NOVEL BIPHASIC OR MULTIPHASIC PULSE GENERATOR AND METHOD
A dynamically adjustable biphasic or multiphasic pulse generation system and method are provided. The dynamically adjustable biphasic or multiphasic pulse generator system may be used as a pulse generation system for a defibrillator or other type of electrical stimulation medical device.
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This application is a continuation and claims priority under 35 USC 120 to U.S. patent application Ser. No. 14/661,949 filed on Mar. 18, 2015 that in turn is a continuation in part of and claims priority under 35 USC 120 to U.S. patent application Ser. No. 14/303,541, filed on Jun. 12, 2014 and entitled “Dynamically Adjustable Multiphasic Defibrillator Pulse System And Method” which in turn claims priority under 35 USC 120 and claims the benefit under 35 USC 119(e) to U.S. Provisional Patent Application Ser. No. 61/835,443 filed Jun. 14, 2013 and titled “Dynamically Adjustable Multiphasic Defibrillator Pulse System and Method”, the entirety of all of which are incorporated herein by reference.
FIELDThe disclosure relates to medical devices and in particular to devices and methods that generate and deliver therapeutic treatment pulses used in medical devices, such as cardioverters and defibrillators, neuro-stimulators, musculo-skeletal stimulators, organ stimulators and nerve stimulators. More specifically the disclosure relates to the generation by such medical devices of a new and innovatively shaped biphasic or multiphasic pulse waveform.
BACKGROUNDIt is well known that a signal having a waveform may have a therapeutic benefit when the signal is applied to a patient. For example, the therapeutic benefit to a patient may be a treatment that is provided to the patient. The therapeutic benefit or therapeutic treatment may include stimulation of a part of the body of the patient or treatment of a sudden cardiac arrest of the patient. Existing systems that apply a signal with a waveform to the patient often generate and apply a well-known signal waveform and do not provide much, or any, adjustability or variability of the signal waveform.
In the context of defibrillators or cardioverters, today's manual defibrillators deliver either an older style Monophasic Pulse (a single high energy single polarity pulse) or the now more common Biphasic Pulse (consisting of an initial positive high energy pulse followed by a smaller inverted negative pulse). Today's implantable cardioverter defibrillators (ICDs), automated external defibrillators (AEDs) and wearable cardioverter defibrillators (WCDs) all deliver Biphasic Pulses with various pulse phase lengths, high initial starting pulse amplitude and various pulse slopes. Each manufacturer of a particular defibrillator, for commercial reasons, has their own unique and slightly different exact timing and shape of the biphasic pulse for their devices' pulses, although they are all based off of the standard biphasic waveform design. Multiple clinical studies over the last couple of decades have indicated that use of these variants of the biphasic waveform has greater therapeutic value than the older monophasic waveform does to a patient requiring defibrillation therapy and that these standard biphasic waveforms are efficacious at appreciably lower levels of energy delivery than the original monophasic waveforms, and with a higher rate of resuscitation success on first shock delivery.
Thus, almost all of the current defibrillator products that use a biphasic waveform pulse have a single high-energy reservoir, which, while simple and convenient, results in severe limitation on the range of viable pulse shapes that can be delivered. Specifically, the second (or Negative) phase of the Biphasic waveform is currently characterized by a lower amplitude starting point than the first (or Positive) phase of the Biphasic waveform, as shown in
The standard biphasic pulse waveform has been in common usage in manual defibrillators and in AEDs since the mid-1990s, and still results in energy levels of anywhere from 120 to 200 joules or more being delivered to the patient in order to be efficacious. This results in a very high level of electrical current passing through the patient for a short period of time which can lead to skin and flesh damage in the form of burns at the site of the electrode pads or paddles in addition to the possibility of damage to organs deeper within the patient's body, including the heart itself. The significant amounts of energy used for each shock and the large number of shocks that these AED devices are designed to be able to deliver over their lifespan, has also limited the ability to further shrink the size of the devices.
WCDs generally need to deliver shocks of 150-200 joules in order to be efficacious, and this creates a lower limit on the size of the electrical components and the batteries required, and hence impacts the overall size of the device and the comfort levels for the patient wearing it.
ICDs, given that they are implanted within the body of patients, have to be able to last for as many years as possible before their batteries are exhausted and they have to be surgically replaced with a new unit. Typically ICDs deliver biphasic shocks of up to a maximum of 30-45 joules, lower than is needed for effective external defibrillation as the devices are in direct contact with the heart tissue of the patient. Subcutaneous ICDs, differ slightly in that they are not in direct contact with the heart of the patient, and these generally deliver biphasic shocks of 65-80 joules in order to be efficacious. Even at these lower energy levels there is significant pain caused to the patient if a shock is delivered in error by the device. Most existing devices are designed to last for between 5-10 years before their batteries are depleted and they need to be replaced.
Another, equally common type of defibrillator is the Automated External Defibrillator (AED). Rather than being implanted, the AED is an external device used by a third party to resuscitate a person who has suffered from sudden cardiac arrest.
A typical protocol for using the AED 800 is as follows. Initially, the person who has suffered from sudden cardiac arrest is placed on the floor. Clothing is removed to reveal the person's chest 808. The pads 804 are applied to appropriate locations on the chest 808, as illustrated in
The disclosure is applicable to various medical devices including all defibrillator types: external (manual, semi-automated, and fully automated), wearable, implantable and subcutaneous implantable. In addition to defibrillators, the medical device may also be cardioverters and external/internal pacers, as well as other types of electrical stimulation medical devices, such as: neuro-stimulators, musculo-skeletal stimulators, organ stimulators and nerve/peripheral nerve stimulators, whether the devices are external or implantable. The novel biphasic or multiphasic waveform generator may be particularly useful for any type of defibrillator and examples of the novel biphasic or multiphasic waveform generator system will be described in the context of a defibrillator for illustration purposes. It will be appreciated, however, that the novel biphasic or multiphasic waveform generator may generate and deliver a much wider range of waveforms than has previously been possible in the art (or as shown in the examples) including a new generation/family of novel biphasic or multiphasic waveforms, as shown in
The novel biphasic or multiphasic waveform generator can be embodied in a number of different ways, constituting a range of different potential circuit designs all of which are within the scope of this disclosure since any of the circuit designs would be able to generate and deliver a wide range of biphasic and/or multiphasic waveforms including the new family/generation of low energy biphasic and/or multiphasic waveforms where the first phase of the waveform has a lower amplitude than the second phase of the waveform.
The novel biphasic or multiphasic pulse waveform 110 may have one or more first phases and one or more second phases wherein the first and second phases may be opposite polarities. In one biphasic waveform example, the first phase may be a positive phase, the second phase may be a negative phase and the second phase of the waveform may be larger in amplitude than the amplitude of the first phase of the waveform as shown in
The control logic unit 108 may be coupled to and/or electrically connected to the multiphasic or biphasic waveform generator 104 and the energy source 106 to control each of those components to generate various version of the biphasic or multiphasic pulse waveform 110. The energy source 106 may be one or more power sources and one or more energy reservoirs. The control logic unit 108 may be implemented in hardware. For example, the control logic unit 108 may be a plurality of lines of computer code that may be executed by a processor that is part of the medical device. The plurality of lines of computer code may be executed by the processor so that the processor is configured to control the multiphasic or biphasic waveform generator 104 and the energy source 106 to generate the biphasic or multiphasic pulse waveform 110. In another embodiment, the control logic unit 108 may be a programmable logic device, application specific integrated circuit, a state machine, a microcontroller that then controls the multiphasic or biphasic waveform generator 104 and the energy source 106 to generate the biphasic or multiphasic pulse waveform 110. The control logic unit may also include analog or digital switching circuitry when the high voltage switching component 109 is part of the control logic unit 108.
As shown in
The energy source 106 is not limited to any particular number of energy reservoirs (such as capacitors) or energy sources (such as batteries). Thus, the medical device system 10 may have a plurality or “n” number (as many as wanted) of subsystems 12, 14 that together can be utilized to generate the various multiphasic or biphasic waveforms. In the example embodiments shown in
Each subsystem 12, 14 of each side, as shown in
In another embodiment (see
In another embodiment (see
Another embodiment of the system makes use of a direct current generation source in order to generate the initial phase of the waveform and then uses one or more reservoirs of stored electrical energy in order to generate the second phase of the waveform and any additional phases of the waveform. The energy reservoirs used may be supplied by one or more energy sources.
Another embodiment of the system makes use of a direct current generation source in order to generate the initial phase of the waveform and then uses one or more additional direct current generation sources, configured alone, together, or else in combination with reservoirs of stored electrical energy, in order to generate the second phase of the waveform and any additional phases of the waveform. The energy reservoirs used may be supplied by one or more energy sources.
In additional embodiments, the pulse generator may be configured with the circuitry, processors, programming and other control mechanisms necessary to separately and individually vary the phase timings, the inter-phase pulse timing(s), the phase tilts and the phase amplitudes necessary to customize and optimize the waveform for the patient at hand and for the specific therapeutic purpose for which the waveform is being used.
The above described functions may be accomplished through the use of a fast switching high-energy/voltage switch system 109 which can be either analog or digital in nature or even some hybrid of the two approaches as shown in
Other embodiments of the system discharge part of the waveform's initial phase energy through the use of a statically or dynamically allocated group of resistive power splitters (see
Many embodiments of the system can make use of one or more additional circuitry modules or subsystems intended to alter the RC constant of the pulse delivery circuitry for one or more of the pulse phases, and hence alter the tilt of the phase of the pulse waveform involved. These modules or subsystems can consist of an array of capacitors or an array of resistors, or of a combination of the two (see
In some embodiments of the system, the system may provide for the recharging of individual energy reservoirs by the energy sources during times (including inter-phase pulse times) that an individual energy reservoir is not selected for discharge. This provides the opportunity to interlace equivalent amplitude initial multiphasic pulses utilizing several different high energy reservoirs.
While the foregoing has been with reference to a particular embodiment of the disclosure, it will be appreciated by those skilled in the art that changes in this embodiment may be made without departing from the principles and spirit of the disclosure, the scope of which is defined by the appended claims.
Claims
1. A multiphasic pulse generator, comprising:
- a pulse waveform generator that generates a pulse waveform having at least one first phase of the pulse waveform and at least one second phase of the pulse waveform, wherein the first phase has an amplitude whose value is less than an amplitude of the second phase and wherein the first phase has a polarity and the second phase has an opposite polarity to the first phase;
- a power source;
- a first subsystem, coupled to the power source to draw power from the power source, that generates at least the first phase of the pulse waveform, the subsystem having an energy reservoir and a high voltage switch;
- a second subsystem, coupled to the power source to draw power from the power source, that generates at least the second phase of the pulse waveform, the second subsystem having a second energy reservoir and a second high voltage switch; and
- a control logic unit that includes the high voltage switch and the second high voltage switch and controls the first and second subsystems to generate the pulse waveform having the at least one first phase and the at least one second phase.
2. The generator of claim 1, wherein the first subsystem further comprises a high voltage generator and the energy reservoir of the first subsystem further comprises one or more capacitors.
3. The generator of claim 2, wherein the second subsystem further comprises a high voltage generator and the energy reservoir of the second subsystem further comprises one or more capacitors.
4. The generator of claim 1, wherein the first subsystem further comprises a high voltage generator and wherein the second subsystem further comprises a high voltage generator.
5. The generator of claim 4, wherein the energy reservoir of the first subsystem further comprises one or more capacitors and the energy reservoir of the second subsystem further comprises one or more capacitors.
6. The generator of claim 1, wherein the power source further comprises a high voltage generator.
7. The generator of claim 6, wherein the energy reservoir of the first subsystem further comprises one or more capacitors.
8. The generator of claim 7, wherein the energy reservoir of the second subsystem further comprises one or more capacitors.
9. The generator of claim 1, wherein the generated pulse waveform has a plurality of first phases and a plurality of second phases to generate a multiphasic pulse waveform.
10. The generator of claim 1, wherein the generated pulse waveform has a single first phase and a single second phase to generate a biphasic pulse waveform.
11. The generator of claim 1, wherein the generated pulse waveform has the first phase that has a positive polarity and the second phase that has a negative polarity.
12. The generator of claim 1, wherein the generated pulse waveform has the first phase that has a negative polarity and the second phase that has a positive polarity.
13. The generator of claim 1, wherein the generated pulse waveform has an energy of between 0.1 to 200 joules of energy delivered to a patient during the first phase and second phase of the generated pulse waveform and an inter-pulse period between the first and second phases.
14. The generator of claim 13, wherein the energy of the generated pulse waveform is delivered to the patient during a 2 ms to 20 ms time period.
15. The generator of claim 1 further comprising an adjustment component that adjusts a slope of at least one phase of the pulse waveform or an amplitude of at least one phase of the pulse waveform.
16. The generator of claim 15, wherein the adjustment component is an array of capacitors wherein one or more capacitors are selected to adjust a slope of at least one phase of the pulse waveform or an amplitude of at least one phase of the pulse waveform.
17. The generator of claim 16, wherein the array of capacitors is one of capacitors connected in series, capacitors connected in parallel and capacitors connected in series and parallel.
18. The generator of claim 15, wherein the adjustment component is an array of resistors wherein one or more resistors are selected to adjust a slope of at least one phase of the pulse waveform or an amplitude of at least one phase of the pulse waveform.
19. The generator of claim 1, wherein the power source is one of a battery and a AC power source.
20. The generator of claim 1 further comprising an H-bridge circuit that delivers the pulse waveform to a patient.
21. A method for generating a multiphasic pulse, comprising:
- providing a power source;
- generating at least a first phase of a pulse waveform using a first subsystem coupled to the power source to draw power from the power source and having an energy reservoir and a high voltage switch;
- generating at least a second phase of the pulse waveform using a second subsystem coupled to the power source to draw power from the power source, that generates at least the second phase of the pulse waveform, the second subsystem and having a second energy reservoir and a second high voltage switch;
- controlling, using control logic including the high voltage switch and the second high voltage switch, the first and second subsystems to generate the pulse waveform having the at least one first phase and the at least one second phase; and
- wherein the first phase has an amplitude whose value is less than an amplitude of the second phase and wherein the first phase has a polarity and the second phase has an opposite polarity to the first phase.
22. The method of claim 21, wherein controlling the first and second subsystems further comprises generating a plurality of first phases and a plurality of second phases to generate a multiphasic pulse waveform.
23. The method of claim 21, wherein controlling the first and second subsystems further comprises generating a single first phase and a single second phase to generate a biphasic pulse waveform.
24. The method of claim 21, wherein the generated pulse waveform has the first phase that has a positive polarity and the second phase that has a negative polarity.
25. The method of claim 21, wherein the generated pulse waveform has the first phase that has a negative polarity and the second phase that has a positive polarity.
26. The method of claim 21, wherein the generated pulse waveform has an energy of between 0.1 to 200 joules of energy delivered to a patient during the first phase and second phase of the generated pulse waveform and an inter-pulse period between the first and second phases.
27. The method of claim 26, wherein the energy of the generated pulse waveform is delivered to the patient during a 2 ms to 20 ms time period.
28. The method of claim 21 further comprising adjusting a slope of at least one phase of the pulse waveform or an amplitude of at least one phase of the pulse waveform.
29. The method of claim 21 further comprising delivering the pulse waveform to a patient using an H-bridge circuit.
Type: Application
Filed: May 22, 2017
Publication Date: Sep 7, 2017
Applicant:
Inventors: Douglas M. Raymond (Livermore, CA), Peter D. Gray (Vallejo, CA), Walter T. Savage (Concord, CA), Shelley J. Savage (Concord, CA)
Application Number: 15/601,386