["Effort index"--estimating abilities of respiratory muscles]

This paper analyzes the actual values of FEV1 and MBC in 240 normal subjects, 147 patients with COPD and 85 cases of cancer tumors, and shows that the actual values of MBC in both COPD patients and cancerous cases are much lower than the calculated values from FEV1. The authors believe that the ratio between the actual values of MBC and its calculated values may be used to reflect the strengths or abilities of the respiratory muscles efforted, called "Effort Index". The formula of MBC calculated from FEV1 is based on the linear regression equation formulated from the actual values of FEV1 and MBC in 240 normal subjects (aged 16-80 yrs). The "Effort Index" is equal to the actual value of MBC/the calculated value of MBC. The "Effort Index" in 240 normal subjects is 1.00 +/- 0.14 (M +/- SD), in mild, moderate and severe cases of COPD being 0.907, 0.807 and 0.626 respectively, and in markedly wasted cancer cases, 0.861 +/- 0.130. The results show that the formula of MBC calculated from FEV1 is useful only for the subjects with normal respiratory muscular abilities; while in COPD patients and markedly emaciated cancerous cases, owing to the chronically tired-out or exhausted respiratory muscular strength, the actual values of MBC are actually lower than those calculated from FEV1, hence the decreased "Effort Index".