title: [Effects of inhaled short-acting bronchodilators on diaphragm function and neural respiratory drive during maximal isocapnic ventilation in patients with chronic obstructive pulmonary disease].
abstract: OBJECTIVE
  To investigate the effects of inhaled short-acting bronchodilators on diaphragm function and neural respiratory drive in patients with chronic obstructive pulmonary disease (COPD) during maximal isocapnic ventilation (MIV).
  
  
  METHODS
  Forty-seven patient with moderate to severe COPD were randomized into 4 groups: placebo group (n=12), salbutamol group (n=13), ipratropium group (n=10), and combined group (salbutamol and ipratropium, n=12). Each subject received an initial MIV for 3 min at baseline and inhaled placebo (400 µg), salbutamol (400 µg), ipratropium (80 µg), or both salbutamol and ipratropium, followed 30 min later by another 3 min of MIV. The parameters of diaphragm function and neural respiratory drive were monitored continuously and calculated during MIV.
  
  
  RESULTS
  During the initial MIV, all the patients experienced a linear increase in root mean square (RMS) of diaphragm electromyogram with a gradual decrease in transdiaphragmatic pressure (Pdi), minute ventilation (VE), and VE/RMS, and these parameters all improved significantly after inhalation of the bronchodilators. Compared with the placebo group at the same time point, the 3 bronchodilator-treated groups showed significantly decreased RMS and Borg score and increased Pdi, VE and VE/RMS; VE/RMS was the highest in the combined treatment group (P<0.05). The Delta Borg was significantly correlated with Delta Pdi, Delta VE, Delta RMS, and Delta VE/RMS (P<0.05).
  
  
  CONCLUSIONS
  In COPD patients, inhaled short-acting bronchodilators can alleviate diaphragm fatigue during MIV, increase lung ventilation, reduce neural respiratory drive, and improve neuro-ventilatory coupling to relieve dyspnoea, and the combination of β-2 agonists and anti-muscarinic antagonists produces a stronger efficacy.
authors.affiliation: Department of Respiratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China. E-mail: liyun.welcom@163.com.
authors.forename: Yun
authors.initials: Y
authors.lastname: Li
authors.forename: Yin-Huan
authors.initials: YH
authors.lastname: Li
authors.forename: Yu-Wen
authors.initials: YW
authors.lastname: Luo
authors.forename: Rui
authors.initials: R
authors.lastname: Xiao
authors.forename: Jin-Lun
authors.initials: JL
authors.lastname: Huang
authors.forename: Kai
authors.initials: K
authors.lastname: Wang
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
mesh_terms: D000280:Administration, Inhalation; D000420:Albuterol / Q000627:therapeutic use*; D001993:Bronchodilator Agents / Q000627:therapeutic use*; D003964:Diaphragm / Q000187:drug effects*; D006801:Humans; D009241:Ipratropium / Q000627:therapeutic use*; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy*; D012119:Respiration
chemical_list: D001993:Bronchodilator Agents; D009241:Ipratropium; D000420:Albuterol