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

Roberta Südy, Gergely H. Fodor, André Dos Santos Rocha, Álmos Schranc, József Tolnai, Walid Habre, Ferenc Peták

Research output: Contribution to journalArticle

Abstract

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 (Zrs) at 0, 3, and 6 cmH2O PEEP levels. Esophageal pressure was measured by a catheter-tip micromanometer to separate Zrs into pulmonary (ZL) and chest wall (Zcw) components. A model containing a frequency-independent Newtonian resistance (RN), inertance, and a constant-phase tissue damping (G) and elastance (H) was fitted to Zrs, ZL, and Zcw spectra. The contribution of Zcw to RN was negligible in all species and PEEP levels studied. However, the participation of Zcw 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.

Original languageEnglish
Pages (from-to)198-204
Number of pages7
JournalJournal of Applied Physiology
Volume127
Issue number1
DOIs
Publication statusPublished - Jan 1 2019

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Keywords

  • Airway resistance
  • Animal models
  • Esophageal pressure
  • Lung mechanics
  • Tissue viscoelasticity

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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