Population and Study Design
This prospective, observational study was conducted in our medical/surgical PICU between March and December 2021, with the approval of our institutional review board (2022/03-10). Written informed consent was obtained from the parents at the time we enrolled the patient. Children between 1 month and 10 years of age who were mechanically ventilated for more than 48 hours via an endotracheal tube in the PICU were screened for inclusion. The patients were assessed daily for ventilator weaning and extubation according to our institutional weaning protocol. Patients who met the following criteria were recruited: 1) recovery from primary disease-causing mechanical ventilation, 2) adequate spontaneous breathing and effective coughing, 3) increasing consciousness, 4) hemodynamic stability with minimal vasoactive support, 5) oxygenation index <6, 6) lack of excessive tracheal secretion (less need for endotracheal suctioning), 7) adequate gas exchange with positive end-expiratory pressure (PEEP) <8 cm H2O and fractional oxygen concentration (fiO2) <60%. The exclusion criteria were as follows: 1) detected diaphragm paralysis, 2) underlying neuromuscular disease and chronic respiratory failure, 3) a current tracheostomy, 4) pleural effusion, pneumothorax or pneumomediastinum.