[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.
Department of Physiology, School of Basic Medical Sciences, WCUMS, Chengdu 610041, China.
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G
Huang
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Fan
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Huang
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