Gas mixing in lung model ventilated by high frequency oscillation: Effect of tidal volume, frequency and molecular diffusivity

  • A. Ben-Jebria
Biomechanics

Abstract

The efficiency of gas mixing during sinusoidal oscillatory flow in a model of human lung cast was assessed by using a multibreath carbon dioxide washout manoeuvre. The experiments were performed at high frequencies (5, 10, 15 and 20 Hz) and low tidal volumes (50, 90 and 120 cm3). A particular effort was made to analyse the influence of flow oscillation conditions (f and Vr) as well as the effect of resident alveolar gas density (molecular diffusion) on the effective diffusion coefficient (Deff). This longitudinal mixing parameter was found to be strongly dependent on the tidal volume (approximately proportional to V r 1·4 ) and weakly dependent on the frequency (approximately proportional to f0·5). However, molecular diffusion was not, in general, a limiting factor in the gas transport process during high-frequency oscillation (HFO).

Keywords

CO2 washout Gas mixing He HFO N2 O2 Physical lung model SF6 

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References

  1. Ben-Jebria, A. andKays, C. (1987) Effective carbon dioxide washout by high-frequency mechanical ventilation.Med. & Biol. Eng. & Comput.,25, 655–660.Google Scholar
  2. Ben-Jebria, A., Choukroun, M. L., Tabka, Z. andUltman, J. S. (1988) High-frequency oscillatory pressure/flow relationship in the airways of laryngo-tracheo-bronchial tree casts.,26, 476–482.CrossRefGoogle Scholar
  3. Bohn, D. J., Miyasaka, K., Marchak, B. E., Thompson, W. K., Froese, A. B. andBryan, A. C. (1980) Ventilation by high frequency oscillation.J. Appl. Physiol.,48, 710–716.Google Scholar
  4. Brusasco, V., Knopp, T. J., Schmid, E. R. andRehder, K. (1984) Ventilation-perfusion relationship during high frequency ventilation.,56, 454–458.Google Scholar
  5. Fredberg, J. J. (1980) Augmented diffusion in the airways can support pulmonary gas exchange.,49, 232–238.Google Scholar
  6. Goldman, L. J. andMacDonald, J. S. (1983) The role of resident gas on CO2 exchange during high frequency oscillation (abstract).Anesthesiology,59, A495.CrossRefGoogle Scholar
  7. Goldstein, D., Slutsky, A. S., Ingram, R. H., Westerman, P., Venegas, J. andDrazen, J. (1981) CO2 elimination by high frequency ventilation (4 to 10 Hz) in normal subjects.Am. Rev. Respirat. Dis.,123, 251–255.Google Scholar
  8. Knopp, T. J., Kaethner, T., Meyer, M., Rehder, K. andScheid, P. (1983) Gas mixing in the airways of dog lungs during high-frequency ventilation.J. Appl. Physiol.,55, 1141–1146.Google Scholar
  9. Reisfeld, B. andUltman, J. S. (1988) Longitudinal mixing in dog lungs during high frequency forced flow oscillation.Respirat. Physiol.,71, 269–286.CrossRefGoogle Scholar
  10. Robertson, H. T., Coffey, R. L., Standaert, T. A. andTruog, W. E. (1982) Respiratory and inert gas exchange during high frequency ventilation.J. Appl. Physiol.,52, 683–689.Google Scholar
  11. Slutsky, A. S., Drazen, J. M., Ingram, R. H., Kamm, R. D., Shapiro, A. H., Fredberg, J. J., Loring, S. H. andLehr, J. (1980) Effective pulmonary ventilation with small volume oscillations at high frequency.Science,209, 609–611.Google Scholar
  12. Slutsky, A. S., Kamm, R. D., Rossing, T. H., Loring, S. H., Lehr, J., Shapiro, A. H., Ingram, R. H. Jr. andDrazen, J. M. (1981) Effects of frequency, tidal volume, and lung volume on CO2 elimination in dogs by high frequency (2–30 Hz), low tidal volume ventilation.J. Clin. Invest.,68, 1475–1484.CrossRefGoogle Scholar
  13. Solway, J., Gavriely, N., Slutsky, A. S. andDrazen, J. M. (1983) Effect of resident gas composition on CO2 output during high frequency ventilation (abstract).Fed. Proc.,42, 1350.Google Scholar
  14. Watson, J. W. andJackson, A. C. (1984) CO elimination as a function of frequency and tidal volumes in rabbits during HFO.J. Appl. Physiol.,57, 354–359.Google Scholar
  15. Worth, H. andPiiper, J. (1978) Model experiments of diffusional equilibration of oxygen and carbon dioxide between inspired and alveolar gas.Respirat. Physiol.,35, 1–7.CrossRefGoogle Scholar

Copyright information

© IFMBE 1991

Authors and Affiliations

  • A. Ben-Jebria
    • 1
  1. 1.Laboratoire de PhysiologieUniversité de Bordeaux-IIBordeaux CédexFrance

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