A tidally breathing model of ventilation, perfusion and volume in normal and diseased lungs

J. S. Yem, M. J. Turner*, A. B. Baker, I. H. Young, A. B.H. Crawford

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

Background. To simulate the short-term dynamics of soluble gas exchange (e.g. CO 2 rebreathing), model structure, ventilation-perfusion ( Vdot A/Q̇) and ventilation-volume (V̇/VA) parameters must be selected correctly. Some diseases affect mainly V̇A/VA distribution while others affect both V̇A/Q̇ and V̇A/VA distributions. Results from the multiple inert gas elimination technique (MIGET) and multiple breath nitrogen washout (MBNW) can be used to select V̇AQ̇ and V̇A/VA parameters, but no method exists for combining V̇AQ̇ and V̇A/ VA parameters in a multicompartment lung model. Methods. We define a tidally breathing lung model containing shunt and up to eight alveolar compartments. Quantitative and qualitative understanding of the diseases is used to reduce the number of model compartments to achieve a unique solution. The reduced model is fitted simultaneously to inert gas retentions calculated from published V̇A/Q̇ distributions and normalized MBNWs obtained from similar subjects. Normal lungs and representative cases of emphysema and embolism are studied. Results. The normal, emphysematous and embolism models simplify to one, three and two alveolar compartments, respectively. Conclusions. The models reproduce their respective MIGET and MBNW patient results well, and predict disease-specific steady-state and dynamic soluble and insoluble gas responses.

Original languageEnglish
Pages (from-to)718-731
Number of pages14
JournalBritish Journal of Anaesthesia
Volume97
Issue number5
DOIs
Publication statusPublished - Nov 2006
Externally publishedYes

Keywords

  • Modelling
  • Ventilation inhomogeneity
  • Ventilation/perfusion distribution

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