Mechanical power (MP) is a summary variable, which includes static and dynamic respiratory parameters, is associated with ventilator-induced lung injury. MP is transferred primarily to smaller functional lung size, often referred to as "baby lung" (BL). Functional lung size (BL) is associated with respiratory system compliance (Crs). For this reason, MP normalized to Crs (MP/Crs) could be an important parameter to evaluate. The objectives of this study were to compare variables according to the MP/Crs cut-off point and to identify the MP components associated with MP/Crs.

In patients with acute respiratory distress syndrome (ARDS), undergoing mechanical ventilation (MV), each respiratory cycle transfers a specific amount of mechanical energy to the lung, aimed to expand and overcome airway resistance. The total mechanical energy multiplied by the respiratory rate (RR) defines the mechanical power (MP). It has been hypothesized that a smaller functional lung size, often referred to as "baby lung" (BL), increases mechanical energy transfer that exacerbates lung damage. Functional lung size (BL) is associated with respiratory system compliance (Crs). Whatever the size of this operational BL, protective ventilation strategies should be aimed at preserving its size and functionality, to avoid ventilator-induced lung injury (VILI). For this reason, MP normalized to Crs (MP/Crs) could be an important parameter to evaluate. Preclinical studies have found that VILI arises primarily from a combination of MP components and not from any of its components individually. We believe that MP/Crs should have the same behavior in relation to MP components as a whole. Therefore, the objectives of this study are to compare variables according to the MP/Crs cut-off point and to identify the MP components associated with MP/Crs.

Inclusion Criteria:

• patients who have been receiving mechanical ventilation (MV) and have been defined as with ARDS according to the Berlin definition

Exclusion Criteria:

• patients with chronic pulmonary disease
• patients with an expected duration of MV shorter than 48 h
• patients with a high risk of death within 3 months for reasons other than ARDS
• patients having made the decision to withhold life-sustaining treatment.

Patients who have been receiving mechanical ventilation (MV) and have been defined as with ARDS according to the Berlin definition

The data will be uploaded in an Excel document and shared with all the researchers participating in the study.