Abstract:
An application for preventing the reuse of a medical device includes a disposable medical device and a handle for accepting the disposable medical device. The handle physically supports the disposable medical device. A circuit for identifying the disposable medical device is imbedded within the disposable medical device and a circuit for reading a status of the identification is located in the handle. Whether the disposable medical device has been used is determined based upon the status.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to the field of medical devices and more particularly to a system for preventing the reuse of sterile medical instruments. 
       BACKGROUND OF THE INVENTION 
       [0002]    Many surgical procedures require the use of sterile probes or other devices that, once contacting a patient, are no longer sterile and should not be used with another patient. In some instances, because of the cost of such probes or devices, medical facilities attempt to clean or sterilize such probes or devices with heat, alcohol or other known procedures. Due to the nature of such probes and medical devices, it is not always possible to completely sterilize them because of their construction and/or their material composition. In such devices, the patient will not know that the device was previously used until a disease or infection occurs; when it is too late. 
         [0003]    Prior to the present invention, other methods of preventing reuse were employed. One method includes packaging the probe or device in a non-resealable encapsulation. This method informs the medical practitioners that the probe or device has been previously used, but often the patient is unaware of such and an overly cost-cutting medical facility would be free to reuse such probes or devices. 
         [0004]    Another method used is to at least partially fabricate the probe or device out of a material that degrades during any attempted sterilization. For example, a plastic handle that melts under the heat of boiling water or a plastic that deforms when contacted by alcohol or other petroleum products. Unfortunately, it is difficult to find materials that cover all forms of sterilization. Furthermore, such materials make it difficult to sterilize during manufacture. Worse yet, in rare cases, a practitioner may choose to simply wipe off the probe or device in an effort to maximize profits. 
         [0005]    What is needed is a system that will prevent the intentional and non-intentional reuse of medical devices. 
       SUMMARY OF THE INVENTION 
       [0006]    In one embodiment, a system for preventing the reuse of a medical device is disclosed including a disposable medical device and a handle for accepting the disposable medical device. The handle physically supports the disposable medical device. A circuit for identifying the disposable medical device is imbedded within the disposable medical device and a circuit for reading a status of the identification is located in the handle. Whether the disposable medical device has been used is determined based upon the status. 
         [0007]    In another embodiment, a method of preventing reuse of a disposable medical device is disclosed including providing a disposable medical device with a circuit for identifying itself imbedded within the disposable medical device and a handle for accepting the disposable medical device. The handle physically supports the disposable medical device has a circuit for reading a status of the circuit for identifying the disposable medical device. The method continues with reading the status from the circuit for identifying and determining if the status indicates the disposable medical device has been previously used. If the status indicates the disposable medical device has been previously used, the disposable medical device is prevented from being used. 
         [0008]    In another embodiment, a system for preventing the reuse of a medical probe is disclosed including a disposable medical probe with at least two electrical conductors and a handle for removably accepting the disposable medical probe. The handle physically supports the disposable medical probe and electrically couples to the electrical conductors. A device for identifying the disposable medical probe is imbedded within the disposable medical probe and a device for reading a status of the device for identifying is located in the handle. A controller determines if the disposable medical probe has been previously used based upon the status. 
         [0009]    In another embodiment, a system for preventing the reuse of a medical probe is disclosed including a disposable medical hemorrhoid probe having two electrical conductors and a handle for removably accepting the disposable medical hemorrhoid probe. The handle physically supports the disposable medical hemorrhoid probe and electrically couples to the two electrical conductors. A tuned circuit is electrically connected to the two electrical conductors and imbedded within the disposable medical hemorrhoid probe for identifying each disposable medical hemorrhoid probe. A sweep frequency generator is electrically coupled to the two electrical conductors through the handle and the impedance of the tuned circuit over the two electrical conductors is measured through the handle while the sweep frequency generator is operational to determine an identification of the probe. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The invention can be best understood by those having ordinary skill in the art by reference to the following detailed description when considered in conjunction with the accompanying drawings in which: 
           [0011]      FIG. 1  illustrates a schematic view of a system of a first embodiment of the present invention. 
           [0012]      FIG. 2  illustrates a schematic view of a system of a second embodiment of the present invention. 
           [0013]      FIGS. 2A ,  2 B and  2 C illustrate schematic views of ID devices of the second embodiment of the present invention. 
           [0014]      FIG. 3  illustrates a schematic view of a system of a third embodiment of the present invention. 
           [0015]      FIG. 4  illustrates a plan view of a typical medical probe of all embodiment of the present invention. 
           [0016]      FIG. 5  illustrates an isometric view of a typical medical probe of all embodiment of the present invention. 
           [0017]      FIG. 6  illustrates an isometric view of a typical medical probe handle of all embodiment of the present invention. 
           [0018]      FIG. 7  illustrates a flow chart of the first embodiment of the present invention. 
           [0019]      FIG. 8  illustrates a flow chart of the second embodiment of the present invention. 
           [0020]      FIG. 9  illustrates a flow chart of the third embodiment of the present invention. 
           [0021]      FIG. 10  illustrates a first flow chart of an alternate method of the third embodiment of the present invention. 
           [0022]      FIG. 11  illustrates a second flow chart of the alternate method of the third embodiment of the present invention. 
           [0023]      FIG. 12  illustrates a schematic diagram of a network according to the alternate method of the third embodiment of the present invention. 
           [0024]      FIG. 13  illustrates a schematic diagram of a controller of all embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Throughout the following detailed description, the same reference numerals refer to the same elements in all figures. The present invention describes a method of preventing reuse of surgical instruments. Although the description is directed toward a disposable surgical probe used in the treatment of hemorrhoids, the methods and apparatus apply to many other types of surgical instruments and probes, all of which are anticipated and included here within. In some embodiments, the probe is a monopolar hemorrhoid probe. Usually, such systems include a disposable portion (e.g., a probe that comes in contact with the patient), a handle into which the probe is inserted and held and, a base station connected to the probe for providing power and therapeutic signals. 
         [0026]    Referring to  FIG. 1 , a schematic view of a system of a first embodiment of the present invention will be described. In this embodiment, a fuse  66  is embedded in the probe  60 . In this embodiment, the fuse is shown bridging the two probe conductors  64 , while in other embodiments having more than two conductors between the probe  60  and probe handle  50 , other fuse arrangements are envisioned. The fuse  66  is an indicator that identifies whether the probe  60  has been previously used. If the fuse  66  is conductive, it is believed that the probe  60  has not been previously used. If the fuse  66  is blown (non-conductive), it is believed that the probe  60  has been previously used. In this embodiment, the probe  60  has two probe tip conductors  62  that are electrically coupled to connector pins  64  in the base of the probe  60 . The connector pins  64  mate with connector pins  56  within the probe handle  50 , which are in electrical communication with a base station  70  through a cable  58  or other means. In some embodiments, the cable  58  is electrically plugged into the base station  70  through a connector  72  while in other embodiments, the cable  58  is hard-wired (captured) to the base station  70 . The base station  70  includes a programmable controller  74  for performing the reuse testing operation and for providing electrical signals to the probe  60  for medical purposes. In this example, one leg of the probe conductors  62 / 64 / 56 / 58  is biased to a voltage potential (Vcc) by a resistor R 2   82  while the other probe conductor  62 / 64 / 56 / 58  is held to ground potential. R 2   82  is of high enough resistance to not interfere with the medical purpose of the device while having a low enough resistance to raise the voltage over the probe  60  high enough to detect the presence/absence of the fuse; for example, a 10 KΩ resistor. The medical electrical drivers are known in the industry and, for example, include a voltage pulse driver  76 . Other types of medical electrical drivers are known in the industry and the present invention is not limited to any particular type. 
         [0027]    An operational amplifier or comparator or other voltage detecting circuit  78  detects the voltage across the probe  60  and is coupled to an input of the controller  74 . Therefore, if there is voltage over the probe  60 , the controller determines the fuse  66  is absent (used probe) and if there is little or no voltage over the probe  60 , the controller  74  determines the fuse  66  is present (new probe). Once it is determined that the fuse  66  is present (new probe), the controller  74  outputs a logic signal to a current/voltage driver transistor  84 , in some embodiments through a current-limit resistor R 1  (typically 1 KΩ). This voltage/current is sufficient to burn the fuse  66  and prevent reuse of the probe  60 . The controller  74  first measures the voltage over the probe  60  using the voltage detection device  78  and if voltage is present, prevents use of the probe  60  because it has been used. If voltage is not present, it determines that the probe has not been already used and drives the transistor  84  to provide enough current to burn/blow the fuse  66 , signaling the probe  60  is now used. In some embodiments, a current limiting resistor  80  couples the controller  74  with the transistor  84 . 
         [0028]    Referring to  FIG. 2  along with  FIG. 2A ,  FIG. 2B  and  FIG. 2C , a system of a second embodiment of the present invention will be described. In this embodiment, an ID device  67  is embedded in the probe  60 . In this embodiment, the ID device  67  is shown bridging the two probe conductors  64 , while in other embodiments having more than two conductors between the probe  60  and probe handle  50 , other ID device  67  arrangements are envisioned. The ID device  67  is an indicator of whether the probe  60  has been previously used. The ID device  67  has a unique or statistically unique characteristic that is detectable by the base station  70  through the probe handle  50 . Many ID devices  67  are envisioned including tuned circuits such as capacitors, inductors and parallel or serial capacitors and inductors. In some embodiments, the ID device  67  is a ROM/EPROM/EEPROM/FLASH, preferably a serial version to reduce pin/conductor requirements. In all examples of ID devices  67 , each device has a statistically unique characteristic or code. For example, a capacitor/inductor in parallel forms a tuned circuit that provides a notch filter providing a low impedance starting at a first frequency and ending at a second frequency. The frequency at which the impedance changes from the low impedance to the high impedance is the cross-over frequency. Each probe  60  is fabricated with a different capacitance and inductance and therefore, each probe  60  has a different impedance vs. frequency response and one or more cross-over frequencies. Measuring this response yields a statistically unique value of set of cross over frequencies that are used to determine if a probe  60  has already been used. It is anticipated that, due to a finite number of capacitor and inductor values possible, after a certain number of probes  60  have been used, the base station will need to be reset to “forget” all of the values already seen. In that, if there are 100 possible combinations of capacitors and inductors, after using 100 probes  60 , the base station need be reset to allow for the next 100 probes, etc. 
         [0029]    The base station  70  keeps track of which statistical unique codes have been used and, if finding a probe  60  with an already used statistically unique code, prevents its use. 
         [0030]    In this embodiment, the probe  60  has two probe tip conductors  62  that are electrically coupled to connector pins  64  in the base of the probe  60 . The connector pins  64  mate with connector pins  56  within the probe handle  50 , which are in electrical communication with a base station  70  through a cable  58  or other means. In some embodiments, the cable  58  is electrically plugged into the base station  70  through a connector  72  while in other embodiments, the cable  58  is hard-wired (captured) to the base station  70 . The base station  70  includes a programmable controller  74  for performing the reuse testing operation and for providing electrical signals to the probe  60  for medical purposes. The medical electrical drivers are known in the industry and, for example, include a voltage pulse driver  76 . Other types of medical electrical drivers are known in the industry and the present invention is not limited to any particular type. 
         [0031]    An analog to digital converter, operational amplifier or comparator or other voltage detecting circuit  78  detects the voltage across the probe  60  and, hence the impedance when a frequency is applied to the conductors. It is coupled to an input of the controller  74 . Therefore, the impedance of the probe  60  is measurable by the controller  74  to determine a statistically unique identification. This statistically unique identification is used to determine if the probe  60  was a previously used probe (e.g., that particular identification or code was previously detected). To determine the impedance of the probe  60 , a series or sweep of frequencies are generated by the controller  74  and amplified, by example, by a transistor  84  while the voltage across the probe is measured by the voltage detection device  78  (operational amplifier, comparator, analog to digital controller, etc). The voltage across the probe  60  will increase as the impedance of the ID device  67  increases (e.g., a cross over frequency). Detection of the changes in voltage measured by the controller  74  is used to determine the cross over frequencies of the probe  60 , thereby determining its statistically unique footprint. In some embodiments, a current limiting resistor  80  couples the controller  74  with the transistor  84 . It is envisioned that multiple parallel and/or serial combinations of capacitors, resistors and inductors will be used to provide a larger number of statistically unique footprints (see  FIGS. 2A ,  2 B and  2 C). In one example, an ID device  67  has a capacitor  300  in series with a resistor  301  to create a low-pass filter having a crossover frequency, f 1  In another example, an ID device  67  has a capacitor  300  in parallel with an inductor  302 , both in series with a resistor  301  to create a filter having a first cross over frequency, f 1  and a second cross over frequency f 2 . In another example, an ID device  67  has two sets of parallel capacitors  300 / 304  and inductors  302 / 305  in series with a resistor  301  to create a dual-notch filter having two notch frequencies, f 1  and f 2 . Therefore, assuming 100 possible unique combinations of capacitors and inductors, 9,900 statistically unique combinations are possible (100 possible first notch frequencies multiplied by 99 possible second notch frequencies assuming the same frequency is not reused). Other combinations of tuned circuits are envisioned. For example, a band-pass filter with a frequency response having a low impedance from zero to f 1  (first cross over frequency) and having a high impedance from f 1  to f 2  (second cross over frequency) then a low impedance at frequencies higher than f 2 . 
         [0032]    Referring to  FIG. 3 , a schematic view of a system of a third embodiment of the present invention will be described. RFIDs  68  are known in the industry as are RFID readers. RFIDs (radio frequency identification devices)  68  contain a data stream that is usually unique, providing a serial number. The serial number is read by radio frequency (RF) radiation from the RFID reader  52  through a wireless connection. The RFID  68  uses parasitic RF energy to power itself and transmit its identification code or serial number. In some embodiments, the RFID reader  52  is integrated into the probe handle  50  (as shown in  FIG. 3 ) while in other embodiments, it is integrated into the base station  70  or external to the base station  70 . It is preferred that the RFID reader  52  be located in the probe handle  50  for several reasons. First, its close proximity to the probe  60  allows more accurate readings of the RFID  68  within the probe utilizing less transmission power. Second, because lower transmission power is used, the RFID  52  reader is less likely to erroneously read an RFID  52  located in a probe  60  that is not installed in the probe handle  50 . 
         [0033]    The RFID reader  52  is communicatively coupled to the controller  74 , in this embodiment by the probe cable  58  and optional probe cable connector  72 . The method of determining reuse will be described in detail later. It consists of reading the RFID  68  before use and looking in a database to determine if the serial number of the RFID  68  has already been used. If it has already been used, use of the probe  60  is prevented. If it hasn&#39;t been used, the serial number is added to the database and the probe  60  is allowed to be used. 
         [0034]    Referring to  FIG. 4 , a plan view of a typical medical probe of all embodiment of the present invention will be described. This probe  60  is for the electrical treatment of hemorrhoids. It is envisioned that the described method of preventing reuse applies to many other types of medical devices and a probe for hemorrhoid treatment is an example of such. The method utilizing an RFID  68  adapts well to devices that have no electrical connection to the probe handle  50 . The probe  60  of this example has two probe connectors  64  at the connector end and two probe tips  62  at the tip end. The probe identification device  66 / 67 / 68  is housed within the probe body  61 . 
         [0035]    Referring to  FIG. 5 , an isometric view of a typical medical probe of all embodiment of the present invention will be described. This probe  60  is for the electrical treatment of hemorrhoids. It is envisioned that the described method of preventing reuse applies to many other types of medical devices and a probe for hemorrhoid treatment is an example of such. The probe  60  of this example has two probe connectors  64  at the connector end and two probe tips  62  at the tip end. The probe identification device  66 / 67 / 68  is housed within the probe body  61 . 
         [0036]    Referring to  FIG. 6 , an isometric view of a typical medical probe handle of all embodiment of the present invention will be described. Although many different sizes, shapes and configurations of probe handles  50  are envisioned, the probe handle  50  shown is an example for use with the probe  60  of  FIGS. 4 and 5 . The probe handle  50  has a connector end  56  for accepting the electrical connections  64  of the probe  60  and an electrical cable  58  for connecting with the base station  70 . In some embodiments, indicators and/or controls are integrated into the probe handle  50  (not shown). 
         [0037]    Referring to  FIG. 7 , a flow chart of the first embodiment of the present invention will be described. The method begins with measuring the voltage  100  across the probe  60 . If the voltage is present  102  (some voltage over 0V), it is determined that the fuse  66  is absent  110  and, therefore, the probe  60  is prevented from being reused. An indication that the probe  60  cannot be reused is made  112  (e.g., illuminating a red LED—not shown). In some embodiments, the system is then disabled  114  preventing any operation of the probe  60 . 
         [0038]    If there is little or no voltage measured  102 , a voltage or current pulse is emitted  104  over the probe  60  to burn the fuse  66 . In some embodiments, the voltage across the probe  60  is re-measured  106  to make sure the fuse  66  is blown. If the voltage is present  108  (some voltage over 0V), it is determined that the fuse  66  has blown and the probe  60  is ready for use. If the voltage is not present  108  (approximately 0V), it is determined that the voltage/current pulse did not blow the fuse  66  and the previous two steps are repeated in an attempt to blow the fuse  66 . In some embodiments (not shown), these steps are repeated a fixed number of times before disabling the probe  60 . For example, someone might attempt to short the probe tip to allow for reuse. 
         [0039]    Referring to  FIG. 8 , a flow chart of the second embodiment of the present invention will be described. To determine if a probe of the second embodiment of the present invention has already been used, the base station performs a sweep generator function by setting an output frequency to a starting frequency  120 . At each frequency, the base station measures the voltage  122  across the probe  60 . If the probe  60  has a higher impedance at that frequency, the voltage across the probe  60  will be higher and if the probe  60  has a lower impedance at that frequency, the voltage across the probe  60  will be lower. The example of  FIG. 8  uses an identification system of the second embodiment having a capacitor  300  in series with a resistor  301  (see  FIG. 2A ). In this, the probe  60  acts like a low-pass filter in that it has a high impedance at low frequencies and a low impedance at high frequencies, the cross-over frequency is determined by the value of the capacitor  300 . At each output frequency, the voltage is measured or compared to a threshold  124 , with a comparator, operational amplifier or analog-to-digital converter  78 . If the voltage is not less than the threshold  124 , the output frequency is increased  126  and, if a terminal frequency is not reached  128 , previous steps are repeated to measure the voltage over the probe  60 , etc. If the terminal frequency is reached  128 , the probe  60  is declared used and cannot be reused  134 , therefore the system is disabled  136 . If the voltage across the probe  60  is less than the threshold (e.g., the tuned circuit is a low impedance at this frequency), the frequency is looked up in a table  130  and if found, it is determined that the probe  60  was previously used and cannot be reused  134 , therefore the system is disabled  136 . The current frequency (frequencies) is stored in the table  138  to prevent future reuse of the current probe  60 . 
         [0040]    In alternate embodiments, multiple tuned frequencies are tracked and recorded and looked up in the table or database (e.g., the embodiment of  FIG. 2C ). 
         [0041]    Referring to  FIG. 9 , a flow chart of the third embodiment of the present invention will be described. This embodiment begins with activating  140  the RFID reader  52  to read the code  142  from the RFID  68 . If the code is not readable  144 , the RFID is not recognized  146  and the system indicates the probe  60  cannot be used  154  and, in many embodiments, the system is disabled  156  until a different probe  60  is installed. If the code is read  144 , the code is looked up in a RFID code table or database  150 . If the code has already been used  152 , the system indicates the probe  60  cannot be used  154  and, in many embodiments, the system is disabled  156  until a different probe  60  is installed. If the RFID code has not already been used  152 , the RFID code is stored in the table or database  158  to prevent the current probe  60  from being reused in the future and the probe  60  is ready for use  159 . 
         [0042]    Referring to  FIGS. 10 and 11 , a first and second flow chart of an alternate method of the third embodiment of the present invention will be described. This embodiment begins with activating  160  the RFID reader  52  to read the code  162  from the RFID  68 . If the code is not readable  164 , the RFID is not recognized  166  and the system indicates the probe  60  cannot be used  186  and, in many embodiments, the system is disabled  188  until a different probe  60  is installed. If the code is read  144 , the code is sent to a server  170  through means known in the industry including sending the code through the internet  10  (see  FIG. 12 ). Within the server, the code is looked up in a RFID code table or database  172 . If the code has already been used  174 , the server responds with an indication that the probe  60  should not be used  176 . If the RFID code has not already been used  174 , the server adds the code to the table or database  180  to prevent future use of the same probe and responds with an indication that the probe is valid and is ok to use  181 . After the response is received  182  at the controller, the response from the server is tested to determine if it is ok to use  184  the probe  60 , If it is ok to use the probe  60 , the system is enabled  190  If it is not ok to use the probe  60  (e.g., the probe was previously used), the system indicates the probe  60  cannot be used  186  and, in many embodiments, the system is disabled  188  until a different probe  60  is installed. 
         [0043]    Referring to  FIG. 12 , a schematic diagram of a network according to the alternate method of the third embodiment of the present invention will be described. This exemplary diagram shows how multiple base stations  20 / 22 / 24  communicate with a server  30  through the Internet  10  as described with  FIGS. 10 and 11 . The server is interfaced with an RFID table or database  32  for determining if a probe  60  (e.g., RFID code) has previously been used by any base station connected to the server. 
         [0044]    Referring to  FIG. 13 , a schematic diagram of a controller of all embodiments of the present invention will be described. Many different computer architectures are known that accomplish similar results in a similar fashion and the present invention is not limited in any way to any particular computer system. In this exemplary system, a processor  210  is provided to execute stored programs that are generally stored for execution within a memory  220 . The processor  210  can be any processor, for example an Intel® 80C51 CPU or the like. The memory  220  is connected to the processor and can be any memory suitable for connection with the selected processor  210 , such as SRAM, DRAM, SDRAM, RDRAM, DDR, DDR-2, etc. Firmware is stored in firmware storage  225  that is connected to the processor  210  and may include initialization software known as BIOS. This initialization software usually operates when power is applied to the system or when the system is reset. In some embodiments, the software is read and executed directly from the firmware storage  225 . 
         [0045]    Also connected to the processor  210  is a system bus  230  for connecting to peripheral subsystems such as a network interface  280 , output bits  240 , input bits  250 , display outputs  260  and control inputs  270 . The display outputs are any known display device including LEDs  265 , numeric displays, alpha-numeric displays, lamps, etc. The control inputs  270  include any known control input  270  including switches, push buttons, rotary switches, thumbwheel switches, dip switches, etc. 
         [0046]    The network interface  280  connects the computer-based system to the world-wide-web  10  through a link  285  which is, in some embodiments, a high speed link such as a cable broadband connection, a Digital Subscriber Loop (DSL) broadband connection, a T 1  line or a T 3  line. 
         [0047]    The output bits  240  control the logic through, for example, a resistor  80  and transistor  84 . Some output bits  240  control the therapeutic outputs  76  of the system of the present invention. 
         [0048]    The input bits  250  interface to the comparator/operational amplifier/analog-to-digital converter  78  to measure the voltage drop over the probe and/or impedance. Some input bits  240  are used to read the RFID code from the RFID reader  52 . 
         [0049]    Equivalent elements can be substituted for the ones set forth above such that they perform in substantially the same manner in substantially the same way for achieving substantially the same result. 
         [0050]    It is believed that the system and method of the present invention and many of its attendant advantages will be understood by the foregoing description. It is also believed that it will be apparent that various changes may be made in the form, construction and arrangement of the components thereof without departing from the scope and spirit of the invention or without sacrificing all of its material advantages. The form herein before described being merely exemplary and explanatory embodiment thereof. It is the intention of the following claims to encompass and include such changes.