Bronchiolitis hospital admission in infancy is associated with later preschool ventilation inhomogeneity

Abstract

Background: Rhinovirus (RV) positive bronchiolitis episodes in infancy confer a higher risk to develop asthma in later childhood with associated lung function impairments. We aimed to investigate the association between the type of virus causing a bronchiolitis hospitalization episode and lung ventilation inhomogeneities at preschool age.

Methods: Infants hospitalized with a clinical diagnosis of moderate (ward admission) or severe (pediatric intensive care ward admission) bronchiolitis were prospectively followed-up at preschool age to assess nitrogen (N₂ ) multiple breath washout (MBW). Lung clearance index (LCI), functional residual capacity (FRC), and concentration normalized phase III slope analysis (Sn_III ) indices were reported from ≥2 technically acceptable trials. Differences between groups were calculated using logistic and linear regression and adjusted for confounders (sex, age at bronchiolitis admission, height at visit, maternal asthma, and doctor-diagnosed asthma, including interaction terms between the latter three). An interaction term was included in a regression model to test for an interaction between RV bronchiolitis severity and MBW parameters at preschool age.

Results: One hundred and thirty-nine subjects attended preschool follow-up, of which 84 out of 103 (82%) performing MBW had technically acceptable data. Children with a history of RV positive bronchiolitis (n = 39) had increased LCI (adjusted β-coefficient [aβ] = 0.33, 95% confidence interval [CI] 0.02-0.65, p = 0.040) and conductive airways ventilation inhomogeneity [S_cond ] (aβ = 0.016, CI 0.004-0.028, p = 0.011) when compared with those with a RV negative bronchiolitis history (n = 45). In addition, we found a statistical interaction between RV bronchiolitis and bronchiolitis severity strengthening the association with LCI (aβ = 0.93, CI 0.20-1.58, p = 0.006).

Conclusion: Children with a history of hospital admission for RV positive bronchiolitis in infancy might be at a higher risk of lung ventilation inhomogeneities at preschool age, arising from the peripheral conducting airways.

Keywords: multiple breath nitrogen washout; preschool children; rhinovirus; ventilation inhomogeneity.