Medical device battery pack with active status indication

A system and method provides a status indicator to a battery pack of a medical device. The battery pack includes a power supply capable of being connected to the medical device. The battery pack also includes an indicator to automatically indicate a status of at least a portion of at least one of the battery pack and the medical device. For example, the indicator can indicate a status of the power supply.

FIELD OF THE INVENTION

The present invention relates generally to battery packs, and more specifically relates to battery packs for a medical device, where the battery pack includes an active status indicator.

BACKGROUND

Many known battery-powered medical devices, such as semi-automatic external defibrillator (“AED”) devices, rely on batteries to power electronics of the device, and, in the case of the AED device, to administer electric shocks to patients. For example, AED devices are used to provide electric shocks to treat patients for a variety of heart arrhythmias. The AED provides relatively high-level shocks to a patient, usually through electrodes attached to the patient's torso, to convert, for example, ventricular fibrillation to a normal sinus rhythm.

Studies have demonstrated that survival rates are high when defibrillation treatment is administered within the first few minutes following cardiac arrest. The likelihood of successful resuscitation, however, decreases by approximately 10 percent with each minute following sudden cardiac arrest. After ten minutes, very few resuscitation attempts are successful. Thus, it is advantageous to construct a portable AED to provide an operator with a better chance of responding to a patient in a timely fashion. The portable AED typically includes a portable power supply, such as a battery pack.

For a defibrillation pulse to be effective in terminating cardiac arrhythmia sufficient energy should reach the heart, through muscle, bone, organs and other tissues. To be effective, the battery pack should be able to deliver a high dose of energy when needed. Since batteries can lose energy over time, however, some battery packs include an expiration date to help an AED operator determine that the battery pack can deliver the necessary energy needed. The operator cannot tell many things from the expiration date, however, for example, whether the battery pack was previously used or whether the batteries of the battery pack contain sufficient energy to function properly. In other devices, the operator does not know the status of the battery pack until it is inserted into the medical device.

Thus, there is a need for an improved battery pack for a medical device such as an AED.

DETAILED DESCRIPTION

FIG. 1Aillustrates a top sectional view of the Semi-Automatic External Defibrillator (“AED”)100that includes a battery system, for example battery pack110. The AED100is a device to treat cardiac arrest that is capable of recognizing the presence or absence of ventricular fibrillation or rapid ventricular tachycardia or other shockable cardiac arrhythmias, and is capable of determining, without intervention by an operator, whether defibrillation should be performed. Upon determining that defibrillation should be performed, the AED automatically charges and requests delivery of electrical energy to electrodes that attach to a patient to deliver the energy to the patient's heart.

The battery pack110provides power to components such as electronics and a charger located in the AED100. The charger charges a capacitor564(FIG. 5) of the AED100that provides the electrical energy to the electrodes attached to the patient. The AED100includes a generally rectangular shaped battery well120that is constructed and arranged to house the battery pack110. The battery pack110is sized to slide in and out of the battery well120to releasably connect a power supply of the battery pack110to the AED100.

FIG. 1Billustrates a top sectional view of the AED100and the battery well120with the battery pack110removed. An entrance210of the battery well120accommodates alignment of the battery pack110within the battery well120.

FIG. 2illustrates a bottom view of the battery pack110. Referring toFIGS. 1B and 2, an opposite end of the battery well120includes a wedge-shaped feature230that corresponds to a wedge-shaped receptacle235located in the battery pack110. When inserting the removable battery pack110to the AED100, the battery pack110is guided along by the battery well120to the wedge-shaped feature230. The battery pack110is aligned at the end of its travel by the wedge shaped feature230in the battery well120via the corresponding wedge shaped receptacle235in the battery pack110.

Referring toFIG. 1A, to maintain the battery pack110in a connected position relative to the AED100, the battery pack110includes a latch130that retains the battery pack110within the battery well120when the battery pack is fully inserted into the battery well120. An end of the latch130connects with a spring132to bias the latch in a normally extended position. In the normally extended position, a latching end134of the latch130extends to enter a corresponding slot136located in the AED100. The latch130is moveable in a plane parallel to the spring132to compress the spring132to release the latching end134from the slot136. When the latching end134is released from the slot136, an ejection spring137located on the AED100pushes on the battery pack110to eject the battery pack110from the battery well120. The battery pack110includes a slot138from which the latch130extends. Even in a fully contracted position, the latch130extends past the slot138.

The battery pack110also includes a printed circuit board (PCB)140including exposed electrical terminals150to connect the printed circuit board140to electrical circuitry contained in the AED100, as described in more detail below. The PCB140includes electrical components that connect to circuitry of the AED100when the battery pack110is installed in the AED100. The battery pack110includes a window160that is located proximate to a visual indicator, such as light emitting diode (LED)550(FIG. 5). The window160allows an operator to view the LED550when the battery pack110is removed from the AED100. Thus, the operator can determine a status of at least one of the AED100and the battery pack110independent of the battery pack110being connected to the AED100. It should be appreciated that the AED100could also include a window located proximate to the battery pack window160so that an operator can view the LED550when the battery pack is inserted in the AED100.

FIG. 3illustrates a side sectional view of the AED100including the battery pack110. The electrical terminals150of the PCB140contact a connector310located within the AED100, to electrically connect the battery pack PCB140with an AED PCB320.

FIG. 4illustrates a side sectional view of the battery pack110. The battery pack110includes a first power supply, such as battery unit410. The battery unit410powers essential power needs of the AED during a main operating mode, for example when the AED is powered on. An essential power need includes, for example, the power necessary to charge the capacitor564to delivery energy to the patient. The battery unit410is preferably not being drained of power when the AED is powered off.

The battery unit410includes one or more battery cells, or other power supplies, that are electrically connected together. The power supply may include other forms of energy storage, for example based on chemical or kinetic principles, such as a flywheel storage device. The battery cells can include, for example, 2/3 A size batteries and/or C size batteries. The number of batteries used varies depending on a particular application but typically includes five or ten 2/3 A size batteries or four C size batteries. The five 2/3 A size batteries or four C size batteries are connected in series. Also, two sets connected in parallel of five 2/3 A batteries connected in series can be used for the battery unit410. The battery unit410preferably powers electronics and a charger located in the AED100.

The battery pack110also includes a secondary power supply, such as secondary battery420. The secondary battery420powers at least a portion of at least one of the AED and the battery pack110in an alternate mode, such as when at least a portion of the AED is powered off. Those skilled in the art will appreciate that the secondary battery420could also be used to power the AED during other modes, such as a sleep mode or when the AED is powered on. The secondary battery420typically includes a single 9 Volt battery, but other power supplies could be used, such as other sized batteries or other forms of energy storage. In a preferred embodiment, the battery pack110accommodates replacement of the secondary battery420. The secondary battery420can be sized smaller than the battery unit410and contain energy sufficient to power, for example, electric circuitry of the AED100and the battery PCB140.

The secondary battery420can be used to power circuitry exclusive of a state of the battery unit410and without draining power from the battery unit. Diodes502(FIG. 5) electrically isolate the battery unit410from the secondary battery420. Electric circuitry of the battery pack PCB140is described in more detail below with regard toFIG. 5. Such circuitry includes a socket to removably receive a memory device (FIG. 4), such as a memory card430or a multi-media card (MMC).

When the AED100is powered on and attached to the patient, the memory card430records the patient's electrocardiogram (ECG) signals, audio signals received from a microphone located on the AED100, and other operational information such as results of an analysis done on the patient by software of the AED100. The memory card430may also hold files that may be used to upgrade the software of the AED100or to provide user training mode software for the AED.

FIG. 5shows a block diagram illustrating battery pack circuitry500contained with the battery pack110, for example, on the battery pack PCB140, and main unit circuitry505. The circuitry500includes a main power switch510. The main power switch510connects with a digital logic, such as micro-controller520, that turns the main power switch510on and off and controls other circuitry500of the battery pack PCB140. In addition to or in place of the micro-controller520, the digital logic can also include a microprocessor, a programmable logic device (PLD), a gate array and a custom integrated circuit. Other digital logic could also be used such as a Programmable Interface Controller (PIC) manufactured by Microchip Technologies, located in Chandler, Ariz.

The micro-controller520connects with a main AED connector530that connects circuitry of the battery pack PCB140to circuitry of the AED100. When the operator engages a power switch592located on the AED100, the micro-controller520receives a signal from the main unit connector530indicating that the power switch has been engaged. Thereafter, the micro-controller520enables the main power switch510to provide an electrical power between the battery unit410of battery pack110and the electronics of the AED100. The battery pack PCB140also includes a main battery connector540to connect the battery unit410to the main unit connector530and other circuitry of the battery pack PCB140.

The micro-controller520also controls a visual indicator, such as LED550and an audio indicator, such as sounder560that are used to automatically communicate information to the operator. For example, when the AED100fails a self-test, the operator is notified by a chirping sound from the sounder560. Moreover, the LED550flashes green to indicate that a status of components of the AED100is within an acceptable operating range. Those skilled in the art can appreciate the opposite could be true, i.e., that a flashing light indicates a fault condition. According to a preferred embodiment, if the LED550is not flashing an error exists, for example, in the circuitry500, or the battery unit410or secondary battery420are depleted. The micro-controller520monitors a signal of a comparator connected to secondary battery420to monitor a status of the secondary battery420, for example, to determine whether or not power of the secondary battery420is low or depleted.

Regarding the main unit circuitry505, a digital signal processor (DSP)562processes instructions and data of the AED100. The DSP562connects with a charger circuit563and discharger circuit565to control the charging and discharging of main unit capacitor564. The capacitor charger563connects the battery unit410to the capacitor564. The capacitor564connects to a discharge circuit565that connects to patient interface566to deliver shocks to the patient.

The micro-controller520also controls a red and green LED567, or a red LED and a green LED, located on the AED100. The micro-controller520connects to the red and green LED567, for example, via pins of the main unit connector530. The micro-controller520causes the LED567to flash green when the AED100is operating properly and causes the LED567to flash red when components of the AED are not within the acceptable operating range, for example, a component of the AED100failed during a self-test procedure. If the LED567is not flashing when the battery pack110is installed into the AED100, components of the AED100and the battery pack110should be checked. The battery pack LED550is preferably disabled when the battery pack110is installed.

The secondary battery420powers the micro-controller520, the LED550and the LED567, which helps to maintain the integrity of the battery unit410that provides power to electronics and the capacitor charger located in the AED100. A secondary battery connector570connects the secondary battery420to the circuitry of the battery pack PCB140.

The battery pack circuitry500also includes an electrically erasable programmable read only memory (EEPROM)580connected to the micro-controller520and the main unit connector530. The EEPROM580stores information that may be relevant to an owner, service person or operator of the AED100. The EEPROM580stores information regarding, for example, the number of shocks the battery unit410has been used for, that the AED100has been activated, the date of manufacture of the battery pack110and status information regarding a status of components of the battery pack110and the AED100. The DSP562of the AED100connects to a bus that connects to a real time clock (RTC)590, the EEPROM580and the micro-controller520. Typically once per power up of the AED100, the DSP accesses the RTC590to set a main unit clock of the AED100that is located in the DSP.

The main unit circuitry505also includes a switch592, such as an ON/OFF switch, that connects to the micro-controller520via the main unit connector530. A shock switch594connects to the DSP562to allow an operator to administer a shock to the patient. A speaker596and indicator LEDs598connect to the DSP562to supply instructions or other information to the operator. Front end circuitry599connects between the DSP562and the patient interface566to process and/or provide the DSP562with information from the patient.

While the invention has been described above by reference to various embodiments, it will be understood that many changes and modifications can be made without departing from the scope of the invention. It is therefore intended that the foregoing detailed description be understood as an illustration of the presently preferred embodiments of the invention, and not as a definition of the invention. It is only the following claims, including all equivalents, which are intended to define the scope of this invention.