Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Reexamination Certificate
1999-04-16
2001-07-17
Kamm, William E. (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
Reexamination Certificate
active
06263238
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to automatic external defibrillators (AEDs) and, more particularly, to a manner of extracting artifacts from a patient's ECG signal to more accurately determine the presence of ventricular fibrillation and the necessity of delivering a defibrillation pulse.
BACKGROUND OF THE INVENTION
Automated external defibrillators (AEDs) are used to analyze electrocardiographic (ECG) signals to detect ventricular fibrillation in victims who may be suffering cardiac arrest. The algorithm used within the AED must determine whether to deliver life-saving defibrillation therapy to the victim, and as such, needs to operate with minimal failure. Most AEDs are rate-based in that they compare a patient's monitored cardiac rhythm to preprogrammed nominal values. The problem with rate-based systems, however, is that often artifacts due to motion and/or cardiopulmonary resuscitation (CPR) can occur in the ECG signals potentially causing the AED to operate inappropriately, e.g., delivering a defibrillation pulse where none is needed or not delivering, a defibrillation pulse where one is needed.
As such, there is a need for a ventricular fibrillation detector that incorporates artifact extraction that can be implemented within an AED to reduce the potential for inappropriate operation. The ventricular fibrillation detector preferably operates continuously and is not rate based.
SUMMARY OF THE INVENTION
A ventricular fibrillation detector of the present invention is preferably implemented in an automatic external defibrillator (AED) and substantially addresses the needs described above. The ventricular fibrillation detector generally comprises three detector portions which are operably connected. The first detector portion receives a cardiac rhythm signal in a series of segments and produces an output for each segment that is representative of the presence or absence of ventricular fibrillation. The second detector portion takes the outputs from the first detector portion and produces an output that is representative of a weighted combination of at least two of the output from the first detector portion. The third detector portion receives the output from the second detector portion and compares that output to a predetermined criterion and determines therefrom whether ventricular fibrillation is present.
A method for detecting, ventricular fibrillation generally comprises the steps of: (1) receiving a cardiac signal in a series of segments; (2) determining the absence or presence of ventricular fibrillation in each of said segments; (3) performing a weighted combination of the determinations from at least two of the segments; and (4) comparing the weighted combination against a predetermined criterion and determining therefrom if ventricular fibrillation is present.
REFERENCES:
patent: 4202340 (1980-05-01), Langer et al.
patent: 4296755 (1981-10-01), Judell
patent: 4796620 (1989-01-01), Imran
patent: 4969465 (1990-11-01), Pless et al.
Brewer James E.
Donohoo Ann M.
Olson Kenneth F.
Kamm William E.
Patterson Thuente Skaar & Christensen P.A.
SurVivaLink Corporation
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