Use of Nasal Pressure to Assess Inspiratory Effort Under Different Oxygen Treatments

Inclusion Criteria: 1. No mechanical ventilation required,Able to tolerate oxygen therapy via nasal cannula, standard face mask, or nasal high-flow oxygen therapy; 2. Respiratory stability:Capable of spontaneous breathing with effective cough for secretion clearance.Oxygen saturation (SpO₂) \> 90% or PaO₂/FiO₂ ≥ 150 mmHg when receiving nasal cannula oxygen at 3 L/min; 3. Hemodynamic stability:Heart rate (HR) ≤ 120 bpm;Systolic blood pressure (SBP) 90-150 mmHg;No vasoactive medications OR norepinephrine dosage \< 0.1-0.2 μg/kg·min (or equivalent doses of other vasoactive agents); 4. Metabolic stability; 5. Compliance with medical instructions.Able to follow prescribed tasks.Esophageal pressure monitoring catheter already in place; 6. Patient or legal guardian agrees to participate and has signed the informed consent form. Exclusion Criteria: 1. Age \< 18 years; 2. Pregnancy; 3. Hemodynamic instability:Mean arterial pressure (MAP) \< 60 mmHg.Heart rate (HR) \> 120 bpm or \< 60 bpm; 4. Respiratory instability:Respiratory rate (RR) \> 35 bpm.Oxygen saturation (SpO₂) \< 90%; 5. Neuromuscular diseases or phrenic nerve injury; 6. Recent trauma or surgery involving the trachea, esophagus, neck, or chest.Contraindications to esophageal catheter placement or inability to monitor esophageal pressure; 7. Nasal obstruction or anatomical abnormalities:Complete nasal obstruction.Severe anatomical abnormalities (e.g., severe septal deviation, nasal polyps, or tumors) preventing catheter placement or compromising ventilation; 8. High-risk craniofacial conditions:Severe facial trauma or skull base fracture with risk of catheter misplacement into the intracranial space.Active epistaxis or incomplete healing after nasal surgery; 9. Bleeding risk:Severe coagulopathy.Esophageal/gastric varices or other conditions predisposing to hemorrhage.