Watchdog timer for automated external defibrillator

• US 5,919,212 A
• Filed: 11/26/1997
• Issued: 07/06/1999
• Est. Priority Date: 08/08/1995
• Status: Expired due to Term

• Current Assignee: Cardiac Science Operating Company (Cardica Incorporated)
• Original Assignee: SurVivaLink Corporation (Cardica Incorporated)
• Inventors: Anderson, Katherine H., Gilman, Byron L., Olson, Kenneth F.
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): LAYNO, CARL HERNANDZ
• Application Number:
  US08/978,908
• Time in Patent Office: 587 Days
• Field of Search: 607/5
• US Class Current: 607/5
• CPC Class Codes: A61N 1/3904 External heart defibrillators [EHD]
• CPC Class Codes: A61N 1/3931 Protecting, e.g. back-up systems

Abstract

An automated external defibrillator automatically performs periodic self-tests on a daily and weekly basis. Self-test failures are identified by a watchdog timer which is reset upon activation of each periodic self-test. If the watchdog timer times out a maintenance indication is activated. The timeout period of the watchdog timer is non-repeating and non-periodic (typically 30 hrs.). Tested functions include the presence and interconnection of defibrillator electrodes, battery charge state, and the operability of the high voltage circuit. Visual and audible indicators are actuated to alert an operator if faults are identified. A record of each self-test is stored in memory, and can be subsequently retrieved through a communications port.

Claims

1. An automated external defibrillator comprising:

an electrical control and shock-delivering system including self test means for performing a self test of the electrical control and shock-delivering system;

means for activating the self test means on a repeating periodic first predetermined time interval; and

means for identifying and indicating a fault in the defibrillator in response to nonactivation of the self test means after passage of a nonrepeating nonperiodic second predetermined time limit greater than the first predetermined time interval.

2. The defibrillator of claim 1 wherein the activating means further comprises a real time clock for implementing the first predetermined time interval on a real time basis.

3. The defibrillator of claim 1 wherein the identifying and indicator means further comprises a maintenance indicator and a watchdog timer for implementing the second predetermined time interval on a real time basis.

4. A method of insuring readiness of an automated external defibrillator comprising:

performing a defibrillator self test of an automated external defibrillator at a repeating periodic first predetermined time interval; and

indicating a fault in response to nonperformance of the repeating periodic self test after passage of a nonrepeating nonperiodic second predetermined time limit greater than the first predetermined time interval.

5. The method of claim 4 wherein the repeating periodic self test includes testing at least one of an electrode, a battery, a real time clock, an A/D converter, a program memory, a data memory, and an event memory of the automated external defibrillator.

6. The method of claim 4 wherein the triggering step is performed by using a watchdog timer electrically connected to a power supply independent of a circuit that performs the repeating periodic self test.

7. An automated external defibrillator comprising:

self initiating means for periodically and automatically initiating defibrillator self tests at a repeating periodic first predetermined time interval; and

means for determining and indicating a fault in the defibrillator upon nonperformance of the self initiating means after passage of a nonrepeating nonperiodic second predetermined time limit greater than the first predetermined time interval.

8. An automated external defibrillator comprising:

an electrical control system;

self test means for testing the electrical control system electrically connected to the control system;

a real time clock electrically connected to the control system for automatically activating the self test means at a repeating periodic first predetermined time interval;

a watchdog timer for identifying a fault in the real time clock in response to nonactivation of the self test means after passage of a non repeating predetermined time limit greater than the first predetermined time interval; and

a fault indicator electrically connected to the watchdog timer.

9. An automated external defibrillator comprising:

an electrical control and shock-delivering system capable of performing a self test to determine operability of the electrical control and shock-delivering system, the system including a microprocessor capable of initiating and controlling the self test;

a real time clock electrically connected to the microprocessor of the control and shock delivering system to provide a real time basis for the microprocessor to initiate the self test of the control and shock delivering system on a repeating periodic first predetermined real time interval;

a watchdog timer electrically connected to the control and shock delivering system capable of monitoring a nonrepeating nonperiodic second predetermined time limit greater than the first predetermined real time interval; and

a fault indicator electrically connected to the watchdog timer and capable of indicating a fault upon the watchdog timer identifying the passage of time equal to the second predetermined time limit.

10. An automated external defibrillator comprising:

an electrical control and shock-delivering system including self test means for performing a self test of the electrical control and shock-delivering system;

means for activating the self test means on a repeating periodic first predetermined time interval; and

means for identifying and indicating a fault in the defibrillator in response to nonactivation of the self test means, the identifying means being electrically connected to a power supply circuit of the defibrillator independently of an electrical connection between the activating means and the power supply circuit.

11. A method of insuring readiness of an automated external defibrillator comprising:

performing a repeating periodic defibrillator self test of an automated external defibrillator at a first predetermined time interval;

indicating a fault in response to nonperformance of the repeating periodic self test;

triggering the fault indication upon passage of a nonrepeating second predetermined time interval greater than the first predetermined interval by using a watchdog timer electrically connected to a power supply independent of a circuit that performs the repeating periodic self test.

12. A method of insuring readiness of an automated external defibrillator comprising:

performing a repeating periodic defibrillator self test of an automated external defibrillator at a first predetermined time interval of twenty four hours;

indicating a fault in response to nonperformance of the repeating periodic self test; and

triggering the fault indication upon passage of a nonrepeating second predetermined time interval of about thirty hours.

13. An automated external defibrillator comprising:

an electrical control system;

self test means for testing the electrical control system electrically connected to the control system;

a power supply circuit;

a real time clock electrically connected to the control system for automatically and periodically activating the self test means at a first predetermined real time interval and being electrically connected to the power supply circuit;

a watchdog timer electrically connected to the control system for identifying a fault in the control system in response to nonactivation of the self test means at the first predetermined real time interval and electrically connected to the power supply circuit independently of the electrical connection between the real time clock and the power supply circuit; and

a fault indicator electrically connected to the watchdog timer.

14. An automated external defibrillator comprising:

an electrical control and shock-delivering system capable of performing a self test to determine operability of the electrical control and shock-delivering system, the system including a microprocessor capable of initiating and controlling the self test and including a power supply circuit connected to the microprocessor;

a real time clock electrically connected to the microprocessor and the power control circuit of the control and shock delivering system to provide a real time basis for the microprocessor to initiate the self test of the control and shock delivering system on a repeating first predetermined real time interval;

a watchdog timer electrically connected to the control and shock delivering system capable of monitoring a nonrepeating second predetermined time limit greater than the first predetermined real time interval and being electrically connected to the power supply circuit independently of the electrical connection between the real time clock, the microprocessor and the power supply circuit; and

a fault indicator electrically connected to the watchdog timer and capable of indicating a fault upon the watchdog timer identifying the passage of time equal to the second predetermined real time limit.