Electromagnetic High-Frequency Chest Wall Oscillation on Pulmonary Mucus Clearance in Patients With Impaired Self-Expectoration

Inclusion Criteria: * Hospitalized patients who require sputum clearance. * Patients who present with fever or respiratory symptoms (cough, sputum) and, after confirmation of findings on imaging studies, are judged by the clinician to require sputum clearance. * Adult patients (≥ 18 years) who have signed the informed consent form, or patients for whom consent has been obtained from a legally authorized representative Exclusion Criteria: * Patients with severe pneumonia requiring intensive care unit (ICU) treatment. * Patients with major pulmonary diseases other than pneumonia, such as active tuberculosis or lung cancer. * Patients with severe respiratory failure (PaO₂/FiO₂ ≤ 200 mmHg). * Patients with hemodynamically unstable cardiovascular disease (myocardial infarction within the past 3 months, or heart failure of NYHA class 3 or higher). * Patients hospitalized for head and neck trauma whose surgical site has not yet healed. * Patients with serious cardiac arrhythmias or hemodynamic instability. * Patients who have had pneumothorax or massive hemoptysis within the past 6 months, or who currently have hemoptysis. * Patients who have undergone spinal surgery within the past 6 months or who have acute spinal injury. * Patients with osteoporosis. * Patients with bronchopleural fistula. * Pregnant or breastfeeding women. * Patients diagnosed with cervical disc disease. * Individuals who have participated in clinical studies two or more times in the same year, or who have participated in another clinical study within the past 6 months (however, patients enrolled in chronic lung disease cohort studies such as asthma or COPD are allowed). * Individuals who, in the judgment of the principal investigator or sub-investigator, have clinically significant findings that make them unsuitable for participation in this study