A comprehensive overview of ventilation intensity and mutual relationship with mechanical power, strain and ventilatory ratio.

Ventilator-induced lung injury (VILI) is a concept developed over the past fifty years, highlighting how aggressive ventilatory settings can contribute to lung damage. This study examines the factors inducing lung injury, such as barotrauma, volutrauma, atelectrauma, and biotrauma. Recent guidelines emphasize the importance of low tidal volume and low driving pressure settings to improve outcomes in ARDS patients and nowadays scientific community is still exploring its effectiveness in other settings. The concept of Ventilation Intensity (VI) is introduced as a new approach, distinct from ventilator intensity, representing the total energy delivered during assisted ventilation. VI is related to the mechanical power (MP) of the respiratory system, which includes dynamic and static elastance, resistance, and respiratory rate, expressed in Joules/minute. VI should be related also to stress and strain, because of lung compliance is a determinant of parenchymal energy absorption during invasive mechanical ventilation, and ventilatory ratio should be considered as a determinant of ventilatory approach and consequently its intensity. At present, VI has not been explored in patients in spontaneous/assisted breathing, and we could just hypothesize that patients drive and efforts could increase VI trough MP and promote patient self-induced lung injury (P-SILI). Additionally, the importance of monitoring VI is discussed to prevent ventilatory aggressiveness and improve outcomes in mechanically ventilated patients. This short review focuses on actual knowledge of VI and plausible correlation with MP, stress, strain and ventilatory ratio to improve its understanding and the potential relationship with VILI and P-SILI.