Forty asthmatic children aged 4 to 6 years performed
histamine inhalation tests over 2 to 3 years. We used a previously reported method for examining
bronchial hyperreactivity; measuring the transcutaneous
oxygen pressure to evaluate whether
bronchial hyperreactivity in younger children with
bronchial asthma changed, and which potential factors affected changes in
bronchial hyperreactivity. Although there was no significant relationship between the severity of
asthma and respiratory threshold to
histamine (RT-Hist) at the initial test, RT-Hist results in the severely asthmatic group were significantly lower than those of the remission and mild groups at the final test (P less than .01), respectively. RT-Hist significantly decreased in only the group whose
asthma worsened (P less than .05). In the remission and improvement groups, RT-Hist did not improve despite their favorable clinical courses. When divided into two subgroups according to the extent of their RT-Hist, a high responder group had significantly more subjects who family histories of
asthma than the low-responder group (P less than .05). There was no difference, however, in family history of allergic diseases between the two groups. We conclude that
bronchial hyperreactivity in younger asthmatic children is influenced by multiple factors that may be congenital or acquired.