Forced expiratory wheezes in a patient with dynamic expiratory narrowing of central airways and an oscillating pattern of the flow-volume curve

Forced expiratory wheezes (FEW) are common and the pathogenesis of this phenomenon might involve fluttering of the airways, but this theory has not been confirmed in patients. We report a case of a patient with FEW and a normal FEV1 that showed a bronchoscopically confirmed collapse of the trachea and main stem bronchi during forced expiration. Superimposed to the flow-volume curve was an oscillating pattern with a frequency that corresponded well with the wheeze generated during forced expiration. The oscillating pattern in the flow-volume curve and the collapse of the major airways supports the theory of wheezes generated by fluttering airways during forced expiration. Although FEW may be found also in healthy subjects, flow limitation is essential for the generation of FEW. The inclusion of a forced expiratory maneuver in the clinical examination might there fore be helpful in guiding the diagnosis towards airways obstruction.