Chest
Volume 123, Issue 4, April 2003, Pages 1082-1089
Journal home page for Chest

Clinical Investigations
PULMONARY FUNCTION
Measurement Variability in Single-Breath Diffusing Capacity of the Lung

https://doi.org/10.1378/chest.123.4.1082Get rights and content

Study objectives:

The single-breath diffusing capacity of the lung (Dlco) is a commonly performed pulmonary function test. The current American Thoracic Society (ATS) recommendations for reproducibility of Dlco measurements suggest that two measurements for the Dlco agree within 10% or 3 mL/min/mm Hg of the average value. The European Respiratory Society (ERS) recommends that two measurements should agree within 10%. The objectives of the present study were to examine whether the current reproducibility criteria were met in a general pulmonary function laboratory and to determine whether alternative criteria might be appropriate.

Design:

Cross-sectional study.

Setting:

University-based pulmonary function laboratory.

Patients or Participants:

Patients referred for spirometry, helium lung volumes, and Dlco measurement.

Interventions:

None.

Measurements and results:

In a sample of 6,193 patients referred for clinical testing, 98.3% had two Dlco values that fulfilled the current ATS criteria for reproducibility. The coefficient of variation (CV) and the percentage difference between two repeat measurements were inversely associated with the baseline Dlco and the FEV1. As the baseline Dlco (percentage of predicted) or FEV1 (percentage of predicted) decreased, there was an increase in the CV and the percentage difference. In contrast, the absolute difference between repeat measurements was relatively stable irrespective of the baseline Dlco or FEV1 values. Other patient factors, such as gender and race, were not associated with measurement variability. Using an absolute difference of 2 to 2.5 mL/min/mm Hg between two Dlco measurements as alternative criteria for reproducibility, 91.5% and 95.8% of the patient sample fulfilled these criteria, respectively.

Conclusions:

Reproducibility of the Dlco measurement is generally much better than current standards allow. Future standards should consider an absolute difference rather than a percentage difference criterion for Dlco reproducibility.

Section snippets

Materials and Methods

We conducted a retrospective review of pulmonary function test (PFT) results for patients referred to the pulmonary function laboratory over a consecutive 3-year period. Approval for use of the pulmonary function data were obtained from the institutional review board on human research. Patient confidentiality was maintained by removing all identifying information from the clinical data. PFT records were reviewed to select patients who underwent spirometry and had Dlco measured during the same

Demographic and Pulmonary Function Characteristics

A total of 6,193 unique PFT records were selected for the current study with availability of spirometry and Dlco measurement during the same visit. Patient characteristics and pulmonary function data for the study sample are summarized in Table 1. The average age was 53.2 years (SD, 15.4 years). The sample consisted of 2,903 women (46.9%) and 3,290 men (53.1%). There were 3,840 white patients (62.0%) and 2,352 African-American patients (38.0%). Of the 6,193 patients with spirometry and Dlco

Discussion

The present study examined the utility of the current recommendations on reproducibility limits for the measurement of single-breath Dlco. Using a consecutive sample of patients referred to a general pulmonary function laboratory, 98.3% patients referred for clinical testing met the current ATS reproducibility criteria for repeat Dlco measurement. The use of alternative criteria that are more stringent did not significantly alter the number of patients that could fulfill these criteria under

ACKNOWLEDGMENT

The authors thank Dr. Robert O. Crapo for his helpful comments.

References (9)

  • KC Beck et al.

    Comparison of four methods for calculating diffusing capacity by the single breath method

    Chest

    (1994)
  • American Thoracic Society

    Single breath carbon monoxide diffusing capacity (transfer factor): recommendations for a standard technique; statement of the American Thoracic Society

    Am Rev Respir Dis

    (1987)
  • JE Cotes et al.

    Standardization of the measurement of transfer factor (diffusing capacity): Report Working Party Standardization of Lung Function Tests, European Community for Steel and Coal; official statement of the European Respiratory Society

    Eur Respir J Suppl

    (1993)
  • American Thoracic Society

    Single-breath carbon monoxide diffusing capacity (transfer factor): recommendations for a standard technique, 1995 update

    Am J Respir Crit Care Med

    (1995)
There are more references available in the full text version of this article.

Cited by (51)

  • Variability in pulmonary diffusing capacity in heart failure

    2020, Respiratory Physiology and Neurobiology
    Citation Excerpt :

    Using a percentage may lead to underestimation of variability in low values and overestimation for high values. Other studies have also suggested using an absolute value rather than a percentage (Punjabi et al., 2003; Robson and Innes, 2001;l Zavorsky and Murias, 2006) since the diffusing capacity was also independent of the magnitude of the measurement. As such, we report intersession variability values for the 4 s breath-hold maneuver for DLNO and DLCO in absolute numbers, but percentages are also provided for an easier interpretation of the variability.

View all citing articles on Scopus

Supported by National Institutes of Health grant No. HL04065.

View full text