High intrathoracic airway obstruction
This
patient received radiotherapy because of a central bronchial
carcinoma. The forced expiratory pattern is definitely abnormal,
exhibiting a ‘shoulder’ in the flow-volume curve
due to variable obstruction in large intrathoracic airways.
The by and large normal inspiratory pattern rules out fixed
airway obstruction. Also shown are the flow-volume curve during
resting ventilation, and (interrupted line) the curve predicted
for age, gender and standing height.
Poor cooperation does not lead to reproducible flow-volume curves. Therefore, if it appears that a patient is co-operating well, take a reproducibly abnormal pattern of the flow-volume curve seriously, and check carefully for the presence of an inspiratory or expiratory stridor.
See also: Tidal flow-volume loop