In young infants with severe acute respiratory syncytial virus bronchiolitis, nCPAP rapidly unloads respiratory muscles and improves respiratory distress symptoms.

Pulmonary function tests are seldom performed in preschool children with asthma. The aim of this multicenter study was to compare pulmonary function in 74 preschool children with asthma (height of 90-130 cm) and 84 healthy control subjects. Functional residual capacity (helium dilution technique) and expiratory interrupter resistance (interrupter technique) were measured. As compared with control children, children with asthma had a significantly higher resistance (0.77 +/- 0.20 vs. 0.92 +/- 0.22 kPa. L-1. second, p < 0.001) and significantly lower specific expiratory interrupter conductance (p < 0.005) values. Resistance values were significantly higher in children with asthma with than without symptoms on exertion (p < 0.05). The effect of bronchodilator administration, expressed as the percentage of baseline and predicted resistance values, was significantly greater in children with asthma than in control subjects (-18.6 +/- 13.6% vs. -11.2 +/- 15.2%, p

The interrupter technique estimates flow resistance. It entails occlusion of the airways during tidal breathing while flow and mouth pressure are recorded. This noninvasive technique is easy to use in young children. The aim of the present study was to measure inspiratory and expiratory interrupter resistance (Rint(insp), Rint(exp)) before and after bronchodilator administration in young healthy white children. We designed a multicenter study using a standardized procedure for Rint measurements. Centers in five French cities studied 91 children (48 boys and 43 girls; height, 92 to 129 cm; mean age 5.3 +/- 1.4 years). Mean values were not significantly different for Rint(insp) and Rint(exp) (0.78 +/- 0.21 versus 0.78 +/- 0.20 KPa x L(-1) x second). However, the difference between Rint(insp) and Rint(exp) decreased significantly with age and being positive before 5 years and negative later on (p < 0.02). Rint(insp) and Rint(exp) decreased significantly with height (Rint(insp) [KPa x L(-1) x second] = 2.289 - 1.37. 10(-2) x H [cm], Rint(exp) [KPa. L(-1) x second] = 2.021 - 1.12.10(-2) x H [cm]; p < 0.001). Bronchodilator (salbutamol) administration significantly decreased Rint(insp) and Rint(exp) (p < 0.001). Bronchodilator-induced changes (% of predicted values) in mean Rint(insp) and mean Rint(exp) were -15% (95% confidence interval, -46 to +15%) and -12% (95% confidence interval, -46 to +22%), respectively. Sex did not affect pre- or postbronchodilator values. Data from the present study may prove useful for testing lung function in young children with respiratory disorders who failed to cooperate with forced expiratory maneuvers.

Pulmonary function tests have rarely been assessed in preschool children with cystic fibrosis (CF). The objective of this multicenter study was to compare pulmonary function in 39 preschool children with CF (height, 90-130 cm; 16 homozygous Delta F508) and in 79 healthy control children. Functional residual capacity (helium dilution technique) and expiratory interrupter resistance (Rint(exp)) (interrupter technique) were measured. As compared with control children, children with CF had significantly higher Rint(exp), expressed as absolute values and as Z-scores (1.05 +/- 0.36 versus 0.80 +/- 0.20 kPa.L(-1). second, p < 0.0001; and 1.31 +/- 1.72 versus 0.19 +/- 0.97, p < 0.0001), and significantly lower specific expiratory interrupter conductance (1.29 +/- 0.34 versus 1.63 +/- 0.43 kPa(-1). second, p < 0.0001). The effect of the bronchodilator salbutamol on Rint(exp) was not significantly different between children with CF and control children. Rint(exp) Z-scores were significantly higher in children with CF who were exposed to passive smoke (n = 8) (p < 0.03). Children with CF and with a history of respiratory symptoms (n = 31) had significantly higher functional residual capacity Z-scores (p < 0.02) and lower specific expiratory interrupter conductance Z-scores (p < 0.04). Genotype did not influence the data. We conclude that Rint(exp) and functional residual capacity measurements may help to follow young children with CF who are unable to perform reproducible forced expiratory maneuvers.

All RVRTC parameters and the CTqb score remained stable between evaluations. The CTqb score showed a higher discriminative power than forced expiratory volume in 0.5 s (FEV ; the main RVRTC parameter) at both visits (66% and 50% of abnormal values vs 30% and 28%, respectively). No correlation was found between CTqb score and the different RVRTC parameters or the plethysmographic functional residual capacity, indicating that they evaluate different aspect of CF lung disease.