Objective: To explore the significance of negative expiratory pressure (NEP) technique in detecting expiratory flow limitation (EFL) in the chronic obstructive pulmonary disease (COPD) patients.
Methods: NEP technique was performed on 54 COPD patients, 45 males and 9 females, aged 69+/-10 (Group A), 8 COPD patients who failed to receive the routine pulmonary function tests (Group B), and 10 normal controls. The subjects in 3 groups, matched in age, height, body weight, and educational level, underwent 5-point EFL scoring, Medical Research Council (MRC) dyspnea scoring, 6-min walk distance scoring, and routine pulmonary ventilation function test.
Results: EFL was detected in 41 of the 54 COPD patients in Group A. NEP test was successfully performed on the 8 patients of Group B, and 7 of them were found as with EFL. The level of forced expired volume in one second percentage (FEV1%) of the patients with the EFL scores of 2, 3, and 4 were 55.71%+/-11.77%, 41.21%+/-13.69%, and 29.84%+/-11.65% respectively, all significantly lower that of the 0-score group (83.76%+/-16.44%, all P<0.05). Multiple stepwise regression analysis showed that only 5-point EFL score, FEV1%, and 6-min walking distance were associated with MRC dyspnea score, and the 5-point EFL score showed the best associativity with dyspnea.
Conclusion: As compared with FEV(1pred)%, 5-point EFL scoring is more reliable in evaluating the dyspnea of COPD patients, it is simple and doesn't't require any cooperation on the part of the patients. NEP technique can be applied in the COPD patients who fail to receive the routine pulmonary function tests.