US 6,208,898 B1 · Impedance estimation with dynamic waveform control in an electrotherapy apparatus

Abstract

An electrotherapy apparatus performs a low level impedance measurement upon the patient to determine the initial charge level on the capacitor used to deliver an electrotherapy waveform to the patient. In addition, the waveform applied to the patient is dynamically controlled to compensate for patient impedance variability. Determining the initial charge level in this manner prevents unnecessarily high peak currents from flowing in low impedance patients while maintaining peak current in high impedance patients at therapeutically beneficial levels. The electrotherapy apparatus includes a measuring device used for measuring a parameter related to the impedance of the patient. The parameter is used for determining low level patient impedance. The measuring device provides a voltage output used by a controller for determining the initial charge level of the capacitor. A first embodiment of a first electrotherapy apparatus includes four electronic switches to deliver a bi-phasic waveform to the patient. The first embodiment of the first electrotherapy apparatus further includes a comparator coupled to a timer to monitor the voltage across the capacitor and control the termination or extension of the waveform applied to the patient. A first embodiment of a second electrotherapy apparatus measures the charge delivered to the patient and sets the time of the first phase of the bi-phasic pulse based upon the time required to deliver a predetermined amount of charge to the patient.

Claims34

Dependent claims

In an electrotherapy apparatus including an energy source, a method for applying electrotherapy to a patient, comprising:

measuring a first parameter relating to an impedance of the patient;
configuring the energy source based upon the first parameter;
coupling the energy source to the patient;
measuring a third parameter related to energy delivered to the patient by the energy source;
and
decoupling the energy source from the patient based upon the third parameter.

3 more elements

An electrotherapy apparatus for performing electrotherapy on a patient through a first electrode and a second electrode, comprising:

an energy source to deliver energy to the patient through the first electrode and the second electrode;
a sensor configured to measure a first parameter related to the energy delivered to the patient;
a first connecting mechanism configured to couple and decouple the energy source to and from, respectively, the first electrode and the second electrode;
a measuring device configured to measure a second parameter that varies with patient impedance through the first electrode and the second electrode;
and
a controller coupled to the first connecting mechanism and the energy source, and arranged to receive the first parameter from the sensor, with the controller configured to actuate the first connecting mechanism to couple the energy source to the first electrode and the second electrode and configured to actuate the first connecting mechanism to decouple the energy source from the first electrode and the second electrode based upon the first parameter, and with the controller arranged to receive the second parameter from the measuring device to configure the energy source based upon the second parameter.

3 more elements

A defibrillator for delivering a multi-phasic waveform through a first electrode and a second electrode to a patient for defibrillation, comprising:

a capacitor for storing charge for delivery to the patient through the first electrode and the second electrode with the capacitor having a first terminal and a second terminal;
a power supply for charging the capacitor;
a first connecting mechanism coupled between the first terminal and the second terminal of the capacitor and the first electrode and the second electrode to permit the first terminal of the capacitor to couple and decouple to and from one of the first electrode and the second electrode and to permit the second terminal of the capacitor to couple and decouple to and from one of the first electrode and the second electrode;
and
a sensor for measuring a first parameter related to the energy supplied by the capacitor;
a circuit to measure a second parameter that varies with patient impedance, with the circuit configured for measuring the second parameter through the first electrode and the second electrode;
and
a controller coupled to the first connecting mechanism and arranged to receive the first parameter, with the controller configured to actuate the first connecting mechanism to decouple the first terminal and the second terminal of the capacitor from the first electrode and the second electrode based upon the first parameter, with the controller arranged to receive the second parameter from the measuring device and to configure the power supply for charging the capacitor based upon the second parameter.

5 more elements

Dependencies are inferred from the claim text.

Impedance estimation with dynamic waveform control in an electrotherapy apparatus

Life of this patent

Impedance estimation with dynamic waveform control in an electrotherapy apparatus

Life of this patent

Abstract

Claims34