Dysanapsis ratio as a predictor for expiratory flow limitation.

To determine the efficacy of the dysanapsis ratio (DR) in predicting expiratory flow limitation during exercise, 146 subjects (73 men, 73 women) performed standard pulmonary function and maximal incremental exercise tests. Tidal flow-volume loops were recorded at maximal exercise with maximal flow-volume loops measured pre- and post-exercise. Men had larger (p<0.05) lung volumes, flow rates, and V˙O2max compared to women, but DR was similar (0.21±0.05 vs. 0.20±0.06, respectively, p>0.05). V˙O2max was not different (p>0.05) between the EFL subjects compared to the non-EFL subjects for both men and women. Men with EFL compared to non-EFL men had smaller FVC (5.16±0.89L vs. 5.67±0.86L, p<0.05) and DR (0.19±0.05 vs. 0.23±0.04, p<0.05). Similarly, women with EFL compared to non-EFL had significantly smaller DR (0.18±0.05 vs. 0.24±0.05), but similar FVC (3.88±0.52 vs. 4.12±0.64, p>0.05). A DR threshold was not determined; however, a DR continuum exists with increasing DR leading to decreased prevalence of EFL. In conclusion, DR is effective in determining the likelihood of EFL at maximal exercise.