EVALUATION OF SPIROMETRIC METHODS USED TO ASSESS ABNORMALITIES IN AIRWAY RESISTANCE

Abstract

The airway resistance measured in a body plethysmograph was compared with spirometric assessments of airway obstruction in 26 patients. There were significant correlations with the per cent [forced expiratory volume in 1 sec] FEV1, [maximal expiratory flow rate] MEFR, [maximal mid-expiratory flow rate] MMF, and FEV1. The correlations with [maximal breathing capacity] MBC and [peak flow rate] PFR were of borderline significance. The spirometric methods showed excellent positive correlation with one another and with aging. Significant postbronchodilator changes in airway resistance may not be detected by the spirometric techniques of assessment. The action of a bronchodilator drug, isoproterenol, appeared to be direct, rather than related to passive airway disease the per cent FEV1, MEFR, MMF, and FEV1 appear to depend mostly upon the mechanical characteristics of lower airways. In the clinical situation, the per cent FEV1, MEFR, MMF, and FEV1 are useiul to assess the abnormalities in the airway resistance but may not be sufficiently sensitive for detection of acute changes in airway resistance following bronchodilator drugs.