Paradoxical deterioration in lung function after nebulised salbutamol in wheezy infants

In 13 infants with a history of wheezing, airways resistance and specific conductance worsened after administration of nebulised salbutamol (0.5 ml sabutamol respirator solution in 1.5 ml normal saline). This paradoxical bronchoconstriction was greatest at 5 min and lasted for up to 15 min. The nebulised solution was found to be acidic and hypo-osmolar, both of which properties have been linked to bronchoconstriction in asthmatic subjects, but even with an initially iso-osmolar solution osmolality increased with time of nebulisation because of evaporation.