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A model of the recruitment-derecruitment and volume of lung units in an excised lung as it is inflated-deflated between minimum and maximum lung volume.

Authors
Frazer-DG; Lindsley-WG; McKinney-W; Reynolds-JS; Franz-GN; Jackson-M; Goldsmith-WT
Source
J Biomech Eng 2013 Mar; 135(3):034503
NIOSHTIC No.
20042309
Abstract
The role of the recruitment-derecruitment of small structures in the lung (lung units) as the lung increases and decreases in volume has been debated. The objective of this study was to develop a model to estimate the change in the number and volume of open lung units as an excised lung is inflated-deflated between minimum and maximum lung volume. The model was formulated based on the observation that the compliance of the slowly changing quasi-static pressure-volume (P-V) curve of an excised rat lung can differ from the compliance of a faster changing small sinusoidal pressure volume perturbations superimposed on the curve. In those regions of the curve where differences in compliance occur, the lung tissue properties exhibit nonlinear characteristics, which cannot be linearized using "incremental" or "small signal" analysis. The model attributes the differences between the perturbation and quasi-static compliance to an additional nonlinear compliance term that results from the sequential opening and closing of lung units. Using this approach, it was possible to calculate the normalized average volume and the normalized number of open units as the lung is slowly inflated-deflated. Results indicate that the normalized average volume and the normalized number of open units are not linearly related to normalized lung volume, and at equal lung volumes the normalized number of open units is greater and the normalized average lung unit volume is smaller during lung deflation when compared to lung inflation. In summary, a model was developed to describe the recruitment-derecruitment process in excised lungs based on the differences between small signal perturbation compliance and quasi-static compliance. Values of normalized lung unit volume and the normalized number of open lung units were shown to be nonlinear functions of both transpulmonary pressure and normalized lung volume.
Keywords
Lung; Models; Lung-function; Analytical-processes; Pulmonary-function; Pulmonary-system; Respiration
CODEN
JBENDY
Publication Date
20130301
Document Type
Journal Article
Email Address
dgf1@cdc.gov
Fiscal Year
2013
NTIS Accession No.
NTIS Price
Identifying No.
B20130321
Issue of Publication
3
ISSN
0148-0731
NIOSH Division
HELD
Priority Area
Manufacturing
Source Name
Journal of Biomechanical Engineering
State
WV
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