Indirect determination of effective values of lung compliance and its clinical applications
Luo, Y.J.; Zhang, Z.Y.; Yin, D.K.; Ye, X.
Hua Xi Yi Ke Da Xue Xue Bao 18(1): 64-67
1987
ISSN/ISBN: 0257-7712 PMID: 3623525 Document Number: 303288
The principle and method of indirect determination of the effective values of the lung compliance (Ceff) are introduced in this paper. The authors, using the guiding principle that MTT is equal to the product of the effective values of the lung compliance and the airway resistance, calculated a formula for Ceff as follows: Ceff (L/cmH2O) = MTT (sec) / [2.4 + 0.3 .ovrhdot.V (L/sec)] Ceff can be calculated with the formula when MTTp (62.5-87.5% FVC) and the partial mean expiratory volume are known. Ceff in 100 normal subjects was detected and the M .+-. SD was 0.1128 .+-. 0.0418L/cm H2O. Ceff increased with age, and its linear regression formula correlating to age was as follows: Ceff (L/cmH2O) = 0.0251 + 0.002 .times. Age(yr.) In 94 cases of COPD Ceff was increased obviously, and especially increased company with emphysema. In 5 cases of diffuse interstitial fibrosis of lung Ceff was decreased obviously. Therefore, the results of Ceff determination showed that it reflected the lung compliance very well. The determination of Ceff is of diagnostic value in some diseases in which the lung elastic recoil pressure is decreased (emphysema) or increased (diffuse interstitial fibrosis of lung), and is especially of significant clinical value in the diagnosis of early emphysema.