Assessment of bronchodilatation after spontaneous recovery from a histamine challenge in asthmatic children

Abstract

Background. It would be convenient to be able to measure airway responsiveness to histamine and to bronchodilator drugs in the same day, but whether this can be done reliably is unknown. Methods. The effect of a prior histamine challenge on the bronchodilator response to salbutamol after spontaneous recovery of FEV1 to 95% of the pre-challenge level was studied in two groups of asthmatic children. Fourteen children inhaled 400 μg salbutamol after spontaneous recovery from a histamine challenge, followed by a further 100 μg salbutamol 20 minutes later. In a second group of eight asthmatic children the study was repeated with 800 μg salbutamol, followed by a further 200 μg 20 minutes later. Results. After histamine challenge FEV1 returned to baseline in 70 minutes or less on all occasions. The FEV1 20 minutes after 400 μg salbutamol was significantly lower after the histamine challenge than on the control day. After the further 100 μg salbutamol FEV1 values were similar after the histamine challenge and on the control day. FEV1 values after 800 μg salbutamol and the further 200 μg dose were not influenced by a prior histamine challenge. Conclusions. In children with stable asthma in whom FEV1 has returned to baseline after a histamine challenge the FEV1 achieved after 800 μg salbutamol is not affected by the histamine challenge. Histamine and bronchodilator responsiveness can thus be assessed reliably on the same day in patients with stable asthma. This has clear advantages for patient care.