Follow up of Ventilatory Function in Infant After Bronchiolitis During the First Year of Life

Asthma affects a large population throughout the world and about two millions of persons in France, killing two hundred patients by year. A significant proportion of cases of asthma are diagnosed during childhood. Understanding the relation between early-life infectious exposures and asthma and atopy appears to be considerable interest. Respiratory infectious illnesses, mostly viral, are very common in childhood. Bronchiolitis is the most common lower respiratory tract illness (LRI) in early life (1). It is commonly caused by respiratory syncytial virus (RSV) and is often associated with subsequent wheezing and childhood asthma (2). Respiratory infectious illnesses caused by other agent than RSV can be also associated with asthma and atopy (3). However, the relation between respiratory infectious illnesses in early life and asthma in childhood is again much debated since some studies show a relationship between bronchiolitis and atopy (4) but not others (5, 6). The present work is a prospective study undertaken to highlight the possible relationship between LRI in early life and trigger of atopy and asthma in 3 year-old childhood, using paediatric lung function testing. Twenty nine infants (8 females and 21 males) were included in our study and 8 of 29 infants were of premature birth. The youngest patient was 3 months old and the older fourteen months old. The beginning of the study started at least three weeks after the first bronchiolitis episode. Pulmonary function test was realized using body plethysmography (Babybody, Erich Jaeger, Germany). Same tests were performed at 18 and 24 months. At 30 and 36 months, pulmonary function was evaluated by measuring respiratory resistances using an oscillometry system and an occlusion system (Masterlab-IOS, Erich Jaeger, Germany). All respiratory tests were performed on patients in asymptomatic respiratory condition and at least one month apart from respiratory infection. If measured data showed an obstruction, a bronchodilator was inhaled to assess reversibility. When results were normal, a bronchial provocation test, using inhaled metacholine, was performed. Skin prick tests (SPTs) were performed at the first exam, and at 24 and 36 months (Stallergenes-DHS). Dermatophagoides pteronyssinus, alternaria, cat dander, cockroach, orchard grass and timothy grass were systematically tested. The SPTs were considered positive when the wheal diameter was over 3 mm and 50% larger than the positive control, and the negative control remained negative (7). The possibility of dermographism was eliminated by a negative reaction of the negative control. Collection of data was largely incomplete due to a number of patients lost of follow up. Briefly, based on the available data, most of lung tests results were in the normal range although a proportion of patients experienced recurrent wheezing episodes during follow up. Nevertheless a bronchial hyper reactivity to metacholine was documented in 41%. Atopy, as screened by SPTs, was detected in a minority of infants (13.5%). Coexistence of bronchial hyper reactivity and atopy was present in only one patient. These incomplete results highlight the complex interplay between symptoms, bronchial obstruction, bronchial hyper reactivity and atopy in the subsequent development of asthma in wheezy children. Long term follow up is necessary to assess the prognostic value of these parameters.