U.S. patent application number 12/542971 was filed with the patent office on 2010-02-18 for dialysis cassettes and related systems and methods.
This patent application is currently assigned to FRESENIUS MEDICAL CARE DEUTSCHLAND GMBH. Invention is credited to Frank Hedmann, Stephan Klatte.
Application Number | 20100038322 12/542971 |
Document ID | / |
Family ID | 41202460 |
Filed Date | 2010-02-18 |
United States Patent
Application |
20100038322 |
Kind Code |
A1 |
Hedmann; Frank ; et
al. |
February 18, 2010 |
DIALYSIS CASSETTES AND RELATED SYSTEMS AND METHODS
Abstract
A method that includes conveying overheated dialysate through a
cassette in a manner to reduce the temperature of the overheated
dialysate, and a dialysis system including a control unit
configured to cause overheated dialysate to be conveyed through a
cassette in a manner to reduce the temperature of the overheated
dialysate.
Inventors: |
Hedmann; Frank; (Volkach,
DE) ; Klatte; Stephan; (Nienburg (Weser),
DE) |
Correspondence
Address: |
FISH & RICHARDSON PC
P.O. BOX 1022
MINNEAPOLIS
MN
55440-1022
US
|
Assignee: |
FRESENIUS MEDICAL CARE DEUTSCHLAND
GMBH
Bad Homburg
DE
|
Family ID: |
41202460 |
Appl. No.: |
12/542971 |
Filed: |
August 18, 2009 |
Current U.S.
Class: |
210/742 ;
210/149 |
Current CPC
Class: |
A61M 2205/3606 20130101;
A61M 1/166 20140204; A61M 1/28 20130101; A61M 2205/127 20130101;
A61M 5/445 20130101; A61M 1/1656 20130101; A61M 2205/3626
20130101 |
Class at
Publication: |
210/742 ;
210/149 |
International
Class: |
B01D 61/32 20060101
B01D061/32 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 18, 2008 |
DE |
102008038097.0 |
Claims
1. A method of controlling the temperature of liquid in a dialysis
cassette, the method comprising: pumping liquid heated to a
temperature greater than a desired temperature from a first pump
chamber of the dialysis cassette to a second pump chamber of the
dialysis cassette.
2. The method of claim 1, further comprising pumping the liquid
from the second pump chamber of the dialysis cassette back to the
first pump chamber of the dialysis cassette.
3. The method of claim 2, wherein the liquid is pumped back and
forth between the first and second pump chambers of the dialysis
cassette until the liquid reaches the desired temperature.
4. The method of claim 1, further comprising turning off a heating
device configured to heat the liquid in the dialysis cassette, and
closing an outlet passage formed in the cassette such that the
liquid is substantially prevented from exiting the cassette via the
outlet passage.
5. The method of claim 4, wherein a fluid line is connected to the
outlet passage and to a patient, and closing the outlet passage
substantially prevents the liquid from being delivered via the
fluid line to the patient.
6. The method of claim 1, wherein unheated liquid is present in the
second pump chamber when the liquid heated to a temperature greater
than the desired temperature is pumped into the second pump
chamber.
7. The method of claim 6, wherein, when a mixture of the unheated
liquid and the liquid heated to a temperature greater than the
desired temperature in the second pump chamber is below a given
temperature, the mixture is conveyed from the second pump chamber
to an outlet passage, then to a heating region of the cassette,
then to the first pump chamber.
8. The method of claim 6, wherein, when a mixture of the unheated
liquid and the liquid heated to a temperature greater than the
desired temperature in the second pump chamber is above a given
temperature, the mixture is conveyed from the second pump chamber
to a heating region of the cassette, then to an outlet passage,
then to the first pump chamber.
9. The method of claim 1, further comprising sensing the
temperature of liquid in the cassette.
10. The method of claim 9, wherein the temperature of liquid in a
heating region of the cassette is sensed.
11. The method of claim 9, wherein the temperature of liquid in the
first pump chamber of the cassette and the temperature of liquid in
the second pump chamber of the cassette is sensed.
12. A dialysis system, comprising: a dialysis cassette comprising a
first pump chamber; a second pump chamber; and a heating region
comprising a fluid passage that can be placed in fluid
communication with the first pump chamber and the second pump
chamber; and a dialysis machine configured to retain the dialysis
cassette, the dialysis machine comprising a first pump configured
to cooperate with the first pump chamber to pump liquid out of the
first pump chamber when the dialysis cassette is retained by the
dialysis machine; a second pump configured to cooperate with the
second pump chamber to pump liquid out of the second pump chamber
when the dialysis cassette is retained by the dialysis machine; and
a control unit configured to pump liquid heated to a temperature
greater than a desired temperature from the first pump chamber of
the dialysis cassette to the second pump chamber of the dialysis
cassette when the dialysis cassette is retained by the dialysis
machine.
13. The dialysis system of claim 12, wherein the dialysis machine
further comprises a heating device configured to heat liquid
flowing through the passage of the heating region of the cassette
when the dialysis cassette is retained by the dialysis machine.
14. The dialysis system of claim 12, further comprising at least
one temperature sensor configured to measure the temperature of
liquid in the cassette.
15. The dialysis system of claim 12, wherein the control unit is
configured to cause the liquid to be pumped back and forth between
the first and second pump chambers of the dialysis cassette until
the liquid reaches the desired temperature.
16. The dialysis system of claim 12, wherein the control unit is
configured to turn off a heating device configured to heat the
liquid in the dialysis cassette, and the control unit is configured
to cause an outlet passage formed in the cassette to be closed such
that the liquid is substantially prevented from exiting the
cassette via the outlet passage.
17. The dialysis system of claim 16, wherein a fluid line is
connected to the outlet passage and to a patient, and closing the
outlet passage substantially prevents the liquid from being
delivered via the fluid line to the patient.
18. The dialysis system of claim 12, wherein the dialysis cassette
further comprises an outlet passage that can be placed in fluid
communication with the first pump chamber, the second pump chamber,
and the fluid passage in the heating region of the dialysis
cassette.
19. The dialysis system of claim 18, wherein the control unit is
configured such that when a mixture of unheated liquid and the
liquid heated to a temperature greater than the desired temperature
in the second pump chamber is below a given temperature, the
control unit causes the mixture to be conveyed from the second pump
chamber to the outlet passage, then to the heating region of the
cassette, then to the first pump chamber.
20. The dialysis system of claim 18, wherein the control unit is
configured such that when a mixture of the unheated liquid and the
liquid heated to a temperature greater than the desired temperature
in the second pump chamber is above a given temperature, the
control unit causes the mixture to be conveyed from the second pump
chamber to the heating region of the cassette, then to the outlet
passage, then to the first pump chamber.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C.
.sctn.119(a) to German Patent Application No. 10 2008 038 097.0,
filed Aug. 18, 2008, the entire contents of which are hereby
incorporated by reference.
TECHNICAL FIELD
[0002] This invention relates to dialysis cassettes and related
systems and methods.
BACKGROUND
[0003] Cassettes for conveying dialysis liquids, such as dialysate,
are known. Some known cassettes include connection elements for the
connection of solution bags and lines leading to a patient and to a
dialysis machine. The cassettes can have at least one pump chamber
with an inflow and an outflow port as well as passages for
conducting the supplied and conveyed liquid. The passages can be
closed by the application of a compressive force acting on the
walls of the passages. A heating device can be used for heating the
dialysis liquid in the cassette to a desired temperature.
[0004] Such cassettes are used, for example, in the area of
peritoneal dialysis. During peritoneal dialysis, the peritoneum is
filled and emptied with the help of a dialysis machine called a
"cycler." The flow of the dialysis liquid, i.e., dialysate, is
controlled by a cassette system. During peritoneal dialysis, the
dialysate is heated to the desired temperature in the cassette and
is subsequently infused into the peritoneum. If an unexpected
stoppage of the cycler occurs and the liquid supply to the patient
is interrupted, the dialysate is no longer circulated in the
cassette. As a result, the dialysate may be heated above the
desired temperature due to the inertia of the heating apparatus.
The overheated dialysate typically cannot be used for infusion into
the patient when the cycler is restarted. Thus, the dialysate is
typically discarded and replaced with new dialysate before the
peritoneal dialysis treatment resumes.
SUMMARY
[0005] In one aspect of the invention, a cassette is provided for
conveying liquids, in particular dialysis liquids. The cassette
includes connection elements for the connection of solution bags
and lines leading to a patient and/or to a dialysis machine. The
cassette further includes at least one pump chamber with an inflow
port and an outflow port. In addition, the cassette forms lines or
passages for conducting the supplied and conveyed liquids through
the cassette. The cassette also includes valves for closing the
lines. A heating device is provided for heating the liquid present
in the passages to a desired temperature (e.g., a preset desired
temperature). A control unit is also provided and is configured to
conduct (e.g., circulate) liquid heated above the desired
temperature until the desired temperature has been reached
again.
[0006] Reducing the temperature of the liquid allows the liquid to
be used again. Excess heat from the overheated liquid can be
transferred to the cassette surrounding it by circulating the
overheated liquid within the cassette.
[0007] In some implementations, at least one temperature sensor is
provided for the measurement of the temperature of the liquid in
the cassette. In certain implementations, the temperature sensor is
positioned within the cassette. In some implementations, the
temperature sensor is located on a dialysis machine and cooperates
with the cassette when the cassette is positioned in a cassette
compartment of the dialysis machine.
[0008] In some implementations, two pump chambers are provided
between which the liquid can be displaced until the liquid reaches
(e.g., cools to) the desired temperature.
[0009] In some implementations, the heating device and a heating
region of the cassette act as a continuous-flow heater. In such
implementations, the heating device and the heating region of the
cassette are configured so that liquid is heated as it flows
through the heating region of the cassette.
[0010] In another aspect of the invention, a method includes
displacing a liquid between the two pump chambers of the cassette
until the liquid reaches (e.g., cools to) a desired
temperature.
[0011] In some implementations, when the desired temperature of the
liquid is exceeded, the passage to which the line draining the
liquid is connected is closed. At the same time, the heating power
of the heating device is reduced. The liquid is pumped through one
of the pump chambers from a heating region of the cassette into the
other pump chamber.
[0012] In the event that a high proportion of cool liquid is
already present in the pump chamber into which the overheated
liquid is conducted, the resulting mixture of liquid (i.e., the
mixture of the overheated liquid and the cool liquid) is conveyed
in reverse operation through a heating region of the cassette into
the other pump chamber in order to simultaneously cool the heating
region of the cassette in this process.
[0013] If, in contrast, due to the admixture of the overheated
liquid in the pump chamber, a liquid overheated at its mixed
temperature should result, the mixed liquid is conveyed in forward
operation through the heating region of the cassette into the other
pump chamber to distribute the excess heat in the cassette.
[0014] An additional aspect of the invention relates to a dialysis
machine, such as a peritoneal dialysis machine, having a device for
the reception of one of the previously described cassettes as well
as a pump unit for actuating the pump chambers of the cassette. The
dialysis machine includes a heating device configured to heat
liquid flowing through a heating region of the cassette and a
control unit configured to conduct (e.g., circulate) liquid heated
above a desired temperature until the desired temperature has been
reached again.
[0015] By using certain dialysis cassettes, systems, and methods
described herein, a dialysis liquid that may have been overheated
can advantageously be returned to a desired temperature without
having to discard the liquid. As a result, the total amount of
dialysis liquid used during the treatment can be reduced because it
is generally unnecessary to discard the overheated dialysis liquid
and replace it with new dialysis liquid. In addition, the amount of
time required for the treatment can be reduced since it is
generally unnecessary to drain the overheated dialysis liquid and
then replace it with new dialysis liquid.
[0016] Other aspects, features, and advantages will be apparent
from the description and drawings, and from the claims.
DESCRIPTION OF DRAWINGS
[0017] FIG. 1 is a plan view of a dialysis cassette.
[0018] FIG. 2 is a front view of a dialysis system including a
dialysis machine and the dialysis cassette of FIG. 1.
[0019] FIG. 3 is a front view of the dialysis machine of FIG. 2
with a door of the dialysis machine open to expose a cassette
compartment of the dialysis machine.
DETAILED DESCRIPTION
[0020] FIG. 1 shows a disposable cassette 10 that can be retained
in a correspondingly designed cassette compartment or mount of a
dialysis machine (e.g., a peritoneal dialysis machine) 100 (shown
in FIG. 2). Referring to FIGS. 1 and 2, the reference numerals 2,
4, 6 characterize connection elements for the connection of
solution bags, of lines leading to the patient and to the dialysis
machine, and of drainage lines. Two fixedly attached hoses or lines
104 and 106 are arranged at the connectors 4 and 6, with one of the
hoses representing the patient hose and the other representing the
drainage hose. The connection elements 2 allow the operator to
connect the solution bags or other medication containers to the
cassette 10.
[0021] Referring again to FIG. 1, the cassette 10 includes a base
body 12 that is made of plastic and can be manufactured using
injection molding technology or deep-drawing technology. Cut-outs
as well as passages extend in the base body 12. The base body 12
partly forms the walls of two pump chambers 20, 22 arranged next to
one another as well as liquid passageways 30, 40, 50, 60 extending
within the cassette 10. Liquid passageways 80 and 90 are likewise
partly formed by the base body 12 between the pump chambers 20 and
22.
[0022] The liquid passageway 50 is serpentine shaped and is
provided within a heating region 52 of the cassette 10. One end of
the passageway 50 is connected to the passageway 30, and the other
end of the passageway 50 is connected to the passageway 40. The
cassette 10, as discussed above, is configured to be retained in a
cassette compartment of the dialysis machine 100. Referring briefly
to FIG. 3, the dialysis machine 100 includes a heating device 108.
When the cassette 10 is positioned within the cassette compartment
of the dialysis machine 100, as shown in FIG. 2, the heating device
108 is positioned adjacent the heating region 52 of the cassette 10
through which the passageway 50 extends. As a result of this
arrangement, the dialysis liquid (e.g., dialysate) flowing through
the passageway 50 is heated when the cassette 10 is positioned
within the cassette compartment of the dialysis machine 100 and the
beating device 108 is activated.
[0023] As shown in FIG. 3, in addition to the heating device 108,
the dialysis machine 100 includes two pumps 110, 112 and multiple
valve tappets T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12,
T13, T14, T15, and T16. The pumps 110, 112 cooperate with the pump
chambers 20, 22 to pump liquid through the various passages of the
cassette 10. The valve tappets T1, T2, T3, T4, T5, T6, T7, T8, T9,
T10, T11, T12, T13, T14, T15, and T16 cooperate with corresponding
valves V1, V2, V3, V4, V5, V6, V7, V8, V9, V10, V11, V12, V13, V14,
V15 and V16 of the cassette 10 to direct the conveyed liquid
through the cassette 10 in a desired manner. The valve tappets T1,
T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, and
T16 can be pneumatically, hydraulically and/or mechanically
controlled.
[0024] Other details regarding the cassette and its function
substantially correspond to those details and functions described
in EP 0 956 876 B1, which is incorporated by reference herein.
[0025] During normal function of the cassette 10 and the dialysis
machine 100, liquid (e.g., dialysate) is conveyed from the pump
chamber 22 through the heating region 52 of the cassette 10 in the
direction of the patient line that carries the liquid to the
patient and that is connected to the connector 4. The liquid thus
flows from the pump chamber 22 via the passageway 80 after the
opening of the valve V4 through the passageway 50 adjacent the
heater 108 of the dialysis machine 100 and via the opened valve V5
as well as the opened valve V6. As the liquid flows through the
passageway 50 adjacent the heater 108, heat emitted from the heater
108 increases the temperature of the liquid. Thus, the heater 108
and the heating region 52 of the cassette 10 together act as a
continuous-flow heating mechanism. At the same time that liquid is
forced out of the pump chamber 22 and through the passageway 50,
the pump chamber 20 is supplied with fresh liquid. The fresh liquid
can, for example, be supplied to the pump chamber 20 via the opened
valves V11 and V1, while the valves V7, V3 and V2 as well as V9 are
simultaneously closed.
[0026] If problems arise in the patient line (e.g., if the patient
line 104 connected to the connector 4 becomes occluded), the liquid
present in the passageway 50 can be overheated due to an
overshooting of the heating regulator. The overheated liquid can
typically not be infused into the peritoneum due to its elevated
temperature.
[0027] When overheating of the liquid in the passageway 50 occurs,
the valve V6 is closed and the heating power in the heater 108 of
the dialysis machine 100 is reduced via a control unit that is
arranged in the dialysis machine 100. At the same time, the valve
V11 is closed to prevent any additional fresh solution from being
delivered to the pump chamber 20. After turning off the heater 108
and closing valves V6 and V11, the overheated solution is pumped
via the pump chamber 22 through the passageway 50 adjacent the
continuous-flow heater and into the pump chamber 20. To do this,
the valve V4, the valve V5, the valve V7, and the valve V1 are
opened. The pump stroke of the pump chamber 22 is ended when the
pump chamber 20 is filled or the pump chamber 22 is emptied.
[0028] Two possibilities now generally result for the cooling of
the liquid in dependence on the ratio of the liquid contained in
the pump chamber 20 to the warm liquid conveyed into the pump
chamber 20.
[0029] If a high proportion of cool liquid (i.e., liquid that has
not passed through the passageway 50 adjacent the heater 108) is
present in the pump chamber 20, the resulting mixed liquid, which
is comparatively cooler than the overheated liquid due to the
mixing of the liquids, is conveyed via the passageway 50 adjacent
the heater 108 into the pump chamber 22 in reverse operation. In
particular, the liquid is pumped back into the pump chamber 22 via
the opened valve V1, the opened valve V7, the opened valve V5, and
the opened valve V4. The partially overheated heating region 52 of
the cassette 10 is also cooled by the comparatively cooler
liquid.
[0030] If, after delivering the overheated liquid to the pump
chamber 20, a high proportion of overheated liquid is present in
the pump chamber 20, the mixture of liquid (i.e., the mixture of
the overheated liquid and any cool liquid that was present in the
pump chamber 20 when the overheated liquid was delivered to the
pump chamber 20) is conveyed in forward operation via the
passageway 50 adjacent the heater 108 into the pump chamber 22.
Starting from the pump chamber 20, the liquid is conducted into the
pump chamber 22 via the opened valve V2, the opened valve V5, the
opened valve V7, and the opened valve V3. In this variant, the
excess heat of the overheated liquid is distributed in the cassette
so that the temperature of the overheated liquid can be lowered to
the desired temperature.
[0031] While the heater 108 has been described as being part of the
dialysis machine 100 and positioned adjacent to the passageway 50
of the cassette 10 when the cassette 10 is positioned in the
cassette compartment of the dialysis machine 100, in certain
implementations, the cassette itself includes a heater or part of a
heater. The heating region of the cassette can, for example, be
equipped with a heating coil. In such cases, the heating coil can
be connected to a power supply of the dialysis machine when the
cassette is inserted into the cassette compartment in order to
provide the coil with power that generates heat.
[0032] While the control unit has been described as being part of
the dialysis machine 100, the control unit can alternatively be
located at any of various other locations outside of the cassette
10.
[0033] Other embodiments are within the scope of the claims.
* * * * *