Assessment of Neural Inspiratory Time Through sEMG and EMGdi

The onset and offset of the neural inspiratory time are fundamentally important measurements in studies of patientventilator interaction, where the level of assistance delivered by the ventilator is controlled by the patient's demand. The onset of neural inspiratory time can be determined in esophageal pressure, transdiaphragmatic pressure, and EMG signals. The investigator compare the onset measured by EMG, esophageal and transdiaphragmatic pressure, and consider that the correlation between them is well in different conditions.

The onset and offset of the neural inspiratory time are fundamentally important measurements in studies of patien-tventilator interaction, where the level of assistance delivered by the ventilator is controlled by the patient's demand. Patient-ventilator asynchrony evaluated using the time lag between onset of the neural inspiratory time and the onset of a mechanical ventilation signal. The onset of neural inspiratory time can be determined in esophageal pressure, transdiaphragmatic pressure, and EMG signals. The investigator compare the onset measured by EMG, esophageal and transdiaphragmatic pressure, and consider that the correlation between them is well in three different conditions.

Firstly, increase the inspiratory threshold load step by step(30%-80%MIP),in order to increase neural respiratory drive. Secondly, do incremental cycle ergometry test with the assisstance of NPPV.

Firstly, increase the inspiratory threshold load step by step(30%-80%MIP),in order to increase neural respiratory drive. Secondly, do incremental cycle ergometry test with the assisstance of NPPV.

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 . And then, the healthy subjects will be increased the neural respiratory drive by increasing the pressure in a water-sealed inspiratory threshold loading device. At last, all subjects will do Incremental cycle ergometry test with the assisstance of NPPV.

Correlation between onsets and duration of measured from espphageal pressure, transdiaphragmatie pressure and EMG.

Inclusion Criteria: normal cardio-pulmonary function without low inspiratory muscle strength non-smoker without history of the nervous system and respiratory system disease sever to very severe stable stage Exclusion Criteria: systemic application of corticosteroids nearly 4 weeks