PULMONARY-FUNCTION IN HOSPITALIZED INFANTS AND TODDLERS WITH CYSTIC-FIBROSIS

In older children with cystic fibrosis (CF), well-documented improveme nts in lung function occur during hospitalization for treatment of pul monary exacerbations. Objectives: (1) To test the hypothesis that impr ovement in lung function occurs in infants and toddlers hospitalized b ecause of CF pulmonary exacerbations. (2) To compare changes in lung f unction measured during forced expiratory flaw and tidal breathing. St udy design: Seventeen infants and toddlers with CF were evaluated at t he beginning and end of hospitalization by the rapid thoracic compress ion 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 durin g the course of hospitalization. The greatest change was observed in m easurements 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)) increase d from 60% +/- 6% to 78% +/- 8% (p < 0.02); lung compliance (C-L) incr eased from 66% +/- 5% to 75% +/- 5% (p < 0.03). The degree of improvem ent of (V) over dot(max)FRC, G(L), and C-L was related to baseline mea surements; those with poorer pulmonary function at baseline had the gr eatest degree of improvement during hospitalization. Conclusion: Asses sments of airflow obstruction from measurements of (V) over dot(max) F RC and GL do not necessarily demonstrate similar findings in a given i nfant with CE perhaps because these two techniques measure different p hysiologic properties. Changes in (V) over dot(max)FRC may best reflec t the predominant pathophysiology of lung disease in infants and toddl ers with CF.