吸烟者流量-容积曲线形状形成的切线时间常数、波速机理及其临床意义

Tangent Time Constant and Wave Speed Mechanism of F V Curve Configuration in Smokers and Clinical Significance

为探讨吸烟者流量 -容积曲线形状形成的切线时间常数 (τt)、波速机理及其临床意义 ,测定了 2 2例被动吸烟者和 94例主动吸烟者的 F- V曲线 ,由此获取 FVC、·V75 、·V5 0 、·V2 5 等数据 ,并计算出高、中、低肺容积的切线时间常数 τt75 、τt5 0 、τt2 5 ,用波速学说进行分析。结果显示 :仅在重度吸烟组和凸型 F- V曲线发生的主要改变为·V5 0 、·V2 5 下降 ;τt2 5 ≥ 1 s;τt75 ≈τt5 0 <τt2 5 呈“喇叭式”(trumpet fashion)改变或τt75 <τt5 0 <τt2 5 呈“塔式”(tower fashion)改变。据此 ,可将τt2 5 ≥ 1 s、τt75 ≈τt5 0 <τt2 5 及τt75 <τt5 0 <τt2 5 认为是受吸烟影响的 3种τt特性。同时 ,此三者均使凸型 F-V曲线的凸度加大 ,均反映了小气道功能下降 ,与 ·V5 0 、·V2 5 降低相似。因此 ,这些 τt特性对鉴定小气道功能具有重要意义 。

This study was conducted to explore the mechanical mechanism of the formation of F V curve configuration with tangent time constant (τ t) and wave speed theory for smokers.F V curves were measured on 22 passive smokers and 94 active ones.FVC,·V 75 ,·V 50 and ·V 25 were obtained, and tangent time constants at high, mid,low lung volumes,τ t75 ,τ t50 and τ t25 were calculated,and analysed with wave speed theory.The results showed that the chief changes taking place only in heavy smokers and convex type of F V curve were:decreased ·V 50 and ·V 25 ;τ t25 ≥1s; τ t75 ≈τ t50 <τ t25 in “trumpet fashion” change; and τ t75 <τ t50 <τ t25 in “tower fashion” change.Then,τ t25 ≥1s,τ t75 ≈τ t50 <τ t25 and τ t75 <τ t50 <τ t25 were assigned as three τ t characters of smoking effect. They led to an increased convexity of the convex type of F V curve,and reflected the decrease of small airway functions.Similar to the decrease of ·V 50 and ·V 25 ,they have important significance in assessing small airway functions and thus merit clinical use.