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Updated: Aug 6, 2026
Micro-Mechanical Characterization of Lung Tissue Using Atomic Force Microscopy
Published on: August 28, 2011
Global mechanical power does not determine regional energy distribution in heterogeneous lungs
Tomasz Urbankowski1, Emilia Urbankowska2, Marek Darowski1
1Department of Modeling and Supporting of Internal Organs Functions, Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland.
Introduction:
Mechanical power (MP) integrates key determinants of ventilatory load and has been associated with ventilator-induced lung injury (VILI). However, because MP is typically derived from airway-opening measurements, it represents a global metric that may not reflect how energy is distributed within mechanically heterogeneous lungs. We aimed to investigate whether global MP uniquely determines regional energy partitioning under heterogeneous conditions.
Methods:
We conducted a deterministic in-silico study using a parallel two-compartment resistance-compliance model under volume-controlled ventilation. Systematic parameter sweeps over compliance and resistance ratios were performed, and a partition index (PI) was introduced to quantify preferential inspiratory energy delivery to the more compliant compartment.
Results:
Across the heterogeneity space, PI varied widely (0.352-0.800), while global MP ranged from 1.46 to 5.85 J/min. Importantly, iso-lines of MP overlapped regions with markedly different PI values, demonstrating that similar global MP can correspond to substantially different energy distributions. Among parameter sets matched within ±5% MP, the maximal difference in PI reached 0.39, indicating pronounced variability in preferential energetic loading despite comparable global energy delivery.
Discussion:
These findings demonstrate a structural non-identifiability: global mechanical power does not uniquely determine how inspiratory energy is partitioned in heterogeneous lungs. The proposed PI provides a compact descriptor of impedance-driven energetic routing and highlights conditions in which acceptable global MP may mask disproportionate regional energy exposure. Incorporating heterogeneity-aware information may therefore be necessary to interpret MP and guide safer ventilation strategies.
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