<原著>強制呼出時の気道動態について : 気管支動態撮影と気道壁内外圧差の観察から
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この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されました。For the purpose of studying the mechanical behavior of bronchial trees during forced vital capacity maneuver, both dynamic bronchography and measurement of intrathoracic pressure at various levels of bronchial wall was performed in normal subjects and COPD patients. The dynamic bronchography was done using serial exposure x ray apparatus (6 exposures per sec.) along with simultaneous recording of flow, volume and intrathoracic pressure. On successive bronchogram films we measured the internal diameter (i. d.) of airways on several fixed points from trachea down to sixth branching of bronchial tree. In another study group we measured lateral pressure at the level of trachea and lobar and segmental bronchus during forced expiration using a small catheter with a side hole on its peripheral end. The results were as follows : The segmental or subsegmental bronchi with i. d. of 3-6mm collapsed most strikingly during the maneuver in both normal and COPD group with higher collapse ratio of 1 : 3 (minimal i. d. / i. d. at TLC) in the latter group compared with the former. No decrease in i. d. of bronchi with i. d. less than 2mm was observed in both normal and COPD group. While an initial rise followed by plateau in intrathoracic pressure curve occurred almost instantaneously in COPD group, pressure change was gradual and the pressure curve took an inversed V configuration over the whole expiratory cycle in normal group. The instantaneous airway collapse at the beginning of forced expiration observed in COPD group reflects the fact that the source of force against bronchial wall is high transmural pressure which developed from high intrathoracic pressure. The transmural pressure which showed no essential difference along the cource of bronchial tree was generally higher than normal in COPD group indicating the decrease in distending pressure in emphysematous lung. The whole descending limb of V-V curve which reflects the airways collapse in small lung volume is considered as a useful measure for the detection of early obstructive disturbance which could not be detected by routine spirometry. In conclusion, the increased airway resistence during forced vital capacity maneuver in COPD patients is the result of flow limiting phenomenon due to airway collapse at the level of segmental bronchus.
- 京都大学の論文
- 1977-03-30