PURPOSE: Many patients with central airway obstruction may receive significant relief from life-threatening symptoms by interventional bronchoscopy. Treatment outcomes are usually measured by subjective criteria such as dyspnea and quality of life, along with objective measures such as pulmonary function tests, computed tomography and bronchoscopy. Flow-volume curves are noninvasive and easy to perform. However, flow-volume curves may not detect several typical abnormalities, especially in stenoses of the unilateral main-stem bronchus. Due to these limitations, we studied how “Asynchrony” affects patients with main-stem bronchial stenosis using the Vibration Response Imaging (VRI). The VRI is an imaging modality that records energy generated by the vibrations of the lungs during a respiration cycle and creates an image that can be viewed dynamically or sequentially. We recorded VRI information regarding regional lung function. We planed to elucidate the threshold level of stenosis causing left and right lung asynchrony using a lung model, then to validate this threshold in patients with main-stem bronchial stenosis.
METHODS: A lung model using extracted pig lungs in a sealed box and connected to a ventilator was used. We measured airway pressure of the right and left bronchus simultaneously using two catheters to manually narrow the airways.
RESULTS: We validated the relation between the rate of stenosis and time delay. Time delay increased significantly from 90% in the pig model (P<0.05). In patients, VEP gap also increased sharply from 90% in main-stem bronchial stenosis. The rate of stenosis was measured by computed tomography using ZAIO soft software and vibration energy peak gaps (VEP gap) in 10 patients with unilateral main-stem bronchial stenosis
CONCLUSIONS: In this study, the VRI was able to identify severe stenoses above 90% in patients. We found VRI was useful in assessing treatment outcomes and decisions on interventional indication.
CLINICAL IMPLICATIONS: VRI was useful in assessing main bronchial stenosis.
DISCLOSURE: The following authors have nothing to disclose: Hirotaka Kida
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