Targeting prEssure-Muscle-index to Avoid Ventilatory Over-Assistance During Pressure Support Ventilation

The TEMA study (Targeting prEssure-Muscle-index to avoid ventilatory over-Assistance during pressure support ventilation) is a prospective, interventional crossover trial investigating the relationship between pressure support (PS) and tidal volume (Vt) in ICU patients with acute hypoxemic respiratory failure (AHRF) receiving pressure support ventilation (PSV). The study aims to assess whether the Pressure-Muscle Index (PMI)-a marker derived from the difference between plateau and peak inspiratory pressure-can help identify the optimal level of ventilatory assistance, preventing over-assistance and its associated complications such as diaphragm atrophy and patient self-inflicted lung injury (P-SILI). By exploring the sigmoidal relationship between PS and Vt, the study seeks to define a physiological threshold (PMI=0) that may serve as a personalized target for PSV titration.

Inclusion Criteria: 1. Age ≥ 18 years 2. Mechanically ventilated in the ICU 3. Diagnosis of Acute Hypoxemic Respiratory Failure (AHRF) 4. Normocapnia or non-severe hypercapnia 5. Receiving Pressure Support Ventilation (PSV) for at least 24-72 hours 6. Presence of an arterial line for blood gas sampling Exclusion Criteria: 1. Age \< 18 years 2. Known neurological or neuromuscular disorders affecting diaphragm function 3. Chronic Obstructive Pulmonary Disease (COPD) or hypercapnic respiratory failure 4. Psychomotor agitation or inadequate sedation