Hazard mitigation in medical device

• US 7,356,740 B2
• Filed: 10/17/2005
• Issued: 04/08/2008
• Est. Priority Date: 01/23/2002
• Status: Expired due to Term

• Current Assignee: Physio-Control Incorporated (Stryker Corporation)
• Original Assignee: Medtronic Physio-Control Corp. (Medtronic Plc)
• Inventors: Kelly, Patrick F., Neumiller, James S., DeBardi, Gary A.
• Primary Examiner(s): Iqbal; Nadeem
• Application Number:
  US11/251,716
• Publication Number:
  US 20060036914A1
• Time in Patent Office: 904 Days
• Field of Search: 714/23, 714/55, 714/56, 714/57, 714/48, 714/32, 607/4, 607/5, 607/148
• US Class Current: 714/55
• CPC Class Codes: H04L 1/22 using redundant apparatus to increase reliability

Abstract

Delivery of energy by a defibrillator or other medical device is inhibited when the processor or software that controls a module of the medical device operates abnormally. A windowed watchdog timer (WWDT) incorporated into one module of the medical device is used to control the operation of other modules of the medical device via a software-based extension technique. As a result, the risk of harm to the patient is reduced compared to medical devices that incorporate over-limit type watchdog timers. In addition, costs associated with implementing WWDTs in multiple modules of the defibrillator are avoided, thereby lowering the overall cost of implementation.

Claims

1. A method comprising:

generating a handshake signal in a first processor of a first functional module of a medical device;

providing the handshake signal to a watchdog timer software process in a second processor of a second functional module of the medical device, wherein the watchdog timer software process corresponds to a watchdog timer hardware unit;

receiving a reset signal from the second processor to reset the first processor when the handshake signal is not provided to the watchdog timer software process within a prescribed time interval; and

receiving a reset signal from the watchdog timer software process to reset the second processor when the handshake signal is not provided to the watchdog timer software process within the prescribed time interval.

2. The method of claim 1, further comprising resetting the first processor and the second processor when the handshake signal is provided before a minimum time or after a maximum time.

3. The method of claim 1, further comprising disabling therapy output hardware when the handshake signal is not provided within the prescribed time interval.

4. The method of claim 1, further comprising detecting a voltage of the medical device, and selectively disabling therapy output hardware as a function of the detected voltage.

5. The method of claim 1, wherein the medical device is an external defibrillator comprising at least one of a therapy control module, a system controller, a user interface module, and a patient parameters module.

6. The method of claim 5, wherein the patient parameters module is configured to obtain at least one of ECG information, vital sign measurements, non-invasive blood pressure (NIBP) measurements, and SpO₂ information from a patient.

7. The method of claim 1, further comprising:

generating another handshake signal in a third processor;

providing the another handshake signal to another watchdog timer software process included in the first processor, wherein the another watchdog timer software process corresponds to the watchdog timer hardware unit; and

receiving a reset signal from the first processor to reset the third processor when the another handshake signal is not provided to the another watchdog timer software process within a prescribed time interval.

8. The method of claim 1, further comprising:

generating another handshake signal in a third processor;

providing the another handshake signal to the watchdog timer software process included in the second processor; and

receiving a reset signal from the second processor to reset the third processor when the another handshake signal is not provided to the watchdog timer software process within a prescribed time interval.

9. The method of claim 1, further comprising:

generating another handshake signal in the second processor;

providing the another handshake signal to the watchdog timer hardware unit; and

receiving a reset signal from the watchdog timer hardware unit to reset the second processor when the another handshake signal is not provided to the watchdog timer hardware unit within a prescribed time interval.

10. A processor-readable computer storage medium containing processor-executable instructions to cause a processor to:

generate a handshake signal in a first processor of a first functional module of a medical device;

provide the handshake signal to a watchdog timer software process in a second processor of a second functional module of the medical device, wherein the watchdog timer software process corresponds to a watchdog timer hardware unit;

receive a reset signal from the second processor to reset the first processor when the handshake signal is not provided to the watchdog timer software process within a prescribed time interval; and

receive a reset signal from the watchdog timer software process to rest the second processor when the handshake signal is not provided to the watchdog timer software process within the prescribed time interval.

11. The processor-readable computer storage medium of claim 10, further containing instructions for resetting the first processor and the second processor when the handshake signal is provided before a minimum time or after a maximum time.

12. The processor-readable computer storage medium of claim 10, further containing instructions for disabling therapy output hardware when the handshake signal is not provided within the prescribed time interval.

13. The processor-readable computer storage medium of claim 10, further containing instructions for detecting a voltage of the medical device, and selectively disabling therapy output hardware as a function of the detected voltage.

14. The processor-readable computer storage medium of claim 10, wherein the medical device is an external defibrillator comprising at least one of a therapy control module, a system controller, a user interface module, and a patient parameters module.

15. The processor-readable computer storage medium of claim 14, wherein the patient parameters module is configured to obtain at least one of ECG information, vital sign measurements, non-invasive blood pressure (NIBP) measurements, and SpO₂ information from a patient.

16. The processor-readable medium of claim 10, further containing instructions for:

generating another handshake signal in a third processor;

providing the another handshake signal to another watchdog timer software process included in the first processor, wherein the another watchdog timer software process corresponds to the watchdog timer hardware unit; and

receiving a reset signal from the first processor to reset the third processor when the another handshake signal is not provided to the another watchdog timer software process within a prescribed time interval.

17. A medical device comprising:

a watchdog timer hardware unit;

a first embedded processor included in a first functional module, configured to generate a handshake signal; and

a second embedded processor included in a second functional module, with a watchdog timer software process corresponding to the watchdog timer hardware unit, wherein the watchdog timer software process is configured to receive the handshake signal and to reset the first embedded processor and the second embedded processor when the handshake signal is not provided to the watchdog timer software process within a prescribed time interval.

18. The medical device of claim 17, wherein the watchdog timer hardware unit is a windowed watchdog timer hardware unit.

19. The medical device of claim 17, wherein at least one of the first and second embedded processors are configured to reset when the handshake signal is provided before a minimum time or after a maximum time.

20. The medical device of claim 17, further comprising therapy output hardware, wherein at least one of the first and second embedded processors is configured to disable the therapy output hardware when the handshake signal is not provided within the prescribed time interval.

21. The medical device of claim 17, further comprising a voltage monitor configured to detect a voltage of the medical device, wherein the voltage monitor is further configured to selectively disable therapy output hardware as a function of the detected voltage.

22. The medical device of claim 17, wherein the medical device comprises at least one of a therapy control module, a system controller, a user interface module, and a patient parameters module.

23. The medical device of claim 22, wherein the patient parameters module is configured to obtain at least one of ECG information, vital sign measurements, non-invasive blood pressure (NIBP) measurements, and SpO₂ information from a patient.

24. The medical device of claim 17, wherein the watchdog timer hardware unit comprises a hardware unit in the second functional module.

25. The medical device of claim 17, further comprising a third functional module including a third embedded processor configured to generate another handshake signal, wherein the first embedded processor includes another watchdog timer software process corresponding to the watchdog timer hardware unit to receive the another handshake signal and to reset the third embedded processor when the handshake signal is not provided within a prescribed time interval.

26. The medical device of claim 17, further comprising a third functional module including a third embedded processor configured to generate another handshake signal, wherein the watchdog timer software process in the second embedded processor receives the another handshake signal and resets the third embedded processor when the another handshake signal is not provided within a prescribed time interval.

27. The medical device of claim 17, wherein the second embedded processor is configured to generate another handshake signal and the watchdog timer hardware unit receives the another handshake signal and resets the second embedded processor when the another handshake signal is not provided within a prescribed time interval.