WO2006097923A1

WO2006097923A1 - A defibrillation system and method for generating a predetermined voltage pulse for defibrillation

Info

Publication number: WO2006097923A1
Application number: PCT/IL2006/000330
Authority: WO
Inventors: Chaim Lotan; Avraham Weiss; Iony Katz; Mendel Mendelbaum; Shraga Gorny; Shimon Rosenheck; Haim Danenberg
Original assignee: Hadasit Medical Research Services And Development Company Ltd.; Yissum Research Development Company Of The Hebrew University Of Jerusalem
Priority date: 2005-03-16
Filing date: 2006-03-14
Publication date: 2006-09-21

Abstract

There is provided a portable defibrillation system, including a low-voltage electrical energy storage, a battery, a predetermined voltage fast charger connected to the energy storage and fed by it, a predetermined energy, predetermined voltage capacitor connected to, and chargeable by, the charger, an output switching unit connected to the capacitor having an output connectable to a pair of electrodes, and a control unit operationally connected to the energy storage, fast charger, voltage capacitor and output switching unit. A method for generating a predetermined voltage pulse for defibrillation, is also provided.

Description

A DEFIBRILLATION SYSTEM AND METHOD FOR GENERATING A

PREDETERMINED VOLTAGE PULSE FOR DEFIBRILLATION Field of the Invention

The present invention relates to intensive care systems for the early treatment of sudden death caused by arrhythmias, and more particularly to such systems which are suitable for domestic or outpatient use on a dying patient, by non-medical personnel. Specifically, the invention is concerned with a portable, small defibrillation apparatus and method for applying, when required, an adequate electrical shock derived from an energy source such as a super density low voltage energy storage, to a person suffering from ventricular fibrillation or cardiac arrest. Background of the Invention

Sudden cardiac death, caused by ventricular fibrillation or cardiac arrest, is the major cause of death amongst adult populations in developed countries. Ventricular fibrillation can be halted and normal heart activity restored by an electrical shock applied to the heart, i.e., the electrical defibrillation procedure. Similarly, cardiac arrest can be treated by pacing electrical signals, which is a pulse train at a rate of 60- 80 pulses per minute.

The defibrillation procedure is usually effective when applied in intensive care units in hospitals, where a fibrillation state is easily detected and defibrillation is quickly applied. Intensive care units in hospitals are equipped with the required expensive defibrillation equipment and the professional personnel able to perform the treatment. The same considerations apply for the cardiac arrest state using an external pacemaker device. Without warning, sudden cardiac arrest (SCA) can afflict anyone, anytime. SCA kills hundreds of thousands of people in the U.S. alone each year. The chance of surviving a cardiac arrest declines by approximately 10% for each minute without defibrillation. Beyond 12 minutes, the chance of survival is 2% to 5%. It is therefore important that a defibrillation procedure be done immediately, otherwise irreversible and irreparable damage is done. The brain, heart and kidneys are damaged within minutes from the start of fibrillation, due to lack of oxygen supply. Early defibrillation restores cardiac and brain function, thus restoring spontaneous respiration and avoiding anoxic brain damage. Automatic external defibrillators (AEDs) that accurately analyze cardiac rhythms and, if appropriate, advise/deliver an electric counter-shock were introduced in 1979. AEDs are widely used by trained emergency personnel (emergency medical technicians EMTs), paramedics, EMT-B 's, EMTTs, and first responders, such as firefighters and police personnel. In such hands, AEDs have proved accurate and effective and have become an essential link in the "chain of survival" as defined by the American Heart Association.

Presently used automatic defibrillation equipment is relatively expensive, e.g., in the range of thousands of dollars. Its size and weight are unsuitable for daily wear on a belt, such as a cellular phone, which would have made it available for treating the owner or other sudden death victims around the owner, and, at the same time issuing an urgent call for ambulatory services.

Disclosure of the Invention

It is therefore one of the objects of the present invention to treat the fibrillation and cardiac arrest everywhere with the provision of a low cost, portable, lightweight, defibrillation system.

It is a further object of the present invention to provide a system and a method for generating a predetermined adequate energy, predetermined adequate voltage pulse, by means of a lightweight, portable apparatus.

In accordance with the invention, this is achieved by providing a portable defibrillation system, comprising a low-voltage electrical energy storage; a battery; a predetermined voltage fast charger connected to said energy storage and fed by it; a predetermined energy, predetermined voltage capacitor connected to, and chargeable by, said charger, an output switching unit connected to said capacitor having an output connectable to a pair of electrodes, and a control unit operationally connected to said energy storage, fast charger, voltage capacitor and output switching unit.

The invention further provides a method for generating a predetermined voltage pulse for defibrillation, comprising providing a low-voltage electrical energy storage; a battery; a predetermined voltage fast charger connected to said energy storage and fed by it; a predetermined energy, predetermined voltage capacitor connected to, and chargeable by, said charger; an output switching unit connected to said capacitor having an output connectable to a pair of electrodes; a control unit operationally connected to said energy storage, fast charger, voltage capacitor and output switching unit; charging the low voltage energy storage; applying stored voltage energy to a predetermined voltage fast charger, and charging a predetermined energy, predetermined voltage capacitor. Brief Description of the Drawing

The invention will now be described in connection with certain preferred embodiments with reference to the following illustrative figure, so that it may be more fully understood.

With specific reference now to the figure in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawing making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.

In the drawing: Fig. 1 illustrates a general block diagram of the automatic defibrillation system according to the present invention. Detailed Description of the Preferred Embodiments

Referring now to Fig. 1 there is illustrated a preferred embodiment of a defibrillator system 2 according to the present invention and the method for generating a selected, predetermined adequate voltage pulse by using the energy stored in a super density low voltage energy storage device. There is seen a conventional DC charger 4 which, in the idle state, will charge both the super density low voltage storage 6, used as the source of energy for the required high voltage applied in case of need, and a rechargeable battery 8, e.g., a Lithium battery, advantageously used as a power source for the electronic circuitry and as a secondary possible source to charge the low voltage storage 6, when the system is disconnected from the charger 4. One of the possible implementations of such a low voltage storage 6 is a type of low voltage small size capacitor.

The low voltage storage 6 feeds a high voltage, fast charger 10 with low voltage energy stored therein, in order to, in turn, charge a high-energy, high-voltage capacitor 12, which will serve as the source energy for the pulse delivered to a patient in case of need. A main control unit 14, based on a microcomputer, governs the operation of the system.

The output switching unit 16, controlled by, preferably a computerized main control unit 14, safely connects a patient to the high energy sources via internal or external electrodes 18, 20, and provides the main control unit 14 with the required signals, in order to make it possible to determine the exact state of the patient and take the required steps.

In operation, the conventional charger 4, which may not necessarily be an integral part of the system, is used to charge the low voltage storage 6 and the battery 8 and to keep both at an adequate voltage level required to be available in case of need, according to decisions made automatically by the main control unit 14 as governed by cardiologists. The energy stored in the battery 8 is used as the energy source of the electronic circuitry and can be used as a secondary source of energy for maintaining the low voltage energy storage 6 at a level that can provide extended use of the defibrillator system.

The fast charger 10 is activated according to the results of the analysis made by the main control unit 14. Only when the results show that a predetermined, adequate voltage discharge is required, and not before, is the charger activated, so as to avoid unnecessary presence of high voltage within the system.

The high voltage capacitor 12 is used to store the energy delivered by the charger 10 from the energy stored in the low voltage energy storage 6 and makes this L2006/000330

energy available at the required time, to be delivered to the patient according to the analysis made by unit 14.

Optionally, the system 2 may also include a pulse-wave shaper 22 connected between the voltage capacitor 12 and the output switching unit 16, for shaping the voltage pulses produced by the selected energy voltage capacitor 12.

The unit 14 may advantageously also be capable of monitoring the state of the patient. In a preferred embodiment, an internal or external electrode pair 24, 26 connects the patient with ECG measurement means (not shown), integrated in the control unit 14. According to the ECG signals thus measured, the unit 14 may effect the recommended treatment, as known in the art, namely, either activate a strong electrical pulse, in the event of heart fibrillation, or no pulse at all, in the event of normal heart functioning. Such an "automatic trigger" may necessitate use of a microcomputer or microcontroller or hard wired digital circuits, to implement predefined decision routines for obtaining the recommended conclusion based on the ECG measurements. The decision as to the state of the patient and the required treatment are transferred as electrical control signals and may also be available to the user by means of an optional display screen 28, and/or voice warning.

A common pair of adhesive electrodes may be used to replace both high voltage electrodes 18, 20 and the ECG electrodes 24, 26. It should be clear that in any case electronic separation between ECG signal and high energy pulses is required, since both are transferred via the same pair of electrodes. In case of VT, the ECG signals may be used to synchronize the generation of the high voltage pulse. In this case, a further condition for generation of the high voltage pulse is the detection of an ECG pulse.

Control unit 14 may also include manual or automatic means for controlling the energy of the electrical pulse applied to electrodes 18, 20. The microcomputer in the control unit 14 computes the required energy to be applied according to the results of monitoring the state of the patient as indicated by the control signals. Power level control signals are thus generated in the unit 14 and are used to set the actual power level of the generated high voltage pulse. The required defibrillation energy level is automatically set according to per-se known guidelines.

Control unit 14 also generates a signal to control the activation of the switching unit 16, and the amplitude of the voltage of the applied pulse.

When the system is used, the pair of electrodes is applied to the patient's chest. The computerized system performs a real time analysis of the electrocardiographic signal received through the electrodes which are applied to the patient's chest. According to the results of the analysis and if a ventricular tachycardia fibrillation signal or cardiac arrest is detected, after voice and visual warning, an adequate waveform is applied to the patient. (Synchronization with a QRS wave, if detectable, is also possible). The waveform and intensity of the current used are calculated using the electrical parameters obtained during the described analysis phase.

Since the user of the system can be a non-professional, the defibrillator may include or be part of means 30, such as a cellular phone adapted to the above, for visually and vocally guiding the user during the whole treatment session. When the user suspects that a heart attack has occurred, the user turns on the means 30, which may present instructions on how to proceed, which instructions may be in the form of visual display messages and/or vocal messages. These may be prerecorded messages in the control unit's memory, which are displayed taking into consideration the patient's state, as well.

The defibrillator means 30 may provide for automatically calling the first aid services over the telephone or wirelessly using dialling circuits and wireless transmitters, as known in the art. Moreover, digital memory means may be used to log or store the whole treatment process, to allow the medical personnel to reconstruct the treatment actions and the patient's reactions, such as to better plan continued treatment.

Other implementations of the present invention are possible. For example, one common microcomputer or microcontroller (not shown) may be used both, for analyzing the ECG signals and to control the power of the pulse applied in the control unit. The electrodes should have a sufficient contact area to reliably transfer the low voltage ECG signals and the high voltage pulse to the patient. A round electrode, e.g., 10 cm or larger, is recommended. In all cases, both monophasic and biphasic waveforms can be generated by the system and are part of the described invention.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrated embodiments and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

WHAT IS CLAIMED IS:

1. A portable defibrillation system, comprising: a low-voltage electrical energy storage; a battery; a predetermined voltage fast charger connected to said energy storage and fed by it; a predetermined energy, predetermined voltage capacitor connected to, and chargeable by, said charger, an output switching unit connected to said capacitor having an output connectable to a pair of electrodes, and a control unit operationally connected to said energy storage, fast charger, voltage capacitor and output switching unit.

2. The system as claimed in claim 1, wherein said low voltage energy storage is rechargeable.

3. The system as claimed in claim 1, wherein said battery is rechargeable.

4. The system as claimed in claim 1, further comprising a charger connectable to said energy storage and/or battery.

5. The system as claimed in claim 1, wherein said battery is a lithium battery.

6. The system as claimed in claim 1, wherein said control unit further comprises a display screen.

7. The system as claimed in claim 1, further comprising a wireless communication system operationally connectable to said control unit.

8. The system as claimed in claim 1, wherein said control unit is a microcomputer-based control unit.

9. The system as claimed in claim 8, wherein said microcontroller includes ECG measuring and analyzing capability.

10. The system as claimed in claim 9, further comprising a pair of built-in or external electrodes connectable or connected to said microcontroller.

11. The system as claimed in claim 1 further comprising a pulse- wave shaper connected between said predetermined energy voltage capacitor and said output switching unit.

12. A method for generating a predetermined voltage pulse for defibrillation, comprising: providing a low-voltage electrical energy storage; a battery; a predetermined voltage fast charger connected to said energy storage and fed by it; a predetermined energy, predetermined voltage capacitor connected to, and chargeable by, said charger; an output switching unit connected to said capacitor having an output connectable to a pair of electrodes; a control unit operationally connected to said energy storage, fast charger, voltage capacitor and output switching unit; charging the low voltage energy storage; applying stored voltage energy to a predetermined voltage fast charger, and charging a predetermined energy, predetermined voltage capacitor.

13. The method as claimed in claim 12, further comprising activating said switching unit to transfer the predetermined voltage pulse stored in said capacitor to the electrodes connected to said switching unit.

14. The method as claimed in claim 12, further comprising the step of shaping the pulse wave generated by the discharge of said capacitor prior to applying it to the electrodes.

15. The method as claimed in claim 12, further comprising: providing an ECG measuring and analysing means; applying a pair of electrodes to a patient for measuring ECG activity data, and transferring the measured data to the control unit for governing the operation of said switching unit.

16. The method as claimed in claim 15, further comprising providing a microprocessor and processing the ECG activity data received for determining the energy required to be applied to the patient.

17. The method as claimed in claim 15, further comprising providing a display screen and displaying the measured ECG activity data on said screen.

18. The method as claimed in claim 12, further comprising providing a display screen and a speaker, and instructing the user to follow a predetermined defibrillation procedure.