The study is outlined in the study flow sheet (Appendix 4). The study physician will examine the patients twice daily at 8-10 a.m. and p.m. during the hospitalization (Appendix 5). The patients will be hospitalized until he or she does not wheeze or have breathing difficulties. After the hospitalization the patients will fill symptom diary for 2 weeks (Appendix 6). Follow-up visit will be 2 weeks after the hospitalization and follow-up telephone contact will be 2 months after the hospitalization. If the patient had a first wheezing episode, he or she will be re-examined 12 months after the study and oscillometric examination will be performed (if older than 24 months).