POCKET-SIZED AUTOMATED EXTERNAL DEFIBRILLATOR

Abstract

The invention relates to automated external defibrillator (AED) devices that may include a high-voltage capacitor (HV Cap) configured to store the energy required to deliver a defibrillation shock to a patient; batteries configured to charge the HV Cap; a DC / DC converter circuit including a high-voltage transformer, a FET switch with an associated controller, and a rectifier diode; an H-bridge circuit configured to transform the energy released from the HV Cap into a biphasic pulse; and a memory and microprocessor configured to operate the AED device.In particular, the HV Cap, DC / DC converter circuit, H-bridge circuit, one or more batteries, and memory and microprocessor may be contained in a pocket-sized housing; the AED device may be configured to continuously monitor and adjust the rate at which the batteries charge the HV Cap; and the AED device may include a variable-frequency relaxation oscillator circuit configured to acquire a patient's Z-body measurement.

Description

POCKET-SIZED AUTOMATED EXTERNAL DEFIBRILLATOR Cross-reference to Related Applications This application claims priority over U.S. Provisional Patent Application No. 63 / 142,910 filed on January 28, 2021, which is incorporated herein by reference. Field of Invention This description refers in general to medical electronics and more specifically to a portable Automated External Defibrillator (AED). Background of the Invention According to the World Health Organization, an estimated 18 million people die from cardiovascular disease (CVD) each year, making CVD the leading cause of death worldwide. Approximately 800,000 Americans suffer a heart attack each year, and according to the American Heart Association (AHA), approximately 300,000 Americans die annually from sudden cardiac arrest (SCA). People with risk factors such as high blood pressure, diabetes, or high cholesterol, or those with heart disease, are at the greatest risk of having a heart attack or cardiac arrest. And each year, approximately 200,000 people who have had a previous heart attack experience a recurrence. Many second heart attacks result in death. Furthermore, 70% of heart attacks are out-of-hospital cardiac arrests (OHCA), and 90% of OHCA cases result in death. During cardiac arrest, survival depends on how quickly a defibrillator can deliver a life-saving shock to the heart, and every minute of delay reduces the chances of survival by 10%. However, in the United States, the average time between a 911 call and the arrival of Emergency Medical Services (EMS) is approximately 8 minutes, or 14 minutes in rural areas. As a result, most heart attack deaths occur because defibrillation therapy is not administered quickly enough. Unfortunately, even if the ambulance or paramedics reach the victim within 8 minutes, brain injury may have already occurred, as irreversible brain damage can result from more than 5 minutes of oxygen deprivation. Therefore, even if a patient survives the cardiac event, they may be in a state of permanent impairment and unable to live a full life thereafter. LC / onn / eznz / e / Y LC / onn / eznz / e / Y To save lives, defibrillation therapy should be made available in the homes of people with risk factors for heart disease. However, conventional AEDs are typically found only in public places, such as airports and gyms. These conventional AEDs are large, bulky, and complicated, and most people find them somewhat intimidating. Conventional AEDs are also often housed in wall-mounted cabinets with a sign indicating that an alarm will sound when the door is opened. In emergency situations, this can be counterproductive, as it increases the apprehension and anxiety of a potential Good Samaritan and, consequently, may discourage them from getting involved. Furthermore, it is estimated that up to 20% of conventional AEDs are inoperable at any given time; however, many of these AEDs do not clearly indicate whether and when maintenance is required. Therefore, it would be desirable to make defibrillation therapy more accessible to people with risk factors for heart disease. It would also be desirable to provide an AED that is compact enough to be carried by a family member or caregiver of a patient with heart disease, easy to use, ready for use whenever and wherever needed, and that provides highly noticeable alerts when service or maintenance is required. Brief Description of the Invention In one aspect, an automated external defibrillator (AED) device is provided that includes a high-voltage capacitor (HV Cap) configured to store the energy required to deliver a defibrillation shock to a patient; one or more batteries configured to charge the HV Cap; a DC / DC converter circuit comprising a high-voltage transformer (HV XEMR), a field-effect transistor (FET) switch with associated driver, and a rectifier diode, preferably configured to boost the battery voltage to approximately 2000 volts; and an H-bridge circuit configured to transform the energy released from the HV Cap into a biphasic pulse.and a memory and microprocessor configured to store and execute computer-executable instructions for the operation of the AED device, wherein the HV Cap, DC / DC converter circuit, H-bridge circuit, one or more batteries, and the memory and microprocessor are contained in a pocket-sized housing. In the modalities, the AED device further includes a pair of defibrillation pads and a cable for operationally connecting the HV Cap to the pair of defibrillation pads, wherein the pads of; LC / onn / eznz / e / Y defibrillation devices are also pocket-sized. LC / onn / eznz / e / Y In another aspect, an AED device is provided that is configured to continuously monitor and adjust the rate at which one or more batteries charge the HV Cap. In a preferred mode, the AED device is configured to simultaneously monitor the discharge current and temperature of one or more batteries to charge the HV Cap at the maximum possible rate with the available energy from one or more batteries, without exceeding a maximum temperature or maximum discharge rate of one or more batteries. In another aspect, an AED device is provided that includes a variable frequency relaxation oscillator circuit configured to acquire a patient's body Z measurement, wherein the circuit is effective at self-oscillating at a frequency that is proportional to the patient's body impedance. In another aspect, an AED device is provided that includes a power controller circuit comprising a real-time clock (RTC) and does not enter a sleep mode when the main microprocessor is powered off, wherein the power controller circuit is configured to control the AED device when the main microprocessor is powered off by the RTC, which is configured to periodically power on the main microprocessor to perform a built-in self-test (BIST) sequence. LC / onn / eznz / e / Y Brief Description of the Figures The detailed description is provided with reference to the accompanying drawings. The use of the same reference numbers may indicate similar or identical items. Different versions may use different items and / or components than those illustrated in the drawings, and some items and / or components may not be present in several versions. The items and / or components in the figures are not necessarily drawn to scale. Figure 1A is a front perspective view of an AED device, according to an embodiment of the described invention. Figure IB is a rear perspective view of the AED device shown in Figure 1A. Figure 2A is a perspective view of defibrillator pads arranged for packaging, according to an embodiment of the described invention. Figure 2B is an exploded view of the defibrillator pads and components shown in Figure 2A. Figure 3A is a front view of an AED circuit board assembly and high voltage capacitor, according to an embodiment of the described invention. Figure 3B is a rear view of the AED circuit board assembly and high voltage capacitor shown in FIG. 3A. Figure 4A is an exploded side view of an AED circuit board, according to an embodiment of the described invention. Figure 4B is a rear perspective view of the AED circuit board shown in Figure 4A. Figure 5 is a software block diagram for an AED device, according to one embodiment of the described invention. Figure 6 is an example of a high-voltage capacitor charging circuit, according to one embodiment of the described invention. Figure 7 is a block diagram representing a body Z measurement sequence, according to an embodiment of the described invention. Figure 8 is an example of a conventional Z-body measurement circuit common in the prior art. Figure 9 is an example of a Z-body measurement circuit using a relaxation oscillator, according to an embodiment of the described invention. Figure 10 is a block diagram representing an ECG and a shock delivery sequence, according to one embodiment of the invention LC / onn / eznz / e / Y described. Figure 11 is a block diagram representing an integrated self-testing sequence (BIST), according to an embodiment of the described invention. Figure 12 is an example of a loudspeaker verification circuit, which uses microphone monitoring, according to one modality form of the described invention. Figure 13 is an example of an analog front-end verification circuit, according to an embodiment of the described invention. LC / onn / eznz / e / Y Detailed Description of the Invention A new, more compact automated external defibrillator (AED) has been developed. Advantageously, it is pocket-sized, a size achieved by combining unique hardware and software components with the operational innovations described herein. Because the AED is small enough to be carried with the patient, it can be readily available whenever and wherever needed. As used herein, the term pocket-sized means that the AED device is small enough to be carried by a person in a jacket or trouser pocket, or in a small purse or handbag, for example, with dimensions less than or equal to 170 mm x 95 mm x 40 mm. One of the keys to reducing the size and weight of the AED compared to conventional AEDs is reducing the size and / or number of batteries required by the device. Obviously, this reduces the amount of stored energy available to operate the AED and therefore necessitated several operational and energy-saving innovations, as described below, to meet regulatory performance requirements while maintaining or exceeding other performance expectations, such as reliability, maintenance / service intervals, and the like. In a preferred configuration, the AED as described here uses four CR2 batteries.Although CR2 batteries are preferred due to the combination of size, charging time, and available power source, the AED device can be adapted to use other suitable types or numbers of commercially available batteries that meet the size and performance requirements of the currently described AED device. Similarly, the dimensions of the defibrillator pads used in the current AED are also reduced compared to the large defibrillator pads used in AEDs LC / onn / eznz / e / Y conventional. In a preferred embodiment, following the minimum permitted pad size according to the EDA, the pad size has been reduced to 6.0 x 3.3 (152mm x 84mm) without loss of effectiveness, which represents a reduction in size compared to those of conventional AEDs. The AED device measures the patient's body impedance, calculates the energy required to deliver the appropriate shock, analyzes the patient's electrocardiogram (ECG), determines if the patient has a shock-appropriate rhythm, and delivers the appropriate energy as a life-saving shock. Advantageously, the AED device described here is small enough to be easily carried by a patient with heart disease, their family member, or another caregiver—for example, in a pocket, purse, or backpack. Consequently, the AED device facilitates lifesaving by bringing defibrillation therapy to the home and other locations where conventional AEDs are unavailable and / or where timely access to emergency medical personnel is not possible. Furthermore, this AED device offers several features that enhance its ease of use and reliability. For example, in certain modes, the AED includes a speaker that provides voice prompts, calmly guiding the user on what to do during a LC / onn / eznz / e / Y emergency. In addition, the speaker also informs the user when the batteries or defibrillator pads need changing, when the device's internal temperature is too high, or when other service is required. Voice prompts can be programmed in multiple languages. Furthermore, in preferred modes, the AED performs a series of self-tests to ensure it is ready when needed or will alert the user in the event of a microprocessor, speaker, or other failure, for example, using the AED's built-in LEDs and a piezoelectric vibrator, so that maintenance can be performed on the AED before it is used. In preferred designs, the front of the AED is uncluttered with a minimum of buttons and text to avoid distracting or intimidating the user. For example, in one preferred design, the AED includes only a single button for the user to turn it on. In some other designs, the AED is activated by a capacitive switch that turns on the device whenever the user touches it, or by a motion sensor that turns it on whenever movement is detected (for example, when removed from a storage bag or case). In these designs, the goal is to make it as simple as possible for the user to operate. LC / onn / eznz / e / Y the device during a stressful medical situation. In Figures 1A-1B, the AED 100 device includes a housing 102 that contains the internal electronic components of the device 100. In a preferred embodiment, the housing 102 measures 6.1 inches (155 mm) long (L), 3.4 inches (86 mm) wide (W), and 1.1 inches (28 mm) high (H) and weighs only about one pound (450 g). As shown in Figure 1A, the face of housing 102 is clear and includes a single POWER button 106, speaker holes 110, piezoelectric vibrator holes 112, and status LEDs 108. The AED device 100 does not include an OFF button, preventing users or bystanders from inadvertently turning off the device during use. As shown in Figure 1B, the rear of housing 102 has a battery compartment cover 114, which is configured to provide access to the batteries in the AED device 100. Extending from the top of housing 102 are two defibrillator cables 104 (which connect to the corresponding defibrillator pads 202, 204) shown in Figures 2A-2B. When not in use, the AED 100 device, defibrillator leads 104 and defibrillator pads 202, 204 can be stored together in a LC / onn / eznz / e / Y LC / onn / eznz / e / Y Small pouch, cover, or case (not shown). For example, it may be a soft cloth bag, a folding case, or similar. The pouch, cover, or case may be designed to minimize the muffling or obscuring, respectively, of audible or visual service notifications emitted by the AED device. One embodiment of the defibrillator pads is shown in Figures 2A-2B. The defibrillator pads 202, 204 are integrated with the defibrillator leads 104 so that when the defibrillator pads 202, 204 are placed on the patient's chest, the shock from the AED device travels through the defibrillator leads 104 to the defibrillator pads 202, 204 to electrocute the patient. As shown in Figure 2A, the defibrillator pad storage assembly 200 includes a laminated paper 206 placed between the conductive gel layers 203, 205 of the defibrillator pads 202, 204, which are stored face-to-face in a sealed airtight bag (not shown). This packaging configuration helps to preserve the integrity of the conductive gel layers 203, 205.As the figures indicate, defibrillator pads 202 and 204 have similar length and width dimensions to housing 102, facilitating their compact storage together. In one configuration, the defibrillator pads... LC / onn / eznz / e / Y 202 and 204 are approximately 6 cm long and 3 cm wide. Other dimensions of defibrillator pads are possible, provided the defibrillator pads meet the relevant regulatory requirements. For example, the U.S. Food and Drug Administration (FDA) requires that defibrillator pads have a total contact surface area of ​​at least 150 cm², or 75 cm² for each pad. Figure 2B shows the construction of the defibrillator pads 202, 204 and the arrangement for packaging. Each defibrillator pad 202, 204 has a conductive side that is coated with a layer of conductive gel 203, 205. A removable pressure-sensitive laminate paper 206 is placed between the layers of conductive gel 203, 205 of the defibrillator pads 202, 204. Figures 3A-3B show the internal electronic components of the AED 100 device, including a high-voltage capacitor (HV Cap) 302 and a circuit board 304 (shown in greater detail in Figures 4A-4B), which together form the internal assembly 300. Figure 3A shows a front view of the internal assembly 300. According to this embodiment, the electronic components are arranged on a main printed circuit board (PCB) 306. More specifically, the front side of the main PCB 306 contains the power button 308 and the speaker. LC / onn / eznz / e / Y 310, piezoelectric vibrator 312, status LEDs 314, a microphone 316, a backup battery 318, and a microSD memory card 320. A primary microprocessor 602 and a secondary microprocessor (not shown) are also integrated into the main PCB 306. The HV cap 302 is attached to the distal end of the circuit board 304 by capacitor leads 322, which connect to capacitor contacts 334 located on the back side of the main PCB 306. Figure 3B shows a rear view of the internal assembly 300. The rear of the main PCB 306 has four (4) battery compartments 328 sized to hold CR2 batteries (not shown), a high-voltage transformer (HV XFMR) 326, capacitor contacts 334, and an area for the defibrillator cable contacts 330. Therefore, the HV Cap 302 is indirectly connected to the batteries (not shown) via the HV XFMR 326. In this configuration, the HV XFMR 326 converts the power supplied by the batteries (not shown) to a level that can be received by the HV Cap 302. The rear of the main PCB 306 also includes rails 332 and an HBridge circuit on a secondary PCB 324, both of which, in various configurations, are standard components of AED devices. Figure 5 is a software block diagram LC / onn / eznz / e / Y represents the arrangement and interaction of these electronic components. The functions of the AED 100 device can be classified into one of two categories: defibrillation tasks and built-in self-test (BIST) tasks. While defibrillation tasks can only be performed when the AED 100 device is fully powered on, BIST tasks will be performed regardless of whether the AED 100 device is powered on or off. In addition to these two primary task categories, the AED 100 device also uses an audio controller (not shown), which is responsible for the interface between the speech synthesizer and the 320GB SD card where these audio files are stored. During defibrillation and BIST tasks, the audio controller extracts the appropriate voice file from the 320GB SD card, routes the audio to the speech synthesizer, and plays it back to the user. The AED 100 device also utilizes a data logging function, which interfaces with the SD 320 card. Any data collected during defibrillation or BIST tasks is stored on the SD 320 card and can then be retrieved on an external device. The AED 100 also includes an IrDA UART controller for interfacing with an IR transmitter or receiver. The IrDA UART is used to communicate with compatible devices. LC / onn / eznz / e / Y For example, the IrDA UART can transmit logged data or receive firmware updates to be installed on the AED 100 device. Returning to the tasks of the primary AED 100 device, Figures 6-10 provide further details on the primary defibrillation tasks, which include loading the HV Cap 302, performing a Z-body measurement, acquiring and analyzing the patient's ECG, and delivering a shock. Because the defibrillation tasks require the AED 100 device to be fully powered on, the user must power on the AED 100 device to initiate any of these tasks. To do so, the user presses the POWER button 106, which is connected to the power button 308, allowing the microprocessor 602 to power on the internal assembly 300. Figure 6 represents an exemplary modality of the 600 HV Cap 302 charging circuit. The AED 100 device uses a 600 flyback topology DC / DC converter represented in Figure 6 to raise the battery voltage (approximately 12 volts) to a voltage high enough for a shock pulse (up to 2000 volts). The converter consists of switch 3002, field-effect transistor (FET), controller 3003, snubber circuit 3006, transformer 326, and rectifier diode 3004. Microcontroller 602 generates a LC / onn / eznz / e / Y pulse trails, under software control, are amplified by controller 3003 to operate the gate of FET switch 3002. The switch opens and closes periodically, allowing current to flow or interrupting the current through the primary winding of transformer 326. When the current is interrupted, a generated Electromagnetic Force (EMF) voltage is generated in the primary winding of transformer 326, in accordance with Lenz's Law, which describes this fundamental property of inductors. Because the number of turns in the secondary winding of transformer 326 is much greater than that of the primary, the EMF voltage in the secondary winding is multiplied by the turns ratio between the primary and secondary windings. This ratio is chosen so that the peak of the reverse EMF pulses can reach 2000 volts. This voltage is rectified by diode 3004, which charges the HV capacitor 302. In a preferred configuration, the AED 100 device uses CR2 batteries to power the AED 100 device and charge the HV Cap 302. Because the batteries are significantly smaller than those used in conventional AED devices, the HV Cap 302 requires a longer charging time than conventional AED devices. LC / onn / eznz / e / Y Conventional AEDs also typically do not begin charging until a shockable heart rhythm is detected. Therefore, to account for smaller batteries, the AED 100 device begins charging the HV Cap 302 immediately after the AED 100 is powered on and before attempting to detect a shockable heart rhythm. In a preferred mode, the HV Cap 302 will be fully charged within 30–40 seconds of the AED 100 being powered on. The 602 microprocessor is programmed to monitor and control the charging rate of the HV Cap 302. To charge the HV Cap 302, the 602 microprocessor transmits a sequence of square wave pulses from the HV XFMR 326 to the HV Cap 302, where the frequency of these pulses effectively controls the charging rate of the HV Cap 302. Thus, the 602 microprocessor is programmed with a feedback circuit that will adjust the pulse frequency to adjust the charging rate as needed. Specifically, the microprocessor 602 of the described AED device is configured to modify the charging rate to ensure that the batteries do not exceed the manufacturer's specified temperature and discharge rate, which is 1000 mA and 60°C for CR2 batteries. Therefore, the charging circuit 600 includes a temperature sensor 604 and a current monitor 606 to collect and provide feedback to the microprocessor. This process ensures that the HV Cap 302 is charged at the fastest possible rate given the available battery power. Furthermore, the AED device's microprocessor 602 is configured to adjust the charging rate to account for the AED 100 device's functions that occur while the HV Cap 302 is charging. For example, the speaker 310 will provide the user with various instructions during the charging process. To account for the current the speaker 310 is drawing from the batteries, the microprocessor 602 will appropriately decrease the current to the HV Cap 302 to maintain the batteries within the specified discharge and temperature thresholds. Once the voice message is complete, the microprocessor 602 will return to the original charging rate. While the HV Cap 302 is charging, the AED 100 device performs two defibrillation tasks before a shock can be delivered, the first of which is to perform a body impedance (Z-body) measurement. A Z-body measurement incorporates both the resistance and capacitance of a patient's body when an AC current is applied. The Z-body measurement is critical for determining the magnitude of the shock to be delivered. Specifically, the shock delivered by the AED 100 device is only effective if the current magnitude is high enough to depolarize the heart. However, the current cannot be so high as to damage the patient's cardiac tissue. Therefore, the Z-body measurement ensures that the shock is within this effective and non-damaging range. The process of performing a Z-body measurement is shown in Figure 7. After the user has turned on the AED 100 device and correctly placed the defibrillator pads 202 and 204 on the patient's chest, the AED 100 will attempt to detect a Z-body measurement. In one example, the AED 100 performs the Z-body measurement using a relaxation oscillator circuit 900, as shown in Figure 9. This process differs significantly from conventional AEDs, which use circuits like the one in Figure 8 to perform the Z-body measurement. The conventional process for performing Z-body measurements typically involves sending a constant, high-frequency AC signal through the defibrillator leads and pads, which is subject to significant external interference.Consequently, conventional AED devices must use expensive precision circuit components to measure these signals and filter them. LC / onn / eznz / e / Y inevitable interference. Therefore, it is advantageous to use a 900 relaxation oscillator circuit because it has a simpler design (and is less expensive), takes up less space, and has greater immunity to interference than conventional Z-body measurement circuits. The 900 circuit, shown in Figure 9, automatically oscillates at the frequency defined by its timing components. The basic iAED principle behind using this type of oscillator for body Z measurement is to include the human body as one of the oscillator's timing components and capture the resulting frequency changes. After calibration, measuring the circuit's output frequency will determine the body Z value of the single variable component (the human body) that caused the change. In a preferred embodiment, the circuit includes a voltage comparator 907, integrated into the microprocessor 602 having its inverting input 908, non-inverting input 909 and output 910, a voltage divider 901 and 905 and an RC timing circuit with fixed resistor 904 and capacitor 906. A human body 911, seen by the circuit as a resistor, is connected in parallel to resistor 904 through two wires called Apex 912 and Sternum 913. LC / onn / eznz / e / Y LC / onn / eznz / e / Y The feedback resistor 902 provides the positive feedback required to initiate the oscillation process. Resistor 903 is used to scale the magnitude of the feedback signal. The circuit is powered from power supply 914 relative to ground potential 915. Comparator 907 is an electronic device whose output state can have only two predefined values: approximately 0 volts (V) or close to the supply voltage, depending on the state of its inputs. If an AED supplies the circuit with 3.3 V, the output of comparator 910 will be approximately 0 V or 3.3 V. Comparator 907 compares the voltages at its inputs 908 and 909 and sets the output 910 accordingly. If the voltage at non-inverting input 909 is higher than the voltage at inverting input 908, output 910 will be set to 3.3V. Otherwise, output 910 will be at 0V. The operation of circuit 900 is as follows: When power is applied to 914, the voltage at the non-inverting input 909 of comparator 907 is set according to the voltage divider 901 and 905, and completed by the Apex voltage 912 through the calibration resistor 903. With resistors 901 and 905 set to equal values, it will be half the supply voltage 914, or 1.65 V, in this example. However, it will increase or decrease according to the voltage at the Apex wire 912 applied to input 909 through resistor 903, which, in turn, depends on the state of the comparator output 910. According to the chosen component values, the voltage at the non-inverting input 909 will be approximately 1.55 V when the output 910 is 0 V and 1.75 V when the output 910 is 3.3 V. Initially, the voltage at the inverting input 908 will be close to zero because capacitor 906 is initially discharged; therefore, the output 910 of comparator 907 will be set to 3.3 V. This voltage is applied to capacitor 906 through feedback resistor 902 and timing resistor 904 in parallel with the human body impedance 911 (body Z). Capacitor 906 will begin to charge from the current flowing through resistor 904 and the human body 911 to the voltage set by the voltage divider formed by feedback resistor 902 and calibration resistor 903. The divider ratio is set so that the final voltage at Apex wire 912 will be greater than 1.75 V. When the voltage across capacitor 906, connected to the inverting input 908, exceeds the 1.75 V present at the non-inverting input 909, the output 910 of comparator 907 switches from 3.3 V to 0 V. This causes the voltage at Apex 912 to drop. LC / onn / eznz / e / Y decreases to a value below 1.55 V, which immediately changes the voltage at the non-inverting input 909 to 1.55 V. Capacitor 906 then begins to discharge through resistor 904 and the human body 911. When it discharges from 1.75 V to 1.55 V, the voltage at the non-inverting input becomes higher than the voltage at the inverting input and the cycle repeats, generating a digital frequency (between 0 V and 3.3 V) at the output 910 of comparator 907. As mentioned earlier, the time required for capacitor 906 to continue charging from 1.55 V to 1.75 V and discharging from 1.75 V to 1.55 V depends on the RC constant, where R consists of resistor 904 and the human body impedance 911 (body Z) in parallel. Because resistor 904 is constant and known, the only variable that determines the final oscillation period (e.g., frequency) at comparator 907's output 910 is the human body impedance 911 (body Z). By calibrating the oscillator against a known set of impedances, the human body's contribution 911 to the oscillator's frequency change can be determined from the signal frequency at comparator 907's output 910, and the value of body Z can be calculated. Therefore, the 602 microprocessor requires LC / onn / eznz / e / Y requires fewer variables to calculate the Z-body measurement. Furthermore, the 900 relaxation oscillator circuit is superior to conventional Z-body measurement circuits because it is completely immune to external interference, as the 900 relaxation oscillator neither uses nor measures analog signals. And, as mentioned earlier, the simplicity of the relaxation oscillator circuit reduces both the manufacturing cost and the device size, because fewer components are required. Furthermore, the 900 relaxation oscillator circuit does not require the use of expensive precision capacitors or resistors. The circuit uses a voltage comparator and only a few non-precision passive resistors and capacitors to drive the output signal, resulting in a significantly reduced component count compared to prior art Z-body measurement circuits. A measurement of the circuit's output frequency is used to determine the patient's body impedance. The output is a digital signal that allows frequency to be measured independently of amplitude, resulting in greater noise immunity compared to prior art Z-body measurement methods. However, it is possible that in some circumstances the AED 100 device may not be able to take this LC / onn / eznz / e / Y measurement. Typically, the AED 100 device will not take a Z-body measurement if the defibrillator pads 202, 204 are not correctly positioned on the patient's chest. Consequently, after a failed Z-body measurement, the user will be prompted to adjust the defibrillator pads 202, 204. In the event of three failed measurements, the user will be prompted to administer cardiopulmonary resuscitation (CPR) instead. If the AED 100 successfully performs the Z-body measurement, it will proceed to the second defibrillation task, which involves reading and analyzing the patient's ECG. This process, typically shown in Figure 10, monitors the patient's heart rhythm to determine if they have one of two shockable rhythm patterns. Defibrillation is only effective when a patient has ventricular tachycardia (Vtach) or ventricular fibrillation (Vfib), so the AED 100 will prompt the user to administer CPR if neither of these shockable rhythms is detected. If Vtach or Vfib is detected, and the HV Cap 302 is sufficiently charged, the AED 100 will instruct the user to stand back before delivering the shock. The user will then be prompted to administer CPR. The process of detecting heart rhythms of The patient utilizes an analog front-end (AFE) circuit (not shown) integrated on the main PCB 306. According to one exemplary modality, the AFE includes a MAX30003 integrated circuit (IC) (not shown) not only to capture ECG data but also to control the gain, sampling rate, bias, polarity, and filter settings necessary to maximize the readability of the ECG signals. In this modality, the IC receives the patient's low-voltage heart rhythms, which are transmitted to an analog-to-digital converter (ADC) (not shown). These digital outputs are periodically sampled, at which point the buffered data is transmitted to the microprocessor 602, which is programmed to determine whether the patient has a shockable heart rhythm.The AED 100 device must capture at least six (6) consecutive heart rhythms of a shockable pattern, or a shock will not be delivered. According to one exemplary model, the AED 100 device uses a software-based high-voltage (HV) shock controller (not shown) to interconnect all the circuits involved in the defibrillation process. More specifically, the HV shock controller software measures the voltage of HV Cap 302 after performing the Z-body measurement, to ensure LC / onn / eznz / e / Y LC / onn / eznz / e / Y that the voltage of HV Cap 302 is charged to an appropriate level. In addition, the HV discharge controller software is also responsible for verifying whether a discharge is actually delivered after collecting the ECG data. When the AED 100 device is powered on and the defibrillator electrodes 202 and 204 are connected to the patient, the AED 100 continuously measures the patient's ECG waveform and classifies it in real time. When the classification is determined to be a shockable waveform—that is, (i) ventricular tachycardia (Vtach) or (ii) ventricular fibrillation (Vfib)—and this classification remains constant for a minimum of six seconds, a high-voltage shock is then delivered to the patient through the defibrillator electrodes. To deliver a shock, the AED 100 device uses the H-Bridge 324 circuit, which transforms the energy released from the HV Cap into a biphasic pulse, defined as two pulses of opposite polarity applied sequentially. After delivering the shock, the AED 100 will prompt the user to administer CPR while continuing to monitor the patient's ECG. After two minutes of CPR, if analysis of the patient's ECG determines that a second shock is needed, the above process will be repeated, and again, if necessary, for a third shock. In each case, the device will prompt the user to administer two minutes of CPR between shocks. In preferred modes, the AED device does not have an OFF button to prevent it from accidentally turning off at an inconvenient time. Instead, the device is configured to power down after a specific period of inactivity, for example, after three minutes of complete inactivity. The 310 speaker will alert the user that the AED 100 device is powering down. In addition to the defibrillation tasks described above, the AED 100 device performs several built-in self-test (BIST) tasks, partly according to the diagram in Figure 11. In general, the BIST tasks ensure that the AED 100 device is functioning correctly, and most of these BIST tasks are performed while the AED 100 device is switched off. Because the present AED device uses significantly smaller batteries than conventional AED devices, the internal components are configured and programmed to conserve as much battery power as possible. Accordingly, an example configuration of the AED 100 device includes a Power Handler system (not shown) to control BIST tasks while conserving as much battery power as possible. More specifically, the Power Handler system ensures that all circuitry, Except for a few ultra-low power components, the AED 100 is powered off when not in use. The ultra-low power components that remain powered on at all times operate in the nanoampere range and include, but are not limited to, the real-time clock (RTC) (not shown). This Power Handler system is unique compared to conventional AED devices, which often enter a Sleep Mode when not in use. However, Sleep Modes still consume significant amounts of power, making the current Power Handler system particularly advantageous for reducing power consumption during extended periods of inactivity. In general, the RTC is programmed to periodically activate microprocessor 602 to initiate the BIST sequence, which involves a series of hardware checks and a battery level check. When the BIST is successful, meaning no errors are identified, the AED 100 device status will be updated so that a green status LED 314 will blink periodically. This green status LED 314 will continue to blink after microprocessor 602 powers down, until the next BIST sequence. If the BIST is unsuccessful and speaker 310 is functioning correctly, a red status LED 314 will blink while a voice message such as "Needs Service" is delivered. Microprocessor 602 will then power down, and while When LC / onn / eznz / e / Y does so, the red status LED 314 will blink and the piezoelectric vibrator 312 will beep. This process repeats every thirty minutes until the AED 100 device is repaired. When the speaker 310 malfunctions, or the microprocessor 602 becomes unresponsive, the red status LED 314 will blink while the piezoelectric vibrator 312 beeps. These alarms are continuous until the AED 100 device is repaired. Returning to the specific checks performed during the BIST sequence, FIG. 12 depicts an example of a 1200 speaker verification circuit. Reliability, sound pressure level, and the integrity of the voice prompts are important for guiding the user's operation of the AED device, so the 310 speaker must be checked frequently. According to one exemplary embodiment, the 310 speaker is integrated into the housing using an O-ring or gasket (not shown) to achieve splash protection or waterproofing to an acceptable ingress protection (IB) level. The speaker 110 holes in the housing 102 allow sound pressure from the 310 speaker to escape the AED device 100, but make the speaker potentially susceptible to damage, for example, from water or a sharp object penetrating the speaker holes. Damage of this type may be imperceptible. LC / onn / eznz / e / Y at first glance, but they can cause voice prompts to become distorted or even nonexistent. According to one exemplary configuration, the main RGB 306 is equipped with a small microphone 316 positioned very close to the speaker 310. When the RTC is activated, the microprocessor 602 generates a brief tone lasting approximately 20–50 ms, which is played back through the speaker 310. The microprocessor 602 also listens for this tone to be repeated through the microphone 316. If the speaker 310 is damaged in any way, the tones will not match, and the microprocessor 602 will enter the necessary alert sequence, as previously described. Another potential vulnerability for a portable AED is the device's temperature. More specifically, an AED is susceptible to damage when stored in high-temperature environments that exceed its specified operating and storage temperature ranges. In one example, the AED 100 uses a temperature-sensing integrated circuit (temp-sense IC), typically shown in Figure 6, to continuously monitor its temperature. The temperature-sensing IC, like the RTC, is an ultra-low-power component and will therefore monitor the AED's temperature even when... LC / onn / eznz / e / Y LC / onn / eznz / e / Y The microprocessor 602 is off. When the temperature of the AED 100 device falls outside the acceptable range, the temperature sensor IC turns on the microprocessor 602, which will enter the necessary alert sequence. The present AED is also exceptionally vulnerable to damage to the defibrillator cables 104 and the defibrillator pads 202, 204. Conventional AEDs are generally stored in secure, wall-mounted housings, so individual components are unlikely to be damaged by ordinary passersby. In contrast, because the AED described herein is designed for personal use, it may be susceptible to handling and damage in ways that conventional AEDs are not, for example, while left at home and / or transported in vehicles and outdoors, where it may be dropped, exposed to water and varying temperatures, etc., and to damage to the cable integrity 104. According to a first exemplary modality, during the BIST sequence, microprocessor 602 generates a low-frequency signal, approximately 30 kHz, and sends this signal through defibrillator leads 104 and defibrillator pads 202, 204. If the signal returns to microprocessor 602 and matches the original, within a predetermined margin of error, defibrillator leads 104 and defibrillator pads 202, 204 are intact. When there is a significant change in the signal, it is likely that defibrillator pads 202, 204 are no longer properly sealed or that the conductive gel layer 203, 205 has dried out. If no signal is returned, at least one of the defibrillator pads 202, 204 and / or defibrillator leads 104 is significantly damaged. In any case where the signals sent and returned do not match, the 602 microprocessor will initiate the necessary alert sequence. In another exemplary modality, the pressure-sensitive laminated paper 206 between the defibrillator pads 202, 204 has at least one small hole so that the conductive gel layers 203, 205 are in direct contact. Here, the microprocessor 602 is programmed to periodically generate a low-voltage DC signal, approximately 3–5 VDC, which is sent through the defibrillator leads 104 and the defibrillator pads 202, 204. As with the modality described above, the microprocessor 602 compares the returned signal, if one is returned, to the original signal to determine whether the defibrillator leads 104 or the defibrillator pads 202, 204 are damaged. The microprocessor 602 will initiate the LC / onn / eznz / e / Y appropriate alert sequence as required when damage is detected in at least one of the defibrillator pads 202, 204 and / or defibrillator leads 104. According to another method, the integrity of the defibrillator leads 104 and the defibrillator pads 202, 204 is verified using a method similar to that described for the Z-body measurement method. Specifically, this verification method uses the relaxation oscillator circuit shown in Fig. 9. During the BIST sequence, the relaxation oscillator will initiate an oscillation within a predetermined frequency range. The microprocessor 602 detects this oscillation and then calculates the oscillation frequency. When the calculated oscillation frequency is within the predetermined range, the defibrillator leads 104 and the defibrillator leads 202, 204 are functioning correctly.If the calculated frequency is outside this range, or the 602 microprocessor cannot detect the oscillation, at least one 202, 204 defibrillator pad and / or 104 defibrillator cable is damaged and the 602 microprocessor will enter the required alert sequence. The EDA requires that the defibrillator pads of AED devices be changed at least every two years. Thus, according to one exemplary model, the RTC is programmed with a timer that will alert the LC / onn / eznz / e / Y microprocessor 602 every two years when defibrillator pads 202, 204 need to be replaced. When microprocessor 602 is alerted that service is required, it will initiate a predetermined alert sequence to inform the user that new defibrillator pads 202, 204 are needed. The BIST sequence also involves verifying the functionality of the AFE circuit. According to one example, this process is performed by the circuit depicted in Figure 13. When the AED 100 device enters the BIST sequence, the 602 microprocessor transmits a low-frequency signal simulating a heartbeat, approximately 1–5 Hz, to the AFE circuit. If this signal is received, the AFE circuit reads and processes it as if it were collecting ECG data and processes and reports the data to the 602 microprocessor accordingly. The AFE circuit is considered to be functioning correctly when the data returned to the 602 microprocessor matches the original signal, within a predetermined margin of error. However, if no data is returned, or if the returned data falls outside the predetermined margin of error, the 602 microprocessor will enter the necessary alert sequence. Furthermore, the BIST sequence involves several additional checks. According to one modality The LC / onn / eznz / e / Y example sequence BIST also checks the supply voltage and battery status. When the power supply voltage is low or a battery status error is detected, the user will receive an appropriate alert. However, the AED 100 device is equipped with a 318 backup battery to ensure that components such as the RTC are always powered. The 318 backup battery is also essential for powering the AED 100 device while the batteries are being serviced (e.g., replaced). The BIST sequence also verifies the functionality of the RAM and SD 320 cards. A primary purpose of the SD 320 card is to store information related to the status of the AED 100 device and any specific components that require servicing. In one example, the SD 320 card is easily removable and will upload all the AED 100 device status information to a computer. This upload allows the user to easily identify whether the AED 100 device needs servicing and, if so, which component and / or system requires service. LC / onn / eznz / e / Y In addition, according to another exemplary model, the 316 microphone can also record ambient audio while the device is in use. Therefore, the AED 100 device, or more specifically the SD card, must have sufficient storage to retain this audio data. This data can be used to provide forensic information for any failed reactivation attempt. The BIST sequence also implicitly verifies the functionality of microprocessor 602. More specifically, microprocessor 602 is malfunctioning if it becomes unresponsive during any of the aforementioned tasks. In such a case, the secondary microprocessor assumes a limited number of processing functions. In particular, the secondary microprocessor will initiate the appropriate alert sequence to inform the user that service is required. As used in this document, the term approximately means plus or minus 10% of the numerical value of the number with which it is used. Although the description has been given with reference to a number of exemplary modalities, those skilled in the art will understand that the description is not limited to such disclosed modalities. Rather, the described modalities may be modified to incorporate any number of variations, alterations, substitutions, or equivalent arrangements not described herein, but which are within the scope of the description.

Claims

1. An automated external defibrillator (AED) device comprising: a high-voltage capacitor (HV Cap) configured to store the energy required to deliver a defibrillation shock to a patient; one or more batteries configured to charge the HV Cap; a DC / DC converter circuit comprising a high-voltage transformer (HV XFMR), a field-effect transistor (FET) switch with associated driver, and a rectifier diode; an H-bridge circuit configured to transform the energy released from the HV Cap into a biphasic pulse; and a memory and a microprocessor configured to store and execute computer-executable instructions for the operation of the AED device, wherein the HV Cap, the DC / DC converter circuit, the H-bridge circuit, one or more batteries, and the memory and microprocessor are contained in a pocket-sized housing.

2. The AED according to claim 1, wherein the DC / DC converter circuit is configured to increase the battery voltage to approximately 2000 volts.

3. The AED according to claim 1 or 2, further comprising: a pair of defibrillator electrodes, and a cable for operationally connecting the HV Cap to the pair of defibrillator pads, wherein the defibrillator pads are pocket-sized.

4. The AED device according to any of claims 1 to 3, wherein the housing has dimensions of 155 mm x 86 mm x 28 mm or less.

5. The AED device according to any of claims 1 to 4, wherein one or more batteries consist of four CR2 batteries.

6. The AED device according to any of claims 1 to 5, wherein the HV Cap is configured to start charging when the AED device is switched on.

7. The AED device according to any of claims 1 to 6, wherein the microprocessor is configured to monitor and adjust the charging rate of the HV Cap so as not to exceed (i) a maximum discharge rate of one or more batteries, and (ii) a maximum operating temperature of one or more batteries, thereby allowing the LC / onn / eznz / e / Y LC / onn / eznz / e / Y HV Cap to charge at the maximum rate possible with the available battery power.

8. The AED device according to claim 7, wherein the maximum discharge rate is 1000 mA and the maximum operating temperature is 75°C.

9. The AED device according to any one of claims 1 to 8, further comprising a real-time clock (RTC) and a temperature sensor integrated circuit (Temp Sensor IC), each of which is configured to turn on the AED device according to dynamic parameters programmed in the RTC and temperature sensor IC, wherein the microprocessor is configured to be completely off (not in sleep mode) when the AED device is not in use.

10. The AED device according to claim 9, wherein, when the AED device is not in use, all circuits and components are switched off with the exception of the RTC, the temperature sensor IC and its supporting circuitry.

11. The AED device according to claim 9 or 10, wherein the RTC is configured to periodically power on the microprocessor to perform a series of built-in automatic tests (BIST) to verify one or more batteries and hardware of the AED device.

12. The AED device according to any of claims 1 to 11, further comprising a speaker contained in the housing and configured to provide voice prompts to a user.

13. The AED device according to claim 12, wherein the AED device further comprises a microphone disposed in the housing near the speaker and the RTC is configured to periodically turn on at least one computer processor to perform a BIST wherein a signal is sent from the computer processor through the speaker, and the computer processor compares the sent signal with the signal received through the microphone to evaluate the integrity of the speaker.

14. The AED device according to claim 12, wherein, during use, the AED device is configured to record and has an external flash memory for storing the audio received by the microphone during operation of the AED device.

15. The AED device according to any of claims 9 to 14, wherein the temperature sensor IC is configured to continuously monitor the temperature of the AED device, even when the rest of the AED device circuit is switched off.

16. The AED device according to any of claims 1 to 14, further comprising a low-power microcontroller configured (i) to be periodically turned on by a signal from the RTC and to monitor the temperature of the AED device housing and / or the defibrillator pads, and (ii) to turn on and alert the microprocessor if the monitored temperature has reached a specified temperature.

17. The AED device according to any of claims 1 to 16, comprising a variable-frequency relaxation oscillator circuit configured for use in a body Z measurement, wherein the circuit is effective at self-oscillating at a frequency that is proportional to the patient's body impedance.

18. The AED device according to any of claims 1 to 17, wherein the microprocessor is configured to verify the integrity of the defibrillator patches and cables.

19. The AED device according to any of claims 1 to 18, wherein the microprocessor is configured to verify the integrity of the electrocardiogram (ECG) circuit in the AED device.

20. The AED device according to claim 19, wherein the microprocessor is configured to periodically generate a signal simulating a heartbeat and send the signal to the analog front-end (AFE) circuit and then compare the sent signal with a signal that has been processed by the AFE circuit.

21. The AED device according to any of claims 1 to 20, wherein the housing has a face having a single button, which is a power button.

22. An automated external defibrillator (AED) device comprising: a high-voltage capacitor (HV Cap) configured to store the energy required to deliver a defibrillation shock to a patient; one or more batteries configured to charge the HV Cap; a DC / DC converter circuit comprising a high-voltage transformer (HV XFMR), a field-effect transistor (FET) switch with associated driver, and a rectifier diode; an H-bridge circuit configured to transform the energy released from the HV Cap into a biphasic pulse; a memory configured to store computer-executable instructions; and at least one microprocessor configured to access the memory and execute the computer-executable instructions to continuously monitor and adjust the rate at which one or more batteries charge the HV Cap;where the AED device is configured to simultaneously monitor the discharge current and temperature of one or more batteries to charge the HV Cap at the maximum possible rate with the available energy from one or more batteries, without exceeding a maximum temperature or discharge rate of one or more batteries.

23. An automated external defibrillator (AED) device comprising: a high-voltage capacitor (HV Cap) configured to store the energy required to deliver a defibrillation shock to a patient; one or more batteries configured to charge the HV Cap; a DC / DC converter circuit comprising a high-voltage transformer (HV XFMR), a field-effect transistor (FET) switch with associated driver, and a rectifier diode; an H-bridge circuit configured to transform the energy released from the HV Cap into a biphasic pulse; and a memory configured to store computer-executable instructions.and at least one microprocessor configured to access memory and execute computer-executable instructions to: read and analyze the patient's ECG to determine if the patient has a shockable heart rhythm, charge the HV cap, determine the discharge current for the defibrillation shock, based at least in part on the patient's Z-body measurement, and deliver the defibrillation shock, wherein the AED device comprises a variable-frequency relaxation oscillator circuit configured to acquire the patient's Z-body measurement, wherein the circuit is effective at self-oscillating at a frequency that is proportional to the patient's body impedance.

24. An automated external defibrillation device (AED) comprising: a high-voltage capacitor (HV Cap) configured to store the energy required to deliver a defibrillation shock to a patient; one or more batteries configured to charge the HV Cap; a DC / DC converter circuit comprising a high-voltage transformer (HV XFMR), a field-effect transistor (FET) switch with associated driver, and a rectifier diode; an H-bridge circuit configured to transform the energy released from the HV Cap into a biphasic pulse; and a memory configured to store computer-executable instructions.and a main microprocessor configured to execute computer-executable instructions for the operation of the AED device, wherein: the AED device further comprises a power controller circuit comprising a real-time clock (RTC) and does not enter sleep mode when the main microprocessor is off, and the power controller circuit is configured to control the AED device when the main microprocessor is off by means of the RTC, which is configured to periodically power on the main microprocessor to perform a built-in self-test (BIST) sequence to verify one or more batteries and hardware of the AED device.

25. The AED device according to any of claims 22 to 24, wherein the DC / DC converter circuit is configured to increase the battery voltage to approximately 2000 volts.

26. The AED device according to any of claims 22 to 25, wherein one or more batteries consist of four CR2 batteries.

27. The AED device according to any of claims 22 to 26, wherein the HV Cap, the DC / DC converter circuit, the H-bridge circuit, one or more batteries, and the memory and microprocessor are contained in a pocket-sized housing.

28. The AED device according to claim 27, wherein the housing has dimensions of approximately 155 mm x approximately 86 mm x approximately 28 mm.

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