Objective To evaluate if the difference between slow vital capacity ( VC) and forced vital capacity ( FVC) could be used to predict severity of airflow limitation in patients with stable chronic obstructive pulmonary disease ( COPD) .
Methods VC and FVC were measured in 200 patients with COPD [ 159 males;mean FEV1 , ( 49.31 ±15.75) % of predicted] and 114 healthy controls [ 64 males; mean FEV1 , ( 99.67 ±13.62) % of predicted] .
Results The difference between VC and FVC ( VC - FVC) , which showed a negative correlation with FEV1 of predicted ( r=- 0.412, P lt;0.001) , was significantly larger in the COPD patients than that in the controls [ ( 145.40 ±157.50) mL vs. ( 21. 10 ±61. 30) mL, P lt; 0. 001] . The FVC/VC ratio was significantly lower in the COPD patients than that in the controls [ ( 93. 61 ± 7. 10) % vs. ( 99.27 ±2.24) % , P lt; 0.001] , and was positively correlated with FEV1 of predicted in the COPD patients ( r =0.517, P lt;0.001) . There was significant difference in VC - FVC in the COPD patients with FEV1≥50% of predicted ( 5 patients in GOLD level 1 and 74 patients in GOLD level 2) and those patients with FEV1 lt;50% of predicted ( 106 patients in GOLD level 3 and 15 patients in GOLD level 4) [ ( 78.23 ±108.26) mL vs. ( 189.26 ±169.21) mL, P =0.003] .
Conclusion The difference between VC and FVC and the FVC/VC ratio, which are more easily obtained from spirometric test, are able to detect severity of airflow limitation in patients with stable COPD.
Citation： YUAN Wei,WANG Haoyan,XU Qiufen,XU Weihan,FU Yaoxuan,YANG Xiaoli,ZHAO Xujuan,LI Bin.. Difference between Slow and Forced Vital Capacity Can Predict Severity of Chronic Obstructive Pulmonary Disease. Chinese Journal of Respiratory and Critical Care Medicine, 2013, 12(4): 329-333. doi: 10 . 7507 /1671 -6205 . 20130080 Copy