1778 BRONCHODILATOR RESPONSE IN INFANTS WITH CYSTIC FIBROSIS

Abstract

Cystic fibrosis infants (CFI) develop airways obstruction which is frequently treated with bronchodilators although no studies have yet documented their efficacy. The purpose of our study was to evaluate the response of CFI to the inhaled bronchodilator metaproterenol (BD). We studied 14 CFI, mean age of 20.5 months (range 3-39). Functional residual capacity (FRC) was measured by helium dilution. Maximal flows at FRC, VmaxFRC, were obtained by the rapid chest compression technique and expressed as size corrected flows, VmaxFRC/FRC. For CFI, a paired t-test revealed no significant change compared to baseline in VmaxFRC/FRC (P>.15) after NS, but an increase (P<0.01) after BD, of the group mean by ±30%. Six of 14 increased by >30% and 8<30% but baseline VmaxFRC/FRC of these 2 groups were similar (.94 vs 1.00) (P>.7). We assessed interpatient variability of BD response by testing 5 normal infants, mean age 6.7 months (range 4.5-8), whose baseline VamxFRC/FRC was similar to CFI (1.05 vs .98) (P>.4). None had a change of>30% with either NS or BD and only 2/5 had an increase post BD. In contrast 13/14 CFI increased flows post BD. Two of 4 CF< 1 year and 5/10<2 years of age increased flows>30% post BD. We conclude that CFI can demonstrate a significant improvement in lung function after inhaled BD. The magnitude of response is not related to age or baseline function.

Supported by NIH Grant #HL01322-01 and #HL990-03 and ALA Fellowship

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