Abstract:
A method and apparatus for transferring patient data recorded by a defibrillator during treatment of a patient. In particular, a recordable memory chip within a medical electrode connector. Further includes a clock associated with the memory also contained within the medical electrode connector. Electrotherapy devices include defibrillators, cardioverters and training devices that simulate the operation of an electrotherapy device. Defibrillators include automatic or semi-automatic external defibrillators (AEDs).

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to a method and apparatus for transferring patient data recorded by a defibrillator during treatment of a patient. In particular, this invention relates to providing a recordable memory chip within the electrode connector. Electrotherapy devices include defibrillators, cardioverters and training devices that simulate the operation of an electrotherapy device. Defibrillators include automatic or semi-automatic external defibrillators (AEDs). 
     2. Description of the Prior Art 
     Electrotherapy devices are used to provide electric shocks to treat patients for a variety of heart arrhythmias. For example, external defibrillators typically provide relatively high-energy shocks to a patient (as compared to implantable defibrillators), usually through electrodes attached to the patient&#39;s torso. External defibrillators are used to convert ventricular fibrillation or shockable tachycardia to a normal sinus rhythm. Similarly, external cardioverters can be used to provide paced shocks to convert atrial fibrillation to a more normal heart rhythm. 
     In 1991 the Advanced Cardiac Life Support Subcommittee of the American Heart Associate made a report to Health Professionals calling for increased access to defibrillation in order to improve the survival rates from sudden cardiac arrest (SCA). [Cummins, et al. “Improving Survival From Sudden Cardiac Arrest: The ‘Chain of Survival’ Concept”  Circulation  83(5): 1832-1847 (1991).] The statistics themselves are staggering. On average 1000 adults die from SCA each day. Over 70% of these deaths occur in the home. Because the survival rate decreases 10% for every minute that passes, unless a defibrillator is available within the first few critical minutes, a victim of SCA has little chance of survival. If defibrillation were available, many of these people would survive. Following the AHA&#39;s recommendations, there has been increased awareness of the importance of public access defibrillation and defibrillators have become increasingly available. [See, e.g., Newman, “Early Defibrillation—Making Waves Across America,” JEMS Suppl. S4-S8 (January 1997).] The first phase of early defibrillation has been training designated lay responders in proper deployment of a defibrillator. Designated lay responders include, for example, fire fighters, police officers, flight attendants and security guards. However, with 70% of SCA occurring in the home, it becomes increasingly important to design a device that can be deployed by the average citizen in a home emergency. 
     One problem that could arise as defibrillators become ubiquitous relates to the ability to quickly and easily transfer patient data through the responder tiers. For example, a patient may initially be treated by a first responder carrying an AED. Information may be collected by the defibrillator relating to the patient ECG, shock decisions, etc. Thereafter a second tier responder, such as a paramedic, may arrive to provide treatment. At that time the second tier responder may wish to attach a defibrillator which provides additional functionality. Finally, the patient is transferred to a hospital. At some point it might be desirable to collected the data that was collected by each of the defibrillators in treating the patient to compose a continuous ECG readout. Where each piece of data is collected by a different machine and then correlated, errors could arise, for example, in the time correlation of the data—for example where the clocks of the two devices are not set to the same base time. 
     What is needed is a method and apparatus for improving the data stream for a patient as he moves from a first tier responder to a second tier responder to a hospital. More specifically, what is needed is a way to provide data collection for the patient which is incorporated into an electrode connector. 
     SUMMARY OF THE INVENTION 
     An electrical medical electrode adapter is disclosed comprising: a housing, wherein at least one end of the housing forms a cable connector; an electrical conductor electrically connected to a socket within a shell of the cable connector; and memory disposed within the housing electrically connected to the electrical conductor. Typically the cable connector forms a male end which mates with a female housing end disposed on a defibrillator. In one embodiment, a pair of defibrillator electrodes electrically connected to the housing. Alternatively, a set of monitoring pads electrically connected to the housing. In its simplest form, a plurality of electrode pads are provided. That plurality includes from 2-12 electrodes; typically, three, five or twelve electrode pads. Where the medical electrode adapter is not formed integrally with the electrode pads, a female portion comprising an interior chamber is also provided which is adapted to receive a male medical electrode cable connector. In addition to memory, the adapter may include a clock. The clock would then be used to associate medical event data to be stored on the memory with time. Where a clock is provided a power source would also be provided. The capacity of the memory provided in the adapter should be sufficient to store 20 minutes of ECG sampled at 200 Hz; or approximately 500 kbytes. 
     A method of deploying a defibrillator is also provided comprising: turning the defibrillator on; attaching electrode pads to a patient; inserting a cable connector associated with the electrode pads into a housing for receiving the cable connector within the defibrillator; recording ECG data to a memory module associated with an electrode adapter associated with the electrode pads; removing the electrode adapter; and retrieving ECG data from the electrode adapter. Additionally, if an advanced tier responder arrives the additional step of disconnecting the electrode adapter from the first defibrillator and attaching the electrode adapter to a second defibrillator, wherein the electrode pads are still attached to the patient. Time data may be associated with patient ECG data using a clock on the electrode adapter associates or a clock associated with each of the defibrillators. In one embodiment, all ECG and event data relating to a medical emergency for a patient is recorded onto the memory. Alternatively, only a selected portion of the ECG data may be recorded. In this instance, optimally, a window of ECG data surrounding an event is recorded. An appropriate window of data is, for example, a twenty second window, i.e., twenty seconds before the event and twenty seconds after the event. Events for which a data window might be appropriate include: shock delivery, shock advised, no shock advised, and heart rate alarm. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1 a  and  1   b  are block diagrams of an electrotherapy device showing a detachable electrode system. In FIG. 1 a,  the electrode system  36  includes a memory module  32 , an electrode adapter  26  and electrodes  28 . In FIG. 1 b,  the electrode system  36  also includes a clock  34 . 
     FIG. 2 a  is a perspective drawing of a pair of an electrode system comprising a pair of disposable electrodes integrally formed with an electrode adapter having memory. 
     FIG. 2 b  is a perspective drawing of an electrode adapter having memory for use in connection with a defibrillator and a pair of disposable electrodes. 
     FIG. 2 c  is a perspective drawing of an electrode adapter having memory for use in connection with a defibrillator and a pair of disposable electrodes showing the interior portions of the male and female ends of the adapter. 
     FIG. 3 shows the major components of a semi-automatic external defibrillator in block diagram form. 
     FIG. 4 is a flow chart showing the method of operating the electrotherapy device according to the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following discussion is presented to enable a person skilled in the art to make and use the invention. Various modifications to the preferred embodiment will be readily apparent to those skilled in the art, and the generic principles herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention as defined by the appended claims. Thus, the present invention is not intended to be limited to the embodiment show, but is to be accorded the widest scope consistent with the principles and features disclosed herein. 
     FIG. 1 a  is a block diagram showing a device  10 . Device  10  is an electrotherapy device. The device  10  may be include the ability to defibrillate, cardiovert, or pace a patient, or a combination of these features. Device  10  has a controller  12  that operates an energy delivery system  14  and performs other aspects of the operation of the device. Software instructions for the operation of the device are accessible from read only memory (ROM), such as incorporated ROM  16 . The controller accesses instructions for operation from ROM  16 . It should be understood that, in this and other embodiments described below, “controller” means a microprocessor, controller, gate array, other control logic, or any combination of these elements. 
     Controller  12  communicates with ROM  16  via a memory bus  18 . A recordable memory module  32  is attached to device  10  via an electrode system  36 , as shown in FIG. 1 a.  Electrode system  36  includes electrodes  28  and an electrode adapter  26 . 
     As contemplated by this embodiment, memory module  32  is integral with the electrode adapter  26 . Electrode adapter  26  is connected to electrodes  28  and is removably connected to the device  10 . A suitable electrode system  36  adaptable for use in this invention would be, for example, Heartstream ForeRunner® electrodes. 
     Once the electrode adapter  26  is attached to the device  10 , memory module  32  communicates with controller  12  over memory bus  30 . 
     Electrodes  28  communicate with a patient monitor  24  via electrode adapter  26  to provide patient ECG data from the patient to the patient monitor  24 . Electrodes include electrodes capable of delivering defibrillation, monitoring a patient condition, delivering pacing pulses, or a combination of those features. In an AED, the patient monitor  24  monitors the patient for a heart rhythm and subsequently determines whether the monitored rhythm is shockable. When the rhythm is shockable, the patient monitor  24  then communicates a shock decision to the controller  12 . The controller  12 , then communicates to the energy delivery system  14 . The energy delivery system  14 , then delivers a therapeutic energy pulse to the patient (not shown) through electrodes  28  attached to the defibrillator  10  via electrode adapter  26 , using the power supply  20  as the energy source. 
     Data collected during the patient treatment event is stored on the memory module  32  associated with the electrode connector (shown in FIGS. 2 a - 2   c ). The data collected includes, for example, full ECG data along with shock decisions, and shock deliveries. Where full ECG data is recorded, the memory module should have the capacity to record, for example, 20 minutes of ECG data which is sampled, for example, at the rate of 200 Hz. A suitable amount of memory in this instance would be approximately 500 kbytes. In another alternative, the data collected can be shortened so that it includes the ECG data for a window surrounding shock delivery (for example, 5 seconds before and after delivery of a shock). In this situation substantially less memory can be used. Or, data collected may just be a summary of the events, for example: 
     Defibrillator Turned On 
     VF Detected 
     Shock Advised 
     No Shock Advised 
     Shock Delivered 
     Normal Sinus Rhythm 
     Heart rate alarm condition 
     In this scenario even less memory would be required. 
     In an alternative embodiment shown in FIG. 1 b,  a clock  34  is included in the electrode adapter  26  in communication with the memory module  32 . Thus, when the defibrillator collects data it can associate the time of the adapter clock with the data. By providing clock information in conjunction with the memory module  32  any deviations that might have occurred from collecting data, which includes time data from defibrillators having clocks set to separate times, would not result, and a more accurate data stream from the patient would be obtained. Where the clock  34  is incorporated in the electrode adapter  26 , a power source (not shown) would be provided to power the clock  34 . A suitable clock would be, for example a DS1306 available from Dallas Semiconductors (www.dalsemi.com), suitable power sources for the clock include, for example, Li coin batteries. 
     Turning to FIG. 2 a,  electrode system  36  comprises an electrode connector housing  40  for connecting the electrode system  36  to device. In this embodiment, the housing comprises a cable connector  50 . The cable connector  50  has one ore more electrical conductors electrically connected to corresponding sockets within a shell. A pair of electrodes  42  is connected to the housing  40  via wires  44 . A memory module  32  (FIGS. 1 a  and  1   b ) is included within the housing  40  for connection to the device. Memory module  32  is configured so that it is electrically connected to the device. For purposes of illustration, FIG. 2 a  has been depicted showing two electrodes. However, it will be appreciated by those of skill in the art that a plurality of electrodes can be used. For example, from 2-12 electrodes are appropriate for use in monitoring patient ECG. Additional information on electrode connector construction can be found in U.S. Pat. No. 5,967,817 by Greenstein entitled “Medical Connector Apparatus,” the disclosure of which is incorporated herein. 
     As discussed above with respect to FIG. 1 b,  a clock  32  and corresponding power supply may also be provided within housing  40 . The actual configuration of the memory module, clock and power supply is not disclosed in order to avoid obscuring the invention. However, suitable configurations are known by those skilled in the art. 
     Turning now to FIG. 2 b,  the housing  40  of the electrode adapter shown in FIG. 2 a  has been modified so that in addition to providing a cable connector  50 , it also is adapted to receive a mating cable connector on one end. Thus, one end forms an interior chamber  52  for receiving a mating cable connector. Electrical conductors electrically connected to sockets within a shell are located within the interior chamber  52  such then when a mating cable connector is inserted into the interior chamber of the adapter it makes electrical contact between the mating cable connector and housing  40 . In this embodiment, the adapter is configured so that it is removable from the electrode pads and the defibrillator and thus is reusable. The advantage of this configuration is that it allows data to be collected without removing the electrode pads from the patient. A caregiver need only disconnect the adapter from the electrode connector and then reconnect the electrode connector to the defibrillator or to another adapter prior to reconnecting to another defibrillator. 
     FIG. 2 c  illustrates the adapter set-up shown in FIG. 2 b  with the interior portions outlined. As illustrated, the interior female chamber  52  houses two connectors with female chambers. The connectors are adapted to slide over male conductors in a corresponding electrode adapter. The male cable connector end  54  has two female chambers each of which contains a male conductor. When the male cable connector end  54  is inserted into a corresponding female chamber (for example, in a defibrillator housing, not shown), the male cable connector end  54  slides into the corresponding female chamber while the two connectors with female chambers within the female chamber  52  slide over the male conductors of a male cable connector (not shown). 
     The major components of an AED are shown in FIG. 3 in block diagram form. Further detailed information about the operation of an AED can be obtained in U.S. Pat. No. 5,836,993, to Cole for “Electrotherapy Device Control System and Method,” the specification of which is incorporated herein. As will be appreciated by those of skill in the art, the invention can be used in a variety of AEDs and is not limited to this configuration, which is used for illustration purposes only. 
     In this illustration, defibrillator control functions are divided among a microprocessor unit (MPU)  102  and two custom gate arrays  104  and  106 . 
     MPU  102  performs program steps according to software instructions provided to it from ROM  114 . MPU  102  controls the operation of certain buttons (such as display contrast buttons  108 ) and certain system LED&#39;s  110  (such as LED&#39;s associated with the shock button and the electrode connector). MPU  102  also receives system status information as shown by block  112 . 
     Gate array  104  implements the memory map to system ROM  114 . System ROM  114  is preferably flash ROM, although EPROM or any other electrically erasable and programmable nonvolatile memory could be used. Gate array  104  also controls a display  118 , a speaker  120 , and a microphone  122 . Gate array  104  can actuate a relay within the shock delivery and ECG front-end system  124  in response to actuation of a shock button  126  by a user during treatment mode. 
     Gate array  106  provides a system monitor function by performing automatic self-tests of the defibrillator and its components. The gate array  106  displays the operational status of the defibrillator on a status display  128 . Details of suitable self-tests may be found in U.S. Pat. No. 5,879,374, to Powers, et al. for “External Defibrillator with Automated Self-Testing Prior to Use,” the specification of which is incorporated herein by reference. Gate array  106  is also the defibrillator&#39;s interface with a user-activated on/off switch  130 . Gate array  106  controls the power management subsystem  132  to provide power to operate system components from power supply  134  and to provide energy to the shock delivery system&#39;s capacitor(s) for a therapeutic shock during treatment mode. Gate array  106  also interfaces with the defibrillator&#39;s ECG front end, enables the shock delivery system to deliver a shock in response to detection of a patient ECG pattern requiring treatment (and actuation of the shock button), and controls delivery of the shock to electrode connector  136  in response to shock delivery status information obtained during delivery of the shock. Further information regarding this last function may be found in U.S. Pat. No. 5,735,879 to Gliner et al. for “Electrotherapy Method for External Defibrillators,” and U.S. Pat. No. 5,607,454, to Cameron et al. for “Electrotherapy Method and Apparatus,” the specifications of which are incorporated herein. 
     These defibrillator components communicate with each other over suitable communication buses, as shown. 
     External defibrillator  100  can be operated in different modes, such as self-test mode, stand-by mode, set-up mode, patient treatment mode, training mode and code-transfer mode. The operational characteristics of defibrillator  100  differ in each mode. In addition, the operational characteristics of the defibrillator in any one of the modes can be changed as explained below. 
     Operation of the external defibrillator of this embodiment commences with the insertion of a power supply  134  or user activation of the power on button. Once gate array  106  confirms that a power supply  134  is inserted, gate array  104  prompts MPU  102  to begin its boot sequence. The boot sequence begins with MPU  102  sending out a series of addresses to power supply  134 . 
     As is known in the art, while in patient treatment mode, the defibrillator  100  typically (1) determines whether electrodes  137  are attached to electrode connector  136 ; (2) receives ECG information from a patient through such electrodes; (3) analyzes the ECG information to determine whether a therapeutic shock is advised; and (4) delivers a shock to the patient through the electrodes  137  if a shock is advised and if the shock button  126  is actuated by a user. 
     Turning to FIG. 4, the method of deploying the invention is shown. Initially, the first responder defibrillator is powered up  200 . After powering the defibrillator, electrode pads are attached to the patient  202 . The attached defibrillator then begins to receive ECG information from the patient through the attached electrode pads. The ECG information is stored on the memory module associated with the electrode adapter (either as full ECG data or selected data as described above)  204 . If an advanced tier responder arrives  206  the adapter is then disconnected  208  from the defibrillator it was attached to in step  202 . The adapter is then attached to the advanced tier responder defibrillator  210 . In the event an advanced tier responder has not arrived, then the defibrillator continues to record ECG data received from the first tier defibrillator to the memory module in the adapter. Once the code is finished  212 , then the adapter is removed  214  and the ECG data recorded onto the adapter is retrieved  216  for use by the advanced caregivers (such as physicians at the hospital). 
     As discussed above, other modifications falling within the scope of this invention will be apparent to persons of skill in the art. Thus, the invention is not to be limited by the specification, but interpreted according to claims that follow.