[Acoustic analysis of wheezing in infants with acute bronchial obstruction. A follow-up study ]

There is some information about wheeze characteristics in infants, however it is not clear whether the different wheeze patterns relates to prognosis and evolution during the first two years of life.

To characterize wheezing and spectral pattern of lung sounds in infants with acute bronchiolitis (AB) and in infants with recurrent wheeze (RW) as well as to compare these parameters with the clinical evolution 2 years after admission.

Seventy six AB infants (48 boys), aged 5.5 +/- 0.7 months (mean +/- SD), 62 RSV (+) and 32 RW infants (20 boys), aged 11.4 +/- 2 months were studied during the first week of admission at the hospital. Patients were studied during spontaneous sleep, breathing with a face mask connected to a pneumotachograph at flows of 0.1 +/- 0.02 L/s. Sounds were registered at baseline and 20 minutes after salbutamol using 2 contact sensors placed at both lower lobes levels. Signals were low-pass filtered, amplified and a Fourier analysis was applied to sounds within a target flow range. Spectral analysis was done between 100 and 1000 HZ.

In 40/76 (53%) AB vs 30/34 (88%) RW sinusoidal wheezing (p < 0.01; chi 2) were observed and a positive bronchodilator response was obtained in 37/76 (49%) AB vs 32/34 (94%) RW (p < 0.01; chi 2). Patients with sinusoidal wheezing (s-w) had more wheezing episodes in follow-up, 26/40 vs 8/36 in complex wheezing (c-w), (p < 0.01: chi 2) and 30/34 in RW (p < 0.01; chi 2). IgE values at 18 months were higher in s-w compared to c-w (63 +/- 7 vs 24 +/- 5 Iu/mL (p < 0.01) and 96 +/- 11 Iu/mL in RW (p < 0.01).

a) Wheezing characteristics in acute bronchiolitis vs recurrent wheezing are different; b) Bronchodilator response relates to wheeze characteristics and c) Higher IgE and more recurrent wheezing episodes are seen in acute bronchiolitis with sinusoidal wheezing. These findings suggest that lung sounds analysis is useful in assessing wheezy patients and have a value to identify infants on risk of developing asthma.