Power in a wearable cardioverter defibrillator (WCD)
A wearable medical device comprising monitoring circuitry to monitor one or more patient parameters of a patient and defibrillation circuitry to provide one or more defibrillation shocks to the patient responsive to a control signal from the monitoring circuitry. The defibrillation circuitry comprises a defibrillation capacitor to provide energy for the one or more defibrillation shocks. The wearable medical device also comprises a power source to provide power to the monitoring circuitry and the defibrillation circuitry. The power source comprises a low current power source (LCPS) to provide power to the monitoring circuitry, and a high current power source (HCPS) to provide power to the defibrillation circuitry.
1. A wearable medical device, comprising:
monitoring circuitry to monitor one or more patient parameters of a patient;
defibrillation circuitry to provide one or more defibrillation shocks to the patient responsive to a control signal from the monitoring circuitry, wherein the defibrillation circuitry comprises a defibrillation capacitor to provide energy for the one or more defibrillation shocks; and
a power source to provide power to the monitoring circuitry and the defibrillation circuitry, wherein the power source comprises:
a low current power source (LCPS) configured to store a first electrical charge and to provide power to the monitoring circuitry; and
a high current power source (HCPS) configured to store a second electrical charge and to provide power to the defibrillation circuitry;
wherein:
the LCPS comprises a high impedance power source configured to provide a first output, and the HCPS comprises a low impedance power source configured to provide a second output that is separate from the first output;
the first output is coupled to the monitoring circuitry and the second output is not coupled to the monitoring circuitry; and
the second output is coupled to the defibrillation circuitry and the first output is not coupled to the defibrillation circuitry.
2. The wearable medical device of claim 1 , wherein:
the defibrillation circuitry has a higher current draw than the monitoring circuitry.
3. The wearable medical device of claim 1 , wherein:
the HCPS is configured to charge the defibrillation capacitor to a predetermined voltage within a predetermined time.
4. The wearable medical device of claim 1 , wherein:
the LCPS comprises a battery; and
the HCPS comprises a supercapacitor.
5. The wearable medical device of claim 1 , wherein:
the LCPS comprises a first battery; and
the HCPS comprises a second battery that is a different type of battery than the first battery.
6. The wearable medical device of claim 1 , further comprising an HCPS charging circuit, wherein the LCPS is configured to top off the HCPS via the HCPS charging circuit to accommodate charge loss in the HCPS.
7. The wearable medical device of claim 1 , further comprising:
an HCPS charging circuit;
wherein:
the HCPS charging circuit is configured to charge the defibrillation capacitor to provide energy to the defibrillation capacitor for the one or more defibrillation shocks; and
the LCPS is configured to recharge the HCPS via the HCPS charging circuit after the HCPS has charged the defibrillation capacitor.
8. The wearable medical device of claim 7 , wherein:
the HCPS is configured to provide power to one or more high-current draw loads in addition to the defibrillation capacitor; and
the one or more high-current draw loads include a fluid deployment mechanism, a gel deployment mechanism, a squib, a communication link, or a positioning location system.
9. The wearable medical device of claim 1 , wherein:
the HCPS is configured to provide power to the monitoring circuitry when charge in the LCPS is below a threshold level.
10. A wearable cardioverter defibrillator (WCD) system, comprising:
a support structure to be worn by a patient including a plurality of electrodes to contact the patient's skin;
monitoring circuitry comprising a processor to monitor an electrocardiogram (ECG) signal of the patient obtained via the plurality of electrodes;
defibrillation circuitry comprising a defibrillation capacitor to provide energy for one or more defibrillation shocks, wherein the defibrillation circuitry is configured to provide the one or more defibrillation shocks to the patient via two of the plurality of electrodes;
a low current power source (LCPS) configured to store a first electrical charge and to provide a low current, high impedance power output to power the monitoring circuitry; and
a high current power source (HCPS) configured to store a second electrical charge and to provide a high current, low impedance power output to the defibrillation circuitry;
wherein:
the LCPS is configured to provide a first output and the HCPS is configured to provide a second output that is separate from the first output;
the first output is coupled to the monitoring circuitry and the second output is not coupled to the monitoring circuitry; and
the second output is coupled to the defibrillation circuitry and the first output is not coupled to the defibrillation circuitry; and
wherein the processor is configured to:
determine whether a shockable event has occurred in the patient based at least in part in the ECG signal; and
send a control signal to the defibrillation circuitry to cause the HCPS to charge the defibrillation capacitor in response to the shockable event.
11. The WCD system of claim 10 , wherein:
the LCPS comprises a battery; and
the HCPS comprises a supercapacitor.
12. The WCD system of claim 10 , wherein:
the LCPS comprises a first battery; and
the HCPS comprises a second battery that is a different type of battery than the first battery.
13. The WCD system of claim 10 , wherein:
the LCPS and the HCPS are contained within a same housing, wherein the housing comprises a removable pack.
14. The WCD system of claim 10 , wherein:
the LCPS is contained within a housing that comprises a removable pack that does not contain the HCPS.
15. The WCD system of claim 10 , further comprising:
a first charger circuit configured to charge the LCPS; and
a second charger circuit configured to charge the HCPS.
16. The WCD system of claim 10 , wherein:
the LCPS is configured to recharge the HCPS via an HCPS charging circuit after the HCPS charges the defibrillation capacitor.
17. The WCD system of claim 10 , wherein:
the LCPS is configured to provide a maintenance charge to the HCPS via an HCPS charging circuit to offset charge loss in the HCPS.
18. The WCD system of claim 10 , wherein:
the HCPS is configured to provide power to one or more high-current draw loads in addition to the defibrillation circuitry; and
the one or more high-current draw loads include a fluid deployment mechanism, a gel deployment mechanism, a squib, a communication link, or a positioning location system.
19. The WCD system of claim 10 , wherein:
the HCPS is configured to charge the defibrillation capacitor to a capacity sufficient to provide a plurality of shocks to the patient from a single charge from the HCPS.