title: Asthma and respiratory physiology: putting lung function into perspective.
abstract: Bronchial asthma is a chronic disease characterized by airway hyperresponsiveness, airway inflammation and remodelling. The hypothesis that the illness is inflammatory in nature has recently been challenged by studies showing that airway smooth muscle (ASM) plays a more important role than previously thought. For example, it is now known that in asthma patients, ASM proliferates more and faster than in healthy subjects, carries intrinsic defects and exhibits impaired relaxation, increased velocity of shortening, plastic adaptation to short length and perturbed equilibrium of actin-to-myosin during cycling. Similar conclusions can be drawn from studies on airway mechanics. For instance, in asthma, abnormal ASM contributes to limiting the response to deep lung stretching and accelerates the return of bronchial tone to baseline conditions, and contributes to increased airway stiffness. Upon stimulation, ASM causes airway narrowing that is heterogeneous across the lung and variable over time. This heterogeneity leads to patchy ventilation. Experimental studies have shown that patchy ventilation may precipitate an asthma attack, and inability to maintain bronchial tone control over time can predict the occurrence of bronchospastic attacks over a matter of a few days. To improve our knowledge on the pathogenesis of asthma, we believe that it is necessary to explore the disease within the framework of the topographical, volume and time domains of the lung that play an important role in setting the severity and progression of the disease. Application of the forced oscillation technique and multiple breath nitrogen washout may, alone or in combination, help address questions unsolvable until now.
authors: Respiratory Unit, San Paolo Hospital, University of Milan, Milan, Italy.
authors: Giuseppe Francesco
authors: GF
authors: Sferrazza Papa
authors: Giulia Michela
authors: GM
authors: Pellegrino
authors: Riccardo
authors: R
authors: Pellegrino
mesh_terms: D056151:Airway Remodeling / Q000502:physiology; D000403:Airway Resistance / Q000502:physiology; D001249:Asthma / Q000150:complications / Q000473:pathology* / Q000503:physiopathology*; D016535:Bronchial Hyperreactivity / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D008176:Lung Volume Measurements; D009130:Muscle, Smooth / Q000503:physiopathology
keywords: airway smooth muscle; asthma; forced oscillation technique; remodelling; respiratory function test