Comparative Effects of Different Noninvasive Ventilation Mode on Neural Respiratory Drive in Recovering AECOPD Patients

• change of the Neural respiratory drive [ Time Frame: 15-20 minute ] [ Designated as safety issue: Yes ]
  In recent studies, The efficiency of neural respiratory drive(NRD) as expressed as a ratio of minute ventilation to diaphragm electromyogram (EMGdi) in patients with COPD is lower than that in healthy subject, suggesting that, to achieve the same minute ventilatory volume, a higher neural drive is required for patients with COPD than for healthy individuals.Furthermore,levels of neural respiratory drive were related to disease severity and dyspnea.Improving the neural respiratory drive efficiency of COPD will help to relieve the clinical symptom and make the patients feel comfort. Because dyspnea relates to respiratory effort.Neural respiratory drive(NRD) and its efficiency as expressed by a ratio of ventilation to the diaphragm electromyogram(EMGdi)may be a good tool to evaluate treatment benefits in Patients with COPD.This study want to investigate the effect of noninvasive positive pressure ventilation(NPPV)on the Neural respiratory drive of COPD patients
  
  

• change of the pressure-time product(PTP) [ Time Frame: 15-20 minute ] [ Designated as safety issue: Yes ]
  The pressure-time product(PTP)means inspiratory effort of the inspiratory muscle In COPD lung mechanical abnormality including airflow obstruction and dynamic hyperinflation and intrinsic positive end-expiratory pressure increase the work load of the respiratory muscles,which will lead to higher inspiratory work. As a result,The efficiency of neural respiratory drive as expressed as a ratio of minute ventilation to diaphragm electromyogram (EMGdi) in patients with COPD is lower than that in healthy subject.This study want to investigate the effect of noninvasive positive pressure ventilation(NPPV)on the inspiratory muscle load of the COPD patients
  
  

Methods: After the baseline data of spontaneous breathing was collected, 13 hypercapnic recovering AECOPD patients were placed on different mode of noninvasive positive pressure ventilation(NPPV, such as the PAV or PSV mode) randomly. For each mode, three levels (PA-, PA, PA+or PS-, PS, PS+), ) of support were applied.PS and PA are set for the patient's comfort . On the basis of these two levels, 25% increase and reduction assisted level of pressure were set both for PS and PA (PA-, PA+or PS-, PS+). At each level, the patients were ventilated at least 20 minutes until the breathing was stable. The respiratory frequency (RR), tidal volume (VT), transdiaphragmatic pressure (pdi) the pressure-time product (PTP) and root-mean-square(RMS) of EMGdi were calculated. Esophageal and gastric balloon－catheters were used to detect the intra-thoracic and abdominal pressure. Airway pressure was also measured simultaneously. EMGdi was recorded from a multipair esophageal electrode .During ventilation Airflow and ventilation were measured with pneumotachograph.