Patent ID: 12237076

DETAILED DESCRIPTION

The present disclosure relates to systems and methods for managing an inventory of surgical articles during a surgical procedure to ensure the proper removal of the surgical articles from the patient following the surgical procedure and thereby prevent the undesirable retention of the surgical articles within the patient.

FIG.1illustrates one such surgical article, a surgical sponge10, having one or more tags for counting or detecting the surgical article before, during, or after a surgical procedure. In particular, the surgical article illustrated inFIG.1may comprise a surgical sponge10further comprising a tag20, as described in detail below. However, while not shown in the Figures, it has been contemplated that other alternatives of the surgical article10can include laparotomy pads, gauzes, implants, towels, suture needles, clips, staples, or surgical instruments. Another example of the surgical article may comprise a surgical instrument, such as a scalpel or forceps, comprising a tag20.

The tag20may comprise counting element(s), detecting element(s), or any combination thereof and may be incorporated within handles, between layers of, or other portions of the surgical article10. As described in detail below, each surgical article10can include one or more tags20, and each tag20may include various combinations of the counting elements or the detecting elements. For example, one of these tags20may comprise an RFID element (RFID tag). However, each tag20can include any number of counting elements and any number of detecting elements, in addition or in the alternative, consistent with the disclosure herein.

The tag20may be configured to include unique identification information for each surgical article10. The unique identification information may comprise a serial number or other identifier that is unique and assigned only to the corresponding article10. The unique identification information may further convey the type, size, weight, manufacturing dates, expiration date, number of similar articles10in a corresponding package, the unique identification of the articles packaged together, or other information used for counting or detecting the article10.

The tag20may convey the unique identification information by transmitting an electromagnetic signal or wave corresponding to the unique identification information. Each surgical article10may comprise, in addition, a second tag (not shown) having the unique identifier or other information in a form scannable by an optical-scanning device or human-readable that can be manually entered into a user interface of the scanning device, computer, or other system. A plurality of tags on a surgical article may be different from one another, yet include the same unique identification information related to the specific surgical article to which the tag is affixed. The tag20may allow an HCP to identify the number of surgical articles10present or to determine a location of the surgical articles10within the body of the patient, within an operating room, or both inside the body of the patient and within the operating room. In other alternatives, the tag(s)20may be detectable within the operating room but not within the body of the patient.

The tag20may be incorporated within handles, between layers of, or other portions of the surgical article10. For example, the tag20can be adhered to or encapsulated within the layers of the surgical article10, embedded within the handle, or coupled to other portions of the article10. Each tag20may be rigid to increase its service life. In other examples, the tag20can be flexible to permit the surgical article10and the tag to be folded or otherwise shaped in a more preferable manner for use within a patient's body. Furthermore, the tag20may be encapsulated in a biocompatible plastic coating, pouch, or housing26that is water-impermeable and sterilizable. The housing26may be coupled to the surgical article10via stitching, adhesive, or similar type of fastener. The counting or detecting elements of the tag20may be configured to cooperate with at least one detector-interrogating antenna (detecting antenna) of a reader, as a scanning device, such as a hand-held device manipulatable by the HCP. Alternatively, a detector-interrogating antenna may be incorporated into a surgical instrument tray, surgical cart, or canister. However, it is contemplated that any suitable antenna, including one integrated within the optical-scanning device can be configured to detect the detecting element included in the tag20. The antenna may further comprise a circuit, coil, or loop configured to define a plane of the antenna, wherein a signal, which can be carried on, or understood as, an electromagnetic field, may be transmitted outward from the plane of the antenna, to be received by the tags20which then provide a response signal that can be projected back to the antenna. The Applicant has described a scanning device or scanning apparatus with an antenna in U.S. Pat. No. 8,181,860, filed on Sep. 13, 2007, the disclosure of which is hereby incorporated by reference.

A wide variety of tags may be commercially available by a number of manufacturers. Certain tags may be configured to provide significant amounts of user accessible memory, sometimes in the form of read-only memory or write-once memory. One exemplary tag is an RFID tag20detectable by a RFID antenna. However, it is contemplated that the surgical article10can include any suitable tag detectable by any corresponding detecting antenna. The Applicant has described a surgical article10and method of managing surgical articles that comprise various tags in PCT Application No. PCT/US2016/057077, filed on Oct. 14, 2016, the disclosure of which is hereby incorporated by reference.

The surgical article may comprise a surgical sponge10comprising an absorbent material body11. The absorbent material body11of the surgical sponge10may comprise a top surface12and an opposing bottom surface14. The surgical sponge10may further comprise a lead, handle or string16. The lead16may comprise a radio opaque marker material that is configured to show up in a medical scan. For example, the lead may comprise a radio opaque marker material configured to show up in an MRI image to allow for identification of a surgical sponge10that was inadvertently retained within a patient.

It may be important for HCPs to track surgical sponges10before, during, and after a surgical procedure to ensure that a surgical sponge10is not inadvertently retained or left within a patient. Therefore, as described above, an RFID tag20may be utilized to identify the location and number of sponges used in a surgical procedure. An RFID tag20may be coupled to the top surface of the absorbent material body11proximate to an edge or corner of the surgical sponge10. While not shown in the Figures, it is contemplated that the RFID tag20may be incorporated into the handle, between layers of the absorbent material or other portions of the surgical sponge10in any number of ways. For example, the RFID tag20can be adhered to or embedded within the handle or coupled to other portions of the surgical sponge10.

The detecting element of the RFID tag20may be used with a multiplex detection system. The RFID tag20can include a capacitor and an antenna (not shown), which receives power from the detecting antenna (RFID antenna) of the reader to charge the capacitor of the RFID tag20. This capacitor becomes the power source for the operation of an unpowered RFID tag20. The RFID tag20can have an integrated circuit, which includes a reading function, a carrier frequency modulating function, and a read-only memory portion with a burned-in code. The integrated circuit and corresponding antenna of the detecting element are encapsulated in an enclosure that is resistant to blood, water, or saline solution. Thus, the RFID tag20can withstand repeated sterilization and be attached to other surgical articles, such as metal instruments, which are sterilized and reused multiple times. Depending on the carrier frequency and the type of RFID tag20, the RFID tag20can vary significantly in cost, size, and resistance to shielding by intervening tissue.

One feature provided by RFID based technology is that the RFID tag20achieves the dual purpose of detecting the location of the surgical sponge10in addition to counting or identifying the surgical sponge10. Thus, certain RFID tags20may serve as both detection elements and counting elements. The RFID tag cooperates with the detecting antenna of the reader to both detect the location of the surgical sponge10and provide data for determining the unique identification information of the surgical sponge10. The RFID tags20may operate above the MHz range. Exemplary frequencies can include about 13.35 to 14.15 MHz (high frequency), a range from 850 to 950 MHz (ultra-high frequency), or a range of microwave frequencies (i.e., 2.45 to 2.55 GHz). The added bandwidth provided by these RFID tags20can increase the probability of detecting and finding the corresponding surgical sponge10within the interrogation zone and within a short period of time.

Turning now toFIG.2, a system for detecting, identifying and managing an inventory of surgical objects during a surgical operation is disclosed. The scanning device may be configured to maintain a record of the surgical articles10used in the procedure in on-board memory, or in cooperation with a server. The scanning device includes an RFID interrogator in communication with the on-board memory. The RFID interrogator includes the physical components and the operating software for generating and receiving the radio frequency signals. Among the physical components of the interrogator are the radio controller, including a signal-generating transmitter, a signal receiver, or a transceiver.

The record of the surgical articles created and maintained by the system may be stored on the scanning device in on-board memory, or else the record may be communicated to a server for storage. The scanning device may have a wired or a wireless connection to the server. In some alternatives, there may be one or more devices disposed in communication between the scanning device and the server. In one example, the scanning device within an operating room may communicate with a computer located in the operating room that is in further communication with other medical devices and tools in the operating room. The computer may communicate information to a router that acts as a gateway to a network. The server is also connected to the network, and thus the scanning device communicates with the server through multiple layers of devices.

At the conclusion of the surgical procedure, the records can be transmitted to a server and matched with patient records, such as electronic medical records, to update the same and provide an indication of which specific surgical articles were used with each patient at which times.

InFIG.2examples of various containers for packaging or bundling two or more surgical sponges10are shown. A strap38or plurality of straps38may be utilized to bundle or package two or more surgical sponges10together. The strap(s)38may be configured to bundle the two or more surgical sponges10to maintain a defined relationship between the RFID tags20of adjacent surgical sponges10in the bundle30. For example, a plurality of surgical sponges10may be stacked on top of one another and packaged together by a strap or band38. The strap38may be configured to bundle2,3,5,10,20, or more surgical sponges10together. Alternatively, one, or two or more surgical sponges10may be packaged or bundled within a pouch or container50. The container50may be similarly configured to the strap, wherein the container50is configured to maintain a defined relationship between the RFID tags20of adjacent surgical sponges10in the container50. The container50may comprise a poly-Tyvek® pouch, a rigid base with a poly-Tyvek® cover, or similar containment apparatus. Any number of surgical sponges10, or surgical instruments may be packaged or bundled by the strap38or within the container50.

Bundling or packaging surgical sponges10as described above can create challenges for scanning the RFID tag(s)20of the individual surgical sponges10included in the bundle30. When attempting to scan the RFID tag20of the surgical sponges10when packaged, one potential challenge is that there is an increased possibility of interference between the RFID tags20that may result in an inaccurate count or reduced detection distance of the surgical sponges10. Providing a sufficient detection distance is important for surgical tools and articles because the sterility of the surgical tools and articles needs to be maintained and the RFID reader may not be sterile or available within the sterile field. If the read distance is insufficient the HCP will need to spend additional time and incur additional costs to sterilely drape the scanner prior to each surgery. On the other hand, simply increasing the scanner power output to overcome the challenges of densely packaged RFID-tagged surgical articles may result in the undesirable counting-in of surgical sponges being transported or stored nearby, including in adjacent operating rooms or other storage locations. Accidental count-in of surgical articles not intended for the active surgical procedure may cause HCPs to waste time and extend the length of a surgical procedure while attempts are made to account for surgical articles never intended to be used in the procedure.

A system100for managing surgical articles during a surgical procedure is illustrated inFIG.2. The system100includes the hardware and software to communicate with RFID-tagged surgical articles, create and maintain database records managing an inventory of the surgical articles, including identifying type number, type, and unique identification of those surgical articles made available for use in a particular surgical procedure. The system100provides the interface for an HCP to enter information into the database, and to access that information and other information in the database before, during and after a surgical operation.

The system100includes a system computer101in communication with a display102. The display102may be an integrated display, such as a tablet computer that further includes a touchscreen104, or other input hardware (not shown). In other alternatives the display102may simply be a monitor with the system computer101and input functionality provided by other hardware in communication with the display102. Other input hardware (not shown) may include a microphone for voice command control, or a video camera or other sensor to provide gesture control. Further alternative input hardware may include a trackball, touchpad, keyboard, mouse, or the like.

The display102may be supported on a base106. The base106may be pole mounted, as illustrated inFIG.2. In other alternatives, the base106may be a mobile cart, or a stationary unit. The base106may be a mechanical support for the display102as an integrated display including the power source, computing and input functionality all in the display itself, such as a tablet computer. Alternatively, the base106may support functions that are not integrated within the display102. For example, the base106may include the system computer101, and a rechargeable battery to provide power to the system100, including providing power to the display102. The base106may house a central processing unit, memory device, data storage device, other hardware for the system computer101.

The base106may also support a RFID reader108in communication with the system computer101. The RFID reader108may be integrated into the base106or may be removable and operate remotely from the base106. The base106may provide a dock for a removeable, mobile RFID reader, such as a hand-held RFID reader108. When docked in base106, the RFID reader may rely on a power source external to itself and may use wired dock connections for communication with the system computer101.

The RFID reader may include an RFID transceiver enabling communication between the RFID reader108and an RFID tag, such as tag20of surgical sponge10. The RFID reader108may include its own power source, data processing, and memory or data storage devices internal to the RFID reader108. The RFID reader108may be configurable to operate with varying levels of power provided to the RFID transceiver to change the effective output of radio energy from the antenna.

The system100may include or be in communication with an external computing device110. This may include additional memory or data storage. The device110may provide wireless connectivity of other systems, such as a router or modem to communicate with remote resources, such as a hospital network or internet server. In other alternatives, network connectivity is integrated into the system computer101without the need for an external device110.

The system100may be provided within a surgical environment such as a hospital operating room. The system100may be adapted to be draped for positioning in the sterile field. Alternatively, the system100may be positioned adjacent to but outside of the sterile field to avoid the need for sterile draping. In further alternatives, the base106may be positioned outside of the sterile field, but the mobile RFID reader108may be separate from the base106and enter into the sterile field with appropriate sterile draping or other sterilization-maintaining measures as may be known in the art.

The system100may be provided with an inventory112of surgical articles tagged with RFID tags to be managed during the surgical procedure. InFIG.2, the inventory of surgical articles is illustrated as a mobile cabinet or cart with drawers114containing the supply of a number of different types of RFID tagged surgical articles, such as surgical sponge10. As described above, surgical sponges10may be packaged or bundled in various quantities. RFID-tagged surgical sponges10come in a variety of shapes from as small as 2 inches by 2 inches to as large as 8 inches by 108 inches. There are also thickness variations in the number of layers that make up a single surgical sponge10. For example, some surgical sponges10may be as few as 4 ply or as many as 32 ply. Most commonly, surgical sponges10are packaged from singly in a package up to 10 units within a package.

Each of the surgical articles, e.g., surgical sponges10, is tagged with an RFID tag, e.g., tag20, containing data to uniquely identify the individual item as well as provide other information relevant to manage an inventory of surgical articles. Referring now toFIG.3, an exemplary identification scheme120that may be stored in the RFID tag20is shown. A variety of tags and data encoding schemes are presently available and the description of the identification scheme120is not intended to be limiting. Generally, RFID tags will be manufactured with a tag identification (TID)122assigned by the manufacturer of the RFID integrated circuit (IC). This TID122is typically stored in a write-once memory location, otherwise known as a read-only memory location on the IC. In addition to the TID122provided by the tag manufacturer, other information may be provided in connection with associating the tag IC to a particular surgical article, such as surgical sponge10.

The identification scheme120may include a portion124dedicated to identifying the type of surgical article to which the tag is affixed, i.e., sponge type ID. In one alternative, the sponge type ID124, as described above is a value which may be used by the system computer101in combination with a look-up table to retrieve further specification information relevant to the sponge type, such as quantity of sponges for that sponge type, name to be displayed on the user-interface, a designated power level for the RFID reader to operate at while counting-in sponges of that type. The look-up table may be stored local to the system computer101, such as in data storage of an integrated display102, data storage provided in the base106, data storage of an external computer device110, or remotely from the system computer101, such as on a hospital network or internet server location. In other alternatives, the sponge type ID124may be encoded to provide certain information directly, rather than requiring correlation to a look-up table value. For example, the sponge type ID124may correspond directly to a designated RFID reader power level associated with the particular type of sponge. In either case, the sponge type ID124may correspond to a power level parameter stored on the RFID tag associated with the sponge type. The power level parameter may directly encode a power level value in dBm, or may otherwise provide data corresponding to a power, current, voltage, or other setting for the reader in controlling or modulating power output, directly or indirectly, from the antenna of the reader. In other alternatives, the sponge type ID124may be correlated to or encoded with an RSSI threshold associated to the sponge type and a minimum read strength for counting-in the surgical article to the surgical procedure, as described in greater detail below.

The identification scheme120may include information serving to identify the package of sponges, how many sponges are in a package and where a particular sponge falls within that quantity. For example, the identification scheme may include a unique package ID126and a sponge number128. Each package of sponges may be assigned a unique identification that will be shared by all members common to a single package. The unique package ID126may also be encoded such that certain values within the unique package ID serve to identify or designate the package as being of a particular type of surgical article. The unique package ID126may also be encoded such that certain values identify the quantity of sponges within the package. For each sponge10in a package, the sponge number128differentiates it from the other sponges in the package. For example, in a package of ten sponges10, there is one sponge with sponge number128of 1, one sponge with 2, and so on up to sponge number128of 10. Together, the unique package ID126and the sponge number128may represent package content information stored on the tag.

The identification scheme120may include a copy130of the read-only TID in the rewritable memory as a security measure to ensure that the written data has been uniquely assigned and not copied from a previous tag. The TID copy130, either alone, or in combination with other data stored on the tag may serve as a unique identifier to uniquely identify the sponge to which the tag is affixed. As a further potential security measure, or a way to ensure that the data has not been corrupted, in the identification scheme120is the checksum134. All or a portion of the data contained in the identification scheme on a tag120may be used as an input for a mathematical algorithm to generate a checksum value. The particular mathematical algorithm may be proprietary to the sponge manufacturer to ensure that its tags are uniquely identifying only first-party produced sponges, or sponges produced by an otherwise authorized party. A simple example of such an algorithm may be to sum all the values in the other data fields of the identification scheme120, divide the sum by a given constant, and use the remainder as the checksum value. Without knowing the particular constant used in the algorithm, unauthorized products may be detected by the system computer101as a step of the count-in process where the tag data is verified for authenticity.

The identification scheme120may include a provision to write to the tag in the course of the count-in or count-out process. For example, identification scheme120inFIG.3includes the count-out bit132which is a flag that is toggled after a sponge has been counted-out. This toggle may be accomplished, for example, by sending instructions from the RFID reader operating in a count-out mode instructing the tag to change the value of this data field upon being counted-out at a conclusion of a surgical procedure. This value may be particularly advantageous in an emergency situation where RFID-tagged sponges are used with a patient without completing the normal count-in procedure. The count-out bit132is a value toggled during the process and may be used by the system computer101in correctly managing the inventory of surgical articles during a surgical procedure.

The system100manages the inventory of surgical articles during a surgical procedure based on the information stored on the RFID tags of the surgical articles, such as surgical sponges10and RFID tags20. The system100may include a database of records storing information necessary to manage the inventory of surgical articles, specifically identifying the counted-in and counted-out status of surgical articles associated with particular surgical procedures. In particular, the system100may be configured to count-in the surgical articles at the beginning of a surgical procedure by scanning the articles with the RFID reader108, and to count-out the surgical articles at the end of the procedure. To overcome the challenges of variable package quantities and different types of surgical articles, e.g., different sizes of sponges in one package versus another, that may be used within a surgical procedure, the RFID reader108may be configured to operate with a dynamic power level based on a power level parameter stored on the tag or retrieved from a look-up table based on data stored on the tag.

More specifically, the system100may operate the RFID reader108first at a default power level. This default power level may represent a mid-range value within the full scope of capability of the RFID reader108. Alternatively, the default power level may be a high extreme or low extreme value depending on the desired first read result set. For example, in an environment with close proximity to storage, such as where the base106is mounted to an extension of inventory cabinet112, it may be desirable to set the default power level to a low extreme value of the RFID reader's108capability. In this way, the system100will not be overwhelmed with an over expansive result set. In an alternative, it may be desirable to set the default power level to a high extreme value of the RFID reader's108capability where the system100is disposed at a greater distance from an inventory storage location and from the sterile field where the surgical procedure will occur. Another consideration may be the amount of ambient electromagnetic noise in the environment that may interfere with the consistent communication between the RFID tags20and the RFID reader108.

The system100may evaluate the strength of the response signal received from a particular tag and assign an indicator reflective of the strength of the received response. In other words, the system100reports the power level of the tag's backscattered response signal in relation to the power level of the RFID reader's initial transmission signal. The response signal strength indicator or RSSI may be used to evaluate the quality of a particular tag's response within the reading zone of the RFID reader.

Operating the RFID reader108at the default power level, the system100receives in response output signals from the RFID tags20within the effective range of the RFID reader108. In one configuration, included within these signals are the unique identifiers, the power level parameters and the package content information for the surgical articles to which the RFID tags20are attached. The system100may select a first such response and reconfigure the RFID reader108to operate at the power level parameter of the first such response, which is different from the default power level. Once reconfigured, the system100operates the RFID reader108at the first power level to receive a first response set at the first power level. Within the first response set are the unique identifiers, the package content information and the power level parameters for all the RFID tags20responding to the RFID reader's108operation at the first power level. Comparing the first response set to the package content information from the first response selected in response to operating the RFID reader at the default power level, the system100is able to determine whether a complete first package is present to be checked-in to the surgical procedure or else to determine an error status. This sequence of steps may be repeated until all desired surgical articles have been counted-in for a particular surgical procedure.

In one alternative, for a particular RFID reader power, the system100may be configured to count-in only those tagged articles providing a strong enough response signal relative to the RSSI associated with the sponge type. For example, operating the RFID reader at a particular power level may yield a large number of responses representing nearby stored articles. Requiring a minimum RSSI for counting-in a surgical article helps to ensure that only those surgical articles specifically presented to the RFID reader for counting-in will be counted in and actually made available for the surgical procedure, and other nearby articles are not unintentionally included.

It may be important to check the completeness of the package during the check-in process to avoid confusion for the HCP and ensure that the proper and expected quantities and types of sponges are present for the surgical procedure. The system100, in comparing the first response set to the first package content information, is verifying that all of the expected surgical articles are actually present. For example, in selecting the first response and reconfiguring to the associated first power level parameter, the system100is configured to determine an error status if fewer than all the packaged contents are present when interrogated at the power level parameter designated for that sponge type. The power level parameter is specifically arranged for a particular sponge type depending on the packaging configuration—such as, how may sponges are in a packaging, as well as the size and thickness of materials that may interfere with the effective communication of the radio signals. Specifically, the power level parameter for a sponge type is selected in order to maintain a preferred read distance greater than a first distance D1and less than a second distance D2between the RFID reader108and the package of surgical articles being presented for counting-in. In a first example, the space defined between the first distance D1and the second distance D2constitutes the preferred read range the surgical articles at a distance from the reader to maintain their sterile condition, and otherwise to minimize the impact of any quantity of sponges stored in proximity to the system100, accounting for differences in packaging or manipulation by the HCP. In one example, the first preferred distance D1is about 12 inches and the second preferred distance D2is 36 inches measured from the RFID reader.

It should be appreciated that the read range of the RFID reader108begins at a zero distance away from the RFID reader108. A RFID tag placed immediately adjacent to the RFID reader108would be responsive to an interrogation at that distance and thus could be read by the RFID reader108. Differences in packaging density, i.e., how many articles are in a package, potential interference by the article materials, and how the article or package is held by the HCP, are all factors that may affect the response signal quality and thus read reliability. However, placing the surgical articles immediately adjacent to the RFID reader may compromise the sterility of the surgical article. Thus, it is preferable to establish a preferred read range far enough away from the RFID reader to maintain product sterility, but not so far away as to induce responses from surgical articles that are merely stored nearby.

These measurements are merely illustrative and are not intended to be limiting. In other examples, other distances are contemplated for the first and second distances to maintain sterility of the surgical articles and minimize the impact other environmental conditions. For example, the inventory of stored sponges is located at a greater distance D3than the max preferred read-in distance D2, and thus is intended to be outside the effective read range of the RFID reader108during the count-in process.

An exemplary table of sponge types (given, for example, in square dimensions and ply where applicable), the number of that type of sponge within a single package, and an associated power level parameter, corresponding to the effective power output at the antenna of the RFID reader108, is presented below.

Quantity inPower,Package typepackagedBm18 × 185148 × 3651412 × 125144 × 1851417 × 26 Towels5144 × 4-16ply10164 × 4-32ply10162 × 210258 × 361104 × 181108 × 1081102 × 361112 × 721118 × 4-12ply10188 × 4-16ply10188 × 4-24ply101818 × 36314

As detailed in the table, the range of power levels associated with the different packages ranges from 10 dBm to 25 dBm. The power unit dBm (otherwise expressed as dBmW) is a unit of level used to indicate a power ratio expressed in decibels (dB) with reference to one milliwatt (mW). The range of package quantities may be between 1 sponge and 10 sponges within a single package, although other quantities are contemplated within the scope of this disclosure. Assuming all else is constant, the more sponges in a package, the higher the associated power level parameter is for the associated sponge type. Packages with only 1 sponge have lower power level parameters. The size of the sponges in a package may affect the power level for the package in addition to considering the number of sponges in the package. For example, several packages are presented in the table above with a quantity of 1 per package, but those sponges with more material—that is, a larger size—are typically associated with a lower power level. In this way, the system100effectively manages the inventory of surgical articles during a surgical procedure, avoiding the inadvertent counting-in of nearby stored surgical articles.

It should also be noted that the table above provides illustrative examples of package types by the primary dimensions of the sponges in the package and the quantity of that type of sponge in a single package. This table is not intended to be limiting, and other sizes, quantities, or types of surgical articles are likewise contemplated by the present disclosure.

The power level associated with a particular package type may be determined empirically. For example, to determine a power level for a particular package type and quantity, an example package of that type and quantity may be scanned at a variety of power levels, in a variety of environmental conditions (i.e. in the presence of differing quantities and locations of articles stored in a relative proximity to the scanner), using a factorial design of experiments. The result sets across the different conditions may be evaluated and the result set that provides the highest confidence of reading all articles in the package while minimizing the impact of environmental noise on the successful read of the package contents. It is further contemplated that other methods of determining the preferred power level may also be employed.

In connection with managing the inventory of surgical articles, the system100includes the display102to communicate the status of the inventory of surgical articles to the HCP. Specifically, the system100may display information identifying the types of surgical articles that have been counted-in and the quantity thereof, as well as the quantity of surgical articles that have been counted-out once the article has been removed from the surgical procedure.

The system100may also be configured to alert the HCP on the determination of an error status, such as where fewer than all of the quantity of sponges within a package appear in a result set when the RFID reader is configured to operate at a power level parameter corresponding to that article type. The system100may display information about the error on the display102, such as identifying the type of sponge presented, the number counted as present, the number expected within the package, and the discrepancy between the two. The system100may, in the alternative or in addition, accompany this alert display with audible alarms, visual alerts such as flashing lights. The system100may also activate a tactile response, for example, within the mobile RFID reader108if the reader108is undocked from the base106. The tactile response may include a vibration pulse or pattern of pulses.

In an alternative, the bundle30may comprise a master tag32that may include unique identification information. For example, the master tag32may include the number of surgical sponges10included in the bundle30, as well as include the unique identification information for each of the sponges10contained in the bundle30. The master tag32may include a unique identification of the package in addition to the unique identifications of the sponges within the bundle30.

The master tag32may be configured to identify the side of bundle30or package/object that should be scanned based on the position of the RFID tags20. For example, the master tag32or the packaging38may include an indicator40to facilitate such placement/orientation, such as an arrow pointing to the side of the bundle30that should be scanned for optimal accuracy. Alternatively, an indicator40could be placed on the side of the bundle that should be placed closest to the scanner. The indicator40may be placed on one or multiple sides of the bundle of sponges30. The indicator40may be placed on any side/face of the bundle.

A container50configured to hold an individual sponge, a plurality of sponges, a bundle30or plurality of bundles30and may comprise a similar master tag52configured to identify the contents of the container50. For example, the container master tag52may identify the contents of the container50, such as the number of sponges, or number of bundles30included in the container50, as well as any additional equipment or medical instruments included in the container50. A container50configured to hold a bundle of surgical sponges30may comprise a similar indicator configured to identify optimal scanning orientation/position/movement as described above with regard to indicator40. A master tag32,52may be provided associated with a bundle30or container50and may provide human readable, or machine-readable information, for example, an RFID tag, bar code, QR code or the like. The master tag32,52may provide additional information or identical information as provided on the article tags, such as RFID tag20. The master tag32,52may be useful in performing additional verifications prior to using the articles in a surgical operation.

A first method400of managing an inventory of surgical articles used during a surgical procedure is illustrated. The surgical articles may be surgical sponges10, as described above. Implementing the described method400assists HCPs in ensuring the proper removal of surgical articles following the surgical procedure. The method includes a first step402of providing an inventory of surgical articles, such as surgical sponges. The inventory may be stored in a container, such as the mobile cabinet112shown inFIG.2. The inventory includes the packages of surgical articles. In a first example, the inventory includes at least a first package containing at least a first surgical sponge of a first sponge type. The first surgical sponge includes a first RFID tag storing a first unique identifier associated with the sponge, first package content information, and a first power level parameter associated with the first sponge type. The first package content information corresponds to a complete content of the first package. The use of designations of “first,” or “second” refer only to separate iterations of the count-in method steps and are not intended to be limiting or to require that “first” is different from “second” except where specifically denoted.

As described above, the package may include more than a single article, such as quantities of 2, 3, 5, 10, 20 or more within a single package. The unique identifier may be a single memory data field of an identification scheme stored on the RFID tag or may combine entries of multiple data fields to constitute a single unique identifier. The package content information includes such information necessary to identify the unique package and the content of the package, such as quantity. In one example, the package content information relates to the unique package ID126of the identification scheme120, and may include sponge type ID124, to retrieve the complete package quantity, and the sponge number128identifying which position in the package a particular sponge occupies among the complete quantity.

The method includes a second step404of operating an RFID reader at a default power level. The step of operating the RFID reader refers to activating the emission of radio energy to elicit a response for the RFID tags within a range of the RFID reader. To initiate this step, an HCP may provide an input to the RFID reader either directly or through some other connected piece of hardware. The default power level denotes a power level setting of the reader which is not necessarily associated with a particular sponge type. For example, the default power level may represent a midrange of the capability of the RFID reader. Alternatively, the default power level may represent a midrange of the power level parameters associated with the different sponge types which the RFID reader is adapted to read. In one example, a default power level parameter may be 15 dBm. In other alternatives, the default power level may be selected to be one of a maximum or minimum extreme of a capable range of the RFID reader depending on the particular environment in which the RFID reader will be operated, or other considerations as described above.

The method includes the step406of receiving, at the RFID reader, a response or responses to operating the RFID reader at the default power level. This step may include the HCP specifically presenting a package of RFID-tagged surgical articles to the RFID reader, or vice versa, positioning them so that the RFID reader is within an effective read range of the RFID reader. The preferred read range may be between 12 inches and 36 inches. The response to step404may include one or more tag data. For example, in an environment where multiple RFID tags are present, the RFID reader may employ anti-collision features or read, collect, and process multiple tag's data in one read operation. For example, such anti-collision features are described in the industry standard ISO/IEC 15693-3:2009—Anticollision and Transmission Protocol. The RFID reader is in communication with or incorporates a computer processing device to execute the operations of the method. Information may be retained in a database stored on a memory of the RFID reader, of another computer processing device, or may be distributed among multiple computer processing devices. The description of any processing or computing step may be performed by the RFID reader, or another device which is in communication with the RFID reader.

Among the response data received, a first tag's data is used for continuing the steps of the method400, the first tag's data including a first unique identifier, the first power level parameter stored in the first RFID tag, and the first package content information for the first tag. The data upon which to continue the method400from this step406, may be the first complete data received in the response time. Alternatively, the response of step406may prioritize the use of some types of sponges over other types of sponges or may use other criteria to designate or select a particular sponge to proceed with the steps of the method400in order. In one example, the response data received at the default power level may be evaluated to determine whether multiple sponges from a single package are present in the response set. If a minimum percentage of sponges from a single package are present in the response data, the first tag for continuing the steps of the method400may be selected from the package having at least the minimum percentage present in the response set. The minimum percentage may be between about 25% to about 50% of the sponges in a complete package. The minimum percentage may be at least 30% of the sponges in a complete package.

Based on the first RFID tag data, the method400includes the step408of reconfiguring the RFID reader to operate according to the first power level parameter, which corresponds to the first sponge type; and the step410of operating the RFID reader at the first power level. This operation constitutes a second interrogation by the RFID reader, but at a different power level from the default power level. The first power level may be higher or lower than the default power level, and this may return more or fewer responsive tags. Where the first power level is higher than the default power level, such as with a sponge type more densely packed with multiple sponges in a single package, more responsive tags may be found as the higher-powered interrogation overcomes the interference caused by the close proximity of the multiple tags. Where the first power level is lower than the default power level, such as with a sponge type packaged singly to a package, fewer responsive tags may be found as the effective read range will be diminished to a closer range. Thus, the method400includes step412of receiving a first response set at the first power level.

During the step412of receiving the first response set at the first power level, the system may be configured to selectively look for a single sponge type, corresponding to the first sponge type. Any response to the interrogation at the first power level that does not match the first sponge type may be automatically excluded from the first response set to reduce the volume of data to be processed.

The method400then includes the step414of comparing the first response set, in response to operating the RFID reader at the first power level and different from the default power level, to the first package content information to determine an error status. Within the first response set are the unique identifications of all the tags present within the effective read range of the RFID reader at the first power level. Based on the response to step404of operating the RFID reader at the default level and receiving the first package content information, a comparison can be made to the first response set—the response from operating the RFID reader at the first power level.

In a situation where the package is complete—that is, no error is present—the first response set will properly contain the identification of all the sponges indicated by the first package content information. Where the first package content information is that of multiple sponges in a single package, this is an important verification that all of the expected articles are actually present so as to minimize errors or confusion for the HCP in managing the use of surgical articles during the surgical procedure and avoiding the undesirable retention of surgical articles within the patient following the surgical procedure. In this case, the complete package of surgical articles may be counted-in to the surgical procedure at step416and the articles may be placed in the appropriate staging area to be at hand for the HCP in the surgical procedure. The above steps, beginning with step404operating the RFID reader at the default power, may be repeated along branch417until the desired inventory of surgical articles has been counted-in and made available for the surgical procedure. As the RFID executes the steps described, different types of sponges may be encountered, having different package quantities and different associated power levels. The different power levels associated with the different package types maintains a preferred read range of between about 12 inches to about 36 inches between the RFID reader and the package of surgical sponge, regardless of sponge type.

Comparing the first response set with the first package content information may indicate that the package is not a complete package. Upon this determination at step418, the HCP may be alerted to the error. This step may be performed in a variety of ways. For example, a visual alert may be displayed to the HCP on a display in communication with the RFID reader. The visual alert may display specific information about the error, such as identifying the type of sponge presented, the number and identity of responding tags, the number expected within the package, and the discrepancy between the two. In the alternative, or in addition, the HCP may be alerted to an error determination with other visual alerts such as illuminated or flashing lights on a display or on the RFID reader. The HCP may be alerted to an error with an audible alarm, or a tactile response, for example within the RFID reader. The tactile response may include a vibration pulse or pattern of pulses.

Upon being alerted to the error condition, the HCP may remedy the error, if possible, or may discard the incomplete package of sponges and move on to other packages provided in the inventory, proceeding along branch419, and repeating the steps of method400beginning with operating the RFID scanner at a default power level and continuing until the desired inventory of surgical articles have been counted-in and made available for the surgical procedure.

Once the desired inventory of surgical articles has been counted-in, the HCP may proceed with the surgical procedure as step420. Upon completion of the surgical procedure, the surgical articles are removed from the patient at step422. Following removal from the patient, the surgical articles are counted-out, for example, by again reading the surgical articles with the RFID reader at step424. In the alternative, counting-out the surgical article may include optically scanning a label provided on the surgical article, or manually entering information so as to designate the surgical article as counted-out.

During the count-out step424, the RFID reader may operate at a default power level. Alternatively, the RFID reader may operate at a power level corresponding to a power level parameter of a sponge type counted-in to the procedure and not yet counted-out. Where multiple sponge types are counted-in, with the sponge types having different associated power level parameters, the RFID reader may operate by performing sequential interrogation operations while cycling operations at different power levels associated with the different sponge types. The RFID reader may receive response sets and register only those responses from sponges of the type corresponding to the power level of the particular interrogation cycle, while excluding any response of other types of sponges not associated with the power level of the particular interrogation cycle.

The method400also includes the step426of displaying the status of the surgical article inventory. Although illustrated at the conclusion of the method shown inFIG.4, it is contemplated that this step may be performed persistently throughout the method, indicating the types of sponges responding to the RFID reader interrogation steps406,412, and maintaining a current count of counted-in and counted-out surgical articles as the surgical procedure proceeds. For example, displaying the status of the article inventory may include displaying a specific count of counted-in and counted-out surgical articles for each type of surgical article present. This display of the inventory status provides direct and immediate accounting of the surgical articles present for the surgical procedure to minimize the burden on HCPs in tracking and counting the use of surgical articles and ensuring that no surgical articles are retained in the patient following the surgical procedure.

A second method500of managing an inventory of surgical articles used during a surgical procedure is illustrated inFIG.5. The surgical articles may be surgical sponges10, as described above. Implementing the described method500assists HCPs in ensuring the proper removal of surgical articles following the surgical procedure. It should be appreciated that any feature/step of any method and system described herein may be used with the other methods and systems described throughout.

The method500includes a first step502of providing an inventory of surgical articles, such as surgical sponges. The inventory may be stored in a container, such as the mobile cabinet112shown inFIG.2. The inventory includes the packages of surgical articles. In a first example, the inventory includes at least a first package containing at least a first surgical sponge of a first sponge type. The first surgical sponge includes a first RFID tag storing a first unique identifier associated with the sponge, first package content information, and a first power level parameter associated with the first sponge type. The first package content information corresponds to the complete content of the first package. The use of designations of “first,” or “second” refer only to separate iterations of the count-in method steps and are not intended to be limiting or to require that “first” is different from “second” except where specifically denoted.

As described above, the package may include more than a single article, such as quantities of 2, 3, 5, 10, 20 or more within a single package. The unique identifier may be a single memory data field of an identification scheme stored on the RFID tag or may combine entries of multiple data fields to constitute a single unique identifier. The package content information includes such information necessary to identify the unique package and the content of the package, such as quantity. In one example, the package content information relates to the unique package ID126of the identification scheme120, and may include sponge type ID124, to retrieve the complete package quantity, and the sponge number128identifying which position in the package a particular sponge occupies among the complete quantity.

The method500includes steps504of operating an RFID reader and506of receiving tag information in response to operating the RFID reader. To initiate this step, an HCP may provide an input to the RFID reader either directly or through some other connected piece of hardware. This step may include the HCP specifically presenting a package of RFID-tagged surgical articles to the RFID reader, or vice versa, positioning them so that the RFID reader is within an effective read range of the RFID reader. The preferred read range may be between 12 inches and 36 inches. The response to step504may include one or more tag data. For example, in an environment where multiple RFID tags are present, the RFID reader may employ anti-collision features or read, collect, and process multiple tag's data in one read operation. For example, such anti-collision features are described in the industry standard ISO/IEC 15693-3:2009—Anticollision and Transmission Protocol. The RFID reader is in communication with or incorporates a computer processing device to execute the operations of the method. Information may be retained in a database stored on a memory of the RFID reader, of another computer processing device, or may be distributed among multiple computer processing devices. The description of any processing or computing step may be performed by the RFID reader, or another device which is in communication with the RFID reader.

Among the response data received, a first tag's data is used for continuing the steps of the method500, the first tag's data includes a first unique identifier and information sufficient to identify a sponge type. The information identifying the sponge type may include or may be used to retrieve an associated RSSI count-in threshold for the particular sponge type. The data upon which to continue the method500from this step506may be the first complete data received in the response time. Alternatively, the response of step506may prioritize the use of some types of sponges over other types of sponges or may use other criteria to designate or select a particular sponge to proceed with the steps of the method500in order.

Based on the first RFID tag data, the method500includes the steps508of determining the RSSI for the first RFID tag response, and510of comparing the determined RSSI with the tag information, including the RSSI threshold associated with the sponge type. The RFID reader may determine the RSSI for the first RFID tag response or it may communicate the information related to the first RFID tag response to another computing device, such as a system computer, for processing the first RFID tag response and determining the RSSI. The RSSI is determined as a measure of the power of the response signal relative to the power of the interrogation signal prompting the response.

If the determined RSSI for a particular tag is at or above the RSSI threshold associated with the sponge type, the associated sponge is counted-in to the surgical procedure for use therewith at step512. It is contemplated that tag responses which do not meet or exceed the associated RSSI threshold for the associated surgical article type do not signify an error about which the HCP must be alerted. Rather, a low RSSI may simply signify a tag response as environmental noise for example, from surgical articles stored nearby, but not intended for use in the surgical procedure. The steps of operating the reader504, receiving tag information506, determining508and comparing510the RSSI values may be continued and repeated until the desired inventory of surgical articles have been checked into the surgical procedure, as shown along branch513.

The method500includes the step520of displaying the status of the article inventory. Although illustrated at the conclusion of the method shown inFIG.5, it is contemplated that this step may be performed persistently throughout the method, indicating the types of sponges responding to the RFID reader interrogation steps506, and maintaining a current count of counted-in and counted-out surgical articles as the surgical procedure proceeds. For example, displaying the status of the article inventory may include displaying a specific count of counted-in and counted-out surgical articles for each type of surgical article present. This display of the inventory status provides direct and immediate accounting of the surgical articles present for the surgical procedure to minimize the burden on HCPs in tracking and counting the use of surgical articles and ensuring that no surgical articles are retained in the patient following the surgical procedure.

If a particular package of surgical articles is presented by an HCP for counting-in but is not acknowledged by the system, such as by updating the displaying step to add the package quantity and type as counted-in, the HCP may attempt to adjust the positioning of the package relative to the RFID reader by moving it closer to the RFID reader or centering the package in front of the reader. The HCP may attempt to count-in the package by rotating the package to adjust its orientation relative to the RFID reader, or combinations of moving and rotating the package relative to the RFID reader. In some instances, the determined RSSI of a particular article may never achieve the threshold RSSI associated with the article type. The HCP may discard the article as defective in this case. Failure to achieve a sufficiently strong responsive signal at a count-in phase may indicate that the article will fail to provide a responsive signal during a count-out phase, potentially leading to confusion in the HCP attempting to manage and account for the article inventory at the conclusion of the surgical procedure.

Once the desired inventory of surgical articles has been counted-in, the HCP may proceed with the surgical procedure as step514. Upon completion of the surgical procedure, the surgical articles are removed from the patient at step516. Following removal from the patient, the surgical articles are counted-out, for example, by again reading the surgical articles with the RFID reader at step518. In the alternative, counting-out the surgical article may include optically scanning a label provided on the surgical article, or manually entering information so as to designate the surgical article as counted-out.

During the count-out step518, the RFID reader may operate at a default power level and count-out sponges when a response to the interrogation signal is received and the sponges has been previously counted-in to the procedure. Alternatively, the RFID reader may operate by varying the power level for successive interrogation cycles according to the power level parameters associated with the sponge types counted-in to the procedure. In a further alternative, the RFID reader may combine the technique of variable power levels described above in step424, with an evaluation of the RSSI for a particular sponge to ensure that the proper sponge is being counted-out. In order to achieve the requisite RSSI during the count-out process, the sponge may be presented within a range of the RFID reader so that sponges remaining in the surgical field are not inadvertently counted-out.

Consistent with the above description, the method500includes displaying the status of the article inventory520, including, for example, providing an identification of counted-in and counted-out articles throughout the surgical procedure.

A further method600of managing an inventory of surgical sponges used during a surgical procedure is illustrated inFIG.6. Similar to the above methods400,500, the surgical articles may be surgical sponges10, as described above and the method may serve to assist HCPs in ensuring the proper removal of surgical sponges following the surgical procedure. Again, as in the above methods400,500, the method600includes a first step602of providing an inventory of surgical articles, such as surgical sponges. The inventory may be stored in a container, such as the mobile cabinet112shown inFIG.2. The inventory includes the packages of surgical articles. In a first example, the inventory includes at least a first package containing at least a first surgical sponge of a first sponge type. The first surgical sponge includes a first RFID tag storing a first unique identifier associated with the sponge, first package content information, and a first power level parameter associated with the first sponge type. The first package content information corresponds to a complete content of the first package. The use of designations of “first,” or “second” refer only to separate iterations of the count-in method steps and are not intended to be limiting or to require that “first” is different from “second” except where specifically denoted.

As described above, the package may include more than a single article, such as quantities of 2, 3, 5, 10, 20 or more within a single package. The unique identifier may be a single memory data field of an identification scheme stored on the RFID tag or may combine entries of multiple data fields to constitute a single unique identifier. The package content information includes such information necessary to identify the unique package and the content of the package, such as quantity. In one example, the package content information relates to the unique package ID126of the identification scheme120, and may include sponge type ID124, to retrieve the complete package quantity, and the sponge number128identifying which position in the package a particular sponge occupies among the complete quantity.

The method600includes steps604of operating an RFID reader and606of receiving tag information in response to operating the RFID reader604. The step604of operating the RFID reader includes operating the RFID reader at an initial power level for a first period of time. During this step604, the RFID reader collects a first response set during the first limited period of time. Based on the initial power level, the first response set is evaluated to determine whether a complete first package is present in the response set—that is, based on the collected tag responses, and the package content information of the tag responses, whether every article of a complete package is present in the response set as having responded to the RFID reader operating at the initial power level for the first period of time. Upon determining a complete package is present in the response set, the method600optionally includes a step of evaluating whether the complete package is of a type having an associated power level that matches the initial power level of the RFID reader in step604.

Upon determining that the complete package is present, and the complete package is of a type having an associated power level matching the initial power level, the articles within the complete package are counted-in to the surgical procedure at step610. It may occur that a complete package is found but that the articles are not of a type having an associated power level that matches the initial power level and, in that case, the articles are not counted-in to the surgical procedure.

Once the articles are counted-in after the initial operation of the RFID reader at an initial power level for the first period of time, the RFID reader may be reconfigured, at step612, to operate at an incremented power level, different from the initial power level. The method may begin with the RFID reader at a low power level and increment to a higher power level, or alternatively may begin with the RFID at a higher power level and increment to a lower power level. At higher power level, it may be more likely that background tag responses from nearby stored articles may be received at the RFID reader. At lower power levels, fewer tag responses may be received from densely packed surgical articles as the tags in close proximity to each other cause interference or attenuation of the RFID reader's interrogator signal. Therefore, it is beneficial to cycle through the range of power levels within the capability of the RFID reader to ensure that the proper set of RFID tagged articles are counted into the surgical procedure.

The steps of operating the RFID reader at incrementing power levels, receiving response sets, and counting-in packages when they are determined complete and are of a type having an associated power level matching the power level of the cycled operation may be continued, along branch613, until the desired RFID tagged article inventory is counted into the procedure. Once the desired inventory of surgical articles has been counted-in to the surgical procedure, the HCP may proceed with the surgical procedure as step614. Upon completion of the surgical procedure, the surgical articles are removed from the patient at step616. Following removal from the patient, the surgical articles are counted-out, for example, by again reading the surgical articles with the RFID reader, at step618. In the count-out step618the RFID reader may operate at a default power level. In an alternative, the count-out step618may be similar to the count-out step424, or step518, both described above. In an alternative, counting-out the surgical article may include optically scanning a label provided on the surgical article, or manually entering information so as to designate the surgical article as counted-out. Consistent with the above description, the method600includes displaying the status of the article inventory, including, for example, providing an identification of counted-in and counted-out articles throughout the surgical procedure.

In one execution example, an inventory of sponges is provided, such as an inventory112, at a step402. An RFID reader, such as RFID reader108, is provided and is toggled to operate in a count-in mode by providing an input at touchscreen104or the RFID reader108. The RFID reader108is configured to initially operate at a default power level value of 15 dBm, which is stored in one of the system computer101or the RFID reader108. The RFID reader108performs an interrogation cycle, such as at step404, and receives the first response set of interrogation responses from a portion of the inventory presented to the RFID reader for counting-in. The system100, either in the system computer101or the RFID reader108, evaluates the first response set in order to identify at least 30% of sponges within a single package, such as at step406. The RFID reader108determines two 18″×18″ lap sponges are present in the first response set having the same unique package ID126.

The RFID reader108reconfigures to operate at 14 dBm, such as at step408, which is the power level parameter associated with the 18″×18″ lap sponge type. The power level parameter is retrieved from a look-up table or database stored in the system computer101or the RFID reader108. The RFID reader108performs an interrogation cycle at 14 dBm, such as at step410. The RFID reader108receives the second response set, such as at step412. The second response set includes response data from five 18″×18″ lap sponges having the same Unique Pack ID126, which represents a complete package. Optionally, the system may exclude any data in the second response set that does not correspond to the 18″×18″ lap sponge type. The system100determines the complete package, such as at step414, and counts-in the five 18″×18″ lap sponges for use in the surgical operation, such as at step416. The RFID reader108reconfigures to operate at the default power level and continues with the remainder of the inventory112until all necessary articles have been counted-in, such as at step417. The RFID reader108follows the same sequence of detecting at least three out of ten 2″×2″ gauge sponges in a package at the default power level, reconfiguring to operate at 25 dBm, and detecting ten out of ten sponges in a package at the 25 dBm power level to count-in a package of ten 2″×2″ gauze sponges. Once the remainder of the inventory112has been counted-in, the surgery is performed with the counted-in articles, such as at step420.

After the surgical operation has been completed, the counted-in articles are counted-out so that no articles are unintentionally retained in the patient following the procedure, such as at step424. The RFID reader108is toggled to operate in the count-out mode by providing an input at touchscreen104or the RFID reader108. The RFID reader108performs successive interrogation cycles at 14 dBm and 25 dBm in 300 ms intervals while looking for the counted-in 18″×18″ lap sponges and the 2″×2″ gauze sponges, respectively. The successive interrogations continue until all of one type of sponge is counted-out, after which successive interrogation cycles will occur only at the power level associated with the counted-in sponge type. Optionally, the system100may evaluate the RSSI associated with each sponge identified in the response set to ensure that a minimum response strength is present before the sponge is counted out.

Several descriptions have been discussed in the foregoing disclosure. However, the discussions herein are not intended to be exhaustive or limit any particular form. The terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations are possible in light of the above teachings and the disclosure may be practiced otherwise than as specifically described.