Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Reexamination Certificate
2000-08-31
2001-10-09
Kamm, William E. (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
Reexamination Certificate
active
06301502
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a defibrillation device, and more particularly to a personal wearable pacer/cardioverter/defibrillator which monitors a patient's condition, detects shockable or paceable arrhythmias, determines consciousness, and, in the case that the patient is determined to be unconscious, administers therapy to the patient.
2. Description of the Related Art
Cardiac arrhythmias, such as ventricular fibrillation and ventricular tachycardia, are electrical malfunctions of the heart, in which regular electrical impulses in the heart are replaced by irregular, rapid impulses. These irregular, rapid impulses can cause the heart to stop normal contractions, thereby interrupting blood flow therethrough. Such an interruption in blood flow can cause organ damage or even death.
Normal heart contractions, and thus normal blood flow, can be restored to a patient through application of electric shock. This procedure, which is called defibrillation, has proven highly effective at treating patients with cardiac arrhythlnias, provided that it is administered within minutes of the arrhythmia. In the past, this was not always possible, since defibrillation units were large, and thus not easy to move, and could only be operated by an experienced clinician.
In response to the foregoing drawbacks of defibrillation units, implantable defibrillators were developed. Such defibrillators, however, also have several drawbacks. Specifically, use of a such a defibrillator requires surgery, thereby making their use inconvenient and even undesirable under certain circumstances. Moreover, implantable defibrillators are also costly, both in terms of the device itself and in terms of the cost of the surgery and subsequent treatments.
To address the foregoing drawbacks of implantable defibrillators, portable automatic external defibrillators (hereinafter “AEDs”) were developed. These defibrillators are typically used by trained emergency medical system personnel. The major shortcoming of these defibrillators is the delay between the onset of ventricular fibrillation and the administering of a first shock. It has been estimated that survival decreases by 10% for each minute that passes after the first minute of ventricular fibrillation.
Temporary high risk patients who do not reach an ICD have little protection against sudden cardiac arrest (“SDA”), particularly with the discovery that anti-arrhythmia drugs have been proven to be less effective than a placebo. Accordingly, there exists a need for a defibrillator, preferably a portable, wearable defibrillator, which addresses the foregoing drawbacks of conventional defibrillators.
SUMMARY OF THE INVENTION
The present invention addresses the foregoing needs. For example, according to one aspect, the present invention is a defibrillator for delivering defibrillation energy to a patient. The defibrillator includes at least one electrode which attaches to the patient for transmitting the defibrillation energy to the patient and for receiving patient information from the patient, and a plurality of capacitors which are switchable so as to alter characteristics of the defibrillation energy. According to the invention, a controller controls switching of the plurality of capacitors in accordance with the patient information received from the at least one electrode.
By monitoring the patient for patient information and switching the plurality of capacitors in accordance with the patient information, the foregoing aspect of the invention makes it possible to deliver, to the patient, defibrillation energy which is appropriate for that patient. As a result, the invention provides increased effectiveness in the treatment of cardiac arrhythmias.
According to another aspect, the present invention is a way in which to increase long-term wear of a sensing electrode, such as a traditional defibrillation electrode (i.e., electrodes having a conductive surface area of over 60 cm
2
), a low-surface-area electrode (i.e., electrodes having a conductive surface area of roughly 60 to 10 cm
2
), or segmented electrodes (i.e., electrodes having a conductive surface area of roughly 8 to 10 cm
2
). Specifically, the invention includes a variety of different techniques for increasing the amount of time that an electrode can be worn by a patient without resulting in substantial skin irritation or damage. For example, according to one embodiment, one or more electrodes are moved on the patient's body periodically. As another example, therapeutic or prophylactic agents are provided in or on the electrode. Also, the size, configuration, and materials used to construct the electrodes contribute the amount of time that the electrodes can be worn by a patient.
According to another aspect, the present invention is a defibrillator for delivering defibrillation energy to a patient. The defibrillator includes a signal generator for generating the defibrillation energy and a plurality of segmented electrodes each having a conductive area for transmitting the defibrillation energy to the patient. The plurality of segmented electrodes are divided into groups of two or more electrodes, each of the groups of electrodes having at least one line connected to the signal generator. Each of the lines has a length that is sufficient for each group of electrodes to be placed on the patient a predetermined distance away from others of the groups of electrodes. In the invention, the electrodes in at least one of the groups are spatially arranged to have an effective conductive area which is greater than a total combined conductive area of the electrodes in the group.
According to still another aspect, the invention is a segmented electrode device for use during ventricular fibrillation of a patient. The segmented electrode device includes a plurality of segmented electrodes each having a conductive area for transmitting defibrillation energy to the patient. The plurality of segmented electrodes are divided into groups of two or more electrodes, each of the groups of electrodes having at least one line connected to a signal generator. Each of the lines has a length that is sufficient for each group of electrodes to be placed on the patient a predetermined distance away from others of the groups of electrodes. In the invention, the electrodes in at least one of the groups are spatially arranged to have an effective conductive area which is greater than a total combined conductive area of the electrodes in the group.
By virtue of the electrode configurations in the foregoing two aspects of the invention, it is possible to simulate a larger conductive area using segmented electrodes. As a result, these aspects of the invention have an advantage over their conventional counterparts. That is, these aspects of the invention are able to provide defibrillation energy to the patient without using large electrodes. Thus, these aspects of the invention provide reduced skin irritation without a corresponding reduction in efficacy.
According to another aspect, the present invention is a defibrillator for delivering defibrillation energy to a patient. The defibrillator includes an external interface, over which patient information is transmitted to an external location, and a patient interface, over which the defibrillation energy is transmitted to the patient, and over which the patient information is received. A processor is included in the defibrillator, which analyzes the patient information received over the patient interface and which controls transmission of the defibrillation energy to the patient based on at least a first portion of the patient information. A memory stores at least a second portion of the patient information prior to transmission of the second portion of the patient information over the external interface.
By controlling transmission of the defibrillation energy to the patient based on at least a first portion of information received from the patient, the invention is able to tailor the defibrillation energy to the pati
Fincke Randall W.
O'Leary James P.
Owen James M.
Totman Mark H.
Cardiac Science Inc.
Gottlieb Rackman & Reisman P.C.
Kamm William E.
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