Hazard mitigation in medical device

• US 6,957,368 B2
• Filed: 01/23/2002
• Issued: 10/18/2005
• Est. Priority Date: 01/23/2002
• Status: Active Grant

• Current Assignee: Physio-Control Incorporated (Stryker Corporation)
• Original Assignee: Medtronic Emergency Response Systems Inc (Stryker Corporation)
• Inventors: Kelly, Patrick F., Neumiller, James S., DeBardi, Gary A.
• Primary Examiner(s): Beausoliel, Robert
• Assistant Examiner(s): MATTHEW, AARON D
• Application Number:
  US10/056,554
• Publication Number:
  US 20030140274A1
• Time in Patent Office: 1,364 Days
• Field of Search: 714/55, 714/23, 714/56, 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. An external defibrillator comprising:

a therapy control module to control delivery of defibrillation shocks to a patient, the therapy control module including a first processor that generates a first handshake signal and a watchdog timer hardware unit that resets the first processor when the first handshake signal is not generated within a first time interval specified by the watchdog timer hardware unit; and

a system control module including a second processor to generate a second handshake signal,

wherein the therapy control module includes a watchdog timer software process on the first processor to reset the first processor when the second handshake signal is not generated within the first time interval.

2. The external defibrillator of claim 1, wherein the watchdog timer hardware unit resets the first processor when the handshake signal is provided before a minimum time or after a maximum time.

3. The external defibrillator of claim 1, further comprising means for disabling therapy output hardware when the first handshake signal is not provided within the first time interval.

4. The external defibrillator of claim 1, further comprising a voltage monitor for detecting an abnormal power condition and disabling therapy output hardware in response to the abnormal power condition.

5. The external defibrillator of claim 1, further comprising a voltage monitor for detecting a voltage of the medical device.

6. The external defibrillator of claim 5, further comprising means for selectively disabling therapy output hardware as a function of the detected voltage.

7. The external defibrillator of claim 1, further comprising at least one of a user interface module and a patient parameters module.

8. The external defibrillator of claim 7, wherein the user interface module is communicatively coupled to at least one of a keyboard, a display screen, and a strip chart recorder.

9. The external defibrillator of claim 7, 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.

10. The external defibrillator of claim 1, wherein the external defibrillator is an automated external defibrillator.

11. The external defibrillator of claim 1, further comprising a functional module including a third processor configured to generate a third handshake signal, wherein the system control module processor includes another watchdog timer software process to receive the third handshake signal and to reset the third processor when the third handshake signal is not provided within a prescribed time interval.

12. The defibrillator of claim 1, wherein the system control module includes a second watchdog timer hardware unit to reset the second processor when the second handshake signal is not generated within a second time interval.

13. The defibrillator of claim 1, wherein the first watchdog timer hardware unit is a windowed watchdog timer hardware unit.

14. The defibrillator of claim 1, further comprising:

a user interface module to control input and output of information for an operator, the user interface module including a third processor that generates a third handshake signal,

wherein the system control module includes a second watchdog timer software process corresponding to the second watchdog timer hardware unit, the second watchdog timer software process resetting the third processor when the third handshake signal is not generated within the second time interval.

15. The defibrillator of claim 1, further comprising:

a patient parameters module to process one or more physiological parameters of the patient, the patient parameters module including a third processor that generates a third handshake signal,

wherein the system control module includes a second watchdog timer software process corresponding to the second watchdog timer hardware unit, the second watchdog timer software process resetting the third processor when the third handshake signal is not generated within the second time interval.

16. The defibrillator of claim 1, further comprising:

a user interface module to control input and output of information for an operator, the user interface module including a third processor that generates a third handshake signal,

wherein the system control module includes a second watchdog timer software process corresponding to the first watchdog timer hardware unit, the second watchdog timer software process resetting the third processor when the third handshake signal is not generated within the first time interval.

17. The defibrillator of claim 1, further comprising:

a patient parameters module to process one or more physiological parameters of the patient, the patient parameters module including a third processor that generates a third handshake signal,

wherein the system control module includes a second watchdog timer software process corresponding to the first watchdog timer hardware unit, the second watchdog timer software process resetting the third processor when the third handshake signal is not generated within the first time interval.