Pulmonary function in hospitalized infants and toddlers with cystic fibrosis

In older children with cystic fibrosis (CF), well-documented improvements in lung function occur during hospitalization for treatment of pulmonary exacerbations. Objectives: (1) To test the hypothesis that improvement in lung function occurs in infants and toddlers hospitalized because of CF pulmonary exacerbations. (2) To compare changes in lung function measured during forced expiratory flaw and tidal breathing. Study design: Seventeen infants and toddlers with CF were evaluated at the beginning and end of hospitalization by the rapid thoracic compression technique to yield maximal flow at forced residual capacity. Tidal mechanics were measured by the esophageal balloon technique to yield lung conductance and compliance. Results: Lung function improved during the course of hospitalization. The greatest change was observed in measurements of maximal flow at functional residual capacity ((V) over dot(max)FRC), increasing from 38.5% +/- 6% predicted (mean +/- SEM) to 59.8% +/- 6% at the end (p < 0.005). Lung conductance (G(L)) increased from 60% +/- 6% to 78% +/- 8% (p < 0.02); lung compliance (C-L) increased from 66% +/- 5% to 75% +/- 5% (p < 0.03). The degree of improvement of (V) over dot(max)FRC, G(L), and C-L was related to baseline measurements; those with poorer pulmonary function at baseline had the greatest degree of improvement during hospitalization. Conclusion: Assessments of airflow obstruction from measurements of (V) over dot(max) FRC and GL do not necessarily demonstrate similar findings in a given infant with CE perhaps because these two techniques measure different physiologic properties. Changes in (V) over dot(max)FRC may best reflect the predominant pathophysiology of lung disease in infants and toddlers with CF.