Clinical Research Directory

Inclusion Criteria: 1. Adult patients (≥18 years of age) with mechanical ventilation or advanced respiratory support in the ICU, regardless of gender; 2. The expected mechanical ventilation time of tracheal intubation is more than 24 hours; 3. The initial ventilator Settings of clinical routine were adopted: oxygen fraction (FIO2) = 50%, respiratory rate = 15/min, positive end-expiratory pressure (PEEP) = 5 cmH2O, tidal volume = 6-8 ml/kg ideal body weight (IBW), inspiration-exhalation ratio =1:2; 4. Agree to participate in this experiment and sign the informed consent. Exclusion Criteria: * 1.Use of any NO-containing drugs (such as nitroglycerin), anti-inflammatory drugs, or drugs or means that affect the airway diameter within 6 hours before the first FeNO measurement; 2. Participating in other clinical research projects; 3. Patients deemed unsuitable by the investigators.