Efficacy and Mechanism of NIV in Relieving Dyspnea After Exercise in Patients With Stable Severe COPD
Condition: Chronic Obstructive Pulmonary Disease; Dyspnea
MeSH terms: Lung Diseases; Lung Diseases, Obstructive; Pulmonary Disease, Chronic Obstructive; Dyspnea
Study type: Interventional

Summary: 
      Exertional dyspnea is a major cause of exercise limitation and anxiety, and contributes
      importantly to reduced quality of life for patients with COPD. The aim of this study is to
      determine the efficacy and mechanism of NIV with a dual-limb circuit plus oxygen therapy in
      relieving exertional dyspnea in patients with severe COPD, so as to provide a guidance for
      clinical use for NIV.
    

Detailed description: 
      Exertional dyspnea was the most characteristic respiratory symptoms in patients with chronic
      obstructive pulmonary disease (COPD), it is a major cause of exercise limitation and anxiety,
      and contributes importantly to reduced quality of life for patients with COPD. COPD patients
      often unconsciously adopt a sedentary lifestyle, probably due to distressing exertional
      dyspnea. The sedentarism results in physical deconditioning and alterations of the peripheral
      muscles, which leads to a vicious circle and contribute to the debilitation of the patients.
      Thereby, intervention should be taken to intervene this vicious cycle. It has been reported
      that noninvasive ventilation (NIV) could help unload the inspiratory muscle, improve dynamic
      pulmonary hyperinflation, improve neuro-mechanical coupling, oxygenation, and thus relieved
      dyspnea during exercise in COPD patients. However, in these reports, NIV was used as add-on
      therapy during exercise or at resting condition before exertional dyspnea occurred. So far,
      there's few studies on the efficacy of NIV used at the time of exertional dyspnea occurred as
      the rescue therapy to relieve dyspnea after exercise in patients with stable severe COPD
      while the patients are already undergoing optimal treatment with bronchodilator and
      anti-inflammatory medication, which might relieve their physiological and perceptional burden
      to limit their activities. The result of the investigators previous study has suggested that
      compared with oxygen therapy, NIV plus oxygen therapy resulted in decrease in dyspnea
      intensity at isotime, however, there's no statistically significant shortening in total
      dyspnea recovery time and NIV was not helpful in all the COPD patients. In another study, it
      was indicated that ventilated by a single-limb tubing with a plateau exhalation valve (PEV)
      caused CO2 rebreathing to COPD patients during exercise. CO2 rebreathing may have a negative
      impact on efficacy. Previous studies have proved that exercise tolerance was improved
      ventilated by noninvasive ventilation with a dual-limb circuit. In theory, NIV with a
      dual-limb circuit consists of one inhalation limb that introduces air into the patient's
      airways and one exhalation limb that leads exhaled gas outside of the airways, there is no
      risk of rebreathing. However, it is unclear whether NIV with a dual-limb circuit could be
      used at the time of exertional dyspnea occurred as rescue therapy to relieve dyspnea after
      exercise in patients with stable severe COPD and what are the mechanisms. The purpose of this
      study was therefore to determine whether assisted with NIV with dual-limb circuit in patients
      with stable severe COPD after exercise with exertional dyspnea (1)dyspnea was relieved after
      exercise in patients with stable severe COPD; (2)the repiratory mechanism.
    

Intervention name(s): noninvasive ventilation; oxygen therapy
Intervention type(s): Device; Device
Intervention description(s): dual-limb circuit NIV were given on maquet servo i apparatus; oxygen therapy were introduced to the side port of the facemask
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: None (Open Label)
Primary purpose: Treatment