have to adjust recuriting paticipants projects and have to halted the research

The purpose of the study is to establish the methodology of bronchial dilation test by salbutamol MDI with Spacer in wheezy infants with asthma and to evaluate the effects of atopy on the exacerbation of wheeze in wheezy infants.

After screening,each participant undergo baseline pulmonary function test(Jaeger Master Screen Baby Body, Germany)and post-bronchodilator measurements that performed 10min after 200ug of salbutamol administered using a metered-dose inhaler and a spacer.

The participants undergo baseline lung function test and bronchial dilation tests on the second and third visits with one-month interval,and whenever there is an exacerbation.

Inclusion Criteria:

• normal term infants.Recurrent wheezing with or without atopy,none of the subjects had a history of respiratory illness, congenital heart disease,dysphagia,oxygen saturation≤90% on room air,an active seizure disorder,or upper airway obstruction,or requirement for assisted ventilation in the neonatal periods,all infants were asymptomatic for at least 2 weeks preceding the test.

Exclusion Criteria:

• subjects had a history of respiratory illness, congenital heart disease,dysphagia,oxygen saturation≤90% on room air,an active seizure disorder,or upper airway obstruction,;all infants were asymptomatic for at least 2 weeks preceding the test.

all the subjects will be recurited from the First Affiliated Hospital of Guangzhou Medical University