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New method of calculating alveolar CO2 transport
Author(s) -
Caucha Luis Jhony,
Cruz Julio Cesar,
Rueda Luis Antonio
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.1037.2
Subject(s) - diffusion , dilution , convection , apex (geometry) , mixing (physics) , volume (thermodynamics) , thermodynamics , tidal volume , expiration , convection–diffusion equation , chemistry , mechanics , respiratory system , geometry , anatomy , physics , mathematics , biology , quantum mechanics
Cruz proposed that the expirogram of CO 2 does not represent the process of gas exchange ( FASEB J. 21:609.4, 2007). It represents a simple alveolar gas dilution by the tidal volume that does not reach the residual volume (RV). Caucha et al. showed that phase II is formed by the distribution of regional dead spaces ( FASEB J. 22:763.6, 2008). However, this latter model could not predict which anatomic Weibel's model generations were involved. Thus, here, we modify Caucha's model by separating the convection‐diffusion process (method 1) in three different steps (method 2): 1. Convection. 2. Convection‐diffusion and 3. Diffusion. As a result, new alveolar CO 2 concentrations at the apex and base regions of the lung were found (see figure, interrupted and continuous lines for method 1 and 2, respectively). This picture was obtained after searching the generations involved: the first 8 generations (step 1), generations 9 th ‐19 th (step 2) and the last 5 generations (step 3), which produced the simulated expirogram similar to the experimental curve. In conclusion, the analysis presented follows our theory of alveolar gas mixing; during inspiration, the alveolar CO 2 is diluted by the tidal volume (figure), and during expiration, the uneven emptying of parallel regions of the lung generates the expirogram. Supported in part by ONG ‐ Centro de Enseñanza Investigación y Servicios.