Evaluation of diffusing capacity in patients with a restrictive lung disease.
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.


METHODS
An observational survey.


METHODS
Pulmonary function department.


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


METHODS
Bleomycin treatment.


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.
Stam
H
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Pathophysiology Laboratory of the Department of Pulmonary Diseases, Erasmus University, Rotterdam, the Netherlands.
Splinter
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TA
Versprille
A
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D000328:Adult; D000964:Antimetabolites, Antineoplastic / Q000009:adverse effects / Q000627:therapeutic use; D001761:Bleomycin / Q000009:adverse effects / Q000627:therapeutic use; D002248:Carbon Monoxide; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000139:chemically induced / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D009373:Neoplasms, Germ Cell and Embryonal / Q000188:drug therapy; D011237:Predictive Value of Tests; D011653:Pulmonary Diffusing Capacity / Q000187:drug effects / Q000502:physiology*; D011659:Pulmonary Gas Exchange / Q000187:drug effects / Q000502:physiology; D013736:Testicular Neoplasms / Q000188:drug therapy; D014109:Total Lung Capacity / Q000187:drug effects / Q000502:physiology
D000964:Antimetabolites, Antineoplastic; D001761:Bleomycin; D002248:Carbon Monoxide