This prospective, observational cohort study aims to evaluate whether the dynamic monitoring of a patient's breathing effort can predict successful liberation from invasive mechanical ventilation. The study will include 120 patients who have undergone 36 hours or more of controlled mechanical ventilation and deep sedation. Patient monitoring will commence immediately upon their transition to an assisted spontaneous breathing mode with pressure support. Starting from this clinical milestone, the researchers will track the patients' longitudinal inspiratory effort daily through four specific variables: maximum occlusion pressure, muscle pressure index, flow index via visual waveform inspection, and diaphragmatic thickening fraction via ultrasound. Concurrently, ventilator safety parameters (plateau pressure, driving pressure, transpulmonary pressure, and compliance) will be recorded. The primary outcome is the time from PSV initiation to successful weaning (defined as 72 hours without ventilator support). Clinical events such as death or return to a controlled mode due to PSV failure will be statistically treated as competing risks. Secondary outcomes include the incidence of pneumonia, ICU-acquired weakness, delirium, mortality, and PSV failure. Data will be analyzed using multivariate joint modeling within a Bayesian framework.
18 years old or more.
Patients undergoing invasive mechanical ventilation for any cause under a controlled ventilation mode for more than 36 hours.
Attending physician's decision to initiate pressure support ventilation according to standard clinical practice.
Pregnancy.
Degenerative neuromuscular disease (e.g., amyotrophic lateral sclerosis, congenital myopathies).
Air leak/fistula that prevents breathing-pause maneuvers.
Diaphragmatic paralysis.
Adult patients admitted to Intensive Care Unit who require invasive mechanical ventilation due to any cause with 36 hours or more with a controlled mode of mechanical ventilation and deep sedation
Cohort
Prospective
Not listed
Daily Inspiratory Effort: diaphragmatic thickening fraction.
Non-invasive monitoring of patient inspiratory effort performed daily starting from the initiation of pressure support ventilation using diaphragmatic thickening fraction measured via ultrasound. Unit of measure: percentage (%).
Daily Inspiratory Effort: pressure muscle index
Non-invasive monitoring of patient inspiratory effort performed daily starting from the initiation of pressure support ventilation using the pressure muscle index measured in the mechanical ventilator during an end-inspiratory occlusion maneuver. Unit of measure: centimeters of water
Daily Inspiratory Effort: maximum occlusion pressure
Non-invasive monitoring of patient inspiratory effort performed daily starting from the initiation of pressure support ventilation using the maximum occlusion pressure measured in the mechanical ventilator during an end-espiratory occlusion maneuver. Unit of measure: centimeters of water
Daily Inspiratory Effort: flow index
Non-invasive monitoring of patient inspiratory effort performed daily starting from the initiation of pressure support ventilation using a qualitative evaluation by analyzing the airway flow waveform on the mechanical ventilator. The profile is categorized daily as positive (presence of effort) or negative (absence of effort). For reporting and analytical purposes, this qualitative assessment is coded as a binary scale where 0 indicates a negative flow index and 1 indicates a positive flow index. Individual daily data trajectories will be analyzed using a Bayesian joint model. Unit of measure: score on a scale, where 0 represents negative flow index and 1 represents a positive flow index
incidence of Ventilator-Associated Pneumonia
proportion of patients who develop ventilator-associated pneumonia based on standard clinical, radiological, and microbiological criteria.
incidence of Intensive Care Unit-Acquired Weakness
development of critical illness weakness evaluated via the Medical Research Council score, which evaluates 6 muscle groups bilaterally, ranging from a total score of 0 (no strength) to 60 (normal muscle strength), where higher scores indicate better muscle strength. Intensive Care Unit-Acquired Weakness will be defined as an MRC sum score of 48 or less.
incidence of delirium
daily screening for delirium using the Confusion Assessment Method for the Intensive Care Unit, which assesses four features: (1) acute onset or fluctuating course, (2) inattention, (3) altered level of consciousness, and (4) disorganized thinking. Delirium is defined as positive when features 1 and 2, and either feature 3 or 4 are present.
incidence of mortality
incidence of death by any cause during the study period (handled as a competing risk in the main analysis).
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