Pulmonary function during the first year of life following acute viral bronchiolitis.

Abstract

It has been suggested that acute viral bronchiolitis in infants may result in functional changes that predispose toward chronic pulmonary disease later in life. We assessed pulmonary function (PF) during the acute phase of viral bronchiolitis in infants and up to 12 mo later from static respiratory system compliance (Crs), using weighted spirometry, the distribution of ventilation by the mixing index (MI), and the functional residual capacity (FRC) measured by closed-circuit helium dilution (FRCHe). The study was performed in 24 infants (13 males and 11 females; median [25 to 75% range] age: 11 [9.6 to 13.3] wk; weight: 4.8 [4.3 to 5.0] kg; crown-to-heel length: 57.7 [55.5 to 59.0] cm) at admission and at 2 wk. In 17 infants, measurements were repeated 3 mo and 12 mo later. Predicted values and individual 95% prediction intervals for Crs, MI, and FRCHe were derived from 69 healthy infants (33 boys and 36 girls; median age [25 to 75% range]: 4.7 [2.0 to 21.4] wk; weight: 3.6 [3.0 to 6.9] kg; crown-to-heel length: 51.5 [48 to 61] cm). Data at admission and after discharge were compared by analysis of variance (ANOVA) with those in the healthy controls matched for crown-to-heel length. At admission all three variables gave lower average results than predicted means. Values for each index had attained a normal level 2 wk after admission; normal levels were maintained at 3 and 12 mo. The prevalence of recurrent wheezing (five of the 17 infants) was comparable with that reported in population studies. These findings suggest that in this population acute viral bronchiolitis did not lead to permanent changes in PF.