AIRWAY RESPONSIVENESS IN ASTHMA - BRONCHIAL CHALLENGE WITH HISTAMINE AND 4.5-PERCENT SODIUM-CHLORIDE BEFORE AND AFTER BUDESONIDE

Inhalation of histamine is commonly used to assess the severity of and to monitor treatment of asthma. Histamine causes airways to narrow by acting directly on specific receptors. Hyperosmolar saline Causes air ways of asthmatics to narrow indirectly by endogenously mediated event s that are potentially modified by drugs used to treat asthma. We wish ed to determine if hyperosmolar saline (S) is a useful challenge for a ssessing the airway responsiveness of asthmatic subjects being treated with steroids and to compare changes in airway responses to those cha nges observed with histamine (H). The airway responses to S and H were assessed by the dose of aerosol provoking a 20% fall in FEV(1) and th e percent fall in FEV(1) per unit dose of aerosol inhaled-the dose res ponse slope (DRS). We studied asthmatic subjects before and during tre atment with budesonide-1000 mu g per day. There was a significant corr elation (Spearman's) between PD20 to H and S and DRS to H and S after budesonide (P < 0.05). After 2 months of treatment; the mean PD20 (95% CI) was increased 4.6 (2.5, 8.6) fold to H, and 9.7 (4.2, 22) fold to S, (P = NS) the DRS reduced 7.0 (4.3, 11.5) fold to H and 166 (8.4,33 ) fold to S (P = NS). Responsiveness to H, measured by PD20 remained t hroughout the treatment, whereas five subjects did not record a 20% fa ll after S and the DRS decreased to values close to those we measured in healthy subjects. in conclusion challenge with 4.5% sodium chloride can be used to assess the early benefits of treatment with aerosol st eroids.