スパイログラムによる老人の肺換気機能に関する研究—（1）呼・吸気一秒率について

A Study on the Timed Expiratory and Inspiratory Vital Capacity (One Second) in the Aged.

I．緒言

　Tiffeneauは呼出障害の程度にもとづく肺気腫診断基準として一秒率を提唱し，一秒率55％以下の場合には気腫性変化，55〜70％の場合には，気腫性変化によらない閉塞性障害によるとした^1）。しかし，周知の如く，呼出障害とは肺・胸廓系における弾性収縮力の低下及び粘性抵抗の増大（すなわち肺・胸廓系における時定数の増大）を招来する種々の成因によつて惹起せられるものであるから，一秒率の低下をもつて肺における気腫性変化の状態を論ずることは，理論上，必ずしも妥当とはいえない。事実，種たの肺疾患における一秒率を検討した中村教授等^1）の成績においても，肺気腫以外の気管支喘息，珪肺等において，かなりの頻度で一秒率55％以下の低下を認めるが，この事実は上述の呼出障害の成因からみて，極めて当然の結果といえよう。

　この点に関し，中村教授等^2）は一秒率と同時に呼気閉塞指数（呼気0.5秒量／吸気0.5秒量）の算定を提唱し，一秒率で鑑別困難な肺気腫と気管支喘息の分離が，呼気閉塞指数の併用により可能になるとした。

In this study, the Leslie's index, the timed expiratory vital capacity (1")/expiratory vital capacity and the timed inspiratory vital capacity (1")/inspiratory vital capacity were examined in the healthy young males, bronchial asthma, the senile patients with chronic pulmonary emphysema and the healthily-looking aged.

1) The Leslie's index were more increased in the bronchial asthma and the senile patients with chronic pulmonary emphysema than in the other two groups. No significant correlation was recognized between the Leslie's index in bronchial asthma and the chronic pulmonary emphy-sema.

2) The timed expiratory vital capacity (1")/expiratory vital capacity were more decreased in bron-chial asthma and chronic pulmonary emphysema than in the other two groups. No significant correlation was recognized between the timed expiratory vital capacity (1")/expiratory vital capacity in the bronchial asthma and the one in the chronic pulmonary emphysema.

3) The timed inspiratory vital capacity (1")/inspiratory vital capacity was more decreased in the bronchial asthma then in the other three groups.

4) From the above results, it was concluded that the differential diagnosis between the chronic pulmonary emphysema and the bronchial asthma was capable by means of the timed inspiratory vital capacity (1")/inspiratory vital capacity, however, the differential diagnosis of the two groups was difficult by means of the timed expiratory vital capacity (1")/expiratory vital capacity.

The mechanism of this method was discussed from the points of view of the ventilatory mecha-nics.