title: Efficiency of neural respiratory drive for the assessment of bronchodilator responsiveness in patients with chronic obstructive pulmonary disease: an exploratory study.
abstract: BACKGROUND
  Conventional lung function parameters, such as forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1) and inspiratory capacity (IC) are often used to assess the therapeutic outcomes of bronchodilators, but they lack sensitivity. A novel indicator, namely efficiency of neural respiratory drive (NRD), may objectively evaluate the physiological changes in patients with chronic obstructive pulmonary disease (COPD). We investigated whether this indicator could be used to more accurately assess the responsiveness to inhaled bronchodilators.
  
  
  METHODS
  Thirty-six subjects with moderate-to-severe COPD were randomized into group A (n=18) and group B (n=18). Participants in group A inhaled 400 µg placebo, 400 µg salbutamol and 80 µg ipratropium in sequence whereas those in group B had the salbutamol and ipratropium reversed. At different time points after administration of placebo or bronchodilators, evaluated indices included FEV1, FVC, IC, root mean square (RMS) of diaphragm electromyogram (EMGdi), and efficiency of NRD [herein defined as the ratio of minute ventilation (VE) to RMS, or VE/RMS].
  
  
  RESULTS
  FEV1, FVC, IC, RMS, and VE/RMS significantly improved after inhaled bronchodilators and VE/RMS had the largest improvement among five indices. The detection efficiency of VE/RMS was greater than FEV1, FVC, IC (all P<0.05), but not different from RMS. The accuracy and sensitivity of VE/RMS were significantly higher than FEV1, FVC, IC, and RMS (all P<0.05).
  
  
  CONCLUSIONS
  Efficiency of NRD may be a sensitive tool to evaluate the efficacy of inhaled bronchodilators in COPD.
authors.affiliation: 1 Department of Respiratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China ; 2 Department of Respiratory Medicine, Guangzhou Panyu Central Hospital, Guangzhou 511486, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Li
authors.affiliation: 1 Department of Respiratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China ; 2 Department of Respiratory Medicine, Guangzhou Panyu Central Hospital, Guangzhou 511486, China.
authors.forename: Yin-Huan
authors.initials: YH
authors.lastname: Li
authors.affiliation: 1 Department of Respiratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China ; 2 Department of Respiratory Medicine, Guangzhou Panyu Central Hospital, Guangzhou 511486, China.
authors.forename: Shuo
authors.initials: S
authors.lastname: Li
authors.affiliation: 1 Department of Respiratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China ; 2 Department of Respiratory Medicine, Guangzhou Panyu Central Hospital, Guangzhou 511486, China.
authors.forename: Yu-Wen
authors.initials: YW
authors.lastname: Luo
authors.affiliation: 1 Department of Respiratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China ; 2 Department of Respiratory Medicine, Guangzhou Panyu Central Hospital, Guangzhou 511486, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Xiao
authors.affiliation: 1 Department of Respiratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China ; 2 Department of Respiratory Medicine, Guangzhou Panyu Central Hospital, Guangzhou 511486, China.
authors.forename: Yu-Xia
authors.initials: YX
authors.lastname: Huang
authors.affiliation: 1 Department of Respiratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China ; 2 Department of Respiratory Medicine, Guangzhou Panyu Central Hospital, Guangzhou 511486, China.
authors.forename: Jin-Lun
authors.initials: JL
authors.lastname: Huang
authors.affiliation: 1 Department of Respiratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China ; 2 Department of Respiratory Medicine, Guangzhou Panyu Central Hospital, Guangzhou 511486, China.
authors.forename: Yi-Tai
authors.initials: YT
authors.lastname: Chen
authors.affiliation: 1 Department of Respiratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China ; 2 Department of Respiratory Medicine, Guangzhou Panyu Central Hospital, Guangzhou 511486, China.
authors.forename: Rong-Chang
authors.initials: RC
authors.lastname: Zhi
authors.affiliation: 1 Department of Respiratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China ; 2 Department of Respiratory Medicine, Guangzhou Panyu Central Hospital, Guangzhou 511486, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
keywords: Chronic obstructive pulmonary disease (COPD); bronchodilator; neural respiratory drive (NRD); respiratory function tests