The Respiratory Physiology Variation of COPD Patients in Inspiratory Muscle Training
Condition: Chronic Obstructive Pulmonary Disease
MeSH terms: Lung Diseases, Obstructive; Pulmonary Disease, Chronic Obstructive
Study type: Interventional
Phase: Phase 2/Phase 3

Summary: 
      Background：Respiratory muscle weakness is observed in chronic obstructive pulmonary
      disease(COPD) patients and contributes to hypercapnia, dyspnoea, nocturnal oxygen
      desaturation and reduced walking distance.During exercise it has been shown that diaphragm
      work is increased in COPD and COPD patients use a larger proportion of the maximal
      inspiratory pressure (MIP) than healthy subjects. This pattern of breathing is closely
      related to the dyspnoea sensation during exercise and might potentially induce respiratory
      muscle fatigue. Inspiratory muscle training(IMT) increases inspiratory muscle strength and
      endurance, and decreases dyspnoea.But the mechanism of IMT still lack of research.

      Purpose：The experiment is aim to compare of the similarities and differences of
      transdiaphragmatic pressure by detecting the transdiaphragmatic pressure of COPD patients and
      healthy volunteers in different intensity of threshold load conditions. Thus investigate how
      inspiratory muscle training works or mechanism in lung rehabilitation programmes of COPD.And
      emerging the theoretical basis of inspiratory muscle training from respiratory physiological
      mechanism.
    

Detailed description: 
      Subjects:

      COPD group ( experimental group ) Ten subjects with moderate COPD were will be recruited from
      the investigators outpatient clinic for the study. According to the criteria of the American
      Thoracic Society (ATS), COPD is defined as postbronchodilator forced expiratory volume in 1
      second (FEV1) of 30% to 79% of the predicted value and a ratio of FEV1 to forced vital
      capacity (FVC) ,70%.

      Inclusion criteria:(1)Severe and very severe COPD (postbronchodilator FEV1/FVC under 70% and
      FEV1 under 50% of the predicted value;(2)Inspiratory muscle weakness（Maximal Inspiratory
      Pressure under 60cmH2O（centimeter water column）.(3) bronchial dilation test(BDT) negative.(4)
      Exclusion of other cardiopulmonary diseases.

      Exclusion criterion:(1)Suffer from acute exacerbation less than 4 weeks.(2) Intravenous or
      oral corticosteroids in 4 weeks.(3) With other heart, lung and brain disorders.(4) With poor
      compliance.

      Healthy volunteers group (control group ) Inclusion criteria:(1) Normal lung
      function(FEV1/FVC above 70% and FEV1 above 50% of the predicted value); (2)Without
      inspiratory muscle weakness（Maximal Inspiratory Pressure above 60cmH2O）(3) without nervous
      system and respiratory diseases.

      Experimental methods : prospective randomized controlled trial（RCT）

        1. record the information of the subjects: sexuality, age ( years ), height ( cm), weight (
           kg ), BMI ;

        2. Pulmonary function tests:forced expiratory volume in 1 second（FEV1）, FEV1 of the
           predicted value (FEV1/Pred%), forced vital capacity (FVC), FVC of the predicted value
           (FVC/Pred%), a ratio of FEV1 to forced vital capacity (FEV1/FVC%).

        3. Synchronous record:mouth pressure ( Pm ), esophageal pressure ( Peso ), intragastric
           pressure ( Pgas ),transdiaphragmatic pressure ( Pdi ), flow ( flow ), tidal volume (
           volume ), Five lead diaphragmatic electromyography of the esophagus ( electromyography
           diaphragm （EMGdi1, EMGdi2, EMGdi3, EMGdi4, EMGdi5 )）.

        4. Measure the maximal inspiratory pressure, records of maximum transdiaphragmatic pressure
           and maximum diaphragmatic electromyography simultaneously.

      Subjects suffer from different level of threshold load generated by threshold loading device.
      Detecting the pressure and electrical while adjust the load to 30%,40%,50%,60%,70%,80% of the
      MIP respectively. The change from baseline in transdiaphragmatic pressure will be detect in
      each level of load.
    

Intervention name(s): Threshold IMT®
Intervention type(s): Device
Intervention description(s): A device used to offer threshold load to inspiratory muscle
Other intervention name(s): threshold inspiratory muscle trainer
Allocation: Randomized
Intervention model: Single Group Assignment
Masking: Single (Participant)
Primary purpose: Treatment