Airway compliance is a key factor in understanding lung mechanics and is used as a clinical diagnostic index. Understanding such mechanics in small airways both physiologically and clinically is critical. We developed a two-step method to visualize small airways (to as small as-150,μm internal diameter) in detail by staining the lung tissue with a radiopaque solution and then visualizing the tissue with a cone-beam micro-CT. And we determined the “morphometic change” and “localized compliance” of small airways. For the smaller airways (D < 300,μm), the diameter was 36% larger at end tidal inspiration (TV) and 89% larger at total lung capacity (TLC), (length was 18% larger at TV and 43% at TLC) compared with the values at functional residual capacity. With increasing lung pressure, the diameter changed dramatically at a particular pressure and the length changed approximately linearly during both inflation and deflation. The percentage of airway volume for the smaller airways did not behave linearly with that of lung volume. Smaller airways were generally more compliant than the larger airways and exhibited hysteresis in their diameter behavior. These results indicated that the smaller airways did not behave homogenously.
抄録全体を表示