Introducing a Custom-Designed Volume-Pressure Machine for Novel Measurements of Whole Lung Organ Viscoelasticity and Direct Comparisons Between Positive- and Negative-Pressure Ventilation

This study introduces a novel, automated volume-controlled pressure–measurement system for characterizing the viscoelastic macromechanics of whole lungs and enabling direct comparison between positive-pressure ventilation (PPV) and negative-pressure ventilation (NPV). Unlike traditional pressure-controlled systems, the device generates standardized, continuous volume–pressure curves without requiring lung degassing, while accounting for air compressibility in real time. Validation using ex vivo murine lungs, elastic balloons, and water bladders demonstrated accurate capture of compliance, hysteresis, preconditioning, and pressure-relaxation behavior. The system revealed clear dependencies of lung mechanics on inflation volume and rate and enabled the first direct experimental comparison between PPV and physiologically relevant NPV mechanics. The platform expands experimental capabilities for studying healthy and diseased pulmonary biomechanics and provides a foundation for improving ventilator strategies.