High intrathoracic expiratory airway obstruction
The
expiratory flow pattern is abnormal, exhibiting a ‘shoulder’
in the flow-volume curve due to a fixed obstruction in larger intrathoracic
airways. The inspiratory pattern is normal, so that extrathoracic
airway obstruction is unlikely. This patient received radiation
therapy for a central tumor of the bronchus. Also shown is the flow-volume
curve during normal tidal breathing, and the MEFV-curve (interrupted
line) for a healthy person of the same age, standing height and
gender.
Poor co-operation does not lead to reproducible curves. In general, therefore, if the patient appears to produce satisfactory efforts leading to a reproducible flow-volume curve with an abnormal pattern, take this seriously. Check carefully whether there is an inspiratory or expiratory stridor.