Different contributions from lungs and chest wall to respiratory mechanics in mice, rats, and rabbits

Changes in lung mechanics are frequently inferred from intact-chest measures of total respiratory system mechanics without consideration of the chest wall contribution. The participation of lungs and chest wall in respiratory mechanics has not been evaluated systematically in small animals commonly...

Full description

Saved in:
Bibliographic Details
Published in:Journal of applied physiology (1985) 2019-07, Vol.127 (1), p.198-204
Main Authors: Südy, Roberta, Fodor, Gergely H, Dos Santos Rocha, André, Schranc, Álmos, Tolnai, József, Habre, Walid, Peták, Ferenc
Format: Article
Language:English
Subjects:
Animal models
Animals
Chest
Damping
Esophagus
Lungs
Mechanical measurement
Mechanics
Mechanics (physics)
Medical instruments
Mice
Pressure
Rabbits
Respiratory system
Respiratory tract
Ventilation
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Changes in lung mechanics are frequently inferred from intact-chest measures of total respiratory system mechanics without consideration of the chest wall contribution. The participation of lungs and chest wall in respiratory mechanics has not been evaluated systematically in small animals commonly used in respiratory research. Thus, we compared these contributions in intact-chest mice, rats, and rabbits and further characterized the influence of positive end-expiratory pressure (PEEP). Forced oscillation technique was applied to anesthetized mechanically ventilated healthy animals to obtain total respiratory system impedance (Z ) at 0, 3, and 6 cmH O PEEP levels. Esophageal pressure was measured by a catheter-tip micromanometer to separate Z into pulmonary (Z ) and chest wall (Z ) components. A model containing a frequency-independent Newtonian resistance (R ), inertance, and a constant-phase tissue damping (G) and elastance (H) was fitted to Z , Z , and Z spectra. The contribution of Z to R was negligible in all species and PEEP levels studied. However, the participation of Z in G and H was significant in all species and increased significantly with increasing PEEP and animal size (rabbit > rat > mice). Even in mice, the chest wall contribution to G and H was still considerable, reaching 47.0 ± 4.0(SE)% and 32.9 ± 5.9% for G and H, respectively. These findings demonstrate that airway parameters can be assessed from respiratory system mechanical measurements. However, the contribution from the chest wall should be considered when intact-chest measurements are used to estimate lung parenchymal mechanics in small laboratory models (even in mice), particularly at elevated PEEP levels. In species commonly used in respiratory research (rabbits, rats, mice), esophageal pressure-based estimates revealed negligible contribution from the chest wall to the Newtonian resistance. Conversely, chest wall participation in the viscoelastic tissue mechanical parameters increased with body size (rabbit > rat > mice) and positive end-expiratory pressure, with contribution varying between 30 and 50%, even in mice. These findings demonstrate the potential biasing effects of the chest wall when lung tissue mechanics are inferred from intact-chest measurements in small laboratory animals.
ISSN:8750-7587
1522-1601
DOI:10.1152/japplphysiol.00048.2019