Primary endpoint: Our primary endpoint will be the time until ready for discharge, which will be defined as a duration of respiratory symptoms score >3 during hospital stay. The respiratory symptoms score, which will be assessed every 12 h during hospitalization, will consist of the degree of dyspnea (0=none, 1=mild, 2=moderate, 3=severe), type of breathing (0=normal, 1=use of stomach muscles, 2=use of intercostal muscles, 3=nasal flaring), severity of auscultatory findings on wheezing (0=none, 1=expiratory, 2=inspiratory and expiratory, 3=audible without stethoscope), and assessment of expiratory:inspiratory time (0=1:2, 1=1:1, 2=2:1, 3=3:1). An estimation of 6 h will be used for the last 12 h period between hospital assessments, i.e. the period during which the patient became ready for discharge.