Am. J. Respir. Crit. Care Med., Vol 155, No. 4, Apr 1997, 1349-1355.
Infant respiratory function after RSV-proven bronchiolitis
C Dezateux, ME Fletcher, I Dundas and J Stocks
Department of Epidemiology and Biostatistics, Institute of Child Health, London, United Kingdom. C.Dezateux@ich.ucl.ac.uk
The mechanisms underlying the increased risk of wheezing in early childhood
following acute bronchiolitis in infancy remain unclear. Previous studies
have reported significant abnormalities in infant respiratory function
after clinical recovery from bronchiolitis, but are difficult to interpret
because of the frequent omission of a concurrent comparison group.
Respiratory function was compared within pairs of previously healthy
full-term caucasian infants admitted with a first episode of acute
bronchiolitis to an inner London hospital, and age- and sex-matched control
infants without prior wheezing, asthma, or lower respiratory illness who
were recruited from local general practices. Respiratory function was
measured in 29 control and 29 asymptomatic index infants, with measurements
in the latter done at a median interval of 36 wk (range: 16 to 49 wk) after
admission, when 16 (55%) had experienced subsequent wheezing. Index infants
tended to be autumn-born and of shorter gestation than control infants, to
have younger mothers, and to have been exposed to tobacco smoke. There were
no statistically significant differences in plethysmographic FRC, initial
inspiratory airway resistance (Raw), or respiratory system compliance (mean
[index minus control] within-pair difference [95% confidence interval]: -11
ml [-29, 7 ml]; -0.2 kPa/L/s [-0.7, 0.4 kPa/L/s]; -8 ml/kPa [-21, 4
ml/kPa], respectively), but respiratory rate and time to peak tidal flow as
a proportion of total expiratory time (tPTEF:tE) were significantly
diminished in index as compared with control infants (-4.0 breaths/min
[-7.6, -0.4 breaths/min], versus - 0.035 [-0.066, -0.005], respectively).
These findings suggest a better prognosis for infant lung function after
acute bronchiolitis than reported previously. Longitudinal studies are
needed to clarify whether subclinical alterations in airway function
precede acute bronchiolitis.
