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 (Rrs) during tidal breathing. In 25 asthmatic and 18 nonasthmatic subjects the forced oscillation technique was used to measure Rrs 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 Rrs between end tidal inspiration and TLC, re-narrowing as Rrs at FRC immediately after DI, as per cent Rrs at end-tidal expiration, and volume dependent tidal fluctuation as the difference between mean Rrs 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.