Research Of Key Technology Of Ventilator Based On EMGdi

Mechanical ventilation is an important measure in the rescue of patients with respiratoryfailure, and the patient-ventilator synchronization is the necessary conditions of ventilationeffect. The ventilator is still failed to solve the problem of patient-ventilator synchronizationthoroughly, mainly due to the change of flow or pressure which is used to trigger theventilator that can be easily interfered by the patient’s lung lesion and the airway resistance.Therefore it’s necessary to find a better mode in order to improve the patient-ventilatorsynchronization and enhance the clinical effects.Diaphragmatic Electromyographic(EMGdi) signals is a weak biological signal generatedfrom the diaphragmatic during respiration. It appears earlier than the change of both airwaypressure and flow. It reflects inspiratory and expiratory time and respiratory effort of therespiratory center. Besides, it is not affected by the lung disease and airway resistance.Therefore, using EMGdi to trigger the ventilator can gain a good patient-ventilatorsynchronization.Surface electromyographic(EMG) signals are comprehensive results at time and space ofskin surface from electrical activity of muscle under epidermis, the paper will study andanalysis surface EMG, design a EMGdi measuring system based on the surface electrodes.Using the kind of convenient medical electrodes, the system detects the surface EMGdi fromskin to amplify and filter， and selects AD620to overcome the common-modeinterference(CMRR). Besides, using high-low filter and50Hz notch filter to respectivelyeliminate the polarization voltage, high-frequency noise and50Hz power frequencydisturbance. It uses mathematical morphological method to eliminate the electrocardiosignal(ECG) interference. Furthermore, seeking the root mean square value to estimate the strengthof EMGdi, it can be the basis of trigger and auxiliary support of the ventilator. Finally theexperimental results verify the effectiveness of the system.