Charge-based defibrillation method and apparatus

• US 20030074025A1
• Filed: 01/18/2000
• Published: 04/17/2003
• Est. Priority Date: 01/18/2000
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Wuthrich, Scott A.
• Granted Patent: US 6,647,290 B2
• Time in Patent Office: Days
• US Class Current: 607/5
• CPC Class Codes: A61N 1/3906 characterised by the form of the shockwave
• CPC Class Codes: A61N 1/3912 Output circuitry therefor, e.g. switches
• CPC Class Codes: A61N 1/3937 Monitoring output parameters

Abstract

A defibrillation method and apparatus are described for delivering a desired quantity of electric charge to a patient. The method and apparatus are applicable both to external defibrillation and to defibrillation by an implanted device. The desired quantity of electric charge may be predetermined or it may be operator-selected. The method includes determining one or more intended waveform parameters based on the desired quantity of electric charge and, optionally, on one or more patient impedance values. A defibrillation waveform is then generated and applied to the patient based on the intended waveform parameters. The patient impedance values may be predetermined or operator-selected, or the method may include the step of determining the patient impedance values. Patient impedance values may be determined prior to, substantially contemporaneous with, and/or during application of the defibrillation waveform to the patient. If a patient impedance value is determined to have changed from a previously determined value, then the intended waveform parameters may be adjusted based on this change in order to provide that the desired quantity of charge is applied to the patient. A defibrillation method is also described in which a flow of current is provided over time through an electrical coupling to a patient. The flow is stopped when the flow of current over time equals a desired quantity of electric charge. The desired quantity of electric charge may be predetermined, or it may be operator-selected. A defibrillator also is described for delivering a desired quantity of electric charge to a patient. The defibrillator includes a charge-determined waveform generator that generates an applied defibrillation waveform based on the desired quantity of electric charge and, optionally, on one or more patient impedance values.

Claims

1. A method for delivering a desired quantity of electric charge to a patient, comprising the steps of:

(1) determining one or more intended waveform parameters based at least in part on the desired quantity of electric charge; and

(2) generating an applied defibrillation waveform based on the intended waveform parameters.

2. The method of claim 1, wherein:

the desired quantity of electric charge is predetermined.

3. The method of claim 1, wherein:

the desired quantity of electric charge is operator-selected.

4. The method of claim 1, further comprising the step of:

(3) electrically coupling the applied defibrillation waveform to the patient.

5. The method of claim 1, wherein:

the waveform parameters are selected from any one or more of the group consisting of;

form, phase, timing of phase transition, maximum duration, minimum duration, maximum voltage, minimum voltage, maximum current, minimum current, maximum energy, minimum energy, maximum power, and minimum power.

6. The method of claim 1, wherein:

step (1) further includes determining the one or more intended waveform parameters based at least in part on one or more patient impedances.

7. The method of claim 6, wherein:

at least one of the patient impedances is predetermined.

8. The method of claim 6, wherein:

at least one of the patient impedances is operator-selected.

9. The method of claim 6, further comprising the step of:

(3) determining at least one of the patient impedances.

10. The method of claim 9, wherein:

step (3) includes sensing a value indicative of an impedance of the patient prior to the execution of step (1).

11. The method of claim 9, wherein:

step (3) includes sensing a value indicative of an impedance of the patient substantially contemporaneous with starting execution of step (2); and

the method further includes the steps of

(4) determining an adjustment, if any, to one or more of the one or more intended waveform parameters based at least in part on the sensed value, and

(5) adjusting the applied defibrillator waveform in accordance with step (4).

12. The method of claim 9, wherein:

step (3) includes sensing one or more values indicative of one or more impedances of the patient during the execution of step (2); and

the method further includes the steps of

(4) determining an adjustment, if any, to one or more of the one or more intended waveform parameters based at least in part on the sensed one or more values, and

(5) adjusting the applied defibrillator waveform in accordance with step (4).

13. The method of claim 1, further comprising the steps of:

(3) during execution of step (2), comparing one or more of the one or more intended waveform parameters with one or more parameters of the applied defibrillation waveform; and

(5) when a difference between the intended waveform parameters and the parameters of the applied defibrillation waveform reaches a threshold value, adjusting the applied defibrillator waveform to conform with the intended waveform parameters.

14. The method of claim 1, wherein:

the patient impedance is a transthoracic impedance.

15. The method of claim 1, wherein:

the patient impedance is a heart impedance.

16. The method of claim 1, wherein:

the applied defibrillation waveform comprises a set of voltage values.

17. The method of claim 16, wherein:

the applied defibrillation waveform comprises a monophasic voltage pulse.

18. The method of claim 16, wherein:

the applied defibrillation waveform comprises a biphasic voltage pulse having first and second phases of opposing polarities.

19. The method of claim 1, wherein:

the applied defibrillation waveform comprises a set of current values.

20. A method for delivering a desired quantity of electric charge to a patient, comprising the steps of:

(1) providing a flow of current over time through an electrical coupling to the patient; and

(2) stopping the flow of current to the patient when the flow of current over time equals the desired quantity of electric charge.

21. The method of claim 20, wherein:

the desired quantity of electric charge is predetermined.

22. The method of claim 20, wherein:

the desired quantity of electric charge is operator-selected.

23. The method of claim 20, wherein:

step (1) includes determining of one or more patient impedance values.

24. The method of claim 20, wherein:

step (1) includes determining one or more parameters of a waveform of the current.

25. The method of claim 24, wherein:

the one or more parameters of the waveform are selected from the group consisting of form, phase, timing of phase transition, maximum duration, minimum duration, maximum voltage, minimum voltage, maximum current, minimum current, maximum energy, minimum energy, maximum power, and minimum power.

26. A method for delivering a desired quantity of electric charge to a patient comprising the steps of:

(1) determining an impedance of the patient;

(2) determining a charge voltage of an energy-storage device based on the impedance and on the desired quantity of electric charge to be delivered to the patient; and

(3) charging the energy-storage device to the charge voltage.

27. The method of claim 26, further comprising the step of:

(4) discharging the charged voltage in response to a discharge request.

28. The method of claim 27, further comprising the steps of:

(5) determining, during the execution of step (4), quantity of current delivered into the patient due to discharging the charged voltage;

(6) determining, based on the flow of delivered current over time, a delivered quantity of electric charge delivered to the patient;

(7) continuing step (4) when the delivered quantity of electric charge is less than the desired quantity of electric charge; and

(8) terminating the discharge of the charged voltage into the patient when the delivered quantity of electric charge is substantially equal to the desired quantity of electric charge.

29. A defibrillator for delivering a desired quantity of electric charge from an energy storage device to a patient, comprising:

a charge-delivery processor constructed and arranged to determine a charge voltage of the energy-storage device based on at least one patient impedance and on the desired quantity of electric charge to be delivered to the patient; and

an applied waveform generator constructed and arranged to charge the energy-storage device to the charge voltage determined by the charge-delivery processor.

30. The defibrillator of claim 29, further comprising:

at least one sensor for determining at least one of the at least one patient impedance.

31. The defibrillator of claim 29, wherein:

the applied waveform generator further is constructed and arranged to discharge the charged voltage into the patient.

32. The defibrillator of claim 31, further comprising:

a feedback processor constructed and arranged to determine, during the discharge of the charged voltage into the patient, a flow of delivered current into the patient due to discharging the charged voltage;

wherein the charge-delivery processor further is constructed and arranged to

(a) determine, based on the flow of delivered current over time, a delivered quantity of electric charge delivered to the patient; and

(b) determine when the delivered quantity of electric charge is substantially equal to the desired quantity of electric charge;

and further wherein the applied waveform generator further is constructed and arranged to terminate the discharge of the charged voltage into the patient responsive to the charge-delivery processor determining that the delivered quantity of electric charge is substantially equal to the desired quantity of electric charge.

33. The defibrillator of claim 29, wherein:

the charge-delivery processor further is constructed and arranged to determine one or more intended waveform parameters selected from the group consisting of form, phase, timing of phase transition, maximum duration, minimum duration, maximum voltage, minimum voltage, maximum current, minimum current, maximum energy, minimum energy, maximum power, and minimum power; and

the applied waveform generator further is constructed and arranged to determine the discharge of the charged voltage into the patient responsive to the one or more intended waveform parameters.

34. A defibrillator for delivering a desired quantity of electric charge to a patient, comprising:

a charge-delivery processor constructed and arranged to determine one or more intended waveform parameters based at least in part on the desired quantity of electric charge.

35. The defibrillator of claim 34, further comprising:

an applied waveform generator constructed and arranged to generate an applied defibrillation waveform based on one or more of the one or more intended waveform parameters.

36. The defibrillator of claim 34, wherein:

the desired quantity of electric charge is predetermined.

37. The defibrillator of claim 36, wherein:

the desired quantity of electric charge is operator-selected.

38. The defibrillator of claim 34, wherein:

the one or more intended waveform parameters are selected from the group consisting of form, phase, timing of phase transition, maximum duration, minimum duration, maximum voltage, minimum voltage, maximum current, minimum current, maximum energy, minimum energy, maximum power, and minimum power.

39. The defibrillator of claim 34, wherein:

the charge-delivery processor further is constructed and arranged to determine the one or more intended waveform parameters based at least in part on one or more patient impedances.

40. The defibrillator of claim 39, wherein:

at least one of the patient impedances is predetermined.

41. The defibrillator of claim 39, wherein:

at least one of the patient impedances is operator-selected.

42. The defibrillator of claim 39, further comprising:

at least one sensor constructed and arranged to determine at least one of the patient impedances.

43. The defibrillator of claim 42, wherein:

a first of the at least one sensor senses a value indicative of an impedance of the patient prior to the charge-delivery processor determining the one or more intended waveform parameters.

44. The defibrillator of claim 42, wherein:

the applied waveform generator further is constructed and arranged to apply the applied defibrillation waveform to the patient;

a second of the at least one sensor senses one or more value s indicative of on e or more impedances of the patient during the application of the applied defibrillation waveform to the patient; and

the charge-delivery processor further is constructed and arranged to determine an adjustment, if any, to one or more of the one or more intended waveform parameters based at least in part on the sensed one or more values of the second sensor.

45. A defibrillator for delivering a desired quantity of electric charge to a patient, comprising:

a charge-determined waveform generator constructed and arranged to

(a) provide a flow of current over time through an electrical coupling to the patient; and

(b) stop the flow of current to the patient when the flow of current over time equals the desired quantity of electric charge.

46. The defibrillator of claim 45, wherein:

the desired quantity of electric charge is predetermined.

47. The defibrillator of claim 45, wherein:

the desired quantity of electric charge is operator-selected.

48. The defibrillator of claim 45, wherein:

the charge-determined waveform generator further is constructed and arranged to determine one or more patient impedance values.

49. The defibrillator of claim 45, wherein:

the charge-determined waveform generator further is constructed and arranged to determine one or more parameters of a waveform of the current.

50. The defibrillator of claim 49, wherein:

the one or more parameters of the waveform are selected from the group consisting of form, phase, timing of phase transition, maximum duration, minimum duration, maximum voltage, minimum voltage, maximum current, minimum current, maximum energy, minimum energy, maximum power, and minimum power.