Abstract:
A modular automated external defibrillator (AED) system includes a base unit and at least one interconnected module. The base unit typically includes a functional circuit and includes an interface that couples the functional circuit to the module. Likewise, the module includes an interface that couples the module to the base unit By manufacturing such modular AED models instead of one-piece, i.e., integrated, AED models, a manufacturer can reduce the cost and complexity of its manufacturing process. Furthermore, the manufacturer may be able to bring such a modular AED to market more quickly than it could bring an integrated model of the AED to market. Moreover, a modular AED allows the manufacturer and customer flexibility in respectively providing and selecting feature sets. In addition, a customer can obtain replacements for broken modules, and the manufacturer can provide cheaper upgrades by upgrading a module or base unit instead of upgrading the entire AED.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The invention relates generally to medical devices, and more particularly to a modular automated external defibrillator (AED), the base unit and modules of the AED, and methods for assembling and using the AED. The modular AED may be manufactured less expensively than a comparable non-modular, i.e., integrated, AED. Furthermore, being a modular AED may facilitate the FDA (Food and Drug Administration) approval/clearance process of the base unit and subsequent combinations of the base unit and modules.  
           [0003]    2. Description of the Prior Art  
           [0004]    AEDs, which have saved many lives in non-hospital settings, are becoming easier to use; consequently, the demand for AEDs is rising. Typically, an AED analyzes a patient&#39;s heart rhythm and, if appropriate, instructs an operator to administer an electrical shock to the patient. For example, a shock can often revive a patient who is experiencing ventricular fibrillation (VF). Because many models of AEDs include only basic diagnostic and safety features, they are often difficult to operate. Therefore, only specially trained persons such as emergency medical technicians (EMTs) can use these older models to administer shocks to patients. Newer models, however, often include advanced diagnostic and safety features that allow minimally trained persons to administer shocks to patients. Consequently, more businesses and individuals are acquiring AEDs to save lives.  
           [0005]    A variety of AED models are currently available. For example, some models allow an operator to make few if any decisions regarding treatment of a patient, and thus are suitable for untrained or minimally trained operators. Conversely, other models allow an operator great flexibility in directing the patient&#39;s treatment, and thus are suitable for trained operators such as EMTs. Furthermore, some models provide audible or readable instructions in respective languages, typically one language per model. In addition, some models are lower-priced because they include a basic set of features, and other models are higher priced because they include a more comprehensive set of features.  
           [0006]    Referring to FIG. 1, most AED models are manufactured, tested, FDA approved, and sold as one-piece, i.e., integrated, units.  
           [0007]    [0007]FIG. 1 illustrates a conventional AED system  10 , which includes an integrated AED  12  having a one-piece, i.e., integral, housing  14 , and which includes defibrillator electrode pads  16   a  and  16   b . The AED  12  includes a battery  18  for supplying power, an on/off key switch  20 , a display  22  for displaying readable operator instructions, cardiac waveforms, or other information, a speaker  24  for providing audible operator instructions, an AED status indicator  26 , a contrast control  27  for the display  22 , and a shock button  28 , which the operator (hands shown in FIG. 1) presses to deliver a shock to a patient (not shown). The AED  12  also includes a connector  30 , which receives a pad connector  32  to allow coupling of the pads  16   a  and  16   b  to the AED. Furthermore, the AED  12  may include a microphone  34  for recording the operator&#39;s voice and other audible sounds that occur during the rescue, and a storage device such as a data card  36  for storing these sounds along with the patient&#39;s ECG and a record of AED events for later study. And in addition to being able to defibrillate the patient, the AED  12  may be able to pace, cardiovert, or provide other electrotherapy to the patient, or may have a manual override that allows the operator more control over otherwise automated functions.  
           [0008]    Because it is an integrated unit, introducing a modified version of the AED  12  to respond to specific customer requirements typically requires a manufacturer to design and produce a separate model of the AED. Removing the contrast control  27 , changing the language of the audible or displayed operator instructions, removing the status indicator  26 , and changing the shape of the housing  12  are examples of modifications that typically require the manufacturer to produce a separate AED model. Moreover, different customers may want the AED  12  to be capable of different electrotherapies or combinations of electrotherapies. For example, one customer may want the AED  12  to be capable of defibrillation only, and another customer may want the AED to be capable of pacing, cardioversion, and defibrillation. Consequently, the manufacturer would typically have to produce a separate AED model for each supported electrotherapy or combination of electrotherapies.  
           [0009]    Unfortunately, the more models of integrated AEDs a manufacturer produces, the more complex and expensive its overall manufacturing and logistical operations. An AED model may be manufactured independently of other AED models. That is, a model may have its own dedicated assembly/test line, and thus may have its own dedicated manufacturing/testing equipment, assemblers, testers, and troubleshooters. If the model is discontinued, then the equipment may be useless to the manufacturer, or may need revamping for use with other models. Also, the manufacturer may need to retrain the assemblers, testers, and troubleshooters for another model. Furthermore, because materials and components are typically more expensive if purchased in smaller lots, producing different AED models having different materials or components may increase the manufacturer&#39;s costs for materials and components. Moreover, the manufacture often must receive FDA approval of each model. The FDA-approval process takes time and may lengthen a model&#39;s time to market. These problems may also plague manufacturers of integrated medical devices other than AEDs.  
           [0010]    Consequently, there is a need for a medical device, such as an AED, that avoids some or all of the shortcomings of a conventionally integrated medical device.  
         SUMMARY OF THE INVENTION  
         [0011]    A modular AED includes an interconnected base unit and one or more modules.  
           [0012]    The base unit includes a functional base-unit circuit and a base-unit interface that electronically couples the circuit to a module. And the module includes a module interface that electronically couples the module to the base unit.  
           [0013]    Such a modular AED is often easier and less expensive to manufacture than an integrated AED. For example, if multiple models of a modular AED incorporate the same base unit and some of the same modules, then the manufacturer can often purchase common components in larger lots and reduce the number of assembly/testing lines as compared to several integrated devices. Furthermore, the manufacturer may reduce the overall time required for FDA approval by seeking separate approval for different base units and modules. For example, if the manufacturer introduces a new model having an approved base unit but one or more new, unapproved modules, then the manufacturer may need FDA approval of the new modules only. The approval process for the new modules may be easier, faster, and cheaper than an approval process for a comparable integrated model or for the whole new model, i.e., the intercoupled base unit and new modules. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 is a view of a conventional AED system that includes an integrated AED.  
         [0015]    [0015]FIG. 2 is an exploded view of a modular AED according to an embodiment of the invention.  
         [0016]    [0016]FIG. 3 is a view of a control module that can replace the pad-cartridge module of FIG. 2 according to an embodiment of the invention.  
         [0017]    [0017]FIG. 4 is a view of a monitor module that can replace the pad-cartridge module of FIG. 2 according to an embodiment of the invention.  
         [0018]    [0018]FIG. 5 is a view of a training-pad-cartridge module that can replace the pad-cartridge module of FIG. 2 according to an embodiment of the invention.  
         [0019]    [0019]FIG. 6 is a view of a communication module that can replace the pad-cartridge module of FIG. 2 according to an embodiment of the invention.  
         [0020]    [0020]FIG. 7 is an exploded view of another modular AED according to an embodiment of the invention.  
         [0021]    [0021]FIG. 8 is a view of an enhanced control module that can replace the control module or the pad-cartridge module of FIG. 7 according to an embodiment of the invention.  
         [0022]    [0022]FIG. 9 is a view of a full-featured control module that can replace one or both of the control module and pad-cartridge module of FIG. 7 according to an embodiment of the invention.  
         [0023]    [0023]FIG. 10 is a view of a monitor module that can replace one or both of the control module and pad-cartridge module of FIG. 7 according to an embodiment of the invention.  
         [0024]    [0024]FIG. 11 is an exploded view of yet another modular AED according to an embodiment of the invention.  
         [0025]    [0025]FIG. 12 is a circuit-block diagram of the AED base units of FIGS. 2, 7, and  11  according to an embodiment of the invention.  
         [0026]    [0026]FIG. 13 is a circuit-block diagram of the AED modules of FIGS. 2-6. and  8 - 11  according to an embodiment of the invention.  
         [0027]    [0027]FIG. 14 is a circuit-block diagram of the modular AEDs of FIGS. 2, 7, and  11  according to an embodiment of the invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]    The following discussion is presented to enable a person skilled in the art to make and use the invention. Various modifications to the preferred embodiments 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 embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein. Furthermore, “automated external defibrillator” or “AED” is any defibrillator that determines whether a patient has a shockable heart rhythm.  
         [0029]    [0029]FIG. 2 is an exploded view of a modular AED system  40 , which includes a pad-cartridge module, i.e., cartridge assembly,  42  and an AED base unit  44  according to an embodiment of the invention. For clarity, like numerals refer to elements common to the system  10  of FIG. 1. The modular AED system  40  is often easier and less expensive to manufacture than the integrated AED system  10  of FIG. 1. For example, multiple models of the modular AED system  40  may incorporate the same base unit  44 . Therefore, the manufacturer can often purchase components for the base unit  44  in relatively large lots, and have a single assembly/testing line for the base unit. Furthermore, once the FDA has approved the base unit  44 , the manufacturer typically need only obtain FDA approval for new modules to be incorporated into the AED system  40 . Similarly, once the FDA has approved a module, the manufacturer typically need only obtain FDA approval for new base units to be incorporated into the AED system  40 .  
         [0030]    The cartridge assembly  42  includes the electrode pads  16   a  and  16   b  and a cartridge  46 . The cartridge  46  has a bottom, i.e., tray,  48 , side walls  50   a - 50   d , and lid  52 , which may be hinged to a side wall such as the side wall  50   a  with one or more hinges  53 . The cartridge  46  also includes an electrode-pad connector  54 , which may extend through a side wall such as the side wall  50   a , helps to secure the cartridge  46  to the AED base unit  44 , and electrically connects the electrode pads  16   a  and  16   b  to the base unit via electrode-pad wire leads  56   a  and  56   b . Alternatively, the connector  54  may extend through the tray  48 . The leads  56   a  and  56   b  are conventionally attached to the connector  54 . The connector  54  may include an information provider such as a groove  57 , which provides information, such as the type (e.g., pediatric, adult, or training) of pads  16   a  and  16   b , to the base unit  44 . The cartridge  46  may also include a conventional latch mechanism (not shown) for latching the lid  52  to one or more of the side walls  50   a - 50   d . This and other embodiments of the cartridge assembly  42  are further discussed in U.S. patent application Ser. No. 09/746,123, entitled CARTRIDGE FOR STORING AN ELECTRODE PAD AND METHODS FOR USING AND MAKING THE CARTRIDGE, filed on Dec. 22, 2000, which is incorporated by reference.  
         [0031]    Still referring to FIG. 2, in addition to the battery  18 , on/off switch  20 , speaker  24 , shock button  28 , microphone  34 , and data card  36 , the AED base unit  44  includes a receptacle  58  and a connector  60  for respectively receiving the cartridge  46  and the connector  54 . The base unit  44  may read the information provided by the groove  57  using conventional techniques or a technique such as that disclosed in U.S. patent application Ser. No. 09/746,123, entitled CARTRIDGE FOR STORING AN ELECTRODE PAD AND METHODS FOR USING AND MAKING THE CARTRIDGE, filed on Dec. 22, 2000, which is heretofore incorporated by reference. The connectors  54  and  60 , which electrically interconnect the cartridge assembly  42  and the base unit  44 , may be the sole means by which the cartridge assembly and the base unit are attached to one another. Alternatively, means such as Velcro® strips (not shown), mating grooves (not shown) in the side walls of the receptacle  58  and the side walls  50   b  and  50   d  of the cartridge  46 , or other conventional means may be included to attach the cartridge  46  to the base unit  44 . Furthermore, the manufacturer may permanently attach the cartridge  46  to the base unit  44  to prevent one from taking the modular AED system  40  apart. One would, however, be able to replace the pads  16   a  and  16   b  without replacing the cartridge  46 . Or, the manufacturer may allow one to remove the cartridge  46  from the base unit  44  such that he/she can replace the cartridge assembly  42  with another cartridge assembly or module (not shown in FIG. 2).  
         [0032]    Furthermore, the AED base unit  44  may include a compartment  62  for storing defibrillator electrode pads, such as the pads  16   a  and  16   b , when a module other than the cartridge assembly  42  is in the receptacle  58 . The connector  60  or another connector (not shown) may connect the pads in the compartment  62  to the base unit  44 . In addition, the compartment  62  may include a lid or other cover (not shown).  
         [0033]    The operation of the modular AED system  40  is discussed according to an embodiment of the invention. During an emergency where it is determined that a patient (not shown) may need a shock, the operator (hands shown in FIG. 2) retrieves the AED base unit  44  and installs the battery  18  if it is not already installed. Next, the operator inserts the connector  54  into the connector  60 , and thus inserts the cartridge  46  into the receptacle  58 , if the cartridge  46  is not already installed. Then, the operator opens the lid  52  and removes the electrode pads  16   a  and  16   b  from the cartridge  46 . Next, the operator activates the base unit  44  by turning the on/off switch  20  to the “on” position, and in response to written or spoken instructions, places the electrode pads  16   a  and  16   b  on the patient (not shown). The base unit  44  then analyzes the patient&#39;s ECG to determine whether the patient is suffering from a shockable heart rhythm. If the base unit  44  determines that the patient is suffering from a shockable heart rhythm, it then instructs the operator to press the shock button  28 . Conversely, if the base unit  44  determines that the patient is not suffering from a shockable heart rhythm, it may inform the operator to seek appropriate non-shock treatment for the patient and may disable the shock button  28 . After the operator has treated the patient, he/she typically installs new pads  16   a  and  16   b  or an entire new cartridge assembly  42 . Thus, with new pads or a new cartridge assembly installed, the modular AED system  40  is ready for its next use. Alternatively, one may wait until the next use of the AED system  40  to install new pads or a new cartridge assembly.  
         [0034]    Although the modular AED system  40  is discussed, other modular medical devices or systems are contemplated. Furthermore, although the AED system  40  is discussed having a pair of pads  16   a  and  16   b , the system may have more or fewer pads. Or, the system  40  may be capable of, and include pads that are suitable for, electrotherapies other than or in addition to defibrillating. Such electrotherapies may include monitoring, cardioverting, or pacing. Moreover, the system  40  may include a manual override that allows the operator (hands shown in FIG. 2) more control over otherwise automated functions. In one embodiment, the modular system  40  is configured with a certain set of one or more modules (such as the cartridge assembly  42 ) in conjunction with the base unit  44 . This configuration is typically determined by the type of AED features the customer/operator desires or the particular model of the AED system  40  that the manufacturer produces. Such a configure-to-order (CTO) scenario allows the customer/operator to choose a modular AED system  40  having the features and functionality he/she needs.  
         [0035]    [0035]FIG. 3 is a control module  70  that can replace the cartridge assembly  42  of FIG. 2 according to an embodiment of the invention. The manufacturer may give an operator (not shown in FIG. 3) the ability to configure the AED system  40  (FIG. 2) to meet his/her needs. Specifically, the operator can configure the system  40  by inserting the module  70  into the receptacle  58  (FIG. 2) of the AED base unit  44  (FIG. 2) in place of the cartridge assembly  42 . The module  70  typically receives power from the base unit  44 , and provides additional features to the modular AED system  40  (FIG. 2) as described below.  
         [0036]    The control module  70  includes a display  72 , status indicator  74 , control knob  76 , pad connector  78 , indicator light-emitting diodes (LEDs)  80 , a connector  82 , and push buttons  84 . The display  72  displays operator information such as patient-treatment instructions or an AED function-select menu. The indicator  74  and LEDs  80  provide the status of the AED  40 . For example, the indicator  74 , LEDs  80 , or both may indicate when the shock circuitry (FIG. 8) is ready to deliver a shock to the patient (not shown). The control knob  76  allows the operator to manipulate the display  72 . For example, the operator may control the brightness or contrast of the display  72  by turning the knob  76 . The connector  78  allows one to connect a set of pads, such as the pads  16   a  and  16   b  (FIG. 2), to the AED system  40 . The connector  82  is similar to the connector  54  (FIG. 2) and mates with the base-unit connector  60  (FIG. 2). Although not shown, the connector  82  may include an information provider such as the groove  57  (FIG. 2). The push buttons  84  allow the operator to select software-menu items from the display  72 , or may provide other features. Alternatively, the display  72  may include a touch-sensitive screen so that the manufacturer can omit the buttons  84 .  
         [0037]    Other embodiments of the control module  70  may have a different layout or different controls, or may provide different features. For example, the positions of the display  72 , status indicator  74 , selection knob  76 , pad connector  78 , indicator LEDs  80 , connector  82 , and push buttons  84  may be rearranged. Furthermore, the knob  76  may control defibrillation functions other than the brightness or contrast of the display  72 . For example, the knob  76  may control the level of the shock energy or the volume of the speaker  24  (FIG. 2). Furthermore, these components may be replaced with equivalent components. For example, although the pad and module connectors  78  and  82  are respectively shown as female and male connectors, they may be male and female connectors. Or the knob  76  or buttons  84  may be replaced with other types of control components such as switches. In addition, the display  72  may provide the status of the AED system  40  so that the manufacturer can omit the status indicator  74  or LEDs  80 . Moreover, although the connectors  82  and  60  (FIG. 2) may be the sole means by which the module  70  is attached to the base unit  44  (FIG. 2), means such as, screws, fasteners, or Velcro® strips (not shown), mating grooves (not shown) in the side walls of the receptacle  58  and the side walls  86   a  and  86   b  of the module  70 , or other conventional means may be included to attach the module  70  to the base unit  44 . Furthermore, the module  70  may provide power to the base unit  44 . In addition, the manufacturer may permanently attach the module  70  to the base unit  44  to prevent one from taking the modular AED system  40  apart. Or, the manufacturer may allow one to remove the module  70  from the base unit  44  such that he/she can replace the module with another module or the cartridge assembly  42  (FIG. 2).  
         [0038]    [0038]FIG. 4 is a monitor module  90  that can replace the cartridge assembly  42  of FIG. 2 according to an embodiment of the invention, where like numbers identify like components with respect to the control module  70  of FIG. 3. Specifically, an operator (not shown in FIG. 4) can insert the module  90  into the receptacle  58  (FIG. 2) of the base unit  44  in place of the cartridge assembly  42 . The module  90  typically receives power from the base unit  44 , and provides additional features to the modular AED system  40  (FIG. 2) as described below.  
         [0039]    Like the control module  70  of FIG. 3, the monitor module  90  includes a display  72 , control knob  76 , pad connector  78 , indicator light-emitting diodes (LEDs)  80 , connector  82 , and push buttons  84 . The display  72  displays information such as patient-treatment instructions, an AED function-select menu, or a patient waveform such as the patient&#39;s electrocardiogram (ECG). The display  72  may also display the status of the AED system  40  (FIG. 2).  
         [0040]    Other embodiments of the monitor module  90  are contemplated. These embodiments may incorporate modifications similar to those discussed above in conjunction with FIG. 3 for the other embodiments of the control module  70 .  
         [0041]    [0041]FIG. 5 is a training cartridge assembly  100  that can replace the cartridge assembly  42  of FIG. 2 according to an embodiment of the invention, where like numbers identify like components with respect to the cartridge assembly  42 . Specifically, an operator (not shown in FIG. 5) can adjust the training-scenario selector  102  to simulate any of a number of different rescue or training scenarios. If power is needed, the selector  102  typically receives it from the base unit  44 , and provides training features to the modular AED system  40  (FIG. 2) as described below. Alternatively, the cartridge assembly  100  may have its own power supply (not shown) such as a battery.  
         [0042]    The cartridge assembly  100  is similar to the cartridge assembly  42  of FIG. 2 except that it includes the training-scenario selector  102 , and, to prevent accidental shock delivery, the connector  54  does not electrically couple the electrode pads  16   a  and  16   b  to the base unit  44  (FIG. 2). Furthermore, to prevent inadvertent use of the assembly  100  during an actual rescue, an optional flag  104  indicates that the assembly  100  is a training assembly.  
         [0043]    In operation, an operator (not shown in FIG. 5) sets a selector knob  106  of the selector  102  to a desired training scenario that allows him/her to train a student (not shown) in the use of the AED system  40  (FIG. 2). For example, the operator can set the knob  106  so that the selector  102  causes the AED base unit  44  to behave as if it has determined that a patient (not shown) is suffering from a shockable heart condition. Then, while the operator studies and comments on his/her performance, the student tries to revive the patient using the AED system  40 . For such training purposes, the patient can be a mannequin. AED training devices and techniques are further discussed in U.S. Pat. Nos. 5,611,815, 5,662,690, and 5,993,219, which are incorporated by reference.  
         [0044]    [0044]FIG. 6 is a communication module  110  that can replace the cartridge assembly  42  of FIG. 2 according to an embodiment of the invention, where like numbers identify like components with respect to the monitor module  90  of FIG. 4. Specifically, an operator (not shown in FIG. 6) can insert the module  110  into the receptacle  58  (FIG. 2) of the AED base unit  44  in place of the cartridge assembly  42 . The module  110  typically receives power from the base unit  44 , and provides additional features to the modular AED system  40  (FIG. 2) as described below.  
         [0045]    In addition to a base-unit connector  82 , the communication module  110  includes a conventional telephone keypad  112 , female telephone connector  114  for receiving a male connector  116 , and an optional antenna  118 . After completion of the patient-rescue operation, the operator (not shown in FIG. 6) connects the connector  114  to the connector  116  and dials the telephone number of a data-collection center (not shown). Then, the AED base unit  44  (FIG. 2) uses the module  110  as a modem to download rescue data from the card  36  (FIG. 2) or from the base unit in general to the data-collection center via a phone line  120 . Alternatively, the base unit  44  uses the module  110  as a wireless modem to download the rescue data via the antenna  118  and a wireless channel. The base unit  44  may also receive data from the data-collection center via the telephone line  120  or the wireless channel. Other functions of the module  110  include downloading new or updated software for the base unit  44 , module  110 , or both, or downloading rescue instructions for the operator.  
         [0046]    Other embodiments of the monitor module  110  are contemplated. These embodiments may incorporate modifications similar to those discussed above in conjunction with FIG. 3 for the other embodiments of the control module  70 .  
         [0047]    [0047]FIG. 7 is an exploded view of a modular AED system  130 , which includes an electrode-pad module, i.e., cartridge assembly,  132 , a control module  134 , and an AED base unit  136  according to an embodiment of the invention. For clarity, like numerals refer to elements common to the AED system  40  (FIG. 2). A difference between the AED system  130  and the AED system  40  is that the base unit  136  lacks a shock button and an on/off switch. Therefore, in this embodiment, the AED  130  requires a control module such as the control module  134 . In addition, although not shown in FIG. 7, the base unit  136  may include a pad storage compartment such as the storage compartment  62  of the base unit  44  (FIG. 2).  
         [0048]    The cartridge assembly  132  includes a connector  138  to which the pads  16   a  and  16   b  are connected via the leads  56   a  and  56   b . Unlike the connector  54  (FIG. 2) of the cartridge assembly  42  (FIG. 2), the connector  138  extends through the bottom  48  of the cartridge  46 . But like the connector  54 , the connector  138  may include an information provider such as the groove  57  (FIG. 2). Otherwise, the cartridge assembly  132  is similar to the cartridge assembly  42 .  
         [0049]    The control module  134  typically receives power from the AED base unit  136 , and includes an on/off switch  140 , shock button  142 , and side walls  144   a  and  144   b . The switch  140  and button  142  may be similar to the on/off switch  20  and the shock button  28  of FIG. 2, respectively. The module  134  also includes a connector (not shown) that extends from the bottom of the module and that may include an information provider such as the groove  57  (FIG. 2). Other embodiments of the module  134  are contemplated. These embodiments may incorporate modifications similar to those discussed above in conjunction with FIG. 3 for the other embodiments of the control module  70 .  
         [0050]    Furthermore, in addition to the battery  18 , speaker  24 , microphone  34 , and data card  36 , the AED base unit  136  includes a receptacle  146  and connectors  148  and  150  for respectively receiving the connector  138  of the cartridge  46  and the connector (not shown) of the control module  134 . The base unit  136  may read the information provided by information providers on the connector  138  and the connector of the module  134 . The connectors,  138 ,  148 ,  150 , and the control-module connector, which electrically interconnect the cartridge assembly  132 , the control module  134 , and the base unit  136 , may be the sole means by which the cartridge assembly and the control module are attached to the base unit. Alternatively, other attachment means, such as those described above in conjunction with FIGS. 2 and 3, may be included to attach the cartridge  46  and the module  134  to the base unit  136 . Furthermore, the manufacturer may permanently attach the cartridge assembly  132  and the control module  134  to the base unit  136  to prevent an operator (hands shown in FIG. 7) from taking the modular AED system  130  apart. Or, the manufacturer may allow the operator to remove the cartridge assembly  132  or the control module  134  from the base unit  136  such that he/she can replace the cartridge assembly or control module with another cartridge assembly or module (not shown in FIG. 7). Where the cartridge assembly  132  is permanently attached to the base unit  136 , the operator can replace the pads  16   a  and  16   b  without replacing the cartridge  46 .  
         [0051]    Still referring to FIG. 7, the operation of the modular AED system  130  is discussed according to an embodiment of the invention. During an emergency where it is determined that a patient (not shown) may need a shock, the operator (hands shown in FIG. 7) retrieves the AED base unit  130  and installs the battery  18  if it is not already installed. Next, the operator inserts the connector  138  into the connector  148 , and thus inserts the cartridge  46  into one end of the receptacle  146 , if the cartridge  46  is not already installed. Similarly, the operator inserts the control-module connector (not shown) into the connector  150 , and thus inserts the control module  134  into the other end of the receptacle  146 , if the control module is not already installed. Then, the operator opens the lid  52  and removes the electrode pads  16   a  and  16   b  from the cartridge  46 . Next, the operator activates the control module  134  and the base unit  136  by turning the on/off switch  140  to the “on” position, and in response to written or spoken (via the speaker  24 ) instructions, places the electrode pads  16   a  and  16   b  on the patient (not shown). The base unit  136  then analyzes the patient&#39;s ECG to determine whether the patient is suffering from a shockable heart rhythm. If the base unit  136  determines that the patient is suffering from a shockable heart rhythm, then it instructs the operator to depress the shock button  142 . Conversely, if the base unit  136  determines that the patient is not suffering from a shockable heart rhythm, it may inform the operator (e.g., via the speaker  24 ) to seek appropriate non-shock treatment for the patient and may disable the shock button  142 . After the operator has treated the patient, he/she installs new pads  16   a  and  16   b , or an entire new cartridge assembly  132 . Thus, with new pads or a new cartridge assembly installed, the AED system  130  is ready for its next use. Alternatively, the operator may wait until the next use of the system  130  to install a new cartridge assembly or pads. Typically, the operator does not detach the control module  134  from the base unit  136  once the control module is installed.  
         [0052]    [0052]FIG. 8 is an enhanced control module  160  that can replace the cartridge assembly  132  or the control module  134  of FIG. 7 according to an embodiment of the invention, where like numbers reference like components with respect to the control module  134 . Typically, an operator (not shown in FIG. 8) inserts the module  160  into the base-unit receptacle  146  (FIG. 7) in place of the control module  134 . The control module  160  has more features than the control module  134  as described below.  
         [0053]    The control module  160  typically receives power from the AED base unit  136  (FIG. 7), and, in addition to the on/off switch  140  and shock button  142 , includes a display  162 , control knob  164 , and push buttons  166 , which are respectively similar to the display  72 , control knob  76 , and push buttons  84  of FIG. 3. The module  160  also includes a connector (not shown) that extends from its bottom and that mates with the connector  150  (FIG. 7) of the base unit  136 . This connector may include an information provider such as the groove  57  (FIG. 2).  
         [0054]    Other embodiments of the control module  160  are contemplated. These embodiments may incorporate modifications similar to those discussed above in conjunction with FIG. 3 for the other embodiments of the control module  70 .  
         [0055]    [0055]FIG. 9 is a full-featured control module  170  that can replace one or both of the cartridge assembly  132  and the control module  134  of FIG. 7 according to an embodiment of the invention, where like numbers reference like components with respect to the control module  160  (FIG. 8). Typically, the module  170  is sized to occupy the entire base-unit receptacle  146  (FIG. 7). Therefore, the operator (not shown in FIG. 9) inserts the module  170  into the base-unit receptacle  146  in place of the cartridge assembly  132  and the control module  134 . The control module  170  has more features than the enhanced control module  160  as described below.  
         [0056]    The control module  170  typically receives power from the AED base unit  136  (FIG. 7), and, in addition to the on/off switch  140 , shock button  142 , display  162 , control knob  164 , and push buttons  166 , includes a status indicator  172 , indicator LEDs  174 , and a pad connector  176 , which are respectively similar to the status indicator  74 , LEDs  80 , and pad connector  78  of FIG. 3. The module  170  also includes a pair of connectors (not shown) that extend from its bottom and that respectively mate with the connectors  148  and  150  of the base unit  136 . One or both of these connectors may include an information provider such as the groove  57  (FIG. 2). Alternatively, the module  170  may include a single connector (not shown) that extends from the its bottom and that mates with one of the connectors  148  and  150  of the base unit  136 .  
         [0057]    Other embodiments of the control module  170  are contemplated. These embodiments may incorporate modifications similar to those discussed above in conjunction with FIG. 3 for the other embodiments of the control module  70 . Furthermore, the module  170  may be sized to occupy only a portion of the base-unit receptacle  146  (FIG. 7) such that the cartridge assembly  132  or another module (not shown) can simultaneously occupy the receptacle  146  with the module  170 .  
         [0058]    [0058]FIG. 10 is a monitor module  180  that can replace one or both of the cartridge assembly  132  and the control module  134  of FIG. 7 according to an embodiment of the invention, where like numbers identify like components with respect to the control module  170  (FIG. 9). Typically, the module  180  is sized to occupy the entire base-unit receptacle  146  (FIG. 7). Therefore, the operator (not shown in FIG. 10) inserts the module  180  into the receptacle  146  of the base unit  136  in place of the cartridge assembly  132  and the control module  134 . The module  180  typically provides additional features to the modular AED system  130  (FIG. 7) as described below.  
         [0059]    The monitor module  180  typically receives power from the AED base unit  136  (FIG. 7), and includes on/off switch  140 , shock button  142 , display  162 , control knob  164 , push buttons  166 , indicator light-emitting diodes (LEDs)  174 , and pad connector  176 . The display  162  displays information such as patient-treatment instructions, an AED function-select menu, or a patient waveform such as the patient&#39;s electrocardiogram (ECG). The display  162  may also display the status of the AED  130 . Furthermore, the module  180  may include a single connector (not shown) that extends from the bottom of the module and that mates with one of the base-unit connectors  148  or  150  (FIG. 7). Alternatively, the module  180  may include two such connectors that each mate with a respective one of the base-unit connectors  148  and  150 . One or both of these connectors may include an information provider such as the groove  57  (FIG. 2).  
         [0060]    Other embodiments of the monitor module  180  are contemplated. These embodiments may incorporate modifications similar to those discussed above in conjunction with FIG. 3 for the other embodiments of the control module  70 . Furthermore, the module  180  may be sized to occupy only a portion of the base-unit receptacle  146  (FIG. 7) such that the cartridge assembly  132  or another module (not shown) can simultaneously occupy the receptacle  146  with the module  180 .  
         [0061]    [0061]FIG. 11 is a modular AED system  188 , which includes an AED base unit  190  and communication module  192  according to an embodiment of the invention, where like numbers identify like components with respect to the AED system  130  (FIG. 7).  
         [0062]    The base unit  190  is similar to the base unit  136  except that it includes a receptacle  194  for receiving the communication module  192 . The receptacle  194  includes a connector  196  for mating with a corresponding connector (not shown) on the bottom of the module  192 .  
         [0063]    The communication module  192  allows an operator (hands shown in FIG. 11) to communicate with someone, such as a doctor (not shown), at a remote location, such as a hospital (not shown), before, during, or after a rescue operation. The module  192  includes a microphone  198  for picking up the operator&#39;s voice, an antenna  200 , which allows wireless communication between the operator and the remote location, and an optional speaker  201 . The speaker  24 , the speaker  201 , or both the speakers  24  and  201  may allow the operator to hear the voice of a person at the remote location. The module  192  may receive power from the base unit  190 , or may include a power supply such as a battery (not shown). Furthermore, where the wireless communication is over a wireless telephone network, the base unit  190  or module  192  includes circuitry (not shown) for dialing a predetermined telephone number. The base unit  190  or module  192  may cause the this circuitry to dial the telephone number automatically when the operator powers on the base unit, or may wait for a specific instruction from the operator.  
         [0064]    Alternate embodiments of the base unit  190  and module  192  are contemplated. For example, the module  192  may include a telephone keypad and telephone line connector like the module  112  (FIG. 6). In such an embodiment, the module  192  can be used for voice communications and for downloading rescue data as discussed above in conjunction with FIG. 6. Furthermore, the module  192  may include a speaker separate from the speaker  24  to allow the operator to hear the voice of a person at the remote location. In addition, the module  192  may lack the microphone  198 , and the microphone  34  may pick up the operator&#39;s voice for transmission to the remote location. Moreover, the microphone  198 , the antenna  200 , the communication circuitry (not shown) within the module  192 , and other components (not shown) of the module  192  may be integral with the base unit  190 . Furthermore, the AED base unit  44  of FIG. 2 can be modified to receive the module  192 . In addition, other embodiments may incorporate modifications similar to those discussed above in conjunction with FIG. 3 for the other embodiments of the control module  70 .  
         [0065]    [0065]FIG. 12 is a schematic block diagram of a base-unit circuit  210 , which the base units  44  (FIG. 2),  136  (FIG. 7), and  190  (FIG. 11) may incorporate according to an embodiment of the invention. The circuit  210  includes a functional circuit  212  and one or more—here n—module interfaces  214 . The functional circuit  212  may include and execute software, and performs functions such as turning on and off the modular AEDs  40 ,  130 , and  188 , analyzing a patient&#39;s heart rhythm and determining whether it is a shockable rhythm, generating a defibrillation shock if the rhythm is shockable, and sending rescue data to a remote location directly or via a module such as the control module  110  (FIG. 6). The circuit  212  may also control the speaker  24  and the microphone  34 , interface with the data card  36 , and manage the power supply for the base unit and any connected control modules. Each module interface  214  interfaces the functional circuit  212  to a respective module such as the control module  134  (FIG. 7). Each interface  214  typically includes at least one connector such as the connector  150  (FIG. 7), and may include an interface circuit (not shown). For example, the base unit  136  (FIG. 7) may include a single module interface  214  having the two connectors  148  and  150 , or may include two interfaces  214  each having a respective one of the connectors  148  and  150 .  
         [0066]    [0066]FIG. 13 is a schematic block diagram of a module circuit  220 , which the modules  42  (cartridge assembly of FIG. 2),  70  (FIG. 3),  90  (FIG. 4),  100  (training cartridge assembly of FIG. 5),  110  (FIG. 6),  132  (cartridge assembly) and  134  (FIG. 7),  160  (FIG. 8),  170  (FIG. 9),  180  (FIG. 10), and  192  (FIG. 11) may incorporate according to an embodiment of the invention. The circuit  220  includes a functional circuit  222  and one or more—here n—base-unit interfaces  224 . The functional circuit  222  may include and execute software, and performs functions such as turning on and off the modular AED systems  130  and  188  (FIGS. 7 and 11), controlling the display of information from the base unit (e.g., base unit  136  of FIG. 7) on a display screen (e.g., display screen  72  of FIG. 3), allowing an operator to select menu items or AED functions from the display screen (e.g. via buttons  84  of FIG. 3), providing a status of the AED (e.g., via indicator  74  or LEDs  80  of FIG. 3), instructing the base unit to deliver a shock in response to an operator (not shown in FIG. 13) pushing the shock button  142  (FIGS. 7-10), and dialing a telephone number (e.g., via the key pad  112  of FIG. 6). Each base-unit interface  224  interfaces the module functional circuit  222  to the base-unit functional circuit  212  (FIG. 12) of a base unit, such as the base unit  136  (FIG. 7), via one or more respective module interfaces  214  (FIG. 12). Each base-unit interface  224  typically includes at least one connector such as the connector  82  (FIG. 3), and may include an interface circuit (not shown). For example, the full-featured control module  170  (FIG. 9) may include a single base-unit interface  224  having two connectors (not shown) that respectively mate with the base-unit connectors  148  and  150  (FIG. 7), or may include two interfaces  224  each having a connector that mates with a respective one of the connectors  148  and  150 .  
         [0067]    Alternatively, for modules such as the cartridge assemblies  42 ,  100 , and  132 , of FIGS. 2, 5, and  7  respectively, the functional circuit  212  may be an energy-attenuation circuit, power circuit, or other type of circuit. Or, these modules may altogether omit the functional circuit  212 .  
         [0068]    [0068]FIG. 14 is a schematic block diagram of an AED circuit  230 , which the modular AED systems  40  (FIG. 2),  130  (FIG. 7), and  188  (FIG. 11) can incorporate according to an embodiment of the invention. Table I below gives examples of which of the circuit blocks are disposed in the base unit  44 ,  136 , or  190  and which of the circuit blocks are disposed in the module or modules connected to the base unit. Furthermore, the defibrillator electrode pads  16   a  and  16   b  are typically coupled to the base unit via a module. But there is no requirement that a particular circuit block be disposed in the base unit or in a module, or that the pads be connected to or be part of a module. Therefore, circuit blocks disposed in the base unit may be disposed in the module or modules, and vice versa, and the pads may be connected directly to the base unit. For clarity, unless otherwise noted, the AED circuit  230  is described as being part of the modular AED system  130  with the cartridge assembly  132  and the enhanced control module  160  (FIG. 8) attached, it being understood that the circuit  230  is similar when part of the modular AED systems  40  and  188 .  
         [0069]    Referring to FIG. 14, the defibrillator electrode pads  16   a  and  16   b  are coupled to the circuit  230  via the connectors  138  and  148  and are operable to sense a patient&#39;s ECG (not shown) and to apply an electrical shock to the patient (not shown). A shock-delivery-and-ECG front-end circuit  232  samples the patient&#39;s ECG during an analysis mode of operation, and provides a shock to the patient via the connectors  138  and  148  and the electrode pads  16   a  and  16   b  during a shock-delivery mode of operation. A gate array  234  receives the ECG samples from the circuit  232  and provides them to a first processor unit (PU)  236 , which stores and analyzes the samples. If analysis of the patient&#39;s ECG indicates that the patient is suffering from a shockable heart rhythm, then the processor unit  236  instructs the circuit  232 , via the gate array  234 , to enable delivery of a shock when an operator (not shown in FIG. 14) presses the shock button  142  (which is coupled to the processor unit  236  via the connector  150  of FIG. 7). Conversely, if analysis of the patient&#39;s ECG indicates that the patient is not suffering from a shockable heart rhythm, then the processor unit  236  may disable the circuit  232  from delivering a shock to the patient, and may instruct the operator via the speaker  24  or display  162  to seek non-shock treatment for the patient. Furthermore, the processor unit  236  can detect and signal the operator (e.g., via the speaker  24 , the LEDs  252 , or status circuit  242 ) when a module is not coupled to the module connector  148  or  150  (FIG. 7).  
         [0070]    The circuit  230  also includes a power-management circuit  238  for distributing power from the battery  18  to the subcircuits of the circuit  230 . The on/off switch  140  turns the circuit  230  “on” and “off”, a status circuit  242  indicates the status of the circuit  230 , and a second processor unit  244  interfaces the power-management circuit  238 , the on/off circuit  140  (via the connector  150  of FIG. 7), and the status circuit  242  to the circuit  232 , the first processor unit  236 , and the gate array  234 . As discussed above in conjunction with FIGS. 2-3, the display  162  (comparable to the display  72  of FIG. 3 in one embodiment) displays information to the operator, the speaker  24  provides audio instructions to the operator, and the microphone  34  records the operator&#39;s voice and other audible sounds. The data card  36  is connected to the gate array  234  via a port  248 . The card  36  stores the operator&#39;s voice and other sounds along with the patient&#39;s ECG and a record of AED events for later study. Alternatively, another storage device such as magnetic tape (not shown) may store this data. A status-measurement circuit  250  provides the status of the circuit  230  subcircuits to the processor unit  236 , and LEDs  252  provide information to the operator such as whether the processor unit  236  has enabled the circuit  232  to deliver a shock to the patient. A contrast control  254 , which the operator may manipulate via the control knob  164  (FIG. 8), allows the operator to control the contrast of the display screen  162 , and a memory such as a read only memory (ROM)  256  stores programming information for the processor units  236  and  244  and the gate array  234 .  
         [0071]    Still referring to FIG. 14, the circuit  230  also includes the optional microphone  198 , a data transmitter/receiver  258 , and a training-scenario selector circuit  260 .  
         [0072]    As discussed above in conjunction with FIGS. 6 and 11, the transmitter/receiver  258  allows communication of data between the AED circuit  230  and a remote location (not shown) such as a hospital via a landline (FIG. 6 ) or wireless telephone channel. For example, the transmitter/receiver  258  may receive data from the data card  36  via the gate array  234  and transmit the data to the remote location. Or, the transmitter/receiver  258  may receive voice data from the microphone  34  or  198  and transmit this data to the remote location. Alternatively, the transmitter/receiver  258  may provide data received from the remote location to the processor  236  via the gate array  234 . The processor unit  236  may convert the received data into a voice using the speaker  24 .  
         [0073]    The training-scenario selection circuit  260  allows training of a student in the operation of the AED system  130  (FIG. 7), when the training cartridge assembly  100  is attached to the base unit  136  (FIG. 7) in a manner similar to that discussed above in conjunction with FIG. 5. When the circuit  260  is coupled to the connector  148 , the pads  16   a  and  16   b  typically are not electrically coupled to the connector  148  to prevent inadvertent delivery of a shock during the training exercise. But the circuit  260  “fools” the processor unit  236  into determining that a selected scenario exists such that the processor unit causes the circuit  230  to operate according to this scenario. For example, the circuit  230  may cause the processor unit  236  to determine that a “patient” is experiencing a shockable heart rhythm, and thus to cause the circuit  230  to operate accordingly. This allows the student to learn the operation of the AED without putting a test patient at risk.  
         [0074]    Once can modify the circuit  230  according to known principles such that the AED system  130  can provide electrotherapies other than defibrillation, such as pacing and cardioversion, or includes a manual override that allows an operator (not shown in FIG. 14) more control over otherwise automated functions.  
         [0075]    An AED circuit similar to the AED circuit  230  and other AED circuits are further discussed in the following references, which are incorporated by reference: U.S. Pat. No. 5,836,993, U.S. Pat. No. 5,735,879 entitled ELECTROTHERAPY METHOD AND APPARATUS, U.S. Pat. No. 5,607,454 entitled ELECTROTHERAPY METHOD AND APPARATUS, and U.S. Pat. No. 5,879,374 entitled DEFIBRILLATOR WITH SELF-TEST FEATURES.  
         [0076]    Table I describes the locations of the circuit blocks of the AED circuit  230  (FIG. 14) and other circuits and components of the base unit and module(s) according to respective embodiments of the invention. Unless otherwise stated, reference numerals in Table I refer to circuit blocks or components in FIG. 14.  
                                 TABLE I                           (One of Modules 1, 2, and 3 Connected to the Base Unit at a Time)            Base Unit   Module 1   Module 2   Module 3               Battery 18   Adult Electrode   Pediatric   Training           Pads 16a and   Electrode Pads   Electrode Pads           16b   16a and 16b   16a and 16b       Speaker 24   Pad Storage   Pad Storage   Pad Storage           Compartment   Compartment   Compartment           (not shown, but   (not shown, but   (not shown, but           similar to the   similar to the   similar to the           compartment   compartment   compartment           62 of FIG. 2)   62 of FIG. 2)   62 of FIG. 2)       On/Off Button 140   Electrode Pad   Electrode Pad   Electrode Pad           Connector   Connector   Connector           (e.g., 176 of FIG. 9)   (e.g., 176 of FIG. 9)   (e.g., 176 of FIG. 9)       Shock Delivery   Module Identifier   Module Identifier   Module Identifier       and ECG 232   Circuit (not   Circuit (not   Circuit (not           shown,   shown,   shown,           identifies type   identifies type   identifies type           of module to   of module to   of module to           base unit)   base unit)   base unit)       Gate Array 234   Module   Module   Module           Unconnected   Unconnected   Unconnected           (to base unit)   (to base unit)   (to base unit)           Circuit (not   Circuit (not   Circuit (not           shown)   shown)   shown)       Pus 236 and 244   Module   Module   Module           Connector   Connector   Connector           (e.g., connector   (e.g., connector   (e.g., connector           82 of FIG. 4)   82 of FIG. 4)   82 of FIG. 4)           and Base-Unit   and Base-Unit   and Base-Unit           Interface   Interface   Interface           Circuitry (e.g.,   Circuitry (e.g.,   Circuitry (e.g.,           base-unit   base-unit   base-unit           interface 224 of   interface 224 of   interface 224 of           FIG. 13)   FIG. 13)   FIG. 13)       Power       Energy   Module Battery       Management       Attenuation   (not shown)       238       Circuit (not               shown)       Status           Training-Scenario       Measurement           Selector 102       250           (FIG. 5)       LEDs 252           Including       ROM 256           Training-       Data Transmitter-           Scenario       Receiver 258           Selector Circuit                   260 (FIG. 14)       Module       Connectors 148       and 150 (and       module interface       circuitry such as       module interface 214       of FIG. 12)