Electrotherapy device performs impedance measurement on patient to determine initial charge level on capacitor

摘要

Electrotherapy device performs a low level impedance measurement on the patient to determine the initial charge level on a capacitor which is used to deliver an electrotherapy waveform to the patient. The waveform is dynamically controlled to compensate for patient impedance variability. The apparatus includes a device for measuring the low level patient impedance. A voltage is outputted to a controller for determining the initial charge level of the capacitor. Four switches deliver a biphasic waveform to the patient and a comparator coupled to a timer monitors the voltage across the capacitor and controls the termination or extension of the waveform applied to the patient. Alternatively the patient impedance is determined based on parameters measured from the application of the electrotherapy waveform and used to correct the low level impedance measurement.