External defibrillator
First Claim
1. An external defibrillator comprising:
- electrodes;
a processor; and
a circuit connecting the processor and the electrodes, wherein when the electrodes are in contact with a patient, the processor performs operations comprising;
receiving electrical signals from the patient;
determining, from the electrical signals, a signal (Z), wherein Z is a measure of transthoracic impedance of the patient;
establishing an electrocardiogram (ECG) of the patient based on the electrical signals;
determining, based on Z, when an interference condition is present andwhen the interference condition is present, inhibiting a shock delivery circuit from delivering a shock to the patient via the electrodes, based on Z, and independent of the ECG, for a defined period of time.
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Accused Products
Abstract
An external defibrillator includes patient electrodes (20) for obtaining the patient'"'"'s electrocardiogram (ECG) and for applying a shock to the patient. A microprocessor (24) analyses the patient'"'"'s ECG using a diagnostic algorithm to detect if the patient'"'"'s heart is in a shockable rhythm, and shock delivery circuitry (10) is enabled when a shockable rhythm is detected by the diagnostic algorithm. The patient electrodes also allow obtaining a signal (Z) which is a measure of the patient'"'"'s transthoracic impedance and the microprocessor is responsive to Z to detect conditions likely to cause the diagnostic algorithm to generate a false detection of a shockable rhythm. If such detection is made, the microprocessor prevents detection of a shockable rhythm by the diagnostic algorithm, at least for a period of time.
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Citations
20 Claims
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1. An external defibrillator comprising:
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electrodes; a processor; and a circuit connecting the processor and the electrodes, wherein when the electrodes are in contact with a patient, the processor performs operations comprising; receiving electrical signals from the patient; determining, from the electrical signals, a signal (Z), wherein Z is a measure of transthoracic impedance of the patient; establishing an electrocardiogram (ECG) of the patient based on the electrical signals; determining, based on Z, when an interference condition is present and when the interference condition is present, inhibiting a shock delivery circuit from delivering a shock to the patient via the electrodes, based on Z, and independent of the ECG, for a defined period of time. - View Dependent Claims (2, 3, 4, 5)
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6. A method comprising:
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determining, via a processor, a transthoracic impedance from electrical data; calculating a first derivative of the transthoracic impedance for a time window; determining an average amplitude of the first derivative within the time window; and when the average amplitude is above a threshold; flagging the electrical data as having an interference; and preventing a diagnostic algorithm from detecting a shockable rhythm from the electrical data for a period of time. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
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14. A defibrillator comprising:
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a shock circuit; a processor; electrodes; and a circuit connecting the processor and the electrodes, wherein when the electrodes are in contact with a patient, the processor performs operations comprising; receiving electrical signals; determining, from the electrical signals and using a high pass filter in combination with a low pass filter, a transthoracic impedance of the patient; establishing an electrocardiogram (ECG) of the patient based on the electrical signals; determining, based on the transthoracic impedance, when an interference condition is present; and when the interference condition is present, inhibiting the shock delivery circuit from delivering a shock via the electrodes, based on the ECG, for a defined period of time. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification