Analyse the Correlation Between sEMG and EMGdi
Condition: COPD
Study type: Interventional

Summary: 
      The most significant pathophysiology change of COPD patients is persistent incompletely
      reversible airflow obstruction and increased lung volume. As a result, the work of
      breathing(WB) and neural respiratory drive (NRD)increased. Noninvasive positive pressure
      ventilation (NPPV) can reduce the load of respiratory muscles. Detection of NRD can be the
      index of monitoring for titration of optimal level of ventilator support in the future. As
      electromyography(EMG) is the most reliable measurement in evaluating NRD that can be used for
      human. Currently the standard method for evaluation of NRD with EMG is using esophageal
      multi-paired electrodes catheter(EMGdi) ,it is reliable but invasive .Surface respiratory EMG
      (sEMG）is a noninvasive measurement. Although it subjected to contamination and less
      sensitive, recently, advance in technology with multiple pair of surface electrodes is
      possible to sufficient signals for evaluation of NRD.So the investigator compare the NRD
      measured by EMGdi and sEMG,and consider that the correlation between them is well in
      different levels.
    

Detailed description: 
      The most significant pathophysiology change of COPD patients is persistent incompletely
      reversible airflow obstruction and increased lung volume. As a result, the work of breathing
      (WB) and neural respiratory drive (NRD) increased. Noninvasive positive pressure ventilation
      (NPPV) is the first-line treatment in acute exacerbation of COPD (AECOPD). One of the
      mechanisms is to reduce the load of respiratory muscles. It has been reported that NRD
      decreased in response to increase of pressure support. Detection of NRD can be the index of
      monitoring for titration of optimal level of ventilator support in the future.

      NRD can be measured with minute ventilation, inspiratory pressure change、mean inspiration
      flow and electromyography(EMG) of inspiratory muscles. However, the first three methods are
      subjected to the influenced of lung volume, airway resistance and compliance of respiratory
      system. So, electromyography is the most reliable measurement in evaluating NRD that can be
      used for human. Currently the standard method for evaluation of NRD with EMG is using
      esophageal multi-paired electrodes catheter ,since it is far away from chest wall and close
      to diaphragm , so the contamination from other respiratory muscles can be reduced .However,
      catheter placement into esophagus is necessary for this measurement, which limits its use in
      daily practice. Surface respiratory EMG is a noninvasive measurement. Although it subjected
      to contamination and less sensitive, recent advance in technology with multiple pair of
      surface electrodes, including surface diaphragm EMG、parasternal EMG and so on, it is possible
      to sufficient signals for evaluation of NRD. It has been the hot topics of research recently
      due to its noninvasive, easiness of use and appropriate for continuing monitor.

      Purpose：

        1. To explore the feasibility of surface respiratory electromyography and its correlation
           with esophageal EMG in conditions of different level of respiratory central drive.

        2. To investigate the dynamic change esophageal EMG and surface EMG in response to increase
           of pressure support level during noninvasive ventilation, in order to evaluate the
           feasibility of using surface EMG for titration of pressure support during noninvasive
           ventilation.

      Methodology:

        1. Electromyography: Multi-paired electrodes esophageal catheter was used for detection of
           esophageal diaphragm electromyography (EMGdi); Surface electrodes for left and right
           diaphragm and parasternal muscle were used to detect surface electromyography (sEMG).

        2. Monitoring of respiratory physiology parameters: Pneumotachometer and differential
           pressure transducer were used for measurement of respiratory flow and pressures. lung
           volume change was calculated with integration of flow.

        3. Regulate neural respiratory drive:1.in normal volunteer,increase the inspiratory
           threshold load step by step(30%-80%MIP),in order to increase neural respiratory
           drive;2.in sever COPD patients,increase the pressure support ventilation step by step,
           in order to decrease neural respiratory drive.

        4. Methods for adjustment of respiratory central drive: (1) The increase of respiratory
           central drive was induced by inspiratory threshold load step by step (30%-80%MIP) in
           normal volunteer. (2) The reduction of respiratory central drive was induced by stepwise
           increase of pressure support level with noninvasive ventilation in COPD patients.

      Analysis and statistics:

        1. The correlation between sEMG and EMGdi at different level of respiratory central drive
           was analyzed with Pearson correlation analysis. The change of Ventilation central drive
           coupling was calculated.

        2. In COPD patients, the change of respiratory central drive in response to increase of
           pressure support level (IPAP increase from 8cmH2O to 20cmH2O) during NPPV was evaluated.

        3. The feasibility using sEMG as guidance for adjustment of pressure support level during
           NPPV was analyzed.
    

Intervention name(s): inspiratory threshold load device and NPPV
Intervention type(s): Device
Intervention description(s): before experiment ,every subject use a flanged mouthpiece attached to a manually operated occlusion valve in order to measure maximal inspiratory pressure (MIP)at functional residual capacity .
healthy subjects:increase the pressure in a water-sealed inspiratory threshold loading device in order to increase the neural respiratory drive.
COPD patients:increase the pressure in a non-invasive positive pressure ventilation in order to decrease the neural respiratory drive
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Outcomes Assessor)
Primary purpose: Other
Keywords: neural respiratory drive; noninvasive positive pressure ventilation; electromyography