The curve delimited by the interrupted line represents the predicted flow-volume curve. The convexity of the curve towards the volume axis before bronchodilatation points to peripheral airway obstruction. There is significant bronchodilator responsiveness, with normalization of the FVC, signifying very significant reversibility of expiratory airway obstruction. The illustration also shows the inspiratory and expiratory flow-volume curve during normal tidal breathing.
See also: Flow-volume curves during quiet tidal breathing