Evaluation of diffusing capacity in patients with a restrictive lung disease

Chest. 2000 Mar;117(3):752-7. doi: 10.1378/chest.117.3.752.


Background: In healthy volunteers, the single-breath diffusing capacity of the lung for carbon monoxide (DLCO) decreases and DLCO normalized per liter alveolar volume (VA; DLCO/VA) increases if VA is decreased. We hypothesized that comparison of DLCO/VA with its predicted value at predicted total lung capacity (TLC) will result in an underestimation of the diffusion disorder in patients with a restrictive lung disease, if a similar relationship exists between DLCO/VA and lung volume as found in healthy volunteers.

Objective: To test this hypothesis, we studied total gas transfer DLCO and DLCO/VA as functions of VA in patients who developed a restrictive lung disease and a diffusion disorder in a short period of time.

Design: An observational survey.

Setting: Pulmonary function department.

Patients: Thirteen patients without any initial pulmonary pathology who developed the mentioned pulmonary pathology due to bleomycin treatment.

Interventions: Bleomycin treatment.

Measurements and results: We performed the single-breath test at various VA levels before, during, and after bleomycin treatment. In the majority of the patients, the DLCO vs VA relationship remained parabolic, but shifted downwards during therapy. Therefore, the linear DLCO/VA vs VA relationship shifted downwards, while the negative slope was not changed, indicating the development of a decreased gas transfer. Six patients also developed a volume restriction.

Conclusions: The agreement of the data with the hypothesis increased its probability. Consequently, to evaluate a diffusion disorder, DLCO/VA at a lower actual TLC of patients with a lung restriction should be compared to a reference DLCO/VA at a lung volume equal to the actual TLC.

MeSH terms

  • Adult
  • Antimetabolites, Antineoplastic / adverse effects
  • Antimetabolites, Antineoplastic / therapeutic use
  • Bleomycin / adverse effects
  • Bleomycin / therapeutic use
  • Carbon Monoxide
  • Humans
  • Lung Diseases, Obstructive / chemically induced
  • Lung Diseases, Obstructive / diagnosis*
  • Lung Diseases, Obstructive / physiopathology
  • Male
  • Neoplasms, Germ Cell and Embryonal / drug therapy
  • Predictive Value of Tests
  • Pulmonary Diffusing Capacity / drug effects
  • Pulmonary Diffusing Capacity / physiology*
  • Pulmonary Gas Exchange / drug effects
  • Pulmonary Gas Exchange / physiology
  • Testicular Neoplasms / drug therapy
  • Total Lung Capacity / drug effects
  • Total Lung Capacity / physiology


  • Antimetabolites, Antineoplastic
  • Bleomycin
  • Carbon Monoxide