[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.


CONCLUSIONS
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.
Huang
G
G
Department of Physiology, School of Basic Medical Sciences, WCUMS, Chengdu 610041, China.
Fan
Z
Z
Huang
J
J
D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008449:Maximal Expiratory Flow-Volume Curves / Q000502:physiology*; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D011660:Pulmonary Heart Disease / Q000503:physiopathology*; D012123:Pulmonary Ventilation / Q000502:physiology*; D012119:Respiration; D012129:Respiratory Function Tests; D014797:Vital Capacity