Abstract:
Apparatus and method for detecting connectivity in a channel in an endoscope undergoing reprocessing using an automatic reprocessor, the apparatus including a source of pressurized fluid which may be a gas alone or gas and liquid and a back pressure detector connected to the channel or channels of interest in the endoscope, the method including providing a source of pressurized fluid, directing the pressurized fluid to a channel in an endoscope, monitoring the time for the back pressure in the pressurized fluid to decay to a predetermined level; and determining whether the channel is connected and open or disconnected by comparing the decay time of the actual back pressure to one or more predetermined values corresponding to the specific channel or channels and model of endoscope undergoing reprocessing.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to the field of reprocessors for devices, particularly medical devices, and more particularly to endoscopes and the like having one or more internal passageways which are to be cleaned and disinfected by an automatic reprocessor. Reprocessing includes washing, disinfecting and drying such devices. As used herein, the terms “endoscope” and “endoscopes” refer not only to endoscopes, but also to similar devices (including accessories) which may suitably be reprocessed using an Automatic Endoscope Reprocessor, or AER. 
     In the past, AERs typically relied upon the human operator to properly connect and inspect the connections between the endoscope and the AER. 
     In the prior art, it was known to pressurize the sheath of an endoscope to test for leaks. In that type of test, if any leakage was measured, the endoscope under test was required to be serviced, since such testing was directed to a closed system in which it was expected and desired to have no leakage. However, with the present invention, testing for connectivity of channels in the endoscope must take leakage into account, since the distal end of the endoscope characteristically has one or more channel openings which will inherently (and properly) leak when the channel or channels are subjected to pressurized fluid. As such, conventional leak testing techniques of the prior art are not suitable for connectivity testing according to the present invention. 
     Endoscopes which are candidates for the present invention include various configurations for through passages or channels, small non-interconnected channels, large non-interconnected channels, interconnected passages having at least one small channel, and interconnected passages having only large channels. 
     SUMMARY OF THE INVENTION 
     The present invention surmounts shortcomings of the prior art by providing apparatus and method to automatically and efficiently detect whether a proper connection exits between the reprocessor and the endoscope or whether there are any missing connections (i.e., disconnection) between a specific channel in the endoscope and the AER. 
     In one aspect, the present invention utilizes a tank which may be pressurized with a suitable fluid (which may be a gas such as air in one or more embodiments), and discharged through an endoscope being reprocessed with a characteristic time to discharge monitored. In another embodiment, a charge or “slug” of liquid is either already present in or delivered to the endoscope and is thereafter combined with the gaseous fluid and discharged through an endoscope being reprocessed, with a characteristic time to discharge monitored. With either embodiment, the present invention determines whether the path or channel is disconnected or connected and open. 
     In another aspect, the fluid is used to detect connectivity and a pump may be used to deliver the fluid to respective paths in the endoscope, with the time monitored to determine when (and if) the pressure drops to a predetermined pressure level, and if the pressure does so drop, a comparison is made to characteristic times corresponding to the conditions in which the path or channel is disconnected or connected and open. 
     In still another aspect, a full shutoff connector may be used with large channels to “reverse” the logic for determining whether the large channel is disconnected, or connected to the reprocessor and open. 
     In yet another aspect, for configurations having at least some large interconnected channels, pressurized liquid is applied to one large channel, and back pressure is monitored in another large channel interconnected therewith to determine whether the respective channels monitored are disconnected or connected and open. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a very diagrammatic view in perspective of a prior art Automatic Endoscope Reprocessor useful in the practice of the present invention. 
         FIG. 2  is a plan view of a prior art rack with an endoscope therein suitable for use with the apparatus of  FIG. 1 . 
         FIG. 3  is simplified diagrammatic view of a certain prior art type of endoscope suitable for reprocessing in the practice of the present invention. 
         FIG. 4  is a simplified diagrammatic view of another prior art type of endoscope suitable for reprocessing in the practice of the present invention. 
         FIG. 5  is a very simplified set of connection paths between the reprocessor and various channel configurations to illustrate various applications of the present invention. 
         FIG. 6  is a simplified schematic flow path with a particular endoscope connected to a reprocessor in one embodiment of the present invention. 
         FIG. 7  is a key for  FIGS. 8 and 9 . 
         FIG. 8  is a first portion of an example hydraulic schematic for a reprocessor useful in the practice of the present invention. 
         FIG. 9  is a second portion of the schematic of  FIG. 8 . 
         FIG. 10  is a pressure versus time waveform illustrating certain aspects of the present invention. 
         FIG. 11  is simplified schematic flow path illustrating application of an alternative embodiment of the present invention to a non-interconnected large channel. 
         FIG. 12  is a pressure versus time waveform illustrating pressure decay characteristics of large and small channels in connection with the practice of the present invention. 
         FIG. 13  is a pressure versus time waveform illustrating further aspects of the alternative embodiment of the present invention. 
         FIG. 14  is a section view of a full shutoff channel connector useful in the practice of the present invention, shown in an open position and connected to an endoscope fitting. 
         FIG. 15  is a section view of the channel connector of  FIG. 14 , shown in a disconnected and closed position. 
         FIG. 16  is an exterior perspective view of the channel connector shown in  FIGS. 14 and 15 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     One example of a system for cleaning, disinfecting and/or drying endoscopes is shown in U.S. Pat. No. 6,641,781 B2, issued Nov. 4, 2003, and the entire contents thereof are hereby incorporated by reference. 
     Another example of a device and method for cleaning and/or disinfecting endoscopes is shown in U.S. Pat. No. 6,260,560 B1, issued Jul. 17, 2001, and the entire contents thereof are hereby incorporated by reference. 
     Still another example of a device and method for cleaning and/or disinfecting endoscopes is shown in European Patent Application EP 0 709 056 A1, published 01.05.1996, and the entire contents thereof are hereby incorporated by reference. 
     Referring now most particularly to  FIG. 1 , a disinfecting device or Automatic Endoscope Reprocessor (or AER)  30  may be seen. The disinfecting device  30  is provided with two trays or basins  31  and  32  in which a rack  34  is, with an endoscope  36  therein, can be accommodated. In  FIG. 1 , a rack of this nature is located in the left hand tray. Each of trays  31  and  32  are provided with a counter-connection block which, when a rack  34  is placed in the tray  31  or  32 , can be connected to the connection block  38  arranged in rack  34 . The counter-connection block arranged in the right hand tray or basin  31  can be seen in  FIG. 1  and is denoted by the reference numeral  40 . A lid  92  is shown in a partially open condition over right basin  32 . 
     Referring now also to  FIG. 2 , the rack  34  may be formed from bent rods  42  and  44  which are fixedly connected to one another. The rack  34  is provided with one or two handles  46 , by means of which the rack can be gripped and lifted up. The rack  34  is furthermore formed in such a manner that an endoscope  36  can be placed therein in a more or less folded state. In order to be able to fix in particular the fragile end  48  of the endoscope, the rack may be provided with a tip holder  50 . One example of a connection made between the reprocessor  30  and the endoscope  36  is illustrated by a biopsy channel connector  82 . 
     The connection block  38  is arranged fixedly in the rack. This connection block is provided with passages and ports  52  which can be connected to the passages of the endoscope  36  by means of flexible tubes  54 . On its underside (not visible in Figure.  2 ), the connection block  38  is provided with connection points for the connection of the counter-connection block in either basin  31  or  32  of device  30 . The connection block  38  is furthermore provided with a handle  56 . By moving the handle  56 , the connection block  38  can be connected to a counter-connection block or removed therefrom. 
     Referring now to  FIGS. 3 and 4 , examples of different types of endoscopes  36 ,  36 ′ to be reprocessed by the device  30  may be seen. Endoscope  36  is a first type of endoscope and endoscope  36 ′ is a second type of endoscope differing from the first type of endoscope  36  in that it is provided with an additional channel  58  with connection  60  and an additional channel  62  with connection  64 . In a head part  66 , the channel  62  is connected to an air channel  68  at a joining part  25 . A biopsy channel fitting  208  may be seen in  FIGS. 3 and 4  to which the connector  82  is attached in  FIG. 2 . 
     Referring to  FIG. 5 , very simplified views of channel configurations to be tested for connectivity may be seen. These include: a. configuration  81 , an independent small channel  74 , b. configuration  83  which shows an interconnected pathway with one or more large channels  76  and a small channel  74 , c. configuration  85  of an interconnected pathway with (only) three large channels  76 , and d. a pathway or configuration  87  with only an independent large channel  76 . It is to be understood that in configurations  81  and  83 , the small channel  74  in the endoscope has a distal end  78  open to atmosphere, and in configurations  85  and  87  the large channel  76  in the endoscope has a distal end  75  open to atmosphere. The dashed line  79  indicates the interface between the reprocessor  30  and the endoscope  36  under test and includes the connection made between the connection block  38  and the counter connection block  40  (see  FIG. 1 ), along with respective flexible tubes  54  (see  FIG. 2 ). In each of these arrangements, one or more valves  70  (which may be understood to correspond to valves  96  in  FIG. 6 , described infra) and one or more pressure sensors  72  (which may be understood to correspond to switches  98  in  FIG. 6 , described infra) are provided in the reprocessor side. Pressure sensors  72  preferably have an adjustable trip point preset to a predetermined pressure level, for example 2 psi. In the top diagram (configuration  81 ) in  FIG. 5 , it has been found preferable to have the feed line  77  be 3 mm in diameter when the diameter of the small channel is about 0.5 mm. 
     In configuration  81  or  83 , connectivity may be determined according to the first embodiment of the present invention wherein a pressurized gaseous fluid is delivered to the endoscope and the time of decay of pressure is monitored to determine the connectivity conditions of connected and open or disconnected. 
     In configuration  83  or  85 , it is also possible to measure connectivity in a second embodiment by filling all channels with liquid under pressure (using, for example, a pump supplying water continuously through feed line  77 ) and measuring back pressure in the other reprocessor channel  77 ′ (with the valve  70  in line  77 ′ closed) to determine whether the endoscope is connected or not. If back pressure exceeds a predetermined level, both reprocessor channels  77  and  77 ′ are connected to the endoscope channels  76 . If pressure is applied in channel  77  and back pressure is absent in channel  77 ′ (as indicated by pressure sensor  72  connected to channel  77 ′) the system will determine that a blockage exists in one or both of channels  77  and  77 ′ or that channel  77  or channel  77 ′ (or both) are disconnected, each of which conditions require that reprocessing be interrupted and the condition appropriately corrected. 
     In configurations  85  and  87 , it is also possible to measure connectivity using a liquid (preferably water) “slug” to test the channels, whether they are large interconnected channels (as in configuration  85 ) or a non-interconnected large channel (as in configuration  87 ). 
     Finally, with configuration  87  it is also possible to use a full shutoff connector (described infra with respect to  FIGS. 14-16 ) in an alternative embodiment of the present invention. 
     Referring now to  FIG. 6 , a less simplified schematic showing connections to a specific model of endoscope  36 ″ (similar to endoscopes  36  and  36 ′) for carrying out the present invention in one embodiment may be seen. Endoscope  36 ″ has a control head  80  including a biopsy fitting on which is received the connector  82 . Endoscope  36 ″ also has a channel separator  84  installed, the details of which may be seen in  FIGS. 3 and 4 . Endoscope  36 ″ also has a light head  86  with a water connector  88 , a suction connector  90 , a jet connector  93 , and an air connector  94 . This embodiment of the present invention uses a conventional connection block  38  to connect to the endoscope  36 .″ In the AER there are respective valves  96  (corresponding to valves  70  in  FIG. 5 ) and pressure switches  98  (corresponding to pressure sensors  72  in  FIG. 5 ). One valve  96  and switch  98  are associated (respectively) with each port  52  and line  54  that may be connected to the endoscope  36 .″ It is to be understood that more or fewer connections than those shown may be used in the practice of the present invention, depending on the complexity of the endoscope to be reprocessed. 
     In the embodiment shown in  FIG. 6 , the parts included within dashed line  100  have been added to carry out the first embodiment of the present invention. In the first embodiment, an air pump  101  provides air at line  102 . Air pump  101  may be a double action reciprocating pump. Alternatively, air may be supplied as system air from a source of pressurized air in the facility in which the AER is installed. Pressurized air at line  102  may be passed through a regulator  104  which may be used to maintain an operating air pressure, which in the embodiment shown is 1.7 bar. A CYLINDER FILL valve  106  may be selectively operated to charge an air cylinder  108 , which, in one embodiment may have a capacity of 0.89 liters. An air cylinder pressure switch  110  may be used to confirm that the air pressure in the cylinder is above a predetermined pressure, preferably 1.4 bar. An air filter  112  and a CHANNEL CONNECT VALVE  114  may be used to complete the connectivity system components in system  100 . Valve  114  may connect either water from a channel pump  116  or air from the air cylinder  108 , under the system control (not shown). 
     In operation with the first embodiment using a gaseous fluid such as air, a channel to be tested for connectivity is first purged of liquid, if necessary, and then the channel connect valve  114  is closed, and the air cylinder  108  is charged to a predetermined volume and pressure, after which the channel connect valve  114  is opened to admit air from the cylinder  108 , it being understood that the endoscope is in place in the rack  34  in the AER  30  with the connection block  38  in fluid communication with the counter connection block  40 . One of valves  96  is opened (either at the same time or after valve  114  is opened) and the time to discharge the particular channel in the endoscope  36 ″ is monitored by the pressure switch  98  associated with and in fluid communication with the valve  96  that is opened. When the pressure drops to a predetermined level, for example, 2 psi, the time to reach that level is recorded by the control, and a determination is made whether that channel of the endoscope  36 ″ is connected to its respective port  52  or whether the channel is disconnected from its port  52 . It is to be understood that the characteristic time to discharge for each channel is measured and stored in the control of the AER  30 . If the time to actually discharge through the channel is shorter than the characteristic time for that channel, the endoscope is disconnected and an error signal indicating CHANNEL DISCONNECTED is given to the operator. If the actual time to discharge through the channel is equal to the characteristic time for that channel (within empirically determined tolerances) the AER  30  determines that the channel is connected and open. 
     It is to be understood that in addition to configuration  81 , configuration  83  may also be tested using the above described embodiment in which case each of feed lines  77  and  77 ′ may be tested independently by shutting off one and testing the other, or by monitoring both pressure sensors  72  while supplying gaseous fluid to one line (e.g., line  77 ), while the other ( 77 ′ in this example) has its respective inlet valve  70  shut off. If both pressure sensors  72  reach the predetermined trip point pressure at about the characteristic time for this configuration, both channels are connected and open. If the time to reach the predetermined trip point pressure is less than the characteristic time, one or both channels are disconnected and an appropriate indication is given to the operator to check both channels  76  for connection to the reprocessor. 
     Referring now to  FIGS. 7 ,  8  and  9 , a hydraulic schematic for the practice of the present invention may be seen.  FIG. 7  is a key to illustrate the arrangement of  FIGS. 8 and 9 .  FIG. 8  is a schematic or circuit  130  for the left basin  31 , and  FIG. 9  is a schematic or circuit  132  for the right basin  32 . Lid  92  is shown schematically in  FIG. 9 . It is to be understood that both a soap reservoir  134  and a pair of disinfectant reservoirs  136  are shared by each circuit  130  and  132 . Circuits  130  and  132  also use a shared soap supply line  138 . Circuits  130  and  132  share a pair of disinfectant supply lines  142  and  143 . It may be also be seen that circuits  130  and  132  are joined at and share the following connections: a water source line  146 , a compressed air source line  148 , a lower pressure air line  150 , preferably supplying air at 0.25 bar, for example, and a higher pressure air line  152  preferably supplying air at 2.0 to 2.4 bar, for example. Circuits  130  and  132  may also share a common drain connection line  154  and a common alcohol supply line  145 . It is to be understood that the apparatus shown in  FIGS. 8 and 9  is preferably contained within the enclosure of device  30  shown in  FIG. 1 . 
       FIG. 10  illustrates more detail about the first embodiment of the present invention in which the system  100  of  FIG. 6  is used. Valve  114  is opened to air from cylinder  108  at a pressure of 20 psi at time t 1    120  and the incremental time from t 1    120  to t 2    122  is measured, by monitoring the appropriate switch  98 , set to trip at 2 psi. The actual time (t actual =t 2  −t 1 ) is compared to the previously recorded characteristic time t CHAR  to determine the connectivity condition of the channel under test. The solid line curve  124  illustrates the pressure decay for a connected and open (unblocked) channel, while dashed line  126  represents a disconnected channel, with switch  98  activating at time  127 . 
     The above described operation will be satisfactory with most small channels because there is a considerable difference between the connected and disconnected conditions. In addition some connectors used for certain small channels (for example the Lift channels and some Jet channels) have additional restriction which tends to decrease the separation between disconnected and connected conditions. 
     Referring now also to  FIG. 12 , a characteristic curve  220  for a large channel pressure decay may be seen in comparison to a corresponding characteristic curve for a small channel pressure decay, e.g., curve  124 . It is to be understood that curve  220  can be taken to represent both connected and disconnected conditions for a large independent channel, because large channels characteristically have low flow restriction and little difference between connected and disconnected conditions and thus do not have enough separation between connected and disconnected conditions to allow the technique of using a flow restriction threshold to be reliable. However, since there are only a small number of types of connectors required to connect to large channels, one approach can be to provide connectors which shut off fluid flow when disconnected. In this type of connector, flow is shut off when the channel is disconnected, and full, generally unrestricted, flow is permitted or enabled when the connector is coupled together and the channel is connected to the AER. A connector with full shutoff when the endoscope channel is disconnected allows a reversal of the logic conditions on whether disconnected or connected conditions restrict flow more. That is (for example) with a full shutoff connector, when the large channel is connected, there is no or little restriction to flow, but when the large channel is disconnected, the full shutoff connector will block flow, allowing detection of the disconnected condition for the large channel. 
     One manufacturer of shutoff connectors is the Colder Products Company, of 1001 Westgate Drive, St. Paul, Minn. 55114, which offers a PMC12 series of shutoff connectors. Another full shutoff connector  200  useful in the practice of one embodiment of the present invention is shown in  FIGS. 14 ,  15  and  16 . The connector  200  has a barbed hose cap  202  threaded on a body  204  which carries a seal and retainer member  206  (similar or identical to the biopsy connector  82  shown in  FIG. 2  received over the biopsy channel fitting  208 , shown in  FIGS. 3 and 4  and as an example endoscope fitting in  FIG. 14 ) formed of a resilient material that may be placed over a fitting  208  on an endoscope  36 . When the connector  200  is disconnected from the endoscope  36 , a spring  210  urges a seal  212  against a seat  211  in the body  204 , blocking flow with respect to the cap  202  and any hose or tubing connected thereto, which is understood to be connected to the reprocessor  30  in operation. When the connector  200  is connected to the endoscope  36 , endoscope fitting  208  urges plunger  214  against spring  210 , lifting seal  212  from seat  211  and opening the fluid flow path through the connector  200 . 
     Full shutoff connector  200  is useful with the configuration  87  for non-interconnected large channels. With that configuration, connector  200  has cap  202  connected to the connection block  38  via a flexible tube  54  and retainer member  206  is to be received over and sealed to an endoscope fitting  208 . 
     Using the connector  200  in the configuration  87  with a non-interconnected large channel, and practicing the present invention according to the first embodiment wherein a gaseous fluid is delivered via feed line  77 , a connected and open condition will be indicated by a rapid decay response of curve  220  as indicated in  FIG. 12 , while a disconnected condition will be indicated by no decay or a relatively slow decay as indicated by curve  226  in  FIG. 13 . 
     Using the connector  200  in the configuration  87  with the second embodiment of pumping water or another liquid into the channel  76  and measuring back pressure can be accomplished by charging the channel  76  with liquid, then closing valve  70  and monitoring for pressure decay. If there is a decay, the channel is connected and open; if there is no decay, the channel is either disconnected or blocked, and must be corrected before continuing reprocessing the endoscope. Alternatively, another pressure switch or sensor may be used on feed line  77  to monitor a stalled head condition for the pump which results in a higher than operating pressure condition. With this approach, normal operating pressure sensed as back pressure indicates a connected and open channel; higher than normal operating pressure indicates that the pump is driving into a closed channel, indicating disconnection or blockage. 
     The alternative embodiment of the present invention mentioned above which uses a liquid (preferably water) “slug” or charge in the channel under test in connection with the gaseous fluid decay sensor system is described here in more detail. This embodiment is useful with the large channel configurations  85  and  87 . 
     Referring now to  FIG. 11 , feed line  77  may be connected to a source of liquid, preferably water, through conduit  222  to fill the reprocessor feed line  77  and the endoscope large channel  76  to which it is connected (or supposed to be connected) with a liquid slug  218  after which air is delivered via conduit  224  via a directional valve  70 ′ through feed line  77  to large channel  76 . The characteristic curves will now appear as in  FIG. 13 , with sequence  228  representing a connected condition and sequence  230  representing a disconnected condition. If the channel  76  is disconnected from the reprocessor, the water will discharge according to sequence  230  and follow curve  220  at time t 3 , with the time from t 0  to t 3  representing the time to clear the water (or other liquid) slug  218  out from the feed line  77  (see e.g., configuration  87  in  FIG. 5 ). If the channel  76  is connected, the water slug will be discharged from distal end  75  at time t 4 , later than time t 3 . The incremental times between times t 0 , t 3 , t 4  and t 5  can be considered delay times and allow discrimination between the disconnected and connected conditions because of the differences in the mass of water propelled by the air pressure and length of channel through which the water is moved between disconnected and connected conditions. Time t 4  represents the time of a switch closure on switch  98  (corresponding to pressure sensor  72  in  FIG. 11 ) for a connected large channel  76 . In the event large channel  76  is disconnected, time t 3  will be monitored and recorded by the control system, indicating a disconnection between the reprocessor  30  and the endoscope  36  at this channel. Similar to the operation with respect to configuration  83 , this method may be used with large interconnected channels as in configuration  85 , in addition to being useful in the large non-interconnected channel configuration  87 . For configuration  85 , liquid is either already present in the feed lines  77  and  77 ′ or is purposely supplied, and is supplied to fill channels  76  out to the distal end  75 . Once the configuration is filled with liquid, feed line  77  is opened to admit air using an arrangement similar to that of conduits  222  and  224  and directional valve  70 ′ as shown in  FIG. 11 . Sensors  72  monitor the time for back pressure to drop to the predetermined level (e.g., 2 psi) and the system can discriminate between a disconnected condition (when sequence  230  occurs with curve  220  sensed at time t 3 ), or a connected and open condition (when sequence  228  occurs and curve  220  is sensed at time t 4 ). 
     This invention is not to be taken as limited to all of the details thereof as modifications and variations thereof may be made without departing from the spirit or scope of the invention.