Thorax
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Randomized Controlled Trial Comparative Study Clinical Trial
Regional lung clearance during cough and forced expiration technique (FET): effects of flow and viscoelasticity.
In vitro studies have suggested that both the viscoelastic properties of lung secretions and the peak flow attained during simulated cough influence clearance. This study examines the possible association of the viscoelastic properties of sputum and maximum expiratory flow with measured effectiveness of mucus clearance induced by instructed cough and by forced expiration technique (FET) in patients with airways obstruction. ⋯ These results confirm that cough and FET both promote effective clearance but suggest that, unlike in vitro studies, sputum production and viscoelasticity, as well as maximum expiratory flow, provide no guide to clearance efficacy in humans.
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Heightened bronchial hyperreactivity is frequently associated with airflow limitation, atopy, or cigarette smoking. The purpose of this study was to evaluate healthy subjects with significantly low values of forced expiratory volume in one second/vital capacity % (FEV1/VC%) by measuring their airway response to exercise and methacholine challenge, compared with a control group with normal spirometric values. ⋯ Bronchial hyperreactivity does not occur more often in asymptomatic subjects with mildly low FEV1/VC% so these subjects do not require special investigations for airway disease.