Defibrillator method and apparatus
First Claim
1. A method of delivering a defibrillation pulse to a patient, comprising:
- (a) choosing an amount of energy to deliver to the patient in the defibrillation pulse;
(b) measuring the patient'"'"'s transthoracic impedance prior to delivering the defibrillation pulse;
(c) determining a pulse amplitude and a pulse duration for a phase of the defibrillation pulse prior to delivering the defibrillation pulse to convey an amount of energy to the patient near or exceeding the chosen amount of energy, wherein the pulse duration is determined based on the patient'"'"'s transthoracic impedance, and the pulse amplitude is determined based on the determined pulse duration, the patient'"'"'s transthoracic impedance, and the chosen amount of energy;
(d) charging an energy store to a level in accordance with the determined pulse amplitude; and
(e) discharging to the patient the charge stored in the energy store to deliver the defibrillation pulse having the determined pulse amplitude and pulse duration.
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Accused Products
Abstract
A defibrillator method and apparatus wherein a patient'"'"'s measured transthoracic impedance (TTI) is used to control the amount of energy contained in a defibrillation pulse applied to the patient. Prior to delivering a defibrillation pulse, the patient'"'"'s TTI is measured by an impedance measuring circuit (11). The patient'"'"'s TTI may also be measured during delivery of a prior defibrillation pulse. A microprocessor (23) uses the measured patient TTI to control the shape of the defibrillation pulse by controlling: (i) the phase duration of the defibrillation pulse; and (ii) the voltage level to which the defibrillator'"'"'s capacitor bank (15) is charged. The defibrillation pulse shape is controlled so that the energy conveyed by the defibrillation pulse to the patient is near or exceeds a desired value. The desired value may be set by an operator via an energy selector (25). A switch (13) controls the connection of defibrillator electrodes (27a, 27b) to the impedance measuring circuit (11) and the capacitor bank (15).
95 Citations
20 Claims
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1. A method of delivering a defibrillation pulse to a patient, comprising:
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(a) choosing an amount of energy to deliver to the patient in the defibrillation pulse; (b) measuring the patient'"'"'s transthoracic impedance prior to delivering the defibrillation pulse; (c) determining a pulse amplitude and a pulse duration for a phase of the defibrillation pulse prior to delivering the defibrillation pulse to convey an amount of energy to the patient near or exceeding the chosen amount of energy, wherein the pulse duration is determined based on the patient'"'"'s transthoracic impedance, and the pulse amplitude is determined based on the determined pulse duration, the patient'"'"'s transthoracic impedance, and the chosen amount of energy; (d) charging an energy store to a level in accordance with the determined pulse amplitude; and (e) discharging to the patient the charge stored in the energy store to deliver the defibrillation pulse having the determined pulse amplitude and pulse duration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A defibrillator for delivering a defibrillation pulse to a patient, comprising:
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(a) electrodes adapted for placement on the patient; (b) an impedance measuring circuit for measuring the patient'"'"'s transthoracic impedance; (c) a defibrillation pulse generator including an energy store; (d) a switch in electrical communication with the impedance measuring circuit and the defibrillation pulse generator for selectively connecting the impedance measuring circuit and the defibrillation pulse generator to the electrodes; and (e) a control system in electrical communication with the impedance measuring circuit, the defibrillation pulse generator, and the switch for; (i) causing the switch to electrically connect the electrodes to the impedance measuring circuit so that prior to delivery of the defibrillation pulse, the impedance measuring circuit measures the transthoracic impedance of a patient coupled to the electrodes; (ii) determining a pulse amplitude and a pulse duration for a phase of the defibrillation pulse to be delivered to the patient to convey an amount of energy to the patient near or exceeding a previously chosen amount of energy, wherein the pulse duration is determined based on the patient'"'"'s transthoracic impedance, and the pulse amplitude is determined based on the determined pulse duration, the patient'"'"'s transthoracic impedance, and the chosen amount of energy; (iii) causing the defibrillation pulse generator to charge the energy store to a level in accordance with the determined pulse amplitude; and (iv) causing the switch to electrically connect the electrodes to the defibrillation pulse generator so that the charge stored on the energy store discharges to deliver the defibrillation pulse to the patient. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method of determining a pulse shape for a defibrillation pulse to be delivered from an energy store to a patient, comprising:
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(a) measuring the patient'"'"'s transthoracic impedance prior to delivering the defibrillation pulse; (b) determining a duration for a phase of the defibrillation pulse based on the patient'"'"'s transthoracic impedance; and (c) determining a voltage level to which the energy store is charged for determining a pulse amplitude of the defibrillation pulse, wherein the voltage level is based on the patient'"'"'s transthoracic impedance, the determined duration, and a previously chosen amount of energy, wherein the defibrillation pulse having the determined pulse duration and amplitude conveys an amount of energy to the patient that is near or exceeds the chosen amount of energy. - View Dependent Claims (18, 19, 20)
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Specification