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Pflügers Archiv

, Volume 403, Issue 4, pp 384–387 | Cite as

Series dead space for inert gases in healthy subjects

  • H. Guenard
  • G. Manier
  • Y. Castaing
  • N. Varene
Heart, Circulation, Respiration and Blood; Environmental and Exercise Physiology

Abstract

In ten normal subjects, series dead space was determined for six intravenously infused inert gases (SF6, ethane, cyclopropane, fluothane, ether, acetone) from their expired and alveolar concentrations. The method for sampling alveolar gas was based on the criterion of identity of mean alveolar and expired gas exchange ratios.

Inert gases were analysed chromatographically. Acetone, the most soluble gas, yielded the lowest dead space, the difference to the other gases being about 4.5%. This is probably due to the non-infinite value of the series dead space ventilation-perfusion ratio (A/Q) which was estimated at about 2,000. The diffusivity, inversely related to the molecular weight, also played a role, the heaviest gas (fluothane) having a greater dead space than the lightest (ethane). The underestimation of the dead space from acetone is expected to be greater in subjects with low tidal volume and high bronchial blood flow, i. e. in some patients with respiratory disease.

Key words

Inert gases Dead space Ventilation/perfusion ratio 

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Copyright information

© Springer-Verlag 1985

Authors and Affiliations

  • H. Guenard
    • 1
  • G. Manier
    • 1
  • Y. Castaing
    • 1
  • N. Varene
    • 1
  1. 1.Service d'Exploration Fonctionnelle Respiratoire et U.E.R. de Biologie et Physiopathologie des Facteurs d'AmbianceUniversité de Bordeaux IIBordeaux CedexFrance

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