The goal of this Multicenter retrospective cohort study is to assessing the association between the development of a tidal volume magnitude > 8 ml/kg of predicted body weight during the first transition to partial support phase in pressure support mode and mortality in the intensive care unit in a general population of patients older than 18 years who require invasive mechanical ventilation, in contrast to individuals who develop tidal volume ≤ 8 ml/kg of predicted body weight. Secondarily, assess the association between elevated VT (tidal volume) during the initiation of the partial support phase in pressure support mode and ventilator-free days, failure in transitioning to spontaneous ventilation, and success in weaning from mechanical ventilation.

The main question it aims to answer are:

• Does exposure to tidal volumes greater than 8 ml/kg of predicted body weight during the first 48 hours of pressure support mode mechanical ventilation increase the risk of death in the intensive care unit compared to those who develop a tidal volume equal to or less than 8 ml/kg of predicted body weight in subjects older than 18 years requiring invasive mechanical ventilation?

The clinical investigation aims to determine whether exposure to tidal volumes greater than 8 ml/kg of predicted body weight during the initial 48 hours of pressure support mode mechanical ventilation is associated with an increased risk of mortality in the intensive care unit when compared to individuals who maintain a tidal volume equal to or less than 8 ml/kg of predicted body weight. This analysis involves subjects aged 18 years and older who require invasive mechanical ventilation

The data of patients from each participating center in the study will be encoded to maintain their anonymity. These center-related data will only be known to the study's Principal Investigator (PI), who will be the sole individual with access to them. Under no circumstances will the centers be able to make comparisons among themselves.

The data collected by each participating unit will be gathered by the investigator or by one of the designated team members assigned to the study, and entered into a REDCap® form specifically designed for this study.

The data collected by each investigator will be randomly supervised by the coordinating group to ensure the quality of the collected data and to detect possible errors in data acquisition. The study's coordinating group will also monitor the daily incorporation of data into the database to supervise and detect, as a double filter, the possibility of errors in data editing and incorporation, thus ensuring the quality and reliability of the information obtained throughout the entire period of patient inclusion.

Inclusion Criteria:

• Patients aged 18 and older admitted to the participating ICUs from January 1, 2019, to April 30, 2023, with a requirement for mechanical ventilation (MV) for any reason for at least 72 hours within the same cycle, who have at least one monitoring session in PC-CSV (pressure support ventilation), and who remain on MV (regardless of the mode) for a period of ≥ 1 calendar day after that monitoring session will be included

Exclusion Criteria:

• Patients who have not initiated the partial support phase in PC-CSV mode or who are extubated within a period of less than 24 hours from the first ventilatory monitoring in PC-CSV will be excluded. Subjects with missing data in exposure and/or outcome variables will also be excluded.

Patients aged 18 years or older in invasive mechanical ventilation who have remained in PC-CSV for at least 24 hours