Relationship Between Bronchial Hyperresponsiveness and Development of Asthma in Wheezy Infants

Study objectives: To evaluate the relationship betweenbronchial hyperresponsiveness (BHR) in infants with wheezing and thesubsequent development of asthma. Intervention: Bronchial reactivity to inhaled methacholine (BRm) during the infantileperiod was studied using the transcutaneous partial pressure of oxygen (tcP o 2 ) method. Children werefollowed long-term for the development of asthma. Patients: Fourteen children with bronchiolitis (mean age,0.7 years) and 48 with wheezy bronchitis (mean age, 2.3 years) wereenrolled. For comparison, 40 children with asthma (mean age, 4.6 years)and 27 healthy control subjects with out chronic respiratory disease(mean age, 2.7 years) were studied. Measurements: Consecutive doses of methacholine were doubled until a 10% decrease intcP o 2 from baseline was reached. The cumulativedose of methacholine (Dmin) at the inflection point of tcP o 2 (Dmin-P o 2 ) wasrecorded. Results: During > 10 years of follow-up, seven patients with bronchiolitis developed asthma and allpatients in the higher BRm set developed asthma, compared with none in the lower BRm set. In the wheezy bronchitis group, Dmin-P o 2 values in the 32 patients whodeveloped asthma were lower than those in patients who had notdeveloped asthma (p Conclusions: Weconcluded that there is a tendency for infants with a clinicaldiagnosis of bronchiolitis or wheezy bronchitis and who show BHR in theinfantile period to develop asthma. The presence of increased BHR afterinfantile respiratory diseases associated with wheezing may be aprelude to the development of childhood asthma.