Method of and apparatus for testing and cleaning of endoscopes

In the program-controlled cleaning of endoscopes in a cleaning apparatus, the head parts are cleaned, rinsed, disinfected and rinsed clean in pressure chambers and, at the same time, the insertion tubes are cleaned, rinsed, disinfected and rinsed clean in pipes, attached to these pressure chambers, in a number of cleaning stages using cleaning liquid which is introduced via a circulation pump at a pressure of approximately 200 mbar. Prior to each of these cleaning stages, compressed air generated in the compressed air unit of the cleaning apparatus is introduced from there through the pressure test attachment of each endoscope, which pressure test attachment is connected by means of a pressure test adaptor to a compressed air attachment of the cleaning apparatus, until an internal pressure of 250 mbar is reached. If this pressure is not reached within 5 min or if the internal pressure of the endoscope drops by more than 30 mbar during a subsequent holding time of 30 sec, the circulation pump is not set in operation and the cleaning is discontinued. Otherwise, the internal pressure in the endoscope is kept at 250 mbar during the cleaning stage. The endoscope is tested in this way for leakproofness and is protected from penetration of cleaning liquid, even when a leak occurs during cleaning.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to a method for program-controlled testing and 
cleaning of endoscopes having a head pan with an attached insertion tube 
and a pressure test attachment, and to a cleaning apparatus for carrying 
out testing and cleaning. 
2. Description of the Related Art 
Endoscopes are used for examining the stomach or intestine and have a head 
part made of strong material, usually plastic, with an ocular and, 
usually, one or more attachments and buttons for triggering certain 
functions of the endoscope, as well as a flexible insertion tube which is 
attached to the head part and contains, protected by a tubular plastic 
sheath, a glass fibre bundle which connects a lens, arranged at the distal 
end, to the ocular, and a further light guide serving for illumination, 
and channels through which liquid can be drawn off by suction, water or 
air can be introduced and instruments can be inserted, for example for the 
removal of tissue samples. 
A supply part is usually connected to the head via a supply tube which 
likewise contains, protected by a plastic sheath, a number of channels 
which can be connected to the channels in the insertion tube, on which 
supply part the said channels and the light guide serving for illumination 
open into attachments for the supply of water, air and light and for the 
removal of liquid by suction. Head part, insertion tube, supply tube and 
supply part are surrounded by an envelope, which consists of the housings 
of the head part and supply part and the sheaths of the insertion tube and 
supply tube and which encloses a continuous inner space containing both 
the channels and light guide mentioned as well as the delicate ocular. 
Also arranged on the supply part is a pressure test attachment which forms 
a connection to the inside of the endoscope. 
The cleaning of endoscopes, which must be carried out very thoroughly for 
reasons of hygiene and must include disinfecting, is extremely involved 
and usually comprises a number of cleaning stages in which at least the 
insertion tube is exposed to a cleaning liquid under pressure. In a known 
method of the generic type (CH-A-675 064) the head part of the endoscope 
is therefore protected by a foam-filled housing, into the inside of which 
compressed air is fed. By this means, cleaning liquid cannot penetrate 
into the endoscope at the head part. However, if the insertion tube has a 
leak, and it is mainly the lower end thereof which is particularly 
susceptible to leaks, cleaning liquid can nevertheless penetrate into the 
inside of the endoscope and damage the ocular of the expensive instrument. 
One further disadvantage is that the head part is not cleaned. 
It is also known to pump the endoscope up, using a hand pump, via the 
pressure test attachment prior to cleaning and in this way to detect any 
leaks. However, this method is not very reliable, mainly because very 
small leaks are rarely detectable, and affords no certainty against leaks 
appearing or increasing in size during cleaning, which can easily happen, 
particularly since the endoscope usually needs to be treated with cleaning 
liquid at a relatively high temperature. In addition, the testing in this 
case is a separate procedure from the cleaning and is relatively 
time-consuming. 
A proven cleaning apparatus of the generic type, whose use nevertheless 
necessitates a leakproofness test prior to cleaning, is known from the 
brochure "Wasch- und Desinfektionsautomat fur Endoskope SME 2000" 
(Automatic washing and disinfection apparatus for endoscopes SME 2000) 
from the company Belimed AG, 5608 Stetten, Switzerland. 
SUMMARY OF THE INVENTION 
The object of the invention involves a method for the integrated testing 
and cleaning of endoscopes, in which method there is no risk of cleaning 
liquid penetrating into the inside of the endoscope even if very small, 
undetectable leaks are present and if leaks appear or increase in size in 
the course of the cleaning. A further object is to propose a suitable 
cleaning apparatus for carrying out the method. 
The invention provides a method in which the testing is carried out at the 
start and preferably before each cleaning stage, and the cleaning is 
discontinued if relatively large leaks are detected. The endoscope is 
additionally protected against the damaging effects of relatively small 
leaks, as can also occur during cleaning. Damage due to penetration of 
cleaning liquid can therefore be ruled out with a high degree of 
certainty. The testing is carried out together with the cleaning in a 
program-controlled manner. It requires rarely any additional expenditure 
in terms of time and no human intervention or attention. In the cleaning 
apparatus according to the invention, both steps can be performed 
automatically.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The cleaning apparatus has a cleaning chamber 1, in which two pressure 
chambers 2a, b made of stainless steel are incorporated, these consisting 
in each case of a lower part and of an upper part which can be swivelled 
open, and also a basket 3. Plastic pipes 4a, b of helical line 
configuration are attached to the pressure chambers 2a, b. Washing arms 
5a, b are suspended in a rotatable manner in the vicinity of the lid and 
the base of the cleaning chamber 1. Arranged on the back wall are two 
pressurized water attachments 6a, b, which are connected to the pressure 
chambers 2a, b via pipes 7a, b, and also, directly underneath the lid, 
compressed air attachments 8a, b. A control panel 9 is arranged alongside 
the opening of cleaning chamber 1 on the front of the cleaning apparatus. 
As can be seen from FIG. 2, the lower part of the cleaning chamber 1 is 
formed by a tank 10 which is connected via a circulation pump 11 to a 
collecting line 12, which supplies the washer arms 5a, b via a first 
branch 12a and supplies the compressed water attachments 6a, b via a 
second branch 12b. The tank 10 can be emptied by means of a suction pump 
13. It is additionally provided with a heating arrangement 14 and a 
temperature sensor 15, and also with a pressure sensor 16 for monitoring 
its degree of filling. A heater fan 17 is connected to the first branch 
12a of the collecting line 12. 
The cleaning apparatus is supplied with water via three attachments. One 
attachment for demineralized water 18 is connected via a first valve 19a 
directly to the cleaning chamber 1 and via a second valve 19b to a boiler 
20. A hot water attachment 21 is connected via a valve 22 and a 
decalcifier (ion exchanger) 23 likewise to the cleaning chamber 1, while a 
cold water attachment 24 is connected via a first valve 25a likewise to 
the decalcifier 23, via a second valve 25b to a regenerating salt storage 
unit 26, upstream of the decalcifier 23, and finally via a third valve 25c 
to a heat exchanger 27 which is arranged in the boiler 20. A line leads in 
each case through the boiler 20 and from the heat exchanger 27 via a valve 
28 and 29, respectively, into the cleaning chamber 1, a further line 
additionally leading via a valve 30 to an outlet 31. A storage unit 36 for 
a cleaner and a storage unit 37 for disinfectant are likewise connected to 
the cleaning chamber 1 in each case via a pump 32 and 33, respectively, 
and a flow rate indicator 34 and 35, respectively. 
The cleaning apparatus additionally has a compressed air unit 38 with a 
pump 39, which supplies the compressed air attachments 8a, b via two 
branches. The first branch has, downstream of the pump 39, a line 40a in 
which a throttle 41a and an admission valve 42a lie, and from which there 
branch a rapid venting valve 43a, a mechanical pressure relief valve 44a, 
with a response pressure of 500 mbar, a throttle outlet valve 45a and a 
compensating medium storage unit 46a for compensating for pressure 
variations. The second branch of the compressed air unit 38 is constructed 
in exactly the same way with a line 40b etc. 
The line 40a leads to a compressed air storage unit 47a which is connected 
to the compressed air attachment 8a and is monitored by a pressure sensor 
48a which controls the admission valve 41a and thus regulates the 
pressure. The line 40b is connected in an analogous manner to the 
compressed air attachment 8b via a compressed air storage unit 47b. 
The endoscope shown in FIG. 3 has a head part 49 with a strong plastic 
housing 50, which lies in the pressure chamber 2a, and an ocular 51, a 
delicate component, which must not come into contact with water or any 
other cleaning liquid, and also, in openings 52 and 53 respectively, an 
air/water valve and a suction valve which, however, are removed for 
cleaning the endoscope and are therefore not shown. Secured on the head 
part 49 is a flexible insertion tube 54 which lies in the pipe 4a and 
contains, surrounded by a plastic sheath 55, a glass fibre bundle 56 which 
connects a lens at the distal end of the insertion tube 54 to the ocular 
51, and also a water channel 57, an air channel 58 and a suction channel 
59. 
The water channel 57 and the air channel 58 open into the opening 52, from 
which continuations 57' and 58' of these channels emerge, these leading 
via a flexible supply tube 60, which is surrounded like the insertion tube 
54 by a plastic sheath 61, to a water attachment 62 and an air attachment 
63 on a supply part 64 with a strong plastic housing 65. The suction 
channel 59 and its continuation 59', which leads via the supply tube 60 to 
a suction attachment 66 on the supply part 64, similarly open into the 
opening 53. An optical fibre 67 runs from a light attachment 68 on the 
supply part 64 via the supply tube 60, the head part 49 and the insertion 
tube 54 as far as the distal end of the latter. On the head part 49 an 
attachment 69 branches off from the suction channel 59, through which 
attachment 69 various instruments can be led into the suction channel and 
through this to the distal end of the insertion tube 54. 
The plastic sheath 55 of the insertion tube 54, the plastic housing 50 of 
the head part, the plastic sheath 61 of the supply tube 60, and the 
plastic housing 65 of the supply part 64 enclose a continuous inner space 
of the endoscope which, as has already been mentioned, also contains the 
ocular 51 and other delicate components. For the leakproofness testing, 
therefore, a pressure test attachment 70 is provided on the plastic 
housing 65 of the supply part 64, with a check valve 71 which forms a 
connection to the inside of the endoscope. 
In order to clean an endoscope, the insertion tube 54 is introduced 
completely into the pipe 4a and the head part 49 is placed in the pressure 
chamber 2a. The supply tube 60, or more exactly an attachment piece for 
the latter on the head part 49, is passed outward in a sealed manner 
through a feed-through opening 72, which is sealed off by means of two 
rubber half-tings and consists of two semicircular recesses in the upper 
part and lower part of the pressure chamber 2a, and introduced into the 
basket 3. The pressure chamber 2a is then closed. The pressure test 
attachment 70 is connected in a sealed manner to the compressed air 
attachment 8a by means of a pressure test adaptor, a plastic tube, which 
is secured on it by means of an attachment piece. A second endoscope is 
introduced in the same way into the second pressure chamber 2b and is 
connected to the compressed air attachment 8b. The cleaning chamber 1 is 
then closed. 
At the start of cleaning, demineralized water is passed into the boiler 20 
via the attachment 18 and the valve 19b and is preheated to 85.degree. C. 
The endoscope is then tested for leakproofness and the first cleaning 
stage, the actual cleaning, is initiated. In this context, reference is 
made to FIGS. 4a and 4b where the degree of filling of the tank 10 is 
shown at the bottom and the internal pressure of the endoscope (continuous 
lines) and the pressure of the cleaning liquid in the pressure chamber 2a 
(broken lines) above are shown in all cases as functions of time. While 
hot water coming from the hot water attachment 21 via the valve 22 and the 
decalcifier 23 is passed into the tank 10, which lasts approximately 100 
sec, the pressure in the compressed air storage unit 47a and thus also in 
the endoscope is increased to a test pressure of 250 mbar by means of the 
pump 39 via the throttle 41a and the admission valve 42a. After a 
compensation time of approximately 5 sec, the air pressure in the 
compressed air storage unit 47a is established (first arrow in FIG. 4a). 
After a holding time of 30 sec, the measurement is repeated (second 
arrow). The same measurements are carried out in the compressed air 
chamber 47b, which has been brought at the same time to a pressure of 250 
mbar via the second branch of the compressed air unit. If the pressure 
measured at the end of the holding time in both compressed air storage 
units 47a, b lies by less than a limit value of 30 mbar below the value 
established at the start of the holding time, the endoscope is recorded as 
being sufficiently leakproof and, therefore, the test result is regarded 
as being positive, and the first cleaning stage is begun by switching on 
the circulation pump 11, while cleaner is metered in from the storage unit 
36 so that the pressure chambers 2a,b fill with cleaning liquid. The 
installation is designed in such a way that the pressure of the cleaning 
liquid lies at approximately 200 mbar. The internal pressure of the 
endoscope is in the meantime held at 250 mbar plus .+-.30 mbar by means of 
the pressure sensors 48a,b, which control the admission valves 42a,b. This 
pressure is tolerated satisfactorily by the endoscopes, whereas it would 
not be possible to exclude damage at pressures above 300 mbar. 
The cleaning liquid is now circulated for approximately 10 minutes. It 
penetrates in each case into the openings 52, 53 of the endoscope and 
flushes through the water channel 57, the air channel 58 and the suction 
channel 59 and emerges at their distal ends and is passed back via the 
open end of the tube 4a and 4b, respectively, into the tank 10. Similarly, 
cleaning liquid flows along the outside of the insertion tube 54 through 
the pipe 4a and 4b, respectively, as a result of which not only is the 
plastic sheath 55 of the insertion tube 54 cleaned, but also suction is 
generated at the distal end of the insertion tube 54 as a result of the 
flow breaking off, which suction increases the pressure difference in 
relation to the openings 52, 53 and effects a good flushing-through of the 
channels at a comparatively low static pressure. 
Cleaning liquid also flows from the openings 52, 53 through the 
continuations 57', 58' and 59' of the above mentioned channels and emerges 
at the water attachment 62, at the air attachment 63 and at the suction 
attachment 66 on the supply part 64. The supply tube 60 and the supply 
part 64 are cleaned on the outside by means of the rotating washer arms 
5a,b, through which cleaning liquid is likewise pumped by the circulation 
pump 11. 
Towards the end of the cleaning stage, during which the boiler 20 has been 
heated to a disinfection temperature of 93.degree. C., the circulation 
pump 11 is shut off and the tank 10 is emptied via the suction pump 13, 
while at the same time compressed air from the compressed air storage 
units 47a,b and thus the endoscopes is let off through the throttle outlet 
valves 45a,b and the pressure is reduced. 
In principle, the next cleaning stage, the rinsing, takes place, including 
the preceding testing of the endoscope, in a completely analogous manner 
to the first stage, except that no cleaner is added and the circulation 
pump 11 runs for only approximately 3 min. 
The next cleaning stage too, the disinfection, which is also preceded by an 
endoscope testing, as described, differs from the preceding stages only in 
the preparation of the cleaning liquid and the duration. Cold water is 
passed into the tank 10 from the cold water attachment 24 via the valve 
25c, the heat exchanger 27, where it is heated in the boiler 20 with 
cooling of the demineralized water, and the valve 29, and disinfectant is 
metered in from the storage unit 37. During the disinfection cold water is 
furthermore passed through the heat exchanger 27 and via the valve 30 to 
the outlet 31, as a result of which the content of the boiler 20 is cooled 
to below 55.degree. C. During disinfection, the circulation pump 11 runs 
for somewhat more than 8 min. 
For the last cleaning stage, the rinsing clean, the demineralized water is 
passed from the boiler 20, which was held at 93.degree. C. for 
approximately 10 min and thus disinfected and then cooled to below 
55.degree. C., since higher temperatures are badly tolerated by 
endoscopes, via the valve 28 into the tank 10 and circulated for 
approximately 2 min. Otherwise, the rinsing clean, including the preceding 
endoscope testing, takes place exactly as the preceding cleaning stages. 
Finally, the endoscopes are dried by hot air issuing from the heater fan 
17. The cleaning lasts approximately 40 min. 
Of course, the cleaning described here represents only one example. The 
cleaning program can be adapted to the requirements and the circumstances 
and can be varied. The only respect in which nothing is altered is in the 
basic sequence of a cleaning stage, with preceding endoscope testing by 
building up an internal pressure in the endoscope, and subsequently 
circulating the cleaning liquid, while simultaneously maintaining the 
internal pressure above the pressure of the cleaning liquid. 
If, for example, the endoscope to be cleaned reveals a large leak in the 
pressure chamber 2b, then the test pressure of 250 mbar in the endoscope 
and, consequently, in the compressed air storage unit 47b is not reached 
within a test interval of 5 min prior to the first cleaning stage. The 
circulation pump 11 is not set into operation and the cleaning is 
discontinued. An error message appears on the control panel 9. 
FIGS. 4a and 4b show the case in which, during cleaning, a leak appears and 
increases in size in the endoscope being cleaned in the pressure chamber 
2a. During the first cleaning stage, the actual cleaning, the endoscope is 
still leakproof; only towards the end do the air pressure variations, 
which are increasing but still lie appreciably below 30 mbar, indicate 
that the endoscope is losing air and the compressed air storage unit 47a 
must be frequently topped up. In the test prior to rinsing out, a 
pronounced pressure drop occurs during the holding time of 30 sec, which 
pressure drop is smaller, however, than the limit value of 30 mbar. This 
points to a relatively small leak. The pressure losses can be compensated 
without difficulty from the compressed air unit. The cleaning stage 
progresses normally, but the pressure in the compressed air storage unit 
47a fluctuates significantly as a result of the losses and the topping-up, 
which is triggered by the pressure sensor 48a controlling the admission 
valve 42a. 
In the test preceding the disinfection, a pressure drop of more than 30 
mbar occurs during the holding time. This points to a relatively large 
leak, and the result of this is that the circulation pump 11 is not 
switched on and the filling of the tank 10 is discontinued. The latter is 
emptied via the suction pump 13. The compressed air is let off via the 
throttle outlet valves 45a,b and the cleaning is discontinued with an 
error message, without it having been possible for the cleaning stage to 
be initiated.