Study objectives: To evaluate the relationship between bronchial hyperrespo
nsiveness (BHR) in infants with wheezing and the subsequent development of
asthma.
Intervention: Bronchial reactivity to inhaled methacholine (BRm) during the
infantile period was studied using the transcutaneous partial pressure of
oxygen (tcPo(2)) method. Children were followed long-term for the developme
nt of asthma.
Patients: Fourteen children with bronchiolitis (mean age, 0.7 years) and 48
with wheezy bronchitis (mean age, 2.3 years) were enrolled. For comparison
, 40 children with asthma (mean age, 4.6 years) and 27 healthy control subj
ects without chronic respiratory disease (mean age, 2.7 years) were studied
.
Measurements:: Consecutive doses of methacholine were doubled until a 10% d
ecrease in tcPo(2) from baseline Was reached. The cumulative dose of methac
holine (Dmin) at the inflection point of tcPo(2) (Dmin-Po-2) was recorded.
Results: During > 10 years of follow-up, seven patients with bronchiolitis
del eloped asthma and ail patients in the higher BRm set developed asthma,
compared with none in the lower BRm set. In the wheezy bronchitis group, Dm
in-Po-2 values in the 32 patients who developed asthma were lower than thos
e in patients who had not developed asthma (p < 0.001).
Conclusions: We concluded that there is a tendency for infants with a clini
cal diagnosis of bronchiolitis or wheezy bronchitis and who show BHR in the
infantile period to develop asthma. The presence of increased BHR after in
fantile respiratory diseases associated with wheezing may be a prelude to t
he development of childhood asthma.