切线时间常数在慢性阻塞性肺疾病及肺心病患者F—V曲线形状转变中的变化及临床意义

Changes of tangent time constant in the transformation of F-V curve configuration in COPD and cor pulmonale patients and clinical implications]

OBJECTIVE: To explore the changes of tangent time constant (tau t) in the transformation of F-V curve configuration in COPD and cor pulmonale patients and clinical implications. METHODS: We determined the F-V curves in 90 COPD patients (43 with chronic bronchitis, 47 with emphysema) and 31 complicated with cor pulmonale; all patients were in the ameliorated period. The tau t at high, mid and low lung volumes, tau t75, tau t50, tau t25, were measured on each F-V curve. RESULTS: 1. Normal ranges: F-V curve configuration with plateau, linear, convex and concave types; |tau t75| > ls or < ls; tau t25 < ls; tau t relationship with "adolescent fashion" or "old fashion". 2. Light and moderate abnormality: With convex type; |tau t75| < ls; tau t25 approximately = ls or > ls; "trumpet fashion" changes. 3. Serious abnormality: With hyperbolic type; |tau t75| < ls; tau t25 = 4s-10s; "tower fashion" changes. CONCLUSION: Hyperbolic type, extreme prolongation of tau t25 and "tower fashion" changes can be assigned as 3 important indices to assess the severity of disease. The convenience and correctness of the method may be available for clinical application.