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

Chest. 2008 May;133(5):1149-54. doi: 10.1378/chest.07-2388. Epub 2008 Feb 8.


Background: The combined measurement of diffusing capacity of the lung for nitric oxide (Dlno) and diffusing capacity of the lung for carbon monoxide (Dlco) is a simple, noninvasive tool, but methodologic factors might influence results and reproducibility. We thus quantified the influence of breath-hold time on Dlco and Dlno in subjects with or without airway disease.

Methods: Simultaneous single-breath measurements of Dlco and Dlno were performed in 10 patients with cystic fibrosis (CF) [mean +/- SD age, 33 +/- 9 years; FEV(1), 69 +/- 28% of predicted] and 10 healthy subjects (age, 31 +/- 9 years; FEV(1), 108 +/- 8% of predicted), using the Masterscreen PFT (Viasys/Jaeger; Höchberg, Germany), with 45 ppm of inspired nitric oxide (NO), and breath-hold times of 4 s, 6 s, 8 s, and 10 s. The last two of three consecutive measurements were used for analysis.

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

Conclusions: Single-breath determinations of dlno and dlco showed no difference between breath-hold times of 6 s and 8 s in subjects with or without airway obstruction, and reproducibility was acceptable. Standardization of breath-hold time for Dlno measurements seems important for clinical and research comparisons.

Publication types

  • Comparative Study

MeSH terms

  • Administration, Inhalation
  • Adult
  • Airway Obstruction / etiology
  • Airway Obstruction / physiopathology
  • Breath Tests / methods
  • Carbon Monoxide / administration & dosage*
  • Cystic Fibrosis / complications
  • Cystic Fibrosis / physiopathology*
  • Female
  • Follow-Up Studies
  • Forced Expiratory Volume / drug effects
  • Forced Expiratory Volume / physiology
  • Humans
  • Male
  • Nitric Oxide / administration & dosage*
  • Prognosis
  • Pulmonary Diffusing Capacity / drug effects*
  • Pulmonary Diffusing Capacity / physiology
  • Respiration / drug effects*
  • Severity of Illness Index
  • Spirometry / methods
  • Time Factors


  • Nitric Oxide
  • Carbon Monoxide