Wearable cardioverter defibrillator (WCD) system with isolated patient parameter component
Embodiments are directed to wearable cardioverter defibrillator (WCD) systems that include patient parameter electrodes, such as ECG electrodes, that are at least substantially electrically isolated from other circuits of the WCD system. In embodiments, the WCD system includes a power source, an energy storage module, and a processor each connected to a first circuit ground. A patient parameter sense port, such as an ECG port, is coupled to the patient. A measurement circuit may render a physiological input from the sensed patient parameter received at the patient parameter sense port, and the measurement circuit includes an isolating circuit that electrically isolates the patient parameter sense port from the first circuit ground. The sensing of physiological inputs of the patient can be improved, resulting in fewer erroneous readings and false alarms.
1. A wearable cardioverter defibrillator (WCD) system, comprising:
a support structure configured to be worn by a patient;
a patient parameter sense port;
Electrocardiogram (ECG) electrodes configured to be coupled to the patient parameter sense port and to sense an ECG signal of the patient;
a first circuit ground;
a second circuit ground electrically isolated from the first circuit ground;
a power source connected to the first circuit ground;
an energy storage module electrically connected to the first circuit ground and configured to be charged from the power source so as to store an electrical charge;
a discharge circuit electrically coupled to the energy storage module;
a measurement circuit configured to render ECG data from the ECG signal received at the patient parameter sense port as sensed by the ECG electrodes, the measurement circuit including an isolating circuit directly coupled to both the first circuit ground and to the second circuit ground, the isolating circuit configured to electrically isolate the patient parameter sense port from the first circuit ground; and
a processor electrically connected to the first circuit ground, operatively coupled to the measurement circuit, and configured to:
determine from the ECG data whether or not a shock criterion is met, and
control the discharge circuit to discharge the stored electrical charge through the patient while the support structure is worn by the patient responsive to the shock criterion being met.
2. The WCD system of claim 1 , in which
the measurement circuit further includes an ECG acquisition circuit operatively coupled to the patient parameter sense port and to the isolating circuit, the ECG acquisition circuit being configured to detect the sensed ECG signal.
3. The WCD system of claim 2 , in which
the isolating circuit includes an isolated digital data coupler configured to output a first digital signal representative of the ECG signal detected by the ECG acquisition circuit, and
the processor is coupled to receive the first digital signal.
4. The WCD system of claim 3 , in which
the processor is further configured to generate a second digital signal,
the isolated digital data coupler is configured to receive the second digital signal and to output a version of the second digital signal responsive thereto, and
the ECG acquisition circuit is coupled to receive the version of the second digital signal.
5. The WCD system of claim 3 , in which
the isolating circuit further includes an isolated power supply configured to transfer power from the power source to the ECG acquisition circuit.
6. The WCD system of claim 2 , in which
the isolating circuit includes an isolating signal coupler configured to receive the sensed ECG signal, and
the ECG acquisition circuit is coupled to receive the sensed ECG signal from the isolating signal coupler.
7. The WCD system of claim 2 , in which
the ECG acquisition circuit operatively couples the isolating circuit to the patient parameter sense port, and
the ECG acquisition circuit is connected to the second circuit ground.
8. The WCD system of claim 1 , in which
the isolating circuit includes an isolation barrier electrically isolating the patient parameter sense port from the first circuit ground with at least 100 volts of protection across the isolation barrier.
9. The WCD system of claim 1 , in which the isolating circuit includes:
an isolated circuit portion that is connected to the second circuit ground and configured to generate a signal representative of the ECG data,
a non-isolated circuit portion connected to the first circuit ground, and
an isolating signal coupler configured to couple the generated signal to the non-isolated circuit portion.
10. The WCD system of claim 9 , in which
the isolating circuit further includes an isolated power supply configured to transfer power from the power source to the isolated circuit portion of the isolating circuit.
11. The WCD system of claim 10 , in which
the isolated power supply includes an isolation transformer having
a first winding coupled to the first circuit ground and
a second winding isolated from the first winding and coupled to the second circuit ground.