Cleaning method utilizing ozonated water and apparatus for producing ozonated water

A method for cleaning an article, such as a used kidney dialyzer, requiring sterilization includes the steps of manually rinsing the article with purified water, inserting the article into an automated reuse apparatus which utilizes ozonated water, and sterilizing the article for a predetermined period of time with ozonated water wherein the ozonated water flows through the article for sterilizing it. The step of inserting the article into the automated reuse apparatus includes the steps of rinsing the article with ozonated water, reversing the flow of ozonated water through the article for backwashing the article, and conducting testing cycles wherein the article is tested for leaks therein and for ensuring it can contain a predetermined quantity of fluid. Preferably, the predetermined period of time of the sterilizing step is approximately thirty minutes. An apparatus for producing ozonated water is further disclosed.

BACKGROUND AND SUMMARY OF THE INVENTION 
This invention relates generally to cleaning methods, and more particularly 
to a novel cleaning method for sterilizing an artificial kidney (i.e., a 
kidney dialyzer) with ozonated water. This invention also relates to an 
apparatus for producing ozonated water used during the performance of the 
cleaning method. 
Disposable artificial kidneys have been reprocessed and reused in chronic 
hemodialysis for more than twenty years. Reuse of artificial kidneys has 
clearly become a standard medical practice in the United States, wherein 
over seventy percent of dialysis facilities are reusing artificial 
kidneys. These facilities treat over seventy percent of the dialysis 
patients in the United States. 
Other than by hand washing the artificial kidney or dialyzer, there are two 
well-known methods for sterilizing the dialyzer. One such method, as shown 
in FIG. 1, is a method utilizing heat to clean the dialyzer. More 
specifically, the dialyzer is subjected to manual rinsing using purified 
water. The dialyzer then is rinsed with purified water, reverse filtered 
(also with purified water) and tested in an automated reuse apparatus 
which is well-known in the art. The dialyzer is then subjected to 105 
degrees Celsius for a period of twenty-four hours for sterilization 
purposes. A disadvantage of this method is that it takes too long to 
complete, especially for hospitals, and other medical facilities, having 
many patients requiring dialysis. Another disadvantage is that the 
dialyzer does not tolerate being subjected to high temperatures very well 
(e.g., the dialyzer becomes cracked, or it may melt) which results in 
fewer reuses thereof. 
The other known method follows the same prescribed method as heat treating, 
except instead of subjecting the dialyzer to heat over a period of time, 
suitable chemicals are used to sterilize it. This method is disclosed in 
FIG. 2. Various chemicals or sterilizing agents which are presently used 
are: cidex.RTM.; diacide.RTM.; sporicidin.RTM.-hd; formaldehyde; 
renalin.RTM.; and peracetic acid. While taking less time than heat 
treating (approximately two and one half hours), one problem associated 
with using chemicals is that there is a risk that the chemicals may remain 
inside the dialyzer and pose a threat to the patient during subsequent use 
of the dialyzer. Another drawback is that the chemicals are difficult to 
dispose of after they have been used. Moreover, many of the aforementioned 
chemicals are very expensive. 
Ozone has been used as a sterilizing agent in the past. For example, in 
U.S. Pat. No. 5,266,275 to Faddis, there is disclosed a method and 
apparatus for sterilizing medical instruments using ozone. However, ozone 
has never heretofore been used to sterilize a used dialyzer. 
Thus, there is presently a need for a method of sterilizing a used dialyzer 
which is not time-consuming and which leaves the dialyzer free of 
chemicals and other contaminants. 
The present invention is directed to a method for cleaning an article, such 
as a used kidney dialyzer, requiring sterilization comprising the steps 
of: (a) manually rinsing the article with purified water; (b) inserting 
the article into an automated reuse apparatus which utilizes ozonated 
water; and (c) sterilizing the article for a predetermined period of time 
with ozonated water, the ozonated water flowing through the article for 
sterilizing it. More specifically, the step of inserting the article into 
the automated reuse apparatus comprises the steps of: rinsing the article 
with ozonated water; reversing the flow of ozonated water through the 
article for backwashing the article; and conducting testing cycles wherein 
the article is tested for leaks therein and for ensuring it can contain a 
predetermined quantity of fluid. Preferably, the predetermined period of 
time of the sterilizing step is approximately thirty minutes. 
An apparatus for producing ozonated water of the present invention 
comprises a container defining a chamber. The container has a first inlet 
for introducing purified water into the chamber, a second inlet for 
introducing vaporized ozone into the chamber, and an outlet for venting 
ozonated water from the chamber. A pump siphons ozonated water from the 
chamber of the container via the outlet of the container. Suitable 
introducing means is provided for introducing vaporized ozone into the 
chamber of the container through the second inlet. A sensor measures 
oxygen reduction potential (ORP) of the ozonated water, and controls the 
amount of vaporized ozone introduced into the chamber of the container by 
the introducing means. 
The introducing means of the apparatus specifically comprises a venturi 
injector in fluid communication with the second inlet of the container for 
injecting vaporized ozone therein. A device is provided for manufacturing 
oxygen, and an ozone generator, in fluid communication with the device and 
with the venturi injector, creates ozone which is then delivered to the 
venturi injector. A level control regulates the level of ozonated water 
contained within the chamber by introducing purified water therein when 
the level of ozonated water is below a predetermined quantity. Moreover, a 
filter is in fluid communication with the chamber of the container for 
further filtering and purifying the ozonated water contained within the 
chamber of the container. 
Accordingly, among the several objects of the present invention are the 
provision of an improved method for cleaning a used dialyzer requiring 
sterilization which requires less time than other known methods; the 
provision of such an improved method which leaves the dialyzer completely 
clean without substantially any residue from chemicals or other 
contaminants being left thereon which present a potential risk to the 
patient and to employees handling the dialyzer; the provision of such a 
method which is a cost-effective alternative to known prior methods of 
sterilization; the provision of such a method which is capable of 
utilizing existing cleaning equipment; the provision of such a method 
which enables the dialyzer to be used immediately after completion of the 
cleaning method; and the provision of such a method which is easy to 
perform, simple to implement, and which little or no specialized training 
is required for persons conducting the method. 
Also among the several objects of the present invention are the provision 
of an apparatus for producing ozonated water which is compact in 
construction and can deliver ozonated water to a device requiring the same 
on site; the provision of such an apparatus which produces sterilized 
ozonated water suitable for medical use; and the provision of such an 
apparatus which is easy to operate, simple in construction, and 
cost-efficient to manufacture and operate. 
Other objects, features and advantages of the invention shall become 
apparent as the description thereof proceeds when considered in connection 
with the accompanying illustrative drawings.

Corresponding reference numerals designate corresponding parts throughout 
the several views of the drawings. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings, and more particularly to FIGS. 3 and 4, 
there is generally designated 10 a method of the present invention (see 
FIG. 3) for cleaning an article, such as a used kidney dialyzer, generally 
designated 12 (see FIG. 4), requiring sterilization. The method 10 of the 
present invention is directed to using ozonated water for sterilizing the 
dialyzer 12. It has been discovered that ozonated water quickly and 
efficiently cleans the dialyzer 12 without having to resort to using a 
temperature cleaning apparatus or to treating the dialyzer with chemicals. 
Referring to FIG. 4, the blood dialyzer 12 is constructed in a typical 
fashion to include a tubular body 14 having an interior region 16 filled 
with a suitable filtration medium (e.g., fibers) which filter the person's 
blood of harmful toxins in the well-known manner. The interior region 16 
is accessed through a first inlet 18a and a first outlet 20a provided at 
opposite open ends of the body 14 of the dialyzer 12 for introducing into 
and exhausting the patient's blood from the dialyzer 12. A second inlet 
18b and a second outlet 20b are provided for introducing and exhausting 
dialyzing fluids into the dialyzer 12. Suitable connectors 22a, 22b, 24a, 
24b (e.g., threaded formations) are located at the inlets 18 and outlets 
20, respectively, so as to enable the dialyzer 12 to be coupled with feed 
and discharge conduits when treating a patient. An example of such a 
dialyzer is that sold by Terumo.RTM. of Somerset, N.J., under the 
trademark Clirans.RTM.. Since many of the presently available blood 
filtration devices can be used more than once, a used dialyzer must be 
thoroughly cleaned so that it is sterile for reuse. As mentioned above, 
there are known methods of sterilizing the used dialyzer, but each suffers 
from one or more noted disadvantages. The present method 10 is superior to 
that of these known methods in that it can be performed at a reduced cost, 
has a quick turnaround time, and more importantly does not present a risk 
to the patient reusing the dialyzer 12 by subjecting the patient to 
harmful chemical residue remaining inside the filtration medium of the 
dialyzer. 
As illustrated in FIG. 3, the used dialyzer 12 is first manually rinsed 
using purified water. This preliminary step is designated by reference 
numeral 26 in FIG. 3. It should be noted that purified water flows through 
the inlets 18 of the used dialyzer 12, through the interior region 16 
having the filtration medium, and out of its outlets 20. The water is 
purified by using well-known methods for sterilizing water used for 
medical purposes. For example, the water can be treated by using a 
distilling process, a deionizing process, or a reverse osmosis process, 
each of these processes being adapted to eliminate aluminum, fluorides, 
and sulfates, for example, from the water. 
Once the used dialyzer 12 is preliminarily rinsed, it is then placed into 
an automated reuse apparatus, such as a dialyzer reprocessing apparatus 
sold by Seratronics Inc. of Walnut Creek, Calif., model nos. DRS4.TM.D and 
DRS4.TM.ND, for a more thorough cleaning. This step of the process and the 
apparatus itself are indicated by reference numeral 28 in FIG. 3. The 
reuse apparatus 28 has suitable connectors which mate with the connectors 
22a, 22b, 24a, 24b of the dialyzer 12 for coupling the dialyzer to the 
reuse apparatus. Thus, it should be observed that the dialyzer 12 is 
adapted to be in fluid communication with the reuse apparatus 28 so that 
it can deliver ozonated water thereto for cleaning the dialyzer. The 
apparatus 28 is capable of delivering ozonated water into the interior 
region 16 of the dialyzer 12 through its inlet 18 for sterilizing the 
filtration medium. 
More specifically, the apparatus 28 rinses the dialyzer 12 with ozonated 
water for a limited time period. Once rinsed with ozonated water, the flow 
of the ozonated water is reversed for backwashing the dialyzer 12. 
Ozonated water is suitably delivered to the reuse apparatus 28 from an 
apparatus for producing ozonated water which is generally designated at 30 
in FIG. 5. 
Next, the reuse apparatus 28 conducts a series of testing cycles on the 
dialyzer 12. One testing cycle includes testing for leaks in the dialyzer 
12 wherein pressurized fluid is supplied within the dialyzer. Leaks formed 
by cracks or unsecured fittings are detected by the apparatus 28 in any 
suitable manner. Another testing cycle includes testing for whether the 
dialyzer 12 is capable of containing a predetermined amount of fluid. It 
is important that the dialyzer be able to contain a predetermined amount 
of fluid (e.g., 80% of a quart). Such tests are well-known in the art of 
reuse apparatus. 
After conducting the rinsing cycle, backwashing cycle, is and testing 
cycle, ozonated water is then passed through the dialyzer 12 for a 
predetermined period of time. This step of the method is indicated by 
reference numeral 32 in FIG. 3. As mentioned above, the reuse apparatus 28 
is connected to the apparatus 30 which produces ozonated water. 
Preferably, the dialyzer 12 is sterilized for a period of approximately 
thirty minutes. It has been discovered that thirty minutes is a sufficient 
amount of time for adequately sterilizing the dialyzer 12 whereupon, 
afterwards, it is ready for reuse. 
It should be observed that the method 10 of the present invention is 
superior to the known methods illustrated in FIGS. 1 and 2 of the prior 
art. For example, using ozonated water reduces the amount of time 
necessary to sterilize the used dialyzer 12. Heat treating requires 
twenty-four hours and chemical treating requires two and one-half hours, 
whereas the method 10 of the present invention requires only one hour 
total. This reduction in time enables the health care facility to reduce 
the number of artificial kidneys for treating patients requiring dialysis 
since the artificial kidneys can be quickly cleaned for reuse. Also, since 
ozonated water is not particularly harmful, any residue thereof on the 
dialyzer 12 is not harmful to the patient. In sharp contrast, chemicals 
left on the dialyzer as a result of chemical treating can potentially be 
very harmful to the patient. 
Referring now to FIG. 5, there is illustrated in schematic format a block 
diagram of the apparatus 30 for producing ozonated water. As mentioned 
briefly above, ozonated water is produced on-site by apparatus 30 and is 
delivered directly to the reuse apparatus 28 for sterilizing the dialyzer 
12. The ozonated water producing apparatus 30 generates ozonated water at 
a rate sufficient for the reuse apparatus 28 to operate. As shown, the 
apparatus 30 comprises a container 34 which defines an inner chamber 36 
wherein purified water is mixed with ozone (O.sub.3) to produce the 
ozonated water. The container 34 has a first inlet 38 for introducing 
purified water from a purified water source 40 into the chamber 36, a 
second inlet 42 for introducing vaporized ozone into the chamber, and an 
outlet 44 for exhausting ozonated water from the chamber. An inlet 
solenoid 46 is disposed between the purified water source 40 and the 
chamber 36 for controlling the introduction of purified water into the 
chamber. 
Ozone is injected into the chamber 36 of the container 34 through the 
second inlet 42 by a venturi injector indicated by reference numeral 48 in 
FIG. 5. The venturi injector 48 is in fluid communication with the chamber 
36 of the container 34 via line 50, and in fluid communication with a 
ozone generator 52 via line 54, the ozone generator 52 creating ozone 
which is delivered to the venturi injector 48. An oxygen producing device 
56 is in fluid communication with the ozone generator 52 by another line 
58. The arrangement is such that the device 56 produces oxygen that is 
delivered to the ozone generator 52 which in turn creates ozone therefrom. 
This ozone is then vaporized by the venturi injector 48 and delivered to 
the container 34 by line 50 where it is mixed with the purified water to 
produce ozonated water. It should be noted that the venturi injector 48, 
ozone generator 52 and oxygen producing device 56 are all stock items that 
can be readily obtained through commercial channels. 
The ozonated water produced in the chamber 36 of the container 34 is 
preferably saturated with ozone for obtaining the highest level of 
sanitation when cleaning the dialyzer 12 pursuant to the method 10 
disclosed herein. The ozonated water is then delivered to the reuse 
apparatus 28 by a pump 60 which is in fluid communication with an outlet 
solenoid 62 via line 64. Excess ozone (unsaturated) which does not mix 
with the purified water is delivered back into the venturi injector 48 for 
atomization and reintroduction into the chamber 36. Thus, it should be 
observed that the apparatus 30 of the present invention conserves ozone 
and ensures that it is not wasted or otherwise released into the 
environment. 
A sensor 66 measures the oxygen reduction potential (ORP) of the ozonated 
water for ensuring the ozonated water is saturated with ozone. This sensor 
66 is in fluid communication with line 64 between the pump 60 and the 
venturi injector 48 and the outlet solenoid 62, and in electrical 
communication with the ozone generator 52 by line 68. The sensor 66 
controls the amount of vaporized ozone introduced into the chamber 36 of 
the container 34 by the venturi injector 48 wherein it increases the 
amount of vaporized water delivered to the chamber when the ORP is below a 
predetermined level (e.g., 900 MV) and vice versa. 
A level control 70 is provided within the chamber 36 of the container 34 
for regulating the level of ozonated water contained therein by 
introducing more purified water into the chamber when the level of 
ozonated water is below a predetermined quantity. The level control 70 is 
in electrical communication with the inlet solenoid 46 via electrical line 
72. A filter 74 is also in fluid communication with the chamber 36 of the 
container 34 for further filtering and purifying the ozonated water. The 
filter 74 further ensures that the ozonated water within the chamber 36 is 
pure and sterile when it is delivered to the reuse apparatus 28. As with 
the other aforementioned components of the apparatus 30, the level control 
70 and filter 74 are also stock items readily available from commercial 
sources. 
The operation of the ozonated water producing apparatus 30 is as follows. 
Purified water is delivered into the chamber 36 of the container 34 by the 
inlet solenoid 46 from source 40. The level control 70 regulates the 
amount or rate of purified water delivered to the chamber 36. Ozone vapor 
is delivered into the chamber 36 by the venturi injector 48, the ozone 
being mixed with the purified water for creating ozonated water within the 
chamber. The sensor 66 controls the amount of ozone which is delivered 
into the chamber 36 by sensing the ORP value of the ozonated water. The 
ozonated water is filtered by filter 74 and then pumped to the reuse 
apparatus 28 by the pump 60. The outlet solenoid 62 controls the amount of 
ozonated water which is delivered to the reuse apparatus 28. It should be 
observed that a suitable microprocessor is provided for controlling the 
operation of the apparatus 30 so that ozonated water having the requisite 
ORP value is delivered to the reuse apparatus 28 upon demand. 
While there is shown and described herein certain specific structure 
embodying the invention, it will be manifest to those skilled in the art 
that various modifications and rearrangements of the parts may be made 
without departing from the spirit and scope of the underlying inventive 
concept and that the same is not limited to the particular forms herein 
shown and described except insofar as indicated by the scope of the 
appended claims.