FEV₁ 69±28 %pred) and 10 healthy subjects (age 31±9 years, FEV₁ 108±8 %pred), using the Masterscreen PFT (Viasys), 45 ppm inspired NO, and breath-hold times of 4, 6, 8, and 10s. The last two of three consecutive measurements were taken for analysis.

Results: In healthy subjects but not CF, DL_NO and DL_CO differed significantly (p<0.05 each) between breath-hold times. Differences primarily occurred regarding 4 and 10s, while at 6 and 8s alveolar volume (VA), DL_NO, DL_CO, and DL_NO/DL_CO were similar. Variability of consecutive measurements (either three or the last two) did not depend on breath-hold time. At 8s mean variability of DL_NO and DL_CO in healthy subjects was 4.9 and 2.5%, and at 6 s it was 4.2 and 3.2%. The respective values for CF were 4.4, 1.9, 7.4, and 3.3%.

Conclusions: Single-breath determinations of the diffusing capacity for NO and CO showed no difference between breath-hold times of 6 and 8s in subjects with or without airway obstruction and reproducibility was acceptable. Standardization of breath-hold time for DL_NO measurements seems important for clinical and research comparisons.

Key Words: Lung diffusing capacity • carbon monoxide • nitric oxide • variability • cystic fibrosis • airway obstruction