Abstract:
There is provided a method of channel leakage detection in a medical device having one or more channels and a housing having an internal volume surrounding at least a portion of the one or more channels, comprising the steps of (a) pressurizing one or more of the channels by introducing air or gas into the channel; and (b) detecting leakage by monitoring pressure increase in the internal volume of the housing.

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to channel leakage detection in connection with reprocessing or reprocessing systems for medical devices having one or more internal channels that need to be cleaned and/or disinfected after use. 
     BACKGROUND 
     Reprocessing and decontamination systems can be used to reprocess previously-used medical devices, such as endoscopes, for example, such that the devices can be used once again. A variety of reprocessing systems exist for reprocessing endoscopes. In general, such systems may include at least one rinsing basin, in which an endoscope that is to be cleaned and/or disinfected can be placed. The basin is commonly supported by a housing that supports a system of lines, pumps, and valves for the purpose of feeding a cleaning and/or disinfecting agent to an endoscope, which has been placed in a rinsing basin. Such devices also include a collection of lines, hoses, conduits, or pipes that are coupled to the pumps and corresponding ports in the endoscope by releasable connectors. Such connectors must achieve a fluid-tight seal while attached to the endoscope, yet be easily releasable at the conclusion of the process. 
     In various circumstances, an endoscope can include an elongate portion, or insertion tube, having a distal end which can be configured to be inserted into the body of a patient and, in addition, a plurality of channels extending through the elongate portion which can be configured to direct water, air, and/or any other suitable fluid into a patient cavity or site. An endoscope can further include a flexible feed hose or light-conductor casing having inlets and channels that may be in fluid communication with the channels in the elongate portion and, in addition, a control head section having one or more valves, and/or switches, configured to control the flow of fluid through the channels in the flexible feed hose and elongate portion. In various circumstances, an endoscope can include an outer housing, which can include an internal volume, wherein the channels of the flexible feed hose and elongate portion of the endoscope can pass through the internal volume. 
     During reprocessing, the endoscope is exposed to reprocessing fluids and ingress of reprocessing fluid into the internal volume of the housing from outside the endoscope housing, for example, from the rinsing basin of the reprocessing system, or from ingress of reprocessing fluids into the internal volume of the housing from the channels. Ingress of reprocessing fluids is undesirable since the internal volume of the housing may contain sensitive electronic equipment such as charge coupled device video and ultrasound transducers. Therefore, it is desirable to identify whether the housing and the channels of the endoscope have been compromised prior to exposure to reprocessing fluids that can potentially damage the sensitive electronic equipment residing in the internal volume of the housing, in order to protect the endoscope. 
     Previous reprocessing systems such as the system described in U.S. Pat. No. 6,986,736, which is incorporated herein by reference in its entirety, test the integrity of the housing to determine whether the housing is compromised by pressurizing the internal volume of the housing directly and monitoring whether pressure drops in the internal volume of the housing over a predetermined time interval. However, this method cannot distinguish if the pressure drop is a result of a leak that is occurring from a breach in a channel that would allow the pressurized fluid to escape from the housing into the channel. The invention disclosed herein provides a method for testing the integrity of the channels of an endoscope to determine whether one or more of the channels are compromised. 
     SUMMARY 
     In at least one embodiment, there is provided a method of channel leakage detection in a medical device having one or more channels and a housing having an internal volume surrounding at least a portion of the one or more channels, comprising the steps of (a) pressurizing one or more of the channels by introducing air or a gas into the channel at a sufficiently high flow rate; and (b) detecting leakage by monitoring pressure increase in the internal volume of the housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is an elevational depiction of an endoscope, showing various channels therein; and 
         FIGS. 2-3  are schematic representations of at least a portion of a reprocessing system that may be employed in connection with various embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , endoscope  21  can include a first channel  1  which may extend, for example, through at least a portion of control head section  23  and elongate portion  25 , and to an outlet at distal end  34 . Endoscope  21  can also include additional channels  2 - 6  which can be configured to convey water or a gas or to receive a surgical instrument therein such that the surgical instrument can be guided into the site through the endoscope. In at least one embodiment, flexible feed hose or light-conductor casing can further include leak test connector  7  in fluid communication with an internal volume  13  inside outer housing  11  of the endoscope  21 . Leak test connector  7  can be configured to introduce a pressurized fluid and/or vacuum into the internal volume  13  of outer housing  11  in order to inspect the integrity of outer housing  11  for leaks. 
     After an endoscope has been used, it can be reprocessed such that it can be used once again. In various circumstances, a reprocessing system can be utilized to decontaminate the endoscope and/or evaluate whether the endoscope has been properly decontaminated. In at least one circumstance, water, sterilant, and/or any other reprocessing fluid, can be flushed through one or more of the channels of the endoscope and over the exterior of the housing to remove debris, and/or any other foreign matter, which may have entered into the channels or adhered to the exterior of the endoscope. 
     In various embodiments, referring to  FIG. 2 , reprocessing system  40  can include basin  14  which can be configured to receive at least a portion of an endoscope, for example endoscope  21 , therein and, tube  42  which can, in at least one embodiment, be configured to receive at least a portion of, or be in fluid communication with, elongate portion  25  of the endoscope  21 . In at least one embodiment, reprocessing system  40  can further include circulation pump  43 , which can be configured to circulate fluid from basin  14 , for example, through endoscope  21  and/or tube  42 , and into line  35 . In certain embodiments, pump  43  can also be configured to push the fluid through heater  45  and into line  46  such that the fluid can be circulated back into basin  14 , for example. In various embodiments, reprocessing system  40  can further include valve  51  which can be configured to divert at least a portion of the fluid flowing within line  35  through the channels of the endoscope  21 . More particularly, in at least one embodiment, reprocessing system  40  can include a number of flush lines  41 , which can be configured to receive fluid from line  35 , wherein each of the flush lines  41  can be placed in fluid communication with one of the channels of the endoscope  21 , i.e., channels  1 - 6 , for example, such that fluid, air, gas, etc. can flow therethrough. Each flush line  41  may be connected to an outlet of a channel pump  41   b . The pumps  41   b  are preferably peristaltic pumps or the like that, for example, pump fluid, such as liquid and air, through the flush lines  41  and any internal channels of the endoscope  21 . The channel pumps  41   b  either can draw liquid flowing within line  35  through valve  51 , or can draw decontaminated air from an air supply system  36  through a valve  52 . The air supply system  36  can include a pump  38  and a microbe removal air filter  37  that filters microbes from an incoming air stream. In various embodiments, each flush line  41  may be provided with a dedicated channel pump  41   b  to ensure adequate fluid pressure and to facilitate the individual monitoring of the fluid pressure in each flush line  41 . In at least one such embodiment, a sensor, such as sensor  39 , for example, can be in fluid communication with each flush line  41  for sensing excessive pressure in the flush line  41 . 
     To perform the channel leakage detection test of the present invention on, for example, channel  1  of the endoscope  21 , system  40  may be configured to monitor fluid communication between channel  1 , and the internal volume  13  of outer housing  11 . Detection of fluid communication can be indicative of fluid leakage from channel  1  into the internal volume  13  of outer housing  11 , which can indicate that channel  1  may be compromised. To monitor fluid communication between channel  1  and internal volume  13  of outer housing  11 , in one embodiment, system  40  may be configured to pressurize channel  1  by flowing air or any suitable gas, and monitor a change in pressure in the internal volume  13  of outer housing  11 . 
     In certain embodiments, referring to  FIG. 2 , to perform the channel leakage detection test on channel  1 , a flush line  41  may be coupled to channel  1  as described above. A microcontroller may cause valve  52  to open in order to allow for fluid communication between air pump  38  and the flush line  41 . The microcontroller may then cause air pump  38  to be activated. Air may flow from air pump  38  through valve  52 . As described above, each flush line  41  may include a separate pump  41   b  and a separate sensor  39  to accurately control and monitor pressure within each channel. In some embodiments, pump  41   b  can be a peristaltic pump or the like that pumps fluid, such as liquid and air. In this event, the microcontroller may cause the pump  41   b  associated with channel  1  to be activated in order to pressurize channel  1  to about 2 to 30 psig, and even as low as about 3 to 5 psig. As pressure is maintained in channel  1 , the microcontroller may obtain several readings from a pressure sensor which measures pressure in the internal volume  13  of outer housing  11 . An increase in pressure of the internal volume  13  of outer housing  11 , beyond a predetermined baseline value, such as an increase of about 0.05 to 0.5 psig, preferably about 0.1 to 0.3, or about 0.2 psig or more within a period of 1 minute or longer if the channels are pressurized to lower pressures, may prompt the microcontroller to stop the test and report a failure in the integrity of channel  1 . If no change, or a change below the predetermined baseline value, is detected, the microcontroller may report a successful completion of the channel leak detection test by channel  1 . The channel leak detection test may be repeated for each of the channels of endoscope  21 . An increase in the pressure of internal volume  13  as a result of pressurizing channel  1  can indicate fluid communication between channel  1  and outer housing  11 , which can indicate a compromise in channel  1 . 
     As outlined above, reprocessing system  40  may sequentially test each of the channels  1 - 6  of endoscope  21  and determine separately whether each of the channels  1 - 6  is compromised. In an alternative embodiment, reprocessing system  40  may test all or some of the channels  1 - 6  simultaneously. For example, all of the channels  1 - 6  of the endoscope  21  can be pressurized simultaneously and the internal volume  13  of outer housing  11  can be monitored for a change in pressure, as described above. If no change, or a change below the predetermined baseline value, is detected, reprocessing system  40  may report a successful completion of the channel leak detection test by channel  1 - 6 . If a change in pressure, beyond the predetermined baseline value, is detected, reprocessing system  40  may report that at least one of the channels  1 - 6  of endoscope  21  is compromised. 
     In various embodiments, the channel leakage detection test, outlined above, can be performed before, during, and/or after reprocessing of endoscope  21 . Performing the channel leakage detection test, for example, prior to the introduction of reprocessing fluids, such as decontamination liquids, into the channels  1 - 6  of endoscope  21 , may mitigate the possibility of contaminating the internal volume  13  of outer housing  11  with reprocessing fluids during the reprocessing procedure. 
     Referring to  FIGS. 1 and 3 , the integrity of outer housing  11  is preferably tested according to the method described in U.S. Pat. No. 6,986,736 before the channel leakage detection test of the present invention, wherein conduit  112  can be coupled to leak test connector  7  of outer housing  11  to allow fluid communication between air pump  110  and the internal volume  13  of outer housing  11  when valve  53  is in the open position. While air is a suitable pressurization medium, other gases could be used. To begin the test, valve  53  may be turned into an open position, and air pump  110  can be activated to pump air through conduit  112  and into outer housing  11  to pressurize the internal volume  13  of outer housing  11 , which may initially be at ambient pressure. Upon reaching a desired pressure, for example about 2 to 5 psig, the valve  53  may be closed, and air pump  110  deactivated. A pressure sensor  116  may look for a change in pressure in the internal volume  13  of outer housing  11 , which could indicate a compromise in the integrity of outer housing  11 . In at least one embodiment, pressure sensor  116  may look for a decrease in pressure in internal volume  13  of outer housing  11 . A decrease in pressure, beyond a predetermined acceptable range, for example a decrease in pressure of about 0.05 to 0.5, preferably about 0.1 to 0.3 psig within a period of 1 minute, may indicate the escape of air through outer housing  11 , which may indicate a compromise in the integrity of outer housing  11 . Alternatively, instead of pressurizing the internal volume of the outer housing, a vacuum may be created in the internal volume, and the pressure sensor could look for an increase in pressure in the internal volume of the outer housing, which may indicate a compromise in the integrity of the outer housing. A control system which may have a microcontroller may be configured to be in communication with air pump  110 , valve  53  and pressure sensor  116  to manage the testing of outer housing  11  as outlined above. If outer housing  11  of endoscope  21  fails the test, the control system may report a test failure. Alternatively, if outer housing  11  of endoscope  21  passes the test, the microcontroller may cause valve  54  to open in order to vent the conduit  112  and return outer housing  11  to ambient pressure prior to conducting the channel leakage detection test of the present invention. 
     Referring again to  FIG. 3 , system  40  may include a valve  54 , which may selectively vent the conduit  112 , and the housing  11  through an optional filter  118  when the testing procedure is complete. System  40  may also include an air buffer  120  to smooth out pulsation of pressure from the air pump  110 . A HEPA or other microbe-removing filter  113  may remove microbes from the pressurizing air; and an overpressure switch or relief valve  114  may prevent accidental over pressurization of outer housing  11  of endoscope  21  during testing. 
     The embodiments described herein are therefore to be regarded as illustrative rather than restrictive. Variations and changes may be made by others without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such equivalents, variations and changes which fall within the spirit and scope of the present invention as defined in the claims be embraced thereby.