RESUMO
In infants paradoxical bronchoconstriction instead of dilatation was observed after beta-2-agonist inhalation and was thought to be due to an osmolality and pH change of the inhalation mixture in the nebuliser cup. Therefore, we measured lung function in 11 asthmatic children and adolescents, and in a healthy control group, after inhalation of a hyperosmolar beta-2-NaCl mixture. 0.5 ml salbutamol in 1.5 ml physiological saline (2 ml total) or 1.0 ml salbutamol in 3 ml NaCl, respectively, were nebulised for 10 minutes. Following nebulisation the patients were asked to inhale for 5 minutes from the residue in the cup. Before and after this procedure lung function was measured. All the patients were symptom-free and were tested on two days at the same time after being off medication for at least 24 hours. Baseline osmolality of the mixtures at the start of nebulisation was 235 +/- 5.0 mmol/kg and increased in the cup after 10 minutes to 322 +/- 7.5 mmol/kg for the low initial volume (2 ml) and to 261 +/- 2.0 mmol/kg for the high initial volume (4 ml). After the 5 minutes' inhalation session osmolality rose further to 460 +/- 25.0 mmol/kg (2 ml) and 278 +/- 1.0 mmol/kg (4 ml), respectively. In all asthmatic children significant changes (p less than 0.01, paired t-test) before and after inhalation occurred (decrease of airway resistance, increase of FEV1, increase of maximal expiratory flows at 75%, 50% and 25% of vital capacity, increase of peak expiratory flow. Thoracic gas volume, residual volume and vital capacity remained unchanged). No changes were seen in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)
