Charge-based defibrillation method and apparatus

• US 6,647,290 B2
• Filed: 01/18/2000
• Issued: 11/11/2003
• Est. Priority Date: 01/18/2000
• Status: Expired due to Fees

• 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.
• Primary Examiner(s): Evanisko, George R.
• Assistant Examiner(s): BRADFORD, RODERICK D
• Application Number:
  US09/484,983
• Publication Number:
  US 20030074025A1
• Time in Patent Office: 1,393 Days
• Field of Search: 607/7, 607/8, 607/5
• 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 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.

Claims

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

(1) determining, as one or more intended waveform parameters, at least one of an initial shape and initial amplitude of a waveform based at least in part on a predetermined electric charge table;

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

(3) simultaneously, sensing a value indicative of an impedance of the patient during the execution of step 2;

(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 defibrillation waveform in accordance with step (4).

2. The method of claim 1, wherein:

an operator selectively provides the intended waveform parameters.

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

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

4. 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.

5. The method of claim 1, wherein:

the impedance of the patient is predetermined.

6. 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 the applied defibrillation waveform; and

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

7. The method of claim 1, wherein:

the patient impedance is a transthoracic impedance.

8. The method of claim 1, wherein:

the patient impedance is a heart impedance.

9. The method of claim 1, wherein:

the applied defibrillation waveform comprises a monophasic voltage pulse.

10. The method of claim 1, wherein:

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

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

a charge-delivery processor constructed and arranged to determine, as one or more intended waveform parameters and based at least in part on a predetermined electric charge table, at least one of an initial shape and initial amplitude of a waveform and to deliver a flow of current over time to the patient;

an applied waveform generator constructed and arranged to apply a defibrillation waveform to the patient based on one or more of the one or more intended waveform parameters; and

at least one sensor constructed and arranged to sense one or more values indicative of said flow,

wherein 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 sensor.

12. The defibrillator of claim 11, 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.

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

(1) determining, as one or more intended waveform parameters, at least one of an initial shape and initial amplitude of a waveform based at least in part on a predetermined electric charge table;

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

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

(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 defibrillation waveform in accordance with step (4).

14. The method of claim 13, wherein:

an operator selectively provides the intended waveform parameters.

15. The method of claim 13, wherein:

the patient impedance is a transthoracic impedance.

16. The method of claim 13, wherein:

the patient impedance is a heart impedance.