Rheological Theory Applied to Mechanical Ventilation in Acute Respiratory Distress Syndrome: A New Paradigm for Understanding and Preventing Ventilator-Induced Lung Injury

The concept of mechanical power (MP) has emerged as a comprehensive indicator of ventilator-induced lung injury (VILI), integrating the effects of tidal volume, airway pressures, respiratory rate, and flow. However, applying MP as an absolute threshold (e.g., 12 J/min) across heterogeneous patients with acute respiratory distress syndrome (ARDS) may be inadequate. This article explores a rheological model for the respiratory system that reconceptualizes the lung as a viscoelastic body and advocates for individualized MP thresholds. We propose adjusting MP based on ideal body weight (J/min/kg) and, more accurately, on static compliance (J/min/L), which better reflects functional lung size ("baby lung") and mechanical vulnerability. This normalization offers a more precise risk stratification and easier setting of ventilation targets, particularly in patients with low compliance or abnormal body composition. Emerging evidence suggests that normalized MP correlates more closely with mortality than absolute MP values and aligns with the physiological stress-strain behavior of pulmonary tissue. Adopting MP normalization within lung-protective strategies could enhance the safety and efficacy of mechanical ventilation, however clinical validation is still required. This review summarizes the theoretical foundations, supporting evidence, and clinical implications of this approach within the broader context of rheological modeling in ARDS.