The Science Journal of the American Association for Respiratory Care

2007 OPEN FORUM Abstracts

LUNG DIFFUSION CAPACITY FOR NITRIC OXIDE AND CARBON MONOXIDE: EVALUATION OF A NEW DEVICE

W. R. Steinhaeusser1, H. Dressel2, R. A. Jörres2, D. De la Motte2, G. Praml2, D. Novak2, R. Fischer3, R. M. Huber3

Background: Lung diffusion testing is a well established and sensitive technique to assess limitations in gas transport. These can have different reasons which may be determined only with additional testing, such as identification of the membrane factor by measurements at different oxygen levels. Due to irregular breathing of the subject and variances in the analysis this method bears high error possibilities.
In contrast, inhaled nitric oxide (DLNO) and carbon monoxide (DLCO) can be used as a simple, non-invasive tool to determine membrane factor (Dm) and pulmonary capillary blood volume (Vc) from a single breath.
Aims: Check methodological factors which might influence the results and reproducibility. Quantify the influence of different NO-concentrations and breath hold times on DLCO and DLNO and to assess variability in repeated measurements.

Methods: Simultaneous single-breath measurements of DLCO and DLNO were performed in 10 healthy subjects with either a custom-made device or the prototype device MasterScreen PFT pro (Viasys, Höchberg) using different NO concentrations (0, 10 and 40 ppm) and breath hold times (4, 6, 8 and 10 s at 40 ppm NO). Measurements were performed in triplicate to assess variability.

Results: DLCO with the combined technique was comparable to that assessed by our existing DLCO analyzer and did not change using different NO concentrations. There was a slight decrease in DLNO with increasing breath hold times, however measurements were stable at 6 and 8 s. The mean ratio DLCO/DLNO ratio was 4.5 at 8 s breath hold time.

Conclusions: Simultaneous measurement of the lung diffusion capacity for nitric oxide and carbon monoxide shows an acceptable reproducibility, especially at 8 s breath hold time, the required minimum time for DLCO-measurements according to international guidelines. Breath hold time can be reduced to 6 s without systematic error, which might be an advantage for patients.

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