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New nitrogen washout model simulation using seven parallel region from apex‐to‐base of the lung (717.3)
Author(s) -
Caucha Luis,
Cruz Julio,
Caucha Yelimer
Publication year - 2014
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.28.1_supplement.717.3
Subject(s) - washout , nitrogen washout , functional residual capacity , expiration , apex (geometry) , lung volumes , dilution , respiratory system , tidal volume , lung , residual , chemistry , residual volume , volume (thermodynamics) , cardiology , medicine , anatomy , mathematics , thermodynamics , physics , algorithm
Caucha et al. [FASEB J. 27: 723.5 (2013)] showed that more dilution of alveolar N 2 is produced in the basal region than at the apex of the lung, with a forced inspiratory‐expiratory maneuver. Now, we modified Caucha’s model to simulate the N 2 washout by inhaling 100% O 2 . Four healthy subjects consented to our study. The results of one of them (FRC=2.3L RV=0.732, VC=5.145L) are shown in the Figure, symbols represent experimental data and continuous lines are from the model. The subject inhaled a tidal volume of approximately 1L from Functional Residual Capacity (FRC) and exhaled back to FRC in 2.8s. Expirograms of O 2 , CO 2 and N 2 were recorded simultaneously for 40 breaths. The model was adjusted to simulate the first N 2 expiration. The following expirations resulted from the alveolar N 2 dilutions. Our model predicted more dilution of the N 2 expirogram from the 10 th breath. Comments: Three distribution models, Milic‐Emili et al [J. Appl. Physiol. 21: 749‐759 (1966)], Sutherland et al [J. Appl. Physiol. 25: 566‐574 (1968)] and Cruz et al. [Respir. Physiol. 110: 47‐56 (1997)] did not produce any significant changes to the results presented in the figure. This is to be expected since the N 2 washout test does not make respiratory maneuvers, such as exhaling to Residual Volume (RV). The excess dilution produced by the model in the last 30 breaths may be due to the assumptions made in calculating the “source term” proposed by Scherer et al [Respir. Physiol. 103: 99‐103 (1996)] that do not affect the expirogram. In conclusion, the uneven emptying of parallel regions, apex‐to‐base of the lung, generates any N 2 expirogram.Grant Funding Source : Centro de Enseñanza, Investigación y Servicios