Fig 1.
(a) Lung anatomy: (A) shows the location of the lungs and airways in the body (B) is a detailed view of the lung structures such as the bronchioles, neuroendocrine cells, alveoli, capillary network, alveolar liquid with surfactant, and interstitial space.
Wikipedia, https://commons.wikimedia.org/wiki/File:Lung_structure_normal.jpg, accessed October 19, 2022. (b) A two-dimensional model of a septal tract with capillary, interstitium, and alveolar compartments. See text for definitions.
Table 1.
Base state parameter values and references.
Fig 2.
(a) Flow rate definitions across boundaries (b) Streamlines, velocity fields, and color-coded pressure field for: (b upper) the base set of parameters, BASE; (b lower) is BASE with pAG = 15 cmH2O PEEP.
Note that the horizontal axis is compressed for 0.1 ≤ X ≤ 0.9 and circumscribed with a blue rectangle. The bounding streamlines in yellow separate alveolar and capillary contributions to the end-exit flows at X=0 and X=1 which become available to lymphatics., (c) Flow calculations for Normal/Recovery including BASE, PEEP and zero absorption velocity, vab = 0. Note QAL = QA0 + QA1 and QcL = Qc0 + Qc1. See text for details.
Fig 3.
Streamlines, velocity fields, and pressure color coding for (a upper) CPE, (a lower) CPE with 15 cmH2O PEEP, (b upper) ARDS, (b lower) ARDS with 15 cmH2O PEEP.
Note that the horizontal axis is compressed for 0.1 ≤ X ≤ 0.9 and circumscribed with a blue rectangle. The bounding streamlines in yellow separate alveolar and capillary contributions to the end-exit flows at X=0 and X=1 which become available to lymphatics. (c) flow calculations for (a), (d) flow calculations for (b), Note QAL = QA0 + QA1 and QcL = Qc0 + Qc1. See text for details.
Fig 4.
Streamlines, velocity fields, and color-coded pressure field for.
(a) CPE with pAG = 7 cmH2O PEEP, (b) CPE with 7 cmH2O PEEP and 10K..
Fig 5.
Comparison of ui (η) at X=0.0, 0.02, 0.05, 0.95,0.98,1.0.
for (a) BASE (b) CPE. (c) ui (η=0) vs X for BASE, CPE, CPE + 10K, CPE + 100K, ARDS. (d) wall shear stress τw for the alveolar membrane for BASE, CPE, CPE with10K, CPE 100K, and ARDS.
Fig 6.
Streamlines, velocity fields, and color-coded pressure field for BASE with
(a)10K and (b) 100K.
Fig 7.
Lymph flow vs average capillary pressure (pa
+pv)/2.