Bronchial Responsiveness (BR) measured by forced pseudorandom noise oscillometry (MFOT) in children who had bronchiolitis, children with asthma and healthy subjects

Abstract

Various environmental factors may influence BR in a negative way, and may worsen the degree of BR with age. The incidence of increased BR in young children is not well known.To measure BR at young age lung function measurements are necessary. MFOT is an ideal method from about 2½ years of age because only passive cooperation is needed. We investigated children who had infant bronchiolitis (i.e. tachypneu, breathlessness, hyperinflation, wide spread crepitations, hypercapnia (pCO₂ > 47 mm Hg) and hypoxemia (pO₂ < 80 mm Hg) and compared these with asthmatic and healthy subjects of the same age. We studied which of the children who had infant bronchiolitis have recurrent episodes of wheeze and cough during later life and whether this goes with abnormal base- line lungfunction, bronchoconstriction and increased BR. 10/16 children, aged 2.6 - 12.8 yrs, who had bronchiolitis showed present recurrent respiratory symptoms. Baseline lung function values were abnormal in 6. Increased bronchial smooth muscle tone (i.e. > 1 SD score change) was present in 7. BR measured by MFOT was expressed as SD score differences from BR in healthy children. BR was more than 1 SD score higher in half of the children with present recurrent respiratory symptoms, in 1/4 with past symptoms and in 0/2 who never had recurrent symptoms after bronchiolitis. Children who had bronchiolitis showed increased bronchial smooth muscle tone as in asthma; BR in those with present recurrent respiratory symptoms corresponds with BR in mild asthmatics. These children might be regarded as mild asthmatics and treated as such.

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