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). It integrates the effects of tidal volume, airway pressures, respiratory rate, and flow. However, applying MP as a universal threshold (e.g., 12 J/min) across heterogeneous patients with acute respiratory distress syndrome (ARDS) may be inadequate. This review introduces the rheological model, which conceptualizes the lung as a viscoelastic body (i.e., one that exhibits both elastic and viscous properties), and applies it to ARDS ventilation. The rheological model may offer individualized MP thresholds. The potential benefits of adjusting MP based on ideal body weight (J/min/kg) are discussed and, more accurately, on static compliance (J/min/L). Static compliance could better reflect functional lung size, though clinical validation remains needed. Preliminary clinical and modeling evidence suggests that normalized MP correlates more closely with mortality than absolute MP and aligns with pulmonary stress–strain behavior. This normalization provides a more precise risk stratification and facilitates the easier setting of ventilation targets, particularly in patients with low compliance or abnormal body composition. This review clarifies definitions and consolidates evidence, highlights the clinical implications of rheology for lung-protective strategies. MP normalization within a lung-protective strategy 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.