Airway re-narrowing following deep inspiration in asthmatic and nonasthmatic subjects

• Published in: The European respiratory journal Vol. 22; no. 1; pp. 62 - 68
• Main Authors: Salome, C.M, Thorpe, C.W, Diba, C, Brown, N.J, Berend, N, King, G.G
• Format: Journal Article
• Language: English
• Published: Leeds Eur Respiratory Soc 01.07.2003; Maney
• Subjects: Adult; Airway Resistance - drug effects; Airway Resistance - physiology; Asthma - physiopathology; Biological and medical sciences; Bronchial Provocation Tests; Female; Forced Expiratory Volume - drug effects; Humans; Inspiratory Capacity - drug effects; Investigative techniques of respiratory function; Investigative techniques, diagnostic techniques (general aspects); Linear Models; Male; Medical sciences; Methacholine Chloride - pharmacology; Middle Aged; Muscle, Smooth - drug effects; Muscle, Smooth - physiopathology; Spirometry; Tidal Volume; Human; Airway re-narrowing asthma deep inspiration forced oscillation technique velocity of shortening; Lung function; Pathophysiology; Respiratory disease; Exploration; Obstructive pulmonary disease; Forced inspiration; Asthma
• ISSN: 0903-1936; 1399-3003
• DOI: 10.1183/09031936.03.00117502

After bronchoconstriction, deep inspiration (DI) causes dilatation followed by airway re-narrowing. Re-narrowing may be faster in asthmatic than nonasthmatic subjects. This study investigated the relationship between re-narrowing and the magnitude of both DI-induced dilatation and the volume-dependence of respiratory system resistance ( R rs ) during tidal breathing. In 25 asthmatic and 18 nonasthmatic subjects the forced oscillation technique was used to measure R rs at baseline and after methacholine challenge, during 1 min of tidal breathing, followed by DI to total lung capacity (TLC) and passive return to functional residual capacity (FRC). Dilatation was measured as the decrease in R rs between end tidal inspiration and TLC, re-narrowing as R rs at FRC immediately after DI, as per cent R rs at end-tidal expiration, and volume dependent tidal fluctuation as the difference between mean R rs at end-expiration and end-inspiration. Asthmatic subjects had greater re-narrowing, less dilatation, and greater tidal fluctuations both at baseline and after challenge. Re-narrowing correlated with baseline tidal fluctuation and inversely with dilatation. Both baseline tidal fluctuation and dilatation were significant independent predictors of re-narrowing. Following deep inspiration-induced dilatation, faster airway re-narrowing in asthmatic than nonasthmatic subjects is associated not only with reduced deep inspiration-induced dilatation but also with some property of the airways that is detectable prior to challenge as an increased volume dependence of resistance.