Abstract
The paper presents a computer-based system for performance and analysis of the single-breath nitrogen washout test (Sb-N2 test). A pneumotachometer and a rapid gas analyser are used for volume flow rate and nitrogen fraction measurements. The data are acquired and analysed by a PDP-11/34 computer. Several sources of measurement errors are considered. An algorithm is proposed to reduce errors in flow measurements due to viscosity variation in respired air. The algorithm for closing volume (CV) detection and calculation of other Sb-N2 parameters is developed from 50 tracings of 18 subjects. The CV is obtained by an iterative linear fitting of the later half of the Sb-N2 curve. Comparisons between computer and hand measurements of three trained readers show good correlations (r=0·87, 0·93, 0·91). The variability of computer CV measurements was comparable with that of the hand reader with the lowest variance. The coefficient of variation of residual volume and slope of alveolar plateau measurements are apparently reduced. The results demonstrate the adequacy and convenience of using the computer to analyse the Sb-N2 test and indicate that the automation allows for reduction of experimental errors and of test parameter variabilities.
Similar content being viewed by others
References
Arieli, R. andvan Liew, H. D. (1981) Corrections for the response time and delay of mass spectrometers.J. Appl. Physiol.: Respirat. Environ. Exercise Physiol.,51, 1417–1422.
Becklake, M. R., Lecrerc, M., Strobach, H. andSwift, J. (1975) The N2 closing volume test in population studies: sources of variation and reproducibility.Am. Rev. Respirat. Dis.,111, 141–147.
Begin, R. andRenzetti, A. D. Jr. (1977) Alveolar-arterial oxygen pressure gradient: I. Comparison between an assumed and actual respiratory quotient in stable chronic pulmonary disease; II. Relationship to aging and closing volume in normal subjects.Respirat. Care,22, 491–500.
Bernard, T. E. (1977) Aspects of on-line digital integration of pulmonary gas transfer.J. Appl. Physiol.: Respirat. Environ. Exercise Physiol.,43, 375–378.
Brunner, J. X., Wolff, G., Cumming, G. andLangenstein, H. (1985) Accurate measurement of N2 volumes during N2 washout requires dynamic adjustment of delay time.J. Appl. Physiol.: Respirat. Environ. Exercise Physiol.,59, 1008–1012.
Buist, A. S. andRoss, B. B. (1973) Predicted values for closing volumes using a modified single breath nitrogen test.Am. Rev. Respirat. Dis.,107, 744–752.
Buist, A. S. (1984) Current status of small airways disease.Chest,86, 100–105.
Burki, N. K., Barker, D. B. andNicholson, D. P. (1975) Variability of the closing volume measurement in normal subjects.Am. Rev. Respirat. Dis.,112, 209–212.
Cormier, Y. andBélanger, J. (1982) Metabolic effect on phase III slopes of single-breath nitrogen tests.Ibid.,,53, 789–792.
Cormier, Y. andNadeau, D. (1980) Ventilation, perfusion, and cardiogenic oscillations of the single-breath N2 test.J. Appl. Physiol.: Respirat. Environ. Exercise Physiol.,49, 552–557.
Craven, N., Sidwall, G., West, P., McCarthy, D. S. andCherniack, R. M. (1976) Computer analysis of the single-breath nitrogen washout curve.Am. Rev. Respirat. Dis.,113, 445–449.
DeGroodt, E. G., Quanjer, P. H. andWise, M. E. (1984) Short and long term variability of indices from the single and multiple breath nitrogen test.Bull. Eur. Physiopathol. Respirat.,20, 271–277.
Ducic, S., Swift, J., Martin, R. R. andMacklem, P. T. (1975) Appraisal of a new test: between-technician variation in the measurement of closing volume.Am. Rev. Respirat. Dis.,112, 621–627.
Fazzi, P., Viegi, G., Paoletti, P., Giuliano, G., Begliomini, E., Fornai, E. andGiuntini, C. (1982) Comparison between two standardized questionnaires and pulmonary function tests in a group of workers.Eur. J. Respirat. Dis.,63, 168–169.
Fowler, W. S. (1949) Lung function studies. III Uneven pulmonary ventilation in normal subjects and in patients with pulmonary disease.J. Appl. Physiol.,2, 283–299.
Gallagher, C. G. andYounes, M. (1987) Closing volume after inspiratory resistive loading to fatigue.Respirat. Physiol.,68, 137–144.
Gelfand, R., Lambertsen, C. J., Peterson, R. E. andSlater, A. (1976) Pneumotachograph for flow and volume measurement in normal and dense atmospheres.J. Appl. Physiol.,41, 120–124.
Guy, H. J., Gaines, R. A., Hill, P. M., Wagner, P. D. andWest, J. B. (1976) Computerized, noninvasive tests of lung function.Am. Rev. Respirat. Dis.,113, 737–744.
Hankinson, J. L. (1977) Computer determined closing volumes.Comput. Biomed. Res.,10, 247–257.
Hankinson, J. L. (1981) Automated pulmonary function testing: interpretation and standardization.Ann. Biomed. Eng.,9, 633–643.
Hankinson, J. L. (1982) Quality control in the pulmonary function laboratory.Respirat. Care,27, 830–833.
Holtz, B., Sixt, R. andBake, B. (1980) Effects of preinspiratory volume on the nitrogen closing volume test.Respirat. Physiol.,40, 241–251.
Kapitan, K. S. andHempleman, S. C. (1986) Computer simulation of mammalian gas-exchange.Comput. Biol. Med.,16, 91–101.
Kelman, G. R. (1968) Computer program for the production of CO2−O2 diagrams.Respirat. Physiol.,4, 260–269.
Lemen, R. J., Gerdes, C. B., Wegmann, M. J. andPerrin, K. J. (1982) Frequency spectra of flow and volume events for forced vital capacity.J. Appl. Physiol.: Respirat. Environ. Exercise Physiol.,53, 977–984.
Linn, W. S. andHackney, J. D. (1973) Nitrogen and helium ‘closing volumes’: simultaneous measurement and reproducibility.J. Appl. Physiol.,34, 396–399.
McCarthy, D. S., Craig, D. B. andCherniack, R. M. (1975) Intra-individual variability in maximal expiratory flow-volume and closing volume in asymptomatic subjects.Am. Rev. Respirat. Dis.,112, 407–411.
McFadden, E. R. Jr., Holmes, B. andKiker, R. (1975) Variability of closing volume measurements in normal man.Ibid.,,111, 135–140.
Mitchell, R. R. (1979) Incorporating the gas analyzer response time in gas exchange computations.J. Appl. Physiol.: Respirat. Environ. Exercise Physiol.,47, 1118–1122.
NHLI (1973) Suggested standardized procedures for closing volume determinations (nitrogen method). Division of Lung Diseases, National Heart & Lung Institute, Bethesda, Maryland, USA.
Pisani, P., Paoletti, P., Marchesi, C., Fornai, E., Fazzi, P., DiPede, F., Pistelli, G. andGiuntini, C. (1980)Automatic computation of single breath nitrogen test in computers in critical care and pulmonary medicine, 1st edn. Plenum Press, New York.
Swanson, G. D. andSherrill, D. L. (1983) A model evaluation of estimates of breath-to-breath alveolar gas exchange,J. Appl. Physiol.: Respirat. Environ. Exercise Physiol.,55, 1936–1941.
Turney, S. Z. andBlumenfeld, W. (1973) Heated Fleisch pneumotachometer: a calibration procedure.J. Appl. Physiol. 34, 117–121.
Wiener, B. J. (1971)Statistical principles in experimental design, 2nd edn. McGraw Hill, New York.
Yeh, M. P., Adams, T. D., Gardner, R. M., andYanowitz, F. G. (1984) Effect of O2, N2, and CO2 composition on nonlinearity of Fleisch pneumotachometers characteristics.J. Appl. Physiol.: Respirat. Environ. Exercise Physiol.,56, 1423–1425.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Melo, M.F.V., Giannella Neto, A. Automatisation of the single-breath nitrogen washout test. Med. Biol. Eng. Comput. 27, 137–146 (1989). https://doi.org/10.1007/BF02446222
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF02446222