Standardization of IMT Dosage (UTIT) in Mechanical Ventilation.

Respiratory muscle weakness prolongs mechanical ventilation (MV) and delays weaning. Currently, there is no standardized dosage for Inspiratory Muscle Training (IMT) in the ICU. This study aims to define an optimal IMT dosage using a new metric called "Total Inspiratory Work Unit" (UTIT), which integrates intensity, repetition, and frequency. The study compares three daily dosage regimens (1,000 UTIT, 2,000 UTIT, and 3,000 UTIT) adjusted daily based on the patient's Negative Inspiratory Force (NIF). The goal is to determine the optimal dose-response relationship for improving inspiratory muscle strength (PiMax) and reducing the duration of mechanical ventilation.

Inclusion Criteria: * Adult patients (\>18 years of age) admitted to the Intensive Care Unit (ICU). * Invasive mechanical ventilation support for more than 48-72 hours. * Hemodynamic stability (defined as absence of vasopressors or receiving stable doses). * Adequate oxygenation and ventilatory parameters: PEEP \< 10 cmH2O, FiO2 \< 0.6, and PaO2/FiO2 ratio \> 150-200. * Ability to cooperate with instructions or absence of deep sedation. Exclusion Criteria: * Pre-existing neuromuscular pathology directly affecting respiratory muscles. * Severe thoracic trauma or recent thoracic surgery. * Unresolved pneumothorax or bronchopleural fistula. * Severe hemodynamic instability or severe cardiac arrhythmias. * Level of sedation that prevents active participation in sessions. * Pregnancy