Paradoxical response to nebulized ipratropium bromide in pre-term infants asymptomatic at follow-up.

Lung function measurements were performed before and after bronchodilator, nebulized ipratropium bromide (10 micrograms kg-1), in 20 pre-term infants [median gestational age 28 weeks (range 23-32 weeks) at a median postnatal age of 10 months (range 6-16 months)]. Eight of the infants had recurrent respiratory symptoms. Thoracic gas volume (TGV) and airways resistance (Raw) were measured by a plethysmographic technique and functional residual capacity (FRC) by a helium gas dilution technique. There was no significant change in either TGV or FRC following bronchodilator in the symptomatic and asymptomatic infants. Nebulized bronchodilator resulted in a significant improvement in Raw amongst the symptomatic infants (P less than 0.05), but a paradoxical response, that is, a deterioration (P less than 0.05) in Raw amongst the asymptomatic infants. In three asymptomatic infants, lung function measurements were repeated before and after nebulized saline and a similar deterioration in Raw was noted. We conclude the demonstration of respiratory symptoms at follow-up is useful in predicting infants who would have a beneficial response to nebulized ipratropium bromide.