Changes in the Flow-Volume Curve According to the Degree of Stenosis in Patients With Unilateral Main Bronchial Stenosis

Abstract

ObjectivesThe shape of the flow-volume (F-V) curve is known to change to showing a prominent plateau as stenosis progresses in patients with tracheal stenosis. However, no study has evaluated changes in the F-V curve according to the degree of bronchial stenosis in patients with unilateral main bronchial stenosis.MethodsWe performed an analysis of F-V curves in 29 patients with unilateral bronchial stenosis with the aid of a graphic digitizer between January 2005 and December 2011.ResultsThe primary diseases causing unilateral main bronchial stenosis were endobronchial tuberculosis (86%), followed by benign bronchial tumor (10%), and carcinoid (3%). All unilateral main bronchial stenoses were classified into one of five grades (I, ≤25%; II, 26%-50%; III, 51%-75%; IV, 76%-90%; V, >90% to near-complete obstruction without ipsilateral lung collapse). A monophasic F-V curve was observed in patients with grade I stenosis and biphasic curves were observed for grade II-IV stenosis. Both monophasic (81%) and biphasic shapes (18%) were observed in grade V stenosis. After standardization of the biphasic shape of the F-V curve, the breakpoints of the biphasic curve moved in the direction of high volume (x-axis) and low flow (y-axis) according to the progression of stenosis.ConclusionIn unilateral bronchial stenosis, a biphasic F-V curve appeared when bronchial stenosis was >25% and disappeared when obstruction was near complete. In addition, the breakpoint moved in the direction of high volume and low flow with the progression of stenosis.

Diagnostic Value of Virtual Bronchoscopic Navigation in the Bronchial Tuberculosis Induced Central Airway Stenosis

“…A total of 188 sites were selected from the central airway, including the stenotic airway and normal airway. On EOB, the stenosis was graded as 0% (no stenosis), B 25%, 26-50%, 51-75%, 76-90% and [ 90% [7]. In the VBN, the degree of bronchial stenosis was calculated as the ratio of stenotic bronchial cross-sectional area to normal bronchial crosssectional area and also graded as described above.…”

Can inhaled foreign body mimic asthma in an adolescent?

“…About F-V curve, it is a graphic plot consisting of inspiratory and expiratory flow against volume obtained while a patient performs maximal forced inspiratory and expiratory maneuvers [ 4 ]. The morphology of F-V curve is different between asthma and unilateral main bronchial stenosis (due to a piece of food in the case of our patient).…”

“…This event can be explained by positive transmural pressure during the inspiration because the bronchial pressure exceeds the surrounding pleural pressure; consequently, no downstream compression occurs, resulting in greater inspiratory flow. Anyway, in unilateral bronchial stenosis, the shape of the biphasic F-V curve changes with the progression of stenosis because of the migration of the breakpoint; moreover, it can be seen when stenosis is >25% of the lumen of the bronchus [ 4 ].…”

Short-length ligamentum arteriosum as a cause of congenital narrowing of the left main stem bronchus

“…Finally, the restrictive pattern on lung function testing, shown by our first three patients, has been observed in several cases of fixed unilateral main stem bronchial stenosis due to extrinsic compression or intrinsic obstruction . Moreover, the biphasic configuration of the inspiratory arm of the flow‐volume loop during a forced inspiration, shown in our third patient, is compatible with unilateral obstruction of a main bronchus .…”