WO1998044989A1

WO1998044989A1 - Automated external defibrillator battery memory, dual cell, and removable configurations

Info

Publication number: WO1998044989A1
Application number: PCT/US1998/007139
Authority: WO
Inventors: Steven D. Barkley; Robert K. Johnson
Original assignee: Survivalink Corporation
Priority date: 1997-04-08
Filing date: 1998-04-08
Publication date: 1998-10-15
Also published as: AU7106398A

Abstract

An AED (10) includes a housing. Electronic circuitry is disposed in the housing for delivery of an electric shock to a stricken patient. A removable battery pack (16) is selectively, operably, and communicatively coupled to the electronic circuitry. The battery pack has an anticipatory detector for generating an anticipatory signal to the electronic circuitry. The signal indicates to the electronic circuitry that the disengagement of the battery pack from the AED is imminent. The present invention further includes a method for ensuring that the high voltage storage circuits of the AED are safely discharged prior to disengaging the battery pack from the AED. In addition, the defibrillator battery pack also comprises a housing (202) having a first set of battery cells having an upper set, a lower set of cells, and a second set of battery cells connected in parallel with one of the upper or the lower sets of the first set of battery cells. A defibrillator battery includes at least one battery cell, a housing surrounding the at the least one battery cell, and a memory connected to the at least one battery cell. The memory can be positioned inside of the housing that surrounds the at least one battery cell. The defibrillator battery can be used with a defibrillator including a battery status indicator which communicates with the defibrillator battery to indicate the status of the defibrillator battery.

Description

AUTOMATED EXTERNAL DEFIBRILLATOR BATTERY MEMORY, DUAL CELL, AND REMOVABLE CONFIGURATIONS

TECHNICAL FIELD

The present invention relates to an automated external defibrillator (AED) and a battery that powers the AED. More particularly, the present invention is an AED with a battery status indication gauge and a battery pack, the battery pack being removable and containing a plurality of individual battery cells, preferably arranged in a dual cell stack configuration, and is designed for use with the AED.

BACKGROUND OF THE INVENTION

There is a need in the industry for a battery pack for use with an AED. Preferably, the battery pack should have the following characteristics. The battery pack should be removably coupled to the AED. When coupled to the AED, the battery pack should be held semi-rigidly in place such that virtually no relative motion occurs between the battery pack and the AED. Additionally, the battery pack should be held securely in place once joined to the AED so that it is very unlikely that the battery pack will become inadvertently disengaged from the AED.

An AED typically uses integral batteries to power various electronic components of the AED and to generate the very high voltages necessary for shocking a patient. The AED has the capability of delivering very high voltage impulses to a stricken patient. Such voltages may exceed 2,000 volts. The high voltages are typically developed from the relatively low voltage battery by charging a capacitor bank prior to delivery of the shock to the patient. Removal of the battery pack from the AED removes power from the electronic components that provide control to the capacitor bank. If the battery is removed from the AED when the capacitors are charged to the high voltage, there is no control remaining over the ultimate discharge of the capacitors. Accordingly, in addition to the aforementioned characteristics, there is a need to sense the imminent removal of the battery from the AED and, while there is still power to the various electronic components and control remaining, to safely discharge the capacitors.

Further, a defibrillation shock electrical pulse selectively applied to a patient is generated within a defibrillator by high voltage generation circuits with energy stored within a capacitor bank of the defibrillator. The capacitor bank forms part of an electrical system along with the battery pack which provides the energy to be stored in the capacitor banks. These shock pulses carry a considerable amount energy of about 200 to 400 joules. This energy, and the generation of the shock pulse, can be dangerous if not handled properly. Accordingly, maintaining control of this potent electrical force under all conditions is imperative.

A microprocessor is typically used to control a defibrillator and its supporting electrical system for charging and generating the shock pulse. Failure of the microprocessor during charging of a capacitor bank or during application of a shock pulse can be detrimental to the patient since the microprocessor would cease control of the charging or application of the shock pulse. The most basic step in maintaining control of the defibrillator with the microprocessor includes maintaining a reliable supply of power to the microprocessor to insure its operation.

Known defibrillator battery packs have a plurality of battery cells connected in series with multiple sets of cells arranged in parallel. For example, as shown in Figure 16, a prior art battery pack 5 includes two sets of four battery cells with a first set 7 of battery cells (6A-6D) and a second set 8 of battery cells (6A-6D) connected in parallel. Diodes 9 are arranged at the top of each set of cells. These diodes protect the cells from attempts to charge each other.

A microprocessor of the defibrillation device can be powered by a 5V supply generated with an external regulator connected to the 12N cell arrangement. Due to inherent inefficiencies, this method wastes energy and can result in a loss of the 5V supply when the 12V supply is lost due to battery depletion or other battery failure. When the voltage of the 12V cell arrangement fluctuates or dips considerably, the 5 V supply drops below a . level sufficient to operate the microprocessor. This voltage drop can cause the microprocessor to malfunction and to no longer control operation of the defibrillation device. Significantly, this lack of control includes no longer controlling the capacitor charging operation already in process. With the microprocessor no longer functioning, the capacitor charging operation continues without regulation by the microprocessor resulting in a charged capacitor bank without safe constraint. Accordingly, a nonfunctioning microprocessor due to a failed battery cell can cause a dangerous condition of having a fully charged defibrillator device with no safety controls or result in misapplication of an ongoing defibrillation shock to a patient.

The use of lithium battery cells in defibrillator battery packs carries additional special considerations. For example, when using lithium sulfur dioxide battery cells, it is critical that the cells not be reversed biased. Reverse biasing can occur if the cells are not properly arranged when connected in parallel and if one attempts to recharge the lithium battery cells in the typical battery pack configuration. If the lithium battery cells become reversed biased, overheating will occur in an irreversible battery cell damaging process. Overheating of the cells causes pressure to build up inside the cells until a violent and noxious outgasing occurs. This battery characteristic limits unrestricted transportation of conventional lithium battery cell packs and the manner of their deployment. Accordingly, lithium battery cells for use in a conventional battery pack configuration require special handling.

In addition, constant readiness of the AED is imperative. This readiness must extend to the power source of the AED, which is commonly a lithium battery. Lithium batteries are characterized by the delivery of a relatively constant voltage over a period of time which then terminates abruptly with little or no warning as the battery loses its ability to deliver energy. When using a defibrillator, an abrupt failure of the power source of a defibrillator without warning is unacceptable. Accordingly, some AEDs include the capability to perform a self test to insure that the battery has energy and that the AED can properly use that energy to deliver a shock. However, these self tests do not reveal the amount of energy left in the battery. Knowing the remaining capacity of the battery is helpful for determining how many more rescues can be performed with an AED, for determining when to replace a battery, and above all, for avoiding battery failure during use of an AED.

SUMMARY OF THE INVENTION The AED of the present invention substantially meets the aforementioned needs. The AED is configured to sense the imminent removal of the battery from the AED and, while there is still power to the various electronic components and control remaining, safely discharge the capacitors of the AED. Means are provided to anticipate the disconnecting of the battery from the AED so that the discharge is accomplished in a controlled manner.

The AED of the present invention has a housing. Electronic circuitry is disposed in the housing for delivery of an electric shock to a stricken patient. A removable battery pack is selectively, operably, communicatively coupled to the electronic circuitry. The battery pack has an anticipatory detector for generating an anticipatory signal to the electronic circuitry. The signal indicates to the electronic circuitry that the disengagement of the battery pack from the AED is imminent. The present invention further includes a method for ensuring that the high voltage storage circuits of the AED are safely discharged prior to disengaging the battery pack from the AED.

A defibrillator battery pack of the present invention comprises a housing having a first set of battery cells having an upper set and a lower set of cells and a second set of battery cells connected in parallel with at least one cell of the first set of battery cells. The first set of battery cells is used for charging a capacitor bank of a defibrillator. The second set of battery cells cannot be used for charging and is only used for developing a nominal 5 volts to drive a microprocessor and other circuitry components of an electrical control system of the defibrillator. This arrangement effectively increases the life or energy capacity of the battery in the lower voltage range necessary for operating the microprocessor and permits the elimination of two battery cells that would otherwise be required in a conventional defibrillator battery pack. Moreover, even when the battery pack does not have enough voltage to adequately charge the capacitor banks of the defibrillator for delivering a shock, the second set of battery cells are available to drive the microprocessor and maintain the intelligence of the electrical control system. In other words, the battery cells supplying power to the microprocessor will always fail after, and not before, a failure of the battery cells supplying power for charging the capacitor bank. This feature insures a safe and graceful shutdown of the microprocessor. A defibrillator battery of the present invention includes at least one battery cell, a housing surrounding the at least one battery cell, and a memory connected to the at least one battery cell. In a preferred embodiment, the memory is positioned inside of the housing that surrounds the at least one battery cell. The defibrillator battery can be used with a defibrillator of the present invention, which includes a battery status indicator which communicates with the defibrillator battery to indicate the status of the defibrillator battery.

A method of determining the defibrillator battery status using the defibrillator battery and associated battery status indicator enables an operator to always determine the remaining charge of the battery and to determine when to replace the battery. This defibrillator battery, and associated battery status indicator, insures constant readiness of the AED for defibrillating a patient by preventing defibrillator failure due to a reduced charge battery.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a perspective view of an automated external defibrillator. Figure 2 is a perspective view of the AED of Figure 1 having the lid opened.

Figure 3 is a perspective view of the AED having a rescue information data card positioned for insertion therein. Figure 4 is a plan view of a diagnostic display of the AED.

Figure 5 is a block diagram of an electrical system of the AED. Figure 6 is a front perspective view of the battery pack of the present invention.

Figure 7 is a rear perspective view of the battery pack disengaged from the AED.

Figure 8 is a rear perspective view of the battery pack positioned with respect to the AED just prior to engagement therewith.

Figure 9 is a rear perspective view of the battery pack with the hinge end thereof partially engaged with the AED. Figure 10 is a front perspective view of the battery pack and AED positioned as depicted in Figure 9.

Figure 11 is a rear quarter perspective view of the battery pack being rotated into engagement with the AED in a position just prior to engagement of the latch end of the battery pack with the AED. Figure 12 is a top planar view of the bottom half of the AED with the battery pack engaged therewith.

Figure 13 is a schematic diagram of the battery removal safety circuit of the present invention.

Figure 14 is a rear elevational view of the battery pack. Figure 15 is a top elevational view of the battery pack.

Figure 16 is a schematic diagram of a typical prior art defibrillator battery pack circuit.

Figure 17 is a schematic illustration of a portion of an electrical system of an automated external defibrillator incorporating a battery circuit of the present invention.

Figure 18 is a schematic diagram of a preferred embodiment of the dual cell stack battery pack circuit of the present invention. Figure 19 is a schematic diagram of an alternative embodiment of the dual cell stack battery pack circuit according to the present invention.

Figure 20 is a schematic diagram of a further alternative embodiment of the dual cell stack battery pack circuit of the present invention.

Figure 21 is a schematic diagram of a further alternative embodiment of the dual cell stack battery pack circuit of the present invention.

Figure 22 is a cut away view of a battery pack illustrating individual battery cells and the memory device.

Figure 23 is a schematic view of a circuit incorporating a memory component of the present invention.

Figure 24 is a schematic view of a portion of electrical system of an AED incorporating a battery pack and status indicator of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to Figures 1-5, an emergency electronic device and, more particularly, an automated external defibrillator (AED) 10 with the ability to store rescue information may be appreciated. The stored rescue information may include patient data, AED operational data and/or sound recorded proximate AED 10.

As shown, AED 10 includes a plastic case 12 with a carrying handle 14 on the front portion. A battery compartment (as will be later described) in the rear portion of AED 10 encloses a battery pack 16, the battery pack 16 being removably disposed within the battery compartment. A visual maintenance indicator 20 and a data access door 22, which conceals a serial connector port 23 and a data card slot 24, (Figure 3) are located on the outside of case 12 for easy access by an operator. Case 12 also includes an electrode compartment 26 defined in the top portion of case 12 (depicted in Figure 2). An illuminatable rescue/resume switch 18 is disposed adjacent to electrode compartment 26. The electrode compartment 26 is closed by lid 27, lid 27 being mounted to case 12 by hinges (not visible). Lid 27 covers the rescue/resume switch 18 when the lid 27 is in the closed disposition, the closed disposition being depicted in Figures 1 and 3. The rescue/resume switch 18 is actually a single switch with illuminatable labels alternatively indicating the "resume" 49 or the "rescue" 48 function, "rescue" 48 appearing above the switch 18 and "resume" 49 appearing below the switch 18, depending on whether AED 10 is cuing the operator to perform a rescue or resume operation by activating switch 18. A data card storage bracket 28 is formed on the inside of the lid 27 for holding a data card 29 for use in recording the parameters of a rescue intervention. The data card 29 is insertable into the data card slot 24, as indicated by Arrow A in Figure 3. A bayonet-type releasable latch 30 holds lid 27 closed when AED 10 is not in use by engaging a receiving recess 31 (Figure 2) defined in the floor of electrode compartment 26. Lid 27 is opened by grasping the underside of latch 30, pushing in to disengage latch 30 from recess 31 and lifting upward on latch 30 to gain access to electrode compartment 26. Opening the lid 27 activates a lid open switch 25. The lid open switch 25 may be any suitable switch such as a reed switch or a Hall effect switch.

An electrode connector 32, speaker 34 and diagnostic display panel 36 are disposed on case 12 within electrode compartment 26. The diagnostic display panel 36 is disposed adjacent to the illuminatable rescue/resume switch 18. Diagnostic display panel 36 includes visual "Battery Status" indicator light 38, "Electrodes" indicator light 40, and "Service" indicator light 42. An instruction and safety label is located in the inside surface of lid 27. Electrodes 50 are disposed within electrode compartment 26 and are removably connected to electrode connector 32 by connector 58. Electrodes 50 typically include a pair of electrodes for attachment to a patient in a sealed package 60.

Figure 5 is a block diagram of the electrical system 70 of AED 10. The overall operation of AED 10 is controlled by a digital microprocessor-based control system 72, which includes a processor 74 interfaced to program memory 76, data memory 77, event memory 78 and real time clock 79. The digital microprocessor-based control system 72 may be initiated by operation of the lid open switch 25 when the lid 27 is opened and may be deactivated by operation of the lid open switch 25 when the lid 27 is closed. The operating program executed by processor 74 is stored in program memory 76. Data memory 77 is used by processor 74 as a scratch pad memory during the execution of the operating program.

Electrical power is preferably provided by a lithium sulphur dioxide battery 80 which is enclosed in battery pack 16, battery pack 16 being removably positioned within the battery compartment. Battery 80 may be comprised of a plurality of battery cells that are electrically coupled together. Battery 80 is connected to power generation circuit 82. The "Battery Status" indicator light 38 indicates the charge status of battery 80 and prompts the operator to replace battery 80 when needed.

During normal operation, power generation circuit 82 generates a 12V supply and regulated ±5V and 3.3V supplies with the power provided by battery 80. The +5V output of battery 80 functions as a back-up battery to power components of electrical system 70 during the execution of self-tests and to activate maintenance indicators and alarms (as described below). Although not separately shown in Figure 5, power generation circuit 82 includes voltage level sensing circuits which are coupled to processor 74. The voltage level sensing circuits provide low battery level signals to processor 74, for illumination of the "Battery Status" indicator light 38. Power generation circuit 82 is also connected to power control circuit 84 and processor 74. Power control circuit 84 is connected to lid switch 25, watch dog timer 86, real time clock 79 and processor 74. Lid switch 25 provides signals to processor 74 indicating whether lid 27 is open or closed. Serial connector port 23 is coupled to processor 74 for two-way serial data transfer using an RS-232 protocol. Rescue/resume switch 18 (and the "rescue" 48 and "resume" 49 indications thereof), maintenance indicator 20, and "Battery Status" indicator light 38, "Electrodes" indicator light 40, and "Service" indicator light 42 of diagnostic display panel 36, as well as Voice circuit 87 and piezoelectric audible alarm 88, are connected to processor 74. Voice circuit 87 is further connected to speaker 34. In response to voice prompt control signals from processor 74, voice circuit 87 and speaker 34 generate audible voice prompts to an operator.

High voltage generation circuit 83 is also connected to and controlled by processor 74. High voltage generation circuits, such as circuit 83, are generally known and disclosed, for example, in the commonly assigned Persson, et al. U.S. Patent No. 5,405,361, which is hereby incorporated by reference. In response to charge control signals provided by the processor 74, high voltage generation circuit 83 is operated in a charge mode during which one set of semiconductor switches (not separately shown) causes a plurality of capacitors (also not shown), to be charged in parallel to about 400V each by the power supplied by power generation circuit 82. Once charged, and in response to discharge control signals provided by processor 74, high voltage generation circuit 83 is operated in a discharge mode during which the capacitors are discharged in series by another set of semiconductor switches (not separately shown) to produce the high voltage defibrillation pulses. The defibrillation pulses are applied to the patient through electrodes 50. The electrodes 50 are connected by connectors 58 to electrode connector 32, which is in turn connected to high voltage generation circuit 83. Under certain circumstances described below, processor 74 causes high voltage generation circuit 83 to be discharged through an internal resistive load 85 rather than connector 32 to electrodes 50.

Impedance measuring circuit 90 is connected to electrode connector 32 and real time clock 79, and is interfaced to processor 74 through analog- to-digital (A/D) converter 91. The impedance measuring circuit 90 receives a clock signal having a predetermined magnitude from clock 79, and applies the signal to electrodes 50 through connector 32. The magnitude of the clock signal received back from electrodes 50 through connector 32 is monitored by impedance measuring circuit 90. An impedance signal representative of the impedance present across electrode connector 32 is then generated by impedance measuring circuit 90 as a function of the ratio of the magnitudes of the applied and received clock signals (i.e., the attenuation of the applied signal). A relatively high resistance (e.g, greater than about two hundred ohms) will be present across connector 32 if the conductive adhesive on electrodes 50 is dried out, if electrodes 50 are not properly connected to connector 32, or if electrodes 50 are not properly positioned on the patient. The resistance across connector 32 will be between about twenty-five and on hundred and eighty ohms when fresh electrodes 50 are properly positioned on the patient with good electrical contacts. The impedance signal representative of the impedance measured by circuit 90 is digitized by A/D converter 91 and provided to processor 74.

AED 10 also includes a data recorder 95 that is interfaced to processor 74 and positioned internally within AED 10 adjacent to data card slot 24 so as to be ready to accept data card 29, as depicted in Figure 3. AED 10 further includes an electrocardiogram (EKG) filter and amplifier 92 which is connected between electrode connector 32 and A/D converter 91. The EKG or cardiac rhythm of the patient, sensed at the electrodes 50, is processed by filter and amplifier 92 in a conventional manner, and digitized by A/D converter 91 before being coupled to processor 74.

The rescue mode operation of AED 10 is initiated when an operator opens lid 27 to access electrodes 50. The opening of lid 27 is detected by lid switch 25. In response to this action, power control circuit 84 activates power generation circuit 82 and initiates the rescue mode operation of processor 74. Processor 74 then begins its rescue mode operation by switching maintenance indicator 20 to a maintenance required state (e.g., a yellow visual display in one embodiment), by flashing the "rescue" light associated with resume/rescue switch 18 and the indicator lights on diagnostic display panel 36, and by performing a lid opened self-test.

During the lid opened self-test, processor 74 checks at least the following: 1) the charge state of battery 80; 2) the interconnection and operability of electrodes 50; 3) the state of event memory 78; 4) the functionality of real time clock 79; and 5) the functionality of A/D converter 91. The charge state of battery 80 is checked by monitoring the voltage level signals provided by power generation circuit 84. If battery 80 is determined to have a low charge, the "battery status" indicator 38 on diagnostic display panel 36 will be illuminated by processor 74 to indicate the sensed status. The interconnection and operability of electrodes 50 are checked by monitoring the impedance signals provided by impedance measuring circuit 90. If electrodes 50 are missing or unplugged from connector 32, or if electrodes 50 are damaged, processor 74 will illuminate "Electrodes" indicator light 40 on diagnostic display panel 36. Further, the functionality of real time clock 79 and A/D converter 91 is checked by monitoring the outputs of these circuit elements for expected signals. Diagnostic display panel "service" light 42 is illuminated by processor 74 if faults are identified in either of real time clock 79 or A/D converter 91.

If the lid opened self-test is successfully completed, processor 74 switches maintenance indicator 20 to an operational state. If a firmware card 29 is not present in card slot 24 and a serial cable is not plugged into the AED 10 at serial connector port 23, the processor 74 initiates the rescue mode of operation of AED 10. The rescue mode of operation generates audible voice prompts through speaker 34 to guide the user through the operations of AED 10 and if necessary, delivery of a defibrillation pulse to a stricken patient. AED 10 determines its rescue mode steps of operation by monitoring the impedance across electrode connector 32 and by monitoring the patient's cardiac rhythm sensed at electrodes 50.

The closing of lid 27 after rescue mode operation activates lid switch 25, which in turn activates processor 74 to initiate and perform a lid closed self-test. During the lid closed self-test, processor 74 performs a comprehensive check of the status and functionality of AED 10, including: 1) the state of event memory 78; 2) the functionality of real time clock 79; 3) the functionality of A/D converter 91; 4) the functionality of program memory 76, data memory 77 and event memory 78; 5) the charge state of battery 80; and 6) the interconnection and operability of electrodes 50. The state of event memory 78, the state of battery 80, the interconnection and operability of electrodes 50, and the functionality of real time clock 79 and A/D converter 91 are checked in a manner identical to that described above with reference to the lid opened self-test.

Conventional memory test routines are implemented to check the functionality of program memory 76, data memory 77 and event memory 78. Maintenance indicator 20 is switched to its maintenance required state by processor 74 if faults are identified during the lid closed self-test in order to alert the operator that maintenance is required. No audible alarms are actuated if faults are identified in the charge state of battery 80 or the interconnection or functionality of electrodes 50 during the lid closed self- test.

A daily self-test is initiated and performed by processor 74 at a predetermined time each day (i.e., every twenty-four hours). During the daily self-test, processor 74 performs all the component check operations described above that are performed during the lid opened and lid closed self- tests. In addition to illuminating the appropriate lights on diagnostic display panel 36, processor 74 switches maintenance indicator 20 to its maintenance required state if faults are identified during the daily self-test.

Processor 74 also initiates and performs a weekly self-test at a predetermined time one day each week. During the weekly self-test processor 74 performs all the component check operations described above that are performed during the daily self-test. In addition, processor 74 causes high voltage generation circuit 83 to sequentially operate in its charge and discharge modes, with the charge being dumped to internal resistive load 85. While high voltage generation circuit 83 is operating in the charge mode, processor 74 monitors the time required to charge the circuit's capacitors and the capacitor voltage. A fault is identified if either is out of nominal conditions. Maintenance indicator 20 and alarm 88 are actuated in the manner described above if any faults are identified during the weekly self-test. Note that all performed test and patient data may be recorded in event memory 78.

Watch dog timer 86 is set to time watch dog time-out periods of about thirty hours (i.e., a period greater than twenty-four hour periods between daily self-tests), and is reset by processor 74 at the beginning of each daily self-test and each time lid 27 is opened activating lid switch 25. In the event control system 72 malfunctions and watch dog timer 86 times out, internal hardware then switches maintenance indicator 20 to the maintenance required state and actuates alarm 88 to alert an operator to the fact that AED 10 requires maintenance. AED 10 facilitates archival storage of rescue information in that data representative of the operation of AED 10, patient data, including the monitored cardiac rhythm of the patient, AED analysis of the patient data, key events detected during the rescue operation, and sound occurring within the immediate vicinity of AED 10 are stored in event memory 78 during rescue mode operation. However, if data card 29, which is preferably a memory card commonly known as a flashcard, is inserted into card slot 24 before beginning the rescue attempt, the rescue information is automatically recorded by data recorder 95 onto data card 29 thereby also facilitating archival storage of rescue information. The data card 29 is preferably a memory card having a RAM storage capability of 4, 8, 10, or 15 megs capacity.

Data card 29 is capable of storing up to twenty minutes of rescue information and sound. With data card 29 inserted, the default settings of AED 10 are such that sound is automatically recorded. The sound recording capability may be disabled, however thereby extending the time that rescue information may be recorded on data card 29 up to five hours.

Note that if data card 29 is inserted already containing previously stored rescue data, a voice prompt will be issued that says "Card full- Storing internally." If upon hearing this prompt, the operator ejects the full data card 29 and inserts an empty data card 29 before placing electrodes 50 on the patient, rescue data will then be stored on the new data card 29. If full card 29 is left in slot 24 when electrodes 50 are placed on the patient, rescue information will then be stored in AED event memory 78.

Stored data representative of the operation of AED 10 includes the real time of the occurrence of each of the following events: 1) the placement of electrodes 50 on the patient, 2) the initiation of the cardiac rhythm analysis voice prompt, 3) the initiation of the charging voice prompt, 4) the completion of the charge mode operation of high voltage generation circuit 83, and 5) the actuation of the rescue/resume switch 18 in the rescue mode. The actual time base of the patient's cardiac rhythm, e.g., EKG information, is also stored. Following a rescue, the stored data can be retrieved from event memory 78 through the use of a personal computer (PC) 93 interfaced to serial connector port 23. Real time clock 79 can also be set through the use of PC 93 interfaced to communications port 22. If the stored data were stored on data card 29 and data card 29 remains in slot 24, the data may also be retrieved through the use of PC 93 interfaced to serial connector port 23. Alternatively, the data card 29 may be ejected from AED 10 and inserted into an appropriate card reader 94 that is directly connected to PC 93, such as a PCMCIA type I card reader.

PC 93 may be used to clear event memory 78 and /or data card 29 of previous rescue information when PC 93 is connected to AED 10 through serial connector port 23. The data card reader 94 of PC 93 may also be used to clear the memory of data card 29. Once rescue information is retrieved from event memory 78 or from data card 29 by PC 93, PC 93 may then be used to enter additional information to help identify the rescue information. This additional information may include patient name, medical identification, name of the responder who performed the rescue and the serial number of AED 10. PC 93 can be used to display all data to the user and to keep logs of performance.

Upon the completion of each lid opened, lid closed, daily and weekly self-test, processor 74 causes a record of the self-test to be stored in event memory 78. Each stored record includes data representative of the date and time of the test and the results of the test. The test results are recorded in the form of a code or other description indicating whether all the functions, components and component status states passed the test, or indicating the nature of any identified faults. In one embodiment, only the records of the twenty most recently performed tests are stored in memory 78. The stored self- test records can be retrieved from memory 78 through PC 93 interfaced to serial connector port 23.

In operation to perform a rescue intervention, when the lid 27 of the AED 10 is opened activating lid switch 25, voice prompts guide an operator through the rescue procedure. Once the electrodes 50 have been placed on the victim, the AED 10 analyzes the victim's cardiac rhythm. If the AED 10 detects a shockable cardiac rhythm, the voice prompt will say "Charging" and the AED 10 will charge preparatory to delivering a pulse or series of pulses to the victim. If the AED 10 does not detect a shockable rhythm at electrodes 50, the voice prompt will say "Check pulse. If no pulse, give CPR". Patient indications sensed at electrodes 50 in conjunction with further prompts from the AED 10 enable the operator to effectively deliver the CPR to the victim.

Referring to Figures 6-12, generally, the AED of the present invention is depicted at 10 (Figure 7). The AED 10 has a front side 112 with a carrying handle 114 formed thereon. The opposed rear side 116 includes the battery pack compartment 118. The battery pack compartment 118 is an enclosure 120 defined by top wall 122, opposed bottom wall 124, latch sidewall 126, hinge sidewall 128, and floor 130.

The AED 10 is formed of a top half 132 and a bottom half 134 joined along a mating juncture 136. As depicted in Figure 12, connecting posts 138 comprise screw receivers for joining the top half 132 and the bottom half 134 in cooperation with a screw (not shown) threaded into a bore defined in the upper margin of the connecting posts 138.

The latch sidewall 126 has a perpendicular wall portion 140 (Figure 12) that is disposed generally perpendicular to floor 130 and is coupled thereto. An angled wall portion 142 extends outwardly from the perpendicular wall portion 140. A latch catch 144 is formed proximate the distal end of the angled wall portion 142.

The hinged sidewall 128 (Figures 7 and 12) includes a recessed receiver 146 defined in part by top wall 122 and bottom wall 124 in conjunction with the perpendicular wall portion 148 (perpendicular to floor 130) and parallel wall portion 150 (parallel to floor 130) of the hinge sidewall 128. The hinge sidewall 128 includes a second perpendicular wall portion 152 (perpendicular to floor 130) extending outward from the parallel wall portion 150.

The first and second battery-installed detector electrodes 154a, 154b (Figures 8, 9, and 12) are disposed in the floor 130 of the battery pack compartment 118. As depicted in Figures 8 and 9, electrodes 154a, 154b have a lower end that is fixedly coupled to the floor 130 with the upper, distal end thereof being free of engagement therewith. The electrodes 154a, 154b are preferably made of a resilient, deflectable metallic material. The electrodes 154a, 154b are deflectable with respect to the fixed lower end thereof. Further, the electrodes 154a, 154b are biased outward from the lower fixed end, such that the electrodes 154a, 154b resist a force tending to move them toward the floor 130. The electrodes 154a, 154b are preferably disposed proximate the latch sidewall 126 of the battery pack compartment 118. The electrodes 154a, 154b are in electrical communication with the electronic components of the AED 10, including the processor 74, described above in conjunction with AED 10. The electrodes 154a, 154b are spaced apart such that the electrodes 154a, 154b are not in electrical communication with each other. Referring to Figures 7 and 12, the main battery electrodes 156a, 156b are also disposed in floor 130 of the battery pack compartment 118. The main battery electrodes 156a, 156b are proximate the hinge sidewall 128 of the battery pack compartment 118. The electrodes 156a, 156b have a fixed (proximate) end 158 fixedly disposed within a recess 160 defined in the floor 130. The distal end 162 of each of the main battery electrodes 156a, 156b is free of engagement. Further, the distal end 162 of each of the main battery electrodes 156a, 156b is preferably radiused, forming a curved electrical contact surface. The curved electrical contact surface of the distal end 162 of the main battery electrodes 156a, 156b is biased outward away from the floor 130. The main battery electrodes 156a, 156b are preferably formed of a resilient, deflectable metallic material. The electrodes 156a, 156b are deflectable with respect to the fixed end 158 thereof. The main battery electrodes 156a, 156b are in electrical communication with the electronic components of the AED 10, including the processor 74.

The battery pack of the present invention is shown generally at 16 in Figures 6-12, 14, and 15. The battery pack 16 has a case 202 that is formed of case halves 204, 206 fixedly joined at a mating juncture 207. Generally, the battery pack 16 has a latch end 208, a hinge end 210, a forward face 212 and a rear face 214. When the battery pack 16 is engaged with the AED 10, the forward face 212 faces inward with respect to the battery pack compartment 118 and is disposed proximate and substantially parallel to the floor 130 of the battery pack compartment 118 when in the engaged disposition with the AED 10, the engaged disposition being depicted in Figure 12.

Referring to Figures 7, 9-11, and 14-15, the latch end 208 of the battery pack 16 has a generally planar end wall 216 that is formed as a part of the case half 206. A latch 218 is formed integral with the case half 206 and extends alongside but is spaced apart from the end wall 216.

The latch 218 has a generally planar latch plate 220. The latch plate 220 has a groove 221 defined therein proximate the point of connection to the case half 206. A pair of outwardly extending ribs 222 are formed at the opposed sides of the latch plate 220. A catch face 224 is formed generally transverse to the plane of the latch plate 220 and extending between the ribs 222. An actuator tab 226 forms the distal end of the latch 218. The actuator tab 226 has a finger groove 228 formed therein to facilitate compressing the latch 218 against a bias designed into the latch 218. Such compression facilitates disengaging the catch face 224 of the latch 218 from the latch catch 144 for removal of the battery pack 16 from the AED 10.

Referring now to Figures 6, 8, 12, and 14-15, the hinge end 210 of the battery pack 16 has a receiver insert 230 formed thereon. The receiver insert 230 has a generally rounded outer surface and is designed to be received within the receiver 146 of the AED 10. An end wall 232 extends outward from the receiver insert 230 and is preferably generally parallel to the end wall 216 of the latch end 208. Turning to Figures 6 and 10, the forward face 212 of the case 202 of the battery pack 16 has a generally planar portion 234 extending from the latch end 208 to a position proximate the receiver insert 230. The planar portion 234 has an access panel 236 that may be removed to gain access to the plurality of battery cells disposed within the battery pack 16. A plate recess 238 is formed in the planar portion 234 proximate the latch end 208. A preferably metallic conductor plate 240 is disposed within the plate recess 238. When the battery pack 16 is in the engaged disposition with the AED 10, the conductor plate 240 is in registry with the battery-installed detector electrodes 154a, 154b. In such disposition, the conductor plate 240 is formed of an electrically conductive material and is in electrical communication with both the battery-installed detector electrodes 154a, 154b. The conductor plate 240 completes an electrical circuit between the battery-installed detector electrodes 154a and 154b.

An inclined portion 242 of the forward face 212 extends from the planar portion 234 to the receiver insert 230. The inclined portion 242 has at least two electrodes 244a, 244b disposed thereon. The electrodes 244a, 244b are in electrical communication with the battery cells disposed within the battery pack 16. The electrodes 244a, 244b are preferably generally elongate, flat metallic strips and are disposed between electrode rib separators 246, formed in the inclined portion 242. When the battery pack 16 is in the engaged disposition with the AED 10, the electrodes 244a, 244b are in registry with the main battery electrodes 156a, 156b. The electrode 244a is in electrical communication with the main battery electrode 156a and the electrode 244b is in electrical communication with the main battery electrode 156b when in such disposition. A pair of end guides 248 are disposed on one side of the electrodes 244a, 244b.

To bring the battery pack 16 into operative engagement with the AED 10, the battery pack 16 is moved with respect to the AED 10 as indicated by Arrow A in Figure 17. Such movement brings the battery pack 16 first into a position as depicted in Figure 9 and then into a disposition as depicted in Figure 11. In the disposition as depicted in Figure 9, the receiver insert 230 is partially received within the receiver 146. In this disposition, the battery-installed detector electrodes 154a, 154b are not in contact with the conductor plate 240 and the main battery electrodes 156a, 156b are not in electrical contact with the electrodes 244a, 244b. Turning now to Figure 11, the battery pack is rotated into the battery pack compartment 118 defined in the rear side 116 of the AED 10 as indicated by the Arrow B. At approximately the disposition as indicated in Figure 11, the main battery electrodes 156a, 156b make electrical contact with the electrodes 244a, 244b and electrical power could be provided by the battery pack 16 to the processor 74 in the AED 10. The battery-installed detector electrodes 254a, 254b, however, are still not in electrical contact with the conductor plate 240.

Figure 12 depicts the battery pack 16 in operable engagement with the AED 10. In the transition between the disposition depicted in Figure 11 and that depicted in Figure 12, the latch 218 is compressed toward the end wall 216 by the action of the ribs 222 riding on the latch sidewall 126 of the battery pack compartment 118. When the catch face 224 of the latch 218 clears the latch catch 144 of the latch sidewall 126, the resilient latch 218 snaps outward with the catch face 224 thereof engaging at the latch catch 144.

In the operable engaged disposition as indicated in Figure 12, the conductor plate 240 is in both compressive and electrical contact with the battery-installed detector electrodes 154a, 154b. This contact has two functions. First, the conductor plate 240 functions as a switch making an electrical contact between the battery-installed detector electrodes 154a, 154b. Second, by being in compressive engagement therewith, the battery- installed detector electrodes 154a, 154b, exert an outwardly directed bias on the battery pack 16, thereby preventing the battery pack 16 from rattling within the battery pack compartment 118.

In the operably engaged disposition as depicted in Figure 12, the main battery electrodes 156a, 156b are in electrical communication with the electrodes 244a, 244b of the battery pack 16. Accordingly, the battery pack 16 is disposed such that energy is available to the AED 10.

To remove the battery pack 16 from the AED 10, the finger groove 228 is engaged and depressed to bring the latch 218 closer to the end wall 216. When the catch face 224 is free of engagement with the latch catch 144, the battery pack 16 may be rotated out of the battery pack compartment 118 by a rotational motion opposite to that as indicated by Arrow B in Figure 11. Such rotational motion progressively electrically disengages the battery pack 16 from the AED 10. The first bit of such rotation, breaks the engagement between the conductor plate 240 and the battery-installed detector electrodes 154a, 154b. This breaks the circuit that existed between the battery-installed detector electrodes 154a and the battery-installed detector electrodes 154b. Such opening of the previously existing circuit provides an anticipatory indication to the processor 74 that disengagement of the battery pack from the AED is imminent. This condition is schematically depicted in Figure 13.

At this point, the main battery electrodes 156a, 156b are still in electrical communication with the electrodes 244a, 244b of the battery pack 16. Accordingly, energy is still being supplied from the battery pack 16 to the processor 74 of the AED 10. In the usual rotation of the battery pack 16 out of the battery pack compartment 118, there is at least a 40 millisecond period of time between when the electrical circuit between the battery- installed detector electrodes 154a, 154b is broken and when the main battery electrodes 156a, 156b are disengaged from the electrodes 244a, 244b. In this period of time, the processor 74 is still powered and detects that the battery is no longer installed. The processor 74 then commands the high voltage board to dump all charges existing in the high voltage capacitors. This dump is accomplished on an orderly basis in such 40 millisecond period before the disengagement of the main battery electrodes 156a, 156b and electrodes 244a, 244b under power of the battery pack 16. At the time of such disengagement, the processor 74 of the AED 10 goes dead for lack of power from the battery pack 16. Figure 18 is a schematic representation of a dual cell battery circuit

300 of the present invention. As shown in Figure 17, in an allternate embodiment, battery circuit 300 of the present invention is electrically connected to at least microprocessor 74, and power generation circuit 82, of AED electral system 70 (see Figure 5). As shown in Figure 18, battery pack circuit 300 is housed within battery pack 16 (Figure 3) for removable insertion and electrical connection within AED case receptacle 118 (Figure 7). Battery pack circuit 300 contains first set 312 of battery cells (319A-319D) having upper set 314 of battery cells (319A, 319B) and lower set 316 of battery cells (319C, 319D). Battery pack circuit 300 also contains second set 318 of battery cells (319E, 319F) which are connected in parallel with lower set 316 of cells (319C, 319D). The individual cells (319A-319F) are preferably three volt nominal voltage lithium sulfur dioxide battery cells. However, other types of battery cells could also be used without departing from the spirit or scope of the present invention. Moreover, more or less than six battery cells (319A-319F) can be used to achieve the selected total voltages. With this arrangement, typically 12V is high current (10A) and 5V is low current (1A).

In addition, in order to protect lithium cells against reverse biasing in a parallel configuration, battery pack circuit 300 includes a pair of reverse biasing protection diodes 320 connected between second set 318 of cells (319E, 319F) and lower set 316 of cells (319C, 319D). In a preferred embodiment, diodes 320 are IN5819 type diodes known in the art and preferably have a forward voltage drop of about 1 volt. Significantly, diodes 320 are not in the high voltage current path that extends from the top of cell 319A to 12 V output line 328.

As further shown in Figure 18, battery pack circuit 300 has four electrically conductive leads for connection to an AED including ground or common line 322, serial data line 324, five volt line 326 and 12 volt line 328. Battery pack circuit 300 also includes node 330, one amp fuse 332, seven amp fuse 334, and thermal fuses 336.

Five volt line 326 is connected to the centerpoint of first set 312 of battery cells (319A-319D). In particular, line 326 is connected at the intersection of upper set 314 of cells (319A, 319B), and lower set 316 of cells (319C, 319D) at node 330. One amp fuse 332 is connected between node 330 and the output of line 326 and seven amp fuse 334 is connected between the top of first set 314 of cells (319A) and the output of line 328. This arrangement eliminates the need for a 5V voltage regulator found in prior art configurations, which managed voltage fluctuations and dips caused by changes in current draw. Larger or smaller fuses may be used for fuses 332 and 334 without departing from the spirit or scope of the present invention. Temperature control fuses 336 are connected between individual cells 319A and 319B of upper cell set 314 and between cells 319C and 319D of lower cell set 316. These temperature fuses prevent the individual cells from overheating.

In the embodiment of Figure 18, second set 318 of cells (319E, 319F) are used to drive microprocessor 74 and other components of AED 10 while upper set 314 of cells 319 A, 319B and either lower set 136 of cells (319C-319D) or second set 318 of cells 319E, 319F are used for charging capacitor bank 83A of AED 10. If needed, lower set 316 of cells (319C, 139D) can be used for operating microprocessor 74 and other components of the AED. Significantly, second set 318 of cells (319E, 319F) cannot be used for charging capacitor bank 83A of AED by virtue of diodes 320. Also, because of the positioning of diodes 320, this battery configuration has the ability to guarantee that one of either lower battery cell set 316 or second battery cell set 318 will fail with the respective other lower set 316 or second set 318 having sufficient power to allow for a controlled shutdown of AED. With this arrangement, AED 10 should never be in the condition where a charge has been delivered from battery pack circuit 300 and the voltage to the processor drops to an unacceptable level causing a malfunctioning processor with a fully charged capacitor bank.

Figure 18 further includes components for operating battery pack 16 including semiconductor chip 340 connected as known in the art with resistors 342, 344, capacitor 346, diodes 348, 350, and over voltage protection device 352.

The dual battery stack configuration of battery pack circuit 300 has numerous advantages. First, this arrangement requires only six 3 V cells to provide a 12 V and a 5 V supply whereas the prior art configuration shown in Figure 16 required eight 3 V cells to provide the same power supply. This reduction in the number of cells results in significant cost savings since each lithium battery cell is expensive, and in space savings since each cell is bulky. Second, by eliminating a reverse bias protecting diode 9 in the 12 V (high voltage) current path (i.e. above cell 19A as shown in Figure 16), the corresponding voltage drop across the diode (e.g., 0.7 to 1 V) is also eliminated, thereby achieving more power from the expensive lithium batteries. Third, reverse biasing diodes 320 act to limit the power tapped off between the upper and lower set of cells, and the second set of cells, so that a nominal 5 V supply is provided. In a prior art configuration, an extra voltage regulator (in addition to the reverse bias protecting diodes) would be required to provide the 5 V supply. Fourth, lower set 316 of cells and second set 318 of cells provide a redundant or parallel arrangement to insure a reliable 5 V supply. Fifth, the location of the reverse bias diodes 320 insures that the 5 V output will remain constant for microprocessor 74 of AED 10 despite wide variations on the load of the 12 V supply. Sixth, the location of the reverse bias protecting diodes 320, a voltage test for determining the remaining end of life, or battery status of battery pack 16 can be performed without affecting the 5 V power output line. Seventh, the 5 volt output line will always fail last, after a failure of the 12 V line to insure that microprocessor 74 and electrical system 70 retain control of the AED 10 at all times throughout battery life.

Figures 19 and 20 illustrate alternative embodiments of battery pack circuit 300 shown in Figure 18. As can be seen in Figure 19, alternative battery pack circuit 360 is identical to battery pack circuit 300 except that the output lines are changed from being ground 322, five volt line 326 and 12 volt line 328 to a system having minus six volt line 362, zero volts line 364 and plus six volt line 366 of electrical system of AED 10. As shown in Figure 20, alternative battery pack circuit 370 is substantially similar to battery circuit 360 except that in battery circuit 370, second set 318 of cells (319E, 319F) is positioned in parallel with upper set 314 of cells (319 A, 319B) instead of being in parallel with lower set 316 of cells (319C, 319D). Battery pack circuit 370 includes a system of output lines including a minus 6 V line 372, zero V line 374, and plus 6V line 376. Diodes 320 are positioned adjacent cells 319A and 319E in a fashion similar to circuit 300.

Battery pack circuit 360 of Figure 19 and circuit 370 of Figure 20 are useful when the high voltage supply (12V total) must be floating relative to the logic circuitry components of AED 10 and for electrical systems otherwise requiring a negative power supply (e.g., - 6 V).

Figure 21 illustrates an alternative battery pack circuit 380 generally similar to battery pack circuit 300 shown in Figure 18. However, battery pack circuit 380 further incorporates a 2V output line 382 tapped off battery cell 319D of lower battery cell set 316 and battery cell 319F of second battery cell set 318 and diodes 384 and 386. In this configuration, cell 319D and cell 319F are connected in parallel at node 388 with diode 384 connected between output line node 382 and node 390 (located between lower set 316 cells 319C and 319D) and diode 386 connected between output line node 382 and node 392 (located between second set 318 cells 319E and 319F). As in the prior embodiments, diodes 384 and 386 prevent the reverse biasing of battery cells 319D and 319F when those cells are connected in parallel. The 2 V output line 382 is preferably provided for operating a real time clock, battery backed memory, watchdog timer, and similar sentinel-type circuit components of an electrical system of AED 10, similar to those components described and illustrated in Olsen, et al. U.S. Patent 5,645,571, and as shown in Figure 5. In addition, providing a 2 V output line 382 with diodes 384 and 386 in the parallel battery cell configuration eliminates the need for a voltage regulator in the electrical system that would have been previously necessary to provide a nominal 2 V supply line.

A dual cell stack battery pack of the present invention offers a number of advantages over known battery packs. As stated above, these include, among other things, having the ability to share cells between differing output voltages, guaranteeing a controlled shutdown of the AED, the elimination of a diode from the high voltage current path, the elimination of unnecessary cells and the possibility of expansion to more than two voltages. The elimination of a diode from the high voltage current path is significant due to expensive nature of battery capacity and elimination of the consequential voltage drop that occurs when diode must be implemented in prior art configuration. The battery pack also eliminates need for an external regulator to provide a 5 V supply and the parallel arrangement of lower set and second set of cells establishes greater reliability for 5 V battery. Moreover, the 5 V supply will remain constant even during wide variation on load of 12 V and the first set 12 of cells can be measured under load to predict the end of life of battery without affecting the 5 V rail supply. In addition, a battery pack of the present invention eliminates two battery cells from prior art battery pack while maintaining same logic battery capacity to support charging and microprocessor. Perhaps most significant, the 5 V battery voltage will always be the last to fail insuring that the microprocessor of AED will safely control the electrical system of AED throughout the battery life of battery pack circuit 10. While the present invention has been described with reference to defibrillators, it may be used with any device requiring batteries.

In another embodiment, Figure 22 schematically illustrates removably insertable battery pack 415. Battery pack 415 contains housing 416 surrounding a plurality of non-rechargeable lithium sulfur dioxide cells 417 (which may include both 12 volt and 5 volt cells). Memory component 418 is located inside housing 416 and includes a memory circuit chip 419.

Figure 23 is a schematic circuit diagram illustrating the construction of memory component 418 in battery pack 415. In the preferred embodiment, circuit chip 419 is a Dallas DS2434 integrated circuit semiconductor chip, but other known memory components can also be used without departing from the spirit or scope of the present invention. Memory circuit chip 419 has three terminals including a read /write terminal 441 for accessing the memory in chip 419. Memory circuit chip 419 operates under a 5V power supply 440 from battery cells 417 and is connected in a manner well known to those skilled in the art with resistor 442, capacitor 444, diodes 446 and 448, over voltage protection device 450, and resistor 452.

Memory component circuit 418 acts as an interface between battery cells 417 and AED 10. Accordingly, battery contact receptacle 420 of AED case 112 provides 12V contact 456A, 5V contact 456B, read/write contact 456C, and ground contact 456D for electrical connection to corresponding battery contacts (458A, 458B, 458C, and 458D) of memory component circuit 418 of battery pack 415. The electrical connection between read /write contact 456C of AED battery receptacle 420 and read /write contact 458C of battery pack 415 permits the read /write terminal 441 of memory chip 419 to communicate with a microprocessor of an electrical control system of AED 10. Likewise, the electrical connection of 5V and 12V power supply contacts 458B and 458A of battery pack 415 to 5V and 12V power supply contacts 456B and 456A of AED battery receptacle 420 provides power from battery cells 417 (via circuit 418) to an electrical system of AED 10.

Figure 2 illustrates a perspective view of AED 10 with battery status indicator 38 of diagnostic display 36 positioned under lid 27. Status indicator 38 is electrically connectable to memory component 418 of battery pack 415 at battery contacts 456C and 458C via a microprocessor of electrical system of AED 10. As shown in greater detail in Figure 4, status indicator 38 has a plurality of green indicator lights 462 and a red replace light 464 to indicate the relative amount of power remaining in the battery cells 417 of battery pack 415. Green indicator lights are arranged with a sufficient number of lights so that an operator can determine the proportional amount of remaining battery capacity by looking at the number of lights illuminated. For example, if indicator 462 includes four lights, illumination of all four green lights indicates full battery status while illumination of three lights indicates three-quarter battery status and illumination of two battery lights indicates one-half battery status, and so on. In this way, an operator may simply look at status indicator 38 to determine how much energy remains in battery pack 415. Moreover, when red replace indicator light 464 is illuminated, battery pack 415 must be replaced. However, memory component 418 and AED 10 can be programmed so that when the red replace light is illuminated, AED 10 can still provide enough additional shocks (e.g., nine) to perform one more rescue with battery pack 415. Figure 24 is a block diagram of a portion of electrical system 70 of defibrillator 10 and further illustrates the relationship of battery pack 415 and electrical system 70 of AED 10 (also shown in Figure 5).

Battery pack 415 containing battery cells 417 is removably connectable between processor 74 and power generation circuit 82 and provides electrical power to system 70. A 12V contact 458A and 5V contact 458B of battery pack 415 are electrically connected to power generation circuit 82 while a read /write contact 458C of memory component 418 of battery pack is electrically connected to processor 74.

Using the electrical power supplied by battery pack 415, power generation circuit 82 generates a regulated +5V, 3.3V and 12V (actually about 13.3V) power supply for use in electrical system 70. The +5V supply of the power generation circuit 82 is used to power the components of electrical system 70. The 3.3V supply of the power generation circuit is coupled to nonvolatile event memory in which data representative of the patient's cardiac rhythm and the rescue mode operation of defibrillator 10 are stored. The 12V supply is received by a high voltage generation circuit for charging capacitors to provide the defibrillating countershock. The read /write connection between processor 74 and battery pack 415 enables processor 74 to read data from and write data to memory component 418 of battery pack 415. Accordingly, to determine the amount of power in remaining in battery pack 415, memory component 418 cooperates and communicates with processor 74 of the electrical control system of AED 10. Program memory 76 (Figure 5) provides an instruction set for processor 74 to cooperate with memory chip 419 to obtain battery related data from electrical system 70 and to store and retrieve battery related information in memory chip 419 in battery pack 415. Memory component 418 of battery pack 415 stores information regarding: (1) the initial capacity of battery cells 416; (2) a parameter of the amount of energy used per day by AED 10 in a dormant, standby mode; (3) a parameter of the amount of energy used per minute during active operation of AED 10; and (4) a parameter of the amount of energy used to charge up "shocking" capacitors of the AED 10 in preparation of delivering a shock. The memory component 418 also stores information regarding: (1) the amount of time AED 10 has been in active operation with battery pack 415; (2) the amount of time the battery pack 415 has been in service (including in standby mode and active operation); and (3) the number of charges that have been delivered by AED 10 with battery pack 415. Based on this information, the amount of energy remaining in the plurality of cells 417 is calculated.

Using the above-identified parameters and battery use information stored in memory component 418, the remaining power in battery pack 415 is calculated using memory component 418 and processor 74 by solving the following equations:

R12 = 112 • (1 - x/A - y/2B - z/2C), and R5 = 15 • (1 - x/A - y/B - z/C) where, 112 represents the predetermined capacity of 12V Cells in mA hours, 15 represents the predetermined capacity of 5V Cells in mA hours,

A represents the predetermined energy to subtract for each high voltage charge in mA hours, B represents the predetermined energy to subtract for each minute of operation in mA hours,

C represents the predetermined energy to subtract for each day in the

AED in mA hours, x represents the number of high voltage charges removed from the battery 15, y represents the number of minutes the battery has been used in active operation of AED 10, z represents the number of days the battery has been in AED 10,

R12 represents the number of mA hours remaining in the 12V cells, and R5 represents the number of mA hours remaining in the 5V cells.

Accordingly, memory component 418 stores all the information necessary to solve the equations 1 and 2 to determine the amount of power remaining in battery pack 415 in mAmp hours. This remaining amount of energy is graphically displayed on status indication gauge 38 with indicator lights 462 or light 464 (Figure 4).

Since failure of a battery pack 415 during use of AED 10 is unacceptable, processor 74 can be instructed to write to memory component 418 that a replace battery indication is warranted when 20 percent (or other predetermined level) of remaining battery capacity is reached. In this manner, an operator is assured that battery pack 415 can be removed and replaced before capacity of battery pack 415 is drained. Using such a fail safe lower limit also requires an adjustment of calculations that determine the relative energy (full, 3/4, 1/2, 1/4) remaining in battery pack 415 so that indicator lights 462 accurately reflect the remaining capacity of battery pack 415 after accounting for the failsafe replace threshold (e.g., 20 percent capacity).

Since battery pack 415 includes memory component 418 built into housing 416, memory component 418 always stays with battery cells 417. Accordingly, if battery pack 415 is removed from an AED 10 after partial use, the history of use of the battery pack 415 is carried with battery pack 415. Accordingly, if partially used battery pack 415 is placed in an AED 10, processor 74 of AED 10 can read memory component 418 to determine when the battery was first previously used and the remaining energy capacity of partially used battery pack 415 as well as display the remaining energy capacity on multi-level status indicator gauge 38.

A combination of memory component 418 in battery pack 415 and processor 74 provides ongoing indication of remaining battery energy as displayed on indicator gauge 38. However, periodic direct tests of the voltage of battery cells 417 is also desirable to insure proper functioning of battery pack 415 and AED 10.

Accordingly, battery voltage level sensing circuits are incorporated into power generation circuit 82 (and coupled to processor 74) and operate independently of battery status indicator gauge 38. The voltage level sensing circuits operate as a failsafe mechanism to provide low battery level signals to processor 74 whenever the voltage levels of battery cells 417 are less than a predetermined value. If a low voltage level signal is sent to processor 74, processor 74 then updates memory component 418 of battery pack 415 to reflect a battery failure. This battery failure is displayed on status indicator gauge 38 by illuminating the replace battery indicator light 464. Accordingly, the battery voltage level sensing circuits can override a calculated value of the remaining energy in battery cells 417 obtained using the above equations.

Moreover, if memory component 418 of battery pack 415 fails or processor 74 otherwise cannot read or write to memory component 418 of battery pack 415 (e.g., due to poor electrical contact), then processor 74 is programmed (via program memory 76) to assume that battery pack 415 is nonfunctional. In response, processor 74 illuminates replace light indicator 464 to indicate on status indicator gauge 38 that battery pack 415 must be replaced. Accordingly, in cooperation with memory component 418 of battery pack 415, processor 74 and status indicator gauge 38 insures that an operator will receive information to replace a battery regardless of the source of failure (e.g., battery cell 417, memory component 418, or other component of battery pack 415). The battery voltage level test is performed at or during several events. First, the battery voltage test is performed just before use of AED 10 and just after use of AED 10, as well as during a daily and weekly self test of AED 10 as described below.

The first event of directly testing battery voltage levels occurs during a rescue mode operation of defibrillator 10 when an operator opens lid 27 to begin a rescue and access the electrodes of AED 10. The opening of the lid 27 is detected by lid switch 90, which effectively functions as an on /off switch. Processor 74 then begins its rescue mode operation which includes performing a lid opened self-test. During the lid opened self-test, processor 74 checks the charge state of battery pack 415 as well as other components such as the interconnection and operability of electrodes 50. As described above, the charge state of battery pack 415 is checked by monitoring the voltage level signals provided by power generation circuit 82. If battery pack 415 is determined to have a low charge, lights 464 on status indicator gauge 38 is illuminated by processor 74 and battery memory 418 is updated by processor to store a "replace battery" status.

If the lid opened self-test is successfully completed, processor 74 permits continued operation of AED 10 in a rescue mode of operation. After detecting an impedance indicating the proper placement of electrodes 50, an automatic sequence of analyzing heart rhythm of the patient for a shockable rhythm and prompting use of CPR as appropriate when a nonshockable rhythm is present. When a shockable cardiac rhythm is detected, processor 74 begins a first charge sequence of charging high voltage generation circuit 83 and initiating a first shock sequence to the patient with cautioning voice prompts to press a rescue/shock button and stand clear. Operator actuation of rescue switch results in the application of a defibrillation pulse of preferably about 200 joules to the patient to complete the first series of analyze /charge /shock sequences.

Following the first series of analyze /charge /shock sequences, processor 74 ends rescue mode operation of defibrillator 10 after a subsequent series of analyze/charge/shock sequences have been performed, or lid 27 is closed.

A lid closed self-test is also initiated and performed by processor 74 when lid 27 is closed following rescue mode operation of the defibrillator

10. During the lid closed self- test processor 74 performs a comprehensive check of the status and functionality of defibrillator 10, including the charge state of battery pack 415. The state of battery pack 415 is checked in a manner like that described for the lid opened self-test.

Of course, both the lid open and lid closed test consume energy from battery pack 415. Processor 74 tracks this use of battery energy using the parameters identified above and updates memory component 418 of battery pack 415 so that status indicator gauge 38 accurately reflects the ongoing battery usage of AED 10.

In addition, a daily self test and a weekly self test of AED 10 is performed during which the voltage level of battery cells 417 of battery pack 415 is checked. The daily self-test is initiated and performed by processor 74 at a predetermined time each day (i.e., every 24 hours) while the weekly self test occurs at a predetermined time one day each week.

Processor 74 illuminates replace battery indicator 464 of status gauge indicator 38 and activates alarm 88 if faults are identified during the daily self-test or weekly self test. The weekly self test also includes a test of the ability of high voltage generation circuit 83 to sequentially operate in its charge and discharge modes, with the charge being dumped to internal load 85. Processor 74 updates memory component 418 of battery pack 415 with the number of charges (parameter x in equations) so that memory component 418 and status indicator gauge 38 reflect the energy capacity used during the weekly self test.

Other parameters can also be stored in memory component 418 in battery pack 415. These parameters include the time and date the battery pack 415 was installed in the AED 10 as well as a serial number of the battery for tracking the origin of the battery. Real time clock 79 (with its own long term internal battery) provides processor 74 with the time/date data for writing and storage in memory component 418. Moreover, the serial number of AED 10 can be written and stored in battery pack 415 to identify the AED 10 in which battery pack 415 was installed.

In alternative embodiment, memory component 418A can be located outside of battery pack 415A. For example, memory component 418A is preferably located in AED case 112 as part of electrical system 70 and is electrically connected to processor 74 and battery cells 417 in a manner similar to that shown in Figure 23. Upon placement of battery pack 415A in AED 10, processor 74 writes to memory component 418A to store a full battery status and begins tracking usage of battery pack 415A in a manner similar to that described above for memory component 418 and displays the remaining battery capacity on status indicator gauge 38. In combination with battery pack 415A and memory component 418A, processor 74 uses equations 1 and 2 as described above to determine the remaining battery capacity and stores that information to memory component 418A. However, since memory component 418A does not travel with battery pack 415A as in the first embodiment, the battery energy calculation is effective only for a new battery pack 415A (with full initial capacity) installed in AED 10. Nevertheless, although memory component 418A does not travel with the battery pack 415A, the memory component 418A and status indicator gauge 38 permit ongoing visual indication of the remaining battery capacity of battery pack 415A.

Finally, regardless of how a memory component (like memory component 418) is implemented for use with a microprocessor of an AED to track and store battery usage (e.g., in the battery pack 415, in the AED case 112, or other location) the present invention includes a defibrillator case having a multi-level fuel indicator gauge for use with a lithium battery cell. The defibrillator graphically displays the relative amount of energy remaining in a lithium battery being used in the defibrillator. A multi- level battery status indicator is significant in an AED since lithium battery cells are characterized by providing a constant voltage until abrupt failure.

A defibrillator with a battery pack and status indicator gauge of the present invention offers considerable advantages. First, a memory component of the present invention, when used with a lithium battery, enables an operator to determine the remaining energy capacity (in mAmp hours) in the lithium battery rather than merely apply a periodic voltage test to determine battery readiness. Second, a multi-level battery gauge of the present invention permits a defibrillator to continuously display the relative remaining battery capacity of a lithium battery used with defibrillator. Third, when a memory component is incorporated into a battery housing with a lithium battery, the memory component always travels with lithium battery so that the battery carries with it a history of its use including its remaining capacity. This permits a battery to be removed from one defibrillator and used in another defibrillator while still maintaining knowledge of the remaining capacity of the battery. Fourth, the memory component is implemented without displacing the conventional voltage battery test for determining lithium battery readiness in the defibrillator.

Although the present invention has been described with reference to preferred embodiments, those skilled in the art will recognized that changes can be made in form and detail without departing from the spirit and scope of the invention.

Claims

WHAT IS CLAIMED IS:

1. A battery pack for being removably disposed in operable engagement with an AED, the AED having electronic circuitry disposed within an AED housing for delivery of an electric shock to a stricken patient, comprising: a battery pack housing; at least one battery disposed in the battery pack housing; at least two battery electrodes being in electric communication with the at least one battery for being disposed in operation engagement with the AED for transmission of power thereto; and anticipatory detector means operably coupled to the battery pack housing and being communicatively coupled to the AED electronic circuitry when the battery pack is in operational engagement with the AED for generating an anticipatory signal communicated to the AED electronic circuitry, said signal indicating that disengagement of the battery pack from the AED is imminent.

2. The battery pack as claimed in claim 1 wherein the anticipatory detector means comprises a conductive plate disposed on an external surface of the battery pack housing.

3. The battery pack as claimed in claim 1 wherein the anticipatory detector means establishes a circuit between a first and a second electrode when the battery pack is disposed in operable engagement with the AED, the first and the second electrodes being communicatively coupled to the AED electronic circuitry.

4. The battery pack as claimed in claim 3 further including the at least two battery electrodes being disposed on an external surface of the battery pack housing, the at least two battery electrodes being spaced apart from the anticipatory detector means and the at least two battery electrodes establishing a circuit with complimentary electrodes disposed on the AED when the battery pack is disposed in operable engagement with the AED for providing power to said complimentary electrodes, the complimentary electrodes being communicatively coupled to the AED electronic circuitry whereby said power powers the AED electronic circuitry.

5. The battery pack as claimed in claim 4 wherein disengagement of the battery pack from the disposition in operable engagement with the AED acts to break the circuit established between the anticipatory detector means and the first and the second electrodes prior to breaking the circuit established between the at least two battery electrodes and the complimentary electrodes disposed on the AED.

6. The battery pack as claimed in claim 4 wherein, during disengagement of the battery pack from the disposition in operable engagement with the AED, the battery pack continues to power the AED electronic circuits by means of the circuit established between the at least two battery electrodes and the complimentary electrodes disposed on the AED for a finite period of time subsequent to breaking the circuit established between the anticipatory detector means and the first and the second electrodes.

7. The battery pack as claimed in claim 1 further including the battery pack housing having a latch end and an opposed hinge end, the latch end having a latch disposed thereon for latching engagement with cooperative latch structure of the AED, and the hinge end having a disengageable hinge portion defining a hinge in cooperation with hinge structure of the AED.

8. The battery pack as claimed in claim 7 wherein disengagement of the battery pack from operable engagement with the AED is effected by rotational motion of the battery pack about the hinge structure of the AED, said rotational motion acting to progressively disengage first the anticipatory detector means and second the at least two battery electrodes from operational engagement with the AED.

9. An AED, comprising: a housing electronic circuitry disposed in the housing for delivery of an electric shock to a stricken patient; a removable battery pack being selectively operably, communicatively coupled to the electronic circuitry, the battery pack having an anticipatory detector means for generating an anticipatory signal to the electronic circuitry, said signal indicating that the disengagement of the battery pack from the AED is imminent.

10. The AED as claimed in claim 9 wherein the first and a second electrodes are biased to exert a force on the anticipatory detector means, said force acting to hold the battery pack in substantially motionless operational engagement with the AED housing.

11. The battery pack as claimed in claim 6 wherein the complimentary electrodes disposed on the AED are biased into compressive engagement with the at least two battery electrodes of the battery pack, said bias acting to maintain the circuit established between the at least two battery electrodes and the complimentary electrodes during an initial rotational portion of the disengagement of the battery pack from the disposition in operable engagement with the AED.

12. The battery pack as claimed in claim 11 wherein the complimentary electrodes each have a proximal end being operably coupled to the AED and a distal end having a curved engaging portion for engaging one of the at least two battery electrodes, the curved engaging portion riding on the battery electrode and maintaining electrical communication therewith during the initial rotational portion of the disengagement of the battery pack from the disposition in operable engagement with the AED.

13. In an AED having electronic circuitry powered by a disengageable battery pack, including high voltage storage circuits controlled by a processor, a method for ensuring that the stored high voltage in the high voltage storage circuits of the AED is safely discharged during disengagement of the battery pack from the AED, comprising the steps of: providing an anticipatory signal to the electronic circuitry, said signal indicating that the disengagement of the battery pack from the AED is imminent; maintaining electrical communication between the battery pack and the processor for a finite period of time after commencement of the disengagement of the battery pack from the AED; and discharging the high voltage circuits under control of the processor upon receipt of the anticipatory signal during the finite period of time.

14. A battery circuit comprising: a first set of battery cells having an upper set of cells arranged in series and a lower set of cells arranged in series; and a second set of battery cells arranged in series, the second set of cells connected in parallel with at least one cell of the first set of cells.

15. The battery circuit of claim 14 and further comprising a first reverse bias protecting diode disposed at the top of the second set of cells and a second reverse biasing protecting diode at the top of at least one of the upper set of cells and the lower set of cells that are connected in parallel to the second set of cells.

16. The battery circuit of claim 14 wherein the second set of battery cells is connected in parallel with at least one of the upper set of cells and the lower set of cells of the first set of cells.

17. The battery circuit of claim 14 wherein the upper set of cells includes two battery cells and the lower set of cells includes two battery cells, and the battery circuit further comprises: a first temperature sensing fuse disposed between the two cells of the upper set of cells and a second temperature sensing fuse disposed between the two cells of the lower set of cells.

18. The battery circuit of claim 15 wherein the second reverse bias protecting diode is disposed at the top of the lower set of cells that are connected in parallel to the second set of cells, and the lower set of cells including a pair of cells and the second set of cells including a pair of cells, the battery circuit further comprising: a third reverse biasing protecting diode connected between a first node, located between the pair of lower set cells, and a second node defining a 2 V output line of the battery circuit, and a fourth reverse biasing protecting diode connected between a third node, located between the pair of second set cells, and the second node.

19. A defibrillator battery comprising: at least one battery cell; a housing surrounding the at least one battery cell; and a memory connected to the at least one battery cell.

20. The battery as in claim 19 wherein the memory is mounted in the housing.

21. The battery of clam 19 wherein the memory is capable of storing an initial energy capacity of the battery.

22. The battery of claim 19 wherein the memory stores a first parameter of how much energy is used by a defibrillator in a standby mode on a daily basis, a second parameter of how much energy is used by a defibrillator during active operation per minute, and a third parameter of how much energy is used by a defibrillator charging up a capacitor bank.

23. The battery of claim 22 wherein the memory stores how many minutes a defibrillator has been in operation, how many days a defibrillator has been in standby mode, and how many charges have been delivered by a defibrillator.

24. The battery of claim 19 wherein the memory is capable of storing a serial number of the battery, an initial use date the battery was placed in service, and a voltage that indicates the battery is dead under high current.

25. The battery of claim 19 wherein the amount of energy remaining in the battery is determined by solution of the equations, R12 = 112 ΓÇó (1 - [x/A] - [y/2B] - [z/2C]), and R5 = 15 ΓÇó (1 - [x/A] - [y/B] - [z/C]) where 112 represents the capacity of 12V Cells in mA hours, 15 represents the capacity of 5V Cells in mA hours, A represents the energy for each high voltage charge of a defibrillator in mA hours, B represents the energy for each minute of active operation of a defibrillator in mA hours, C represents the energy for each day the battery is in a defibrillator in a standby mode in mA hours, x represents the number of high voltage charges removed from the battery, y represents the number of minutes the battery has been used for active operation, z represents the number of days the battery has been in a defibrillator, R12 represents the number of mA hours remaining in the 12V battery cells, and R5 represents the number of mA hours remaining in the 5V battery cells.

26. A defibrillator comprising: a defibrillator case; a battery comprising: at least one battery cell; a housing surrounding the at least one battery cell; and a memory connected to the at least one battery cell; and a multi-level battery status indication gauge.

27. A defibrillator comprising: a defibrillation case; a lithium battery; and a multi-level battery gauge.

28. The defibrillator of claim 27 wherein the battery is removably insertable into the defibrillator case.

29. The defibrillator of claim 27 and further comprising a microprocessor of an electrical system of the defibrillator which cooperates and communicates with the lithium battery and the multi-level battery gauge to display a relative energy capacity of the lithium battery on the multi-level battery gauge.

30. The defibrillator of claim 27 wherein the defibrillator case further includes a memory capable of electrical communication with the battery and the multi-level battery gauge for determining the relative energy capacity of the battery.

31. A method of monitoring status of a lithium battery in an automated external defibrillator comprising: providing a automated external defibrillator having a battery status indication gauge and a lithium battery; tracking an amount of use of the battery in the defibrillator and determining the remaining energy capacity of the battery by comparing the amount of use against predetermined energy use parameters of the battery and the defibrillator; displaying the remaining energy capacity of the battery by illumination of the battery status indication gauge.

32. A defibrillation device comprising: at least one of a defibrillator and a battery; the defibrillator or the battery having at least one of a memory for tracking battery use, an indication gauge for displaying battery use, a multiple battery cell arrangement, and an anticipatory battery separation detector means.

33. An AED and battery pack comprising: means to signal separation of the battery from the AED.