Morphometric model for pulmonary diffusing capacity I. Membrane diffusing capacity

Ewald R. Weibel, William J. Federspiel, Fabienne Fryder-Doffey, Connie C W Hsia, Martin König, Vilma Stalder-Navarro, Ruth Vock

Research output: Contribution to journalArticlepeer-review

119 Scopus citations


The pulmonary diffusing capacity is related to the quantitative design characteristics of the pulmonary gas exchanger. The current model for estimating DlO2 from morphometric data breaks the diffusion path for O2 into four steps, three of which represent the membrane part of DlO2. A critique of this model on the basis of newer evidence leads to a modification of the model where the path from the alveolar surface to the erythrocyte membrane is considered as a single step. The structural determinant of this model for DmO2 is the ratio of effective diffusion surface to effective total barrier thickness. The effective surface is formulated as a fraction of the alveolar surface area, the most robust measure of lung design, whereas the effective barrier thickness is the harmonic mean distance - or mean proximity - between alveolar surface and erythrocyte surface. The methods for obtaining the morphometric measurements are discussed. The results show that the new morphometric estimates of DmO2 are 33% lower than those obtained with the old model, resulting in a reduction of the estimates of DlO2 by 10-20%.

Original languageEnglish (US)
Pages (from-to)125-149
Number of pages25
JournalRespiration Physiology
Issue number2
StatePublished - Aug 1993


  • Diffusing capacity
  • Gas exchange
  • Model
  • Morphometry
  • lung
  • pulminary

ASJC Scopus subject areas

  • Physiology
  • Pulmonary and Respiratory Medicine


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