Computed Inspiratory Muscle Pressure to Monitor Inspiratory Effort During Pressure Support Ventilation

The goal of this study is to validate computed inspiratory muscle pressure (cPmus) for monitoring inspiratory effort in adults receiving pressure support ventilation. Researchers will compare cPmus with reference inspiratory muscle pressure calculated using an esophageal balloon catheter, a thin pressure-measuring tube placed in the esophagus. The study will look at how closely the two methods are related and whether they give similar results. Participants will undergo simultaneous monitoring with cPmus and an esophageal balloon catheter. Researchers will adjust pressure support across six levels, recording measurements from both methods at each level.

Inclusion Criteria: 1. Age 18 years or older. 2. Receiving pressure support ventilation. 3. Written informed consent provided by the participant or a legally authorized representative. Exclusion Criteria: 1. Contraindication to esophageal catheter placement, including uncontrolled coagulopathy, skull base fracture, upper gastrointestinal bleeding, tumor or surgery, neck surgery, or esophagogastric varices. 2. Chest trauma, a postoperative state following lung surgery, an active pulmonary air leak (pneumothorax, pneumomediastinum, or bronchopleural fistula), or an indwelling chest drain. 3. Neuromuscular disease, diaphragmatic dysfunction, or diaphragmatic surgery. 4. Impaired central respiratory drive due to intracranial hypertension or brainstem injury. 5. Hemodynamic instability, defined as mean arterial pressure \180 mmHg, heart rate \150 beats/min, or norepinephrine dose \>1 mcg/kg/min. 6. Pregnancy or breastfeeding. 7. A decision to withdraw life-sustaining treatment or provide palliative care.