Influence of lung function and postnatal age on the response to nebulized ipratropium bromide in children born prematurely.

Nebulized ipratropium bromide reduces airways resistance in young children born prematurely, but that response is not invariable. We have assessed whether postnatal age or baseline lung function influences the effect of ipratropium bromide. Forty-five children, median gestational age 28 weeks (range 23-34) were studied at a postnatal age of 10 months (range 6-18). Twenty-four were symptomatic at follow-up. Airways resistance (Raw) was measured using a whole body plethysmograph before (baseline) and 20 min after nebulized ipratropium bromide. Sixteen patients had a significant improvement in Raw (a reduction in Raw greater than twice the coefficient of variation of the measurement). The baseline Raw of those 16 infants was significantly higher than the baseline Raw of the other 29 infants (P < 0.01). Multiple regression analysis, after taking into account baseline lung function and symptom status, demonstrated there was a significant relationship between the change in Raw following ipratropium bromide and postnatal age (P < 0.01). We conclude that both baseline lung function and postnatal age influence the response to nebulized ipratropium bromide in young children born prematurely.