Nebulised 3% Hypertonic Saline Versus 0.9% Saline for Treating Patients Hospitalized With Acute Bronchiolitis

Inclusion Criteria: 1. Children admitted to the hospital with the clinical diagnosis of acute bronchiolitis, which is defined as an apparent viral respiratory tract infection associated with airway obstruction manifested by at least one of following symptoms: * Tachypnoea (WHO definition). * Increased respiratory effort manifested as follows: 1. Nasal flaring; 2. Grunting; 3. Use of accessory muscles; 4. Intercostal and/or subcostal chest wall retractions; 5. Apnoe. * Crackles and/or wheezing. 2. Aged 5 weeks - 24 months old. 3. A caregiver must provide written informed consent. Exclusion Criteria: 1. Infants hospitalised with severe bronchiolitis (requiring mechanical ventilation or intensive care, or oxygen saturation \< 85% on room air). 2. History of prematurity (gestational age \<34 weeks). 3. Diagnosis of a clinically significant chronic disease (cardiac, respiratory, neuromuscular, or metabolic). 4. Immunodeficiency. 5. Gastro-oesophageal reflux. 6. Diagnosis or suspicion of asthma. 7. Inhaling a nebulised 3% hypertonic saline solution within 12 hours before enrolment. 8. Inhaling bronchodilators within 24 hours before enrolment. 9. Inhaling steroids within 24 hours before enrolment. 10. Systemic steroid therapy in the preceding 2 weeks.