AIRWAY MUCOSAL BLOOD-FLOW IN BRONCHIAL-ASTHMA

As an inflammatory airway disease, asthma is expected to be associated with an increase in airway blood flow. We therefore compared airway m ucosal blood flow ((Q) over dot(aw)) among normal subjects (n = 11) an d patients with stable asthma receiving (n = 13) or not receiving (n = 10) long-term inhaled glucocorticosteroid (CS) therapy. (Q) over dot( aw) was calculated from the uptake of dimethyl ether in the anatomic d ead space minus the most proximal 50 ml (DS), and expressed as blood f low per mi DS. Mean (+/- SE) (Q) over dot(aw) was 38.5 +/- 5.3 mu l.mi n(-1).ml(-1) in normals, 68.2 +/- 7.9 mu l.min(-1).ml(-1) in GS-naive asthmatics (p < 0.01), and 55.4 +/- 5.3 mu l.min(-1).ml(-1) in GS-trea ted asthmatics (p < 0.05). Ten minutes after administration of 180 mu g albuterol by metered dose inhaler, mean (Q) over dot(aw) increased b y 83 +/- 26% in normal subjects (p < 0.01), but did not change signifi cantly in CS-naive (+5 +/- 8%) or GS-treated (+32 +/- 15%) asthmatics. These results demonstrate that (Q) over dot(aw) is increased in stabl e asthmatics and resistant to further increase by a standard inhaled d ose of a beta-adrenergic agonist.