title: [To compare negative expiratory pressure technique with conventional tests in detecting expiratory flow limitation in chronic obstructive pulmonary diseases patients.].
abstract: OBJECTIVE
  To compare negative expiratory pressure (NEP) technique with conventional test in detecting expiratory flow limitation (EFL) in chronic obstructive pulmonary diseases (COPD) patients.
  
  
  METHODS
  EFL was measured with NEP technique and conventional method respectively in 72 COPD patients;EFL was measured with NEP technique in 20 COPD patients who failed to perform conventional test.
  
  
  RESULTS
  EFL was detected in 54 of the 72 COPD patients. NEP test was successfully performed on the 20 patients, and 19 of them were found with EFL. The level of forced expired volume in one second percentage (FEV(1)%) of the patients with 2-score group (46.92 +/- 12.74)% and 3-score group (33.35 +/- 8.96)% were significantly lower than that of the 1-score group (63.60 +/- 16.65)%. Area under curve of NEP technique and conventional test in ROC is 0.903 and 0.761 respectively.
  
  
  CONCLUSIONS
  As compared with conventional test, EFL detected with NEP technique is more reliable in evaluating dyspnea of COPD patients. It is simple and doesn't require any cooperation of the patients. NEP technique can be applied in COPD patients who fail to receive conventional test.
authors.affiliation: State Key Lab of Respiratory Disease, First Affiliated Hospital of Guangzhou Medical College, Guangzhou 510120, China. Email: chenrc@vip.163.com.
authors.forename: Rui
authors.initials: R
authors.lastname: Chen
authors.forename: Rong-Chang
authors.initials: RC
authors.lastname: Chen
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.forename: Yan-Yi
authors.initials: YY
authors.lastname: Cen
authors.forename: Lian
authors.initials: L
authors.lastname: Chen
mesh_terms: D004417:Dyspnea; D005541:Forced Expiratory Volume; D006801:Humans; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis; D012129:Respiratory Function Tests