There is frequently a need to ensure that pairs of tubes or pipes are reliably connected together, to prevent leakage of fluid flowing between them, and to ensure that a significant flow of liquid into the second tube. This can be of critical importance for example in washing operations, such as machines used to wash endoscopes.

Endoscopes are devices used in medical investigations to view the interior of the body. In the main, they consist of an external tube containing a series of inner tubes, which serve various functions. For instance, one may have a light at the end and an optical system or miniature video camera for transmitting an image to the eye. Other tubes however are used to transport liquids or gases and require thorough disinfection after use. Examples include gastroscopes and bronchoscopes.

The size of the tube is variable depending upon the intended use of the endoscope. For instance, they may be also be used in obtaining biopsy samples, in which case, they need to be of relatively wide bore in order to accommodate long forceps or the like.

After use, it is necessary to ensure that the endoscope tube is thoroughly washed and disinfected before it can be used again.

In order to achieve this, the tube is connected to a washing device, which pumps washing liquids or disinfectants through the tubes. These devices typically wash several tubes at any one time. Generally, the flow of liquid through the tubes is

monitored in order to ensure that there are no blockages, leaks or restrictions in the tubes, and also that the connection between each wash liquid supply tube and the endoscope tube is firmly in place.

This can be done using a pressure switch, located in the supply tube, which detects any changes in liquid pressure caused for example by blockages or by the disengagement of the tubes, which may occur when liquid under pressure is passed through them. Although these may work well, when the endoscope tube being irrigated is of relatively narrow bore compared to the wash liquid supply tube as any inadvertent disconnection will cause a significant reduction in pressure. However, with larger bore endoscope tubes, such as biopsy tubes, the change in pressure caused by inadvertent disconnection with the wash liquid supply tube will be much less and therefore it is very difficult to detect reliably.

According to the present invention, there is provided a detector system for identifying the engagement of a first tube in a second tube, said detector system comprising a connector fixable to an end of said first tube and insertable into said second tube, said connecter having an internal channel allowing liquid to flow from said first tube into said second tube when the connector is in place between the first and second tubes, said internal channel being shaped so as to create a backpressure of liquid flowing in said first tube, said internal channel being crossed by a transverse channel which opens to at least one side of the connector, sealing means arranged on either side of all openings of the transverse channel, and arranged to seal against the inner surface of the second tube when the first tube is fully engaged therein, and a sensor sensor arranged to detect a reduction in a flow of liquid passing from the first tube through the connector into the second tube; whereby liquid can flow out through the transverse channel when the connector is not engaged in the second tube, so as to reduce said flow of liquid.

This system provides a means for reliably and, if required, continuously monitoring the integrity of a connection between two tubes.

The sensor suitably comprises a pressure switch arranged to detect a reduction in the pressure of liquid flowing from the first tube through the connector into the second tube.

Alternatively, it may comprise a liquid flow sensor device, such as are known in the art. This may be arranged to measure the rate of flow of liquid passing from the first tube through the connector into the second tube. For example, it may be arranged to measure the flow of liquid in the second tube downstream of the connector.

Suitably the internal channel of the connector has at least two regions, a first region at the end which is fixable to the first tube, and which has a first cross sectional area, and a second region, arranged at the opposite end of the connector, which has a cross sectional area smaller than that of the first region. Suitably the first cross sectional area is similar in size to that of the bore of the second tube. When liquid flows from the first tube into the second tube through the connector, it will pass through the first and second regions of the internal channel. The relatively narrow bore of the second region will create a backpressure downstream of that region which will be felt in the liquid flowing in the first tube.

Suitably the transverse channel is arranged to cross the internal channel in the region where the first and second regions join. When liquid is flowing through the connector, it will fill the transverse channel, but provided the connector is in position, it will be prevented from leaking out by the sealing means surrounding the opening. Should the connector become disengaged from the second tube however, liquid will flow freely out of the second channel as well as the first.

By including a connector with a relatively small bore region as compared to the first tube, ensures that a liquid stream flowing through the first tube will be at relatively high pressure. Thus failure to engage the connector, or the inadvertent release of the connector, will allow liquid to flow through both the internal channel and the transverse channel will result in a significantly lower pressure, which can be readily detected by for example a pressure switch, arranged to detect the backpressure in the first tube. It will also reduce the amount of liquid flowing into the second tube and this may be detected using a liquid flow detector, located downstream of the connector.

Suitably the ratio of the cross sectional area of the first tube to the second region of the internal channel of the connector is in the range of from 1 to 2 or more, for example from 1 to 6. The transverse channel is preferably relatively large in cross sectional area compared to the second region of the internal channel, for example of a similar order to that of the first tube, to ensure that the pressure difference, when liquid is able to flow through this, is significant.

For example, the tubes used to supply wash, disinfectant or sterilising liquids in endoscope devices typically have a bore size of from 2 to 3mm in diameter. In such cases, the bore size in the second region in the internal channel in the connector is suitably 0.6 mm diameter.

The connector is suitably of a moulded plastics or stainless steel material.

It is suitably fixable to the end of the first tube by the provision of a conventional hose tail connection, which engages firmly in the first tube to be secure and provide a seal.

Suitable sealing means include O-rings, for example of rubber or resilient plastics material, provided around the outside of the connector, on either side of the opening or openings of the

transverse channel. Grooves may be provided in the outer surface of the connector to locate the O-rings.

The transverse channel and the associated sealing means are suitably arranged such that when the connector is inserted into an end of the second tube, they are close to that end. This will ensure that if the connector is only slightly displaced from the second tube, the sealing means will fail, allowing liquid to flow freely through the transverse channel, thereby causing a detectable change in liquid pressure.

Suitably the sensor such as the pressure switch is connected to an alarm or alerting mechanism, which can draw an operator's attention to the fact that a tube has become disengaged and/or stop the machine cycle.

Supplementary means for keeping the first and second tubes connected together are suitably provided. These may be of various constructions. However, in one embodiment, a first flange is provided on an end of the second tube, a second flange is provided on the connector, and a retaining collar arranged to engage the first and second flanges. Other embodiments may use screw threads, or teeth arranged to engage resilient materials incorporated for example in the retaining collar, as illustrated hereinafter.

Preferably sealing means, such as"O"rings of rubber or resilient plastics material are provided between the collar and at least one of the flanges. In addition, it may be preferable to provide holes within the retaining collars, to allow washing, disinfecting or sterilising liquids to be introduced into the end of the second tube, between use, to ensure that bacteria and other organisms are not harboured within the retaining collar or the surrounding region.

Connectors for use in the system of the invention form a further aspect of the invention.

A further aspect of the invention comprises a method of monitoring the integrity of a connection between a first and a second tube using a system as described above, the method comprising fixing a connector to a first tube, inserting the connector into the second tube such that the sealing means are in sealing contact with the inner surface of the tube, causing liquid to flow from the first tube to the second tube through the connector, and monitoring the flow of liquid into the second tube using the sensor, whereby a reduction in said flow indicates a loss of integrity of the connection. In particular, the sensor is a pressure switch, which measures the backpressure of liquid created in the first tube, as an indicator of the flow of liquid into the second tube.

Suitably the second tube is an endoscope tube, and the first tube is a wash, disinfectant and/or sterilising liquid supply tube of an endoscope washing machine. However, the invention can be used in any situation where a good connection between two tubes is required and it is desirable to monitor the connection is still in place during liquid flow.

The invention will now be particularly described by way of example with reference to the accompanying diagrammatic drawings in which Figure 1 which shows a section through a system of the invention, in position in an endoscope washing device; and Figures 2 to 5 are sections through different alternative embodiments of the system of the invention.

In the device of Figure 1, a flexible plastics tube (1) of an endoscope-washing device (not shown) is fixed to a connector (2) by engagement of a hose tail (3) on one end of the connector (2) into the inner surface of the bore of the tube (1). The connector (2) includes an internal channel with a first region (4A) and a relatively narrow second region (4B) extending through it.

Crossing this internal channel at the junction of the first region (4A) and the second region (4B) is a hole (5), which extends transversely through the connector (2). A pair of O- rings (6,7) is provided around the connector (2) in grooves (8,9) adjacent either side of the hole (5).

The other end of the connector (2) is inserted into an endoscope tube (10) such that the O-rings (6,7) form a watertight seal against the inner wall of the tube (10). The end of the tube (10) is provided with a flange (11). A further flange (12) is provided around the body of the connector (2) at a position just beyond the end of the tube (10). A retaining collar (13) is positioned such that it engages both the flange (11) and the flange (12), the former by way of an O-ring (14).

This should ensure that the tubes (1, 10) remain engaged together.

A series of wash holes (17) are provided spaced around the retaining collar (13).

A pressure switch (15) is provided such that it is responsive to the pressure of a flow of liquid in the tube (1).

In use, washing and disinfectant liquids are pumped through the tube (1) when the connector (2) is in place in the endoscope tube (10) in the direction of the arrow. The liquid is therefore forced through the first region of the internal channel (4A) and then through the second region (4B) in the connector (2). This will generate a backpressure downstream of the region (4B), which will be felt in the tube (1) and therefore registered by the pressure switch (15). Liquid passing through the channel region (4B) enters the endoscope tube (10) where it will flow through the length of the tube, and out to a drain, thus washing the inside of the tube (10).

It will also flow out through the hole in the connector (5) and will fill a gap (16) between the connector (2) and the tube (10). However, the O-rings (6,7) will prevent any further

leakage or liquid out though this route and thus, the pressure within the tube (1) will not be affected.

However, should the connector (2) begin to become disconnected from the tube (10), the O-ring (7) will move backwards in the direction of the flange (11) and the seal with the wall of the tube (11) will be broken. Liquid will then flow freely out through the hole (5) in the connector (2), and so the backpressure of liquid in the tube (1) will be substantially reduced, thus causing activation of the pressure switch (15).

This activation suitably activates an alarm or alerting device, which will preferably automatically cancel the machine cycle so that the problem with the connection can be rectified.

In this way, the integrity of the connection between the endoscope tube (10) and the wash tube (1) can be continuously and reliably monitored throughout a washing and disinfection or sterilising operation.

Similarly, if the connector (2) is inadvertently not positioned in the endoscope tube prior to an operation, (which is a possibility as generally multiple tubes are washed at the same time), the backpressure will not develop in the tube (1). This also can be registered by the pressure switch (15) and thus the operation halted, until all the tubes are properly connected.

The device of Figure 2 is configured slightly differently, in that the second tube (18) is formed in a larger structure, such as the sample biopsy port of an endoscope washing machine.

Furthermore in this embodiment, the internal channel 19 of the connector (2) comprises essentially four sections, each of different cross-sectional area. The widest section 19A, is arranged to be adjacent the flexible tube (1), the subsequent sections 19B and 19C are of progressively reduced cross- sectional area, whilst the final section 19D is expanded as compared to section 19C. The hole (5) in this case is arranged at the junction of section 19C and 19D. In this arrangement, a flow of liquid in the direction of the arrow results in a

backpressure of liquid, as it is force through the progressively narrower sections.

As before, O-ring seals (6,7) are arranged in grooves provided in the body of the connector (2) on either side of the hole (5), and are able to sealingly engage walls of the tube (18) when the connector is properly engaged.

In this embodiment, the connector (2) is held onto the biopsy port by means of a retaining collar (20), which engages an annular projection (27) around the entry to the tube (18). A further O-ring (22) seals the collar (20) to the projection (27).

The collar (20) also engages a flange (12) on the connector (2).

A channel (21) is provided through the collar (20).

In use, when the tube (1) is correctly attached to the tube (18) by the connector (2), liquid flows through the channel (19) and a backpressure is built up which can be monitored using a pressure switch located in the tube (1) (not shown).

However, if the connector (2) disengages from the tube (18), liquid is able to flow out through the hole (5) and also through the channel (21), causing a significant and measurable drop in the backpressure, which can be recorded using the pressure switch.

In the embodiment of Figure 3, with is illustrative of a sample suction port connection in an endoscope washing machine, a retaining collar (23) is provided with a lining (24) of a resilient material such as rubber or plastics. This collar (23) engages a flange (12) on the connector (2) in a manner similar to that described in the embodiments above. However in this case, it is fixed to the second tube (28) by engagement of the resilient lining (24) with a series of rearwardly extending

teeth (25), which project from the outer surface of the second tube (28).

As before, if this connection fails, liquid flowing in the direction of the arrow will exit through the hole (5) in the connector (2), causing a reduction in the backpressure and also a reduction in the flow of liquid downstream through the tube (28).

The embodiment of Figure 4 shows an alternative arrangement of retaining collar (29) which extends over the teeth (25), and engages with the rearward most set by way of a resilient seal (30). A channel (31) is provided though the collar to act as wash hole.

In Figure 5, the retaining collar (32) is provided with an internal screw thread (33), which is arranged to screw over an annular projection (34) surrounding the opening to the second tube (28). If the integrity of the connection is broken, the seal (7) will no longer prevent liquid exiting through the hole (5), and so the screw thread provides a further pathway for the liquid, resulting in a measurable change in the liquid flow.

Therefore the systems described provides continuous monitoring of the integrity of the connection between the tubes. This is particularly useful in for example endoscope cleaning machines, where several tubes are washed at the same time, and it is of vital importance that all the tubes are thoroughly cleaned, and so that wash liquid is reliably fed through all the tubes.