Nonreversible conductive airway ventilation heterogeneity in mild asthma.
A multiple-breath washout technique was used to assess residual ventilation heterogeneity in the conductive and acinar lung zones of asthmatic patients after maximal beta(2)-agonist reversibility. Reversibility was assessed in 13 patients on two separate visits corresponding to a different baseline condition in terms of forced expiratory volume in 1 s [FEV(1); average FEV(1) over 2 visits: 92 +/- 21% of predicted (SE)]. On the visit corresponding to each patient's best baseline, 400 micro g salbutamol led to normal acinar ventilation heterogeneity, normal FEV(1), and normal peak expiratory flow; i.e., none was significantly different from that obtained in 13 matched controls. By contrast, conductive ventilation heterogeneity and forced expiratory flow after exhalation of 75% forced vital capacity remained significantly different from controls (P < or = 0.005 on both indexes). In addition, the degree of postdilation conductive ventilation heterogeneity was similar to what was previously obtained in asthmatic individuals with a 19% lower baseline FEV(1) and twofold larger acinar ventilation heterogeneity (Verbanck S, Schuermans D, Noppen M, Van Muylem A, Paiva M, and Vincken W. Am J Respir Crit Care Med 159: 1545-1550, 1999). We conclude that, even in the mildest forms of asthma, the most consistent pattern of non-beta(2)-agonist-reversible ventilatory heterogeneity is in the conductive lung zone, most probably in the small conductive airways.
Verbanck
Sylvia
S
Respiratory Division, Academic Hospital, Vrije Universiteit Brussel, 1090 Brussels, Belgium. sylvia.varbanck@az.vub.ac.be
Schuermans
Daniël
D
Paiva
Manuel
M
Vincken
Walter
W
D000318:Adrenergic beta-Agonists / Q000627:therapeutic use; D000328:Adult; D000420:Albuterol / Q000627:therapeutic use; D001249:Asthma / Q000188:drug therapy / Q000503:physiopathology*; D001993:Bronchodilator Agents / Q000627:therapeutic use; D016022:Case-Control Studies; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D010366:Peak Expiratory Flow Rate / Q000187:drug effects; D012119:Respiration / Q000187:drug effects; D012720:Severity of Illness Index; D014797:Vital Capacity / Q000187:drug effects
D000318:Adrenergic beta-Agonists; D001993:Bronchodilator Agents; D000420:Albuterol