NZ623899B2 - Sensing system for detecting a substance in a dialysate - Google Patents
Sensing system for detecting a substance in a dialysate Download PDFInfo
- Publication number
- NZ623899B2 NZ623899B2 NZ623899A NZ62389912A NZ623899B2 NZ 623899 B2 NZ623899 B2 NZ 623899B2 NZ 623899 A NZ623899 A NZ 623899A NZ 62389912 A NZ62389912 A NZ 62389912A NZ 623899 B2 NZ623899 B2 NZ 623899B2
- Authority
- NZ
- New Zealand
- Prior art keywords
- gas
- dialysate
- ammonia
- detector
- sensing system
- Prior art date
Links
- 239000000126 substance Substances 0.000 title claims abstract description 26
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 199
- 230000002209 hydrophobic Effects 0.000 claims abstract description 78
- 239000012530 fluid Substances 0.000 claims abstract description 56
- QGZKDVFQNNGYKY-UHFFFAOYSA-O ammonium group Chemical group [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 claims abstract description 43
- 238000004891 communication Methods 0.000 claims abstract description 41
- 230000001419 dependent Effects 0.000 claims abstract description 5
- 239000007789 gas Substances 0.000 claims description 134
- 238000000502 dialysis Methods 0.000 claims description 88
- 239000002594 sorbent Substances 0.000 claims description 43
- 239000000463 material Substances 0.000 claims description 15
- 238000001514 detection method Methods 0.000 claims description 11
- 239000012159 carrier gas Substances 0.000 claims description 9
- 238000009833 condensation Methods 0.000 claims description 7
- 230000005494 condensation Effects 0.000 claims description 7
- 238000001631 haemodialysis Methods 0.000 claims description 7
- 230000000322 hemodialysis Effects 0.000 claims description 7
- 238000000034 method Methods 0.000 claims description 7
- 150000001875 compounds Chemical class 0.000 claims description 2
- KISFEBPWFCGRGN-UHFFFAOYSA-M sodium;2-(2,4-dichlorophenoxy)ethyl sulfate Chemical compound [Na+].[O-]S(=O)(=O)OCCOC1=CC=C(Cl)C=C1Cl KISFEBPWFCGRGN-UHFFFAOYSA-M 0.000 claims 1
- 238000003860 storage Methods 0.000 description 50
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- 231100000803 sterility Toxicity 0.000 description 8
- 210000004369 Blood Anatomy 0.000 description 7
- 210000003734 Kidney Anatomy 0.000 description 7
- 239000008280 blood Substances 0.000 description 7
- 239000003792 electrolyte Substances 0.000 description 7
- 229950003499 FIBRIN Drugs 0.000 description 6
- BWGVNKXGVNDBDI-UHFFFAOYSA-N Fibrin Chemical compound CNC(=O)CNC(=O)CN BWGVNKXGVNDBDI-UHFFFAOYSA-N 0.000 description 6
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- XSQUKJJJFZCRTK-UHFFFAOYSA-N urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 4
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
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- 239000002441 uremic toxin Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- PPNXXZIBFHTHDM-UHFFFAOYSA-N Aluminium phosphide Chemical compound P#[Al] PPNXXZIBFHTHDM-UHFFFAOYSA-N 0.000 description 1
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- 229940035295 Ting Drugs 0.000 description 1
- LEHOTFFKMJEONL-UHFFFAOYSA-N Trioxopurine Chemical compound N1C(=O)NC(=O)C2=C1NC(=O)N2 LEHOTFFKMJEONL-UHFFFAOYSA-N 0.000 description 1
- 229940045136 Urea Drugs 0.000 description 1
- 229940116269 Uric Acid Drugs 0.000 description 1
- ZCBJDQBSLZREAA-UHFFFAOYSA-N [4-[2-(4-acetyloxyphenyl)-3-oxo-4H-1,4-benzoxazin-2-yl]phenyl] acetate Chemical compound C1=CC(OC(=O)C)=CC=C1C1(C=2C=CC(OC(C)=O)=CC=2)C(=O)NC2=CC=CC=C2O1 ZCBJDQBSLZREAA-UHFFFAOYSA-N 0.000 description 1
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- WHXSMMKQMYFTQS-UHFFFAOYSA-N lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
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Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M1/00—Suction or pumping devices for medical purposes; Devices for carrying-off, for treatment of, or for carrying-over, body-liquids; Drainage systems
- A61M1/14—Dialysis systems; Artificial kidneys; Blood oxygenators ; Reciprocating systems for treatment of body fluids, e.g. single needle systems for hemofiltration or pheresis
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M1/00—Suction or pumping devices for medical purposes; Devices for carrying-off, for treatment of, or for carrying-over, body-liquids; Drainage systems
- A61M1/14—Dialysis systems; Artificial kidneys; Blood oxygenators ; Reciprocating systems for treatment of body fluids, e.g. single needle systems for hemofiltration or pheresis
- A61M1/16—Dialysis systems; Artificial kidneys; Blood oxygenators ; Reciprocating systems for treatment of body fluids, e.g. single needle systems for hemofiltration or pheresis with membranes
- A61M1/1694—Dialysis systems; Artificial kidneys; Blood oxygenators ; Reciprocating systems for treatment of body fluids, e.g. single needle systems for hemofiltration or pheresis with membranes with recirculating dialysing liquid
- A61M1/1696—Dialysis systems; Artificial kidneys; Blood oxygenators ; Reciprocating systems for treatment of body fluids, e.g. single needle systems for hemofiltration or pheresis with membranes with recirculating dialysing liquid with dialysate regeneration
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M1/00—Suction or pumping devices for medical purposes; Devices for carrying-off, for treatment of, or for carrying-over, body-liquids; Drainage systems
- A61M1/14—Dialysis systems; Artificial kidneys; Blood oxygenators ; Reciprocating systems for treatment of body fluids, e.g. single needle systems for hemofiltration or pheresis
- A61M1/28—Peritoneal dialysis ; Other peritoneal treatment, e.g. oxygenation
- A61M1/287—Dialysates therefor
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M1/00—Suction or pumping devices for medical purposes; Devices for carrying-off, for treatment of, or for carrying-over, body-liquids; Drainage systems
- A61M1/36—Other treatment of blood in a by-pass of the natural circulatory system, e.g. temperature adaptation, irradiation ; Extra-corporeal blood circuits
- A61M1/3621—Extra-corporeal blood circuits
- A61M1/367—Circuit parts not covered by the preceding subgroups of group A61M1/3621
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M2205/00—General characteristics of the apparatus
- A61M2205/12—General characteristics of the apparatus with interchangeable cassettes forming partially or totally the fluid circuit
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2313/00—Details relating to membrane modules or apparatus
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/24—Dialysis ; Membrane extraction
- B01D61/32—Controlling or regulating
Abstract
Disclosed is a sensing system for detecting a substance in a dialysate. The sensing system comprises a hydrophobic barrier, a detector (141), an interface (40a, 40b) and one or more delivery mechanisms (151). The hydrophobic barrier is capable of allowing the substance in the dialysate to equilibrate to a gas. The detector (141) is capable of detecting the gas. The interface (40a, 40b) disposed between the hydrophobic barrier and the detector (141) and configured to allow fluid communication of the gas between the hydrophobic barrier and the detector (141). The one or more delivery mechanisms (151) are capable of transporting the gas from the hydrophobic barrier through the interface (40a, 40b) to the detector (141). The one or more delivery mechanisms (151) allow the gas to move either back and forth within the interface (40a, 40b). The substance is ammonium and the gas is ammonia gas, and the gas is in a pH dependent equilibrium with the substance in the dialysate. e to a gas. The detector (141) is capable of detecting the gas. The interface (40a, 40b) disposed between the hydrophobic barrier and the detector (141) and configured to allow fluid communication of the gas between the hydrophobic barrier and the detector (141). The one or more delivery mechanisms (151) are capable of transporting the gas from the hydrophobic barrier through the interface (40a, 40b) to the detector (141). The one or more delivery mechanisms (151) allow the gas to move either back and forth within the interface (40a, 40b). The substance is ammonium and the gas is ammonia gas, and the gas is in a pH dependent equilibrium with the substance in the dialysate.
Description
SENSING SYSTEM FOR DETECTING A SUBSTANCE IN A DIALYSATE
Technical Field
The present ion relates to a dialysis device
and in particular to a portable or wearable dialysis
device. The ion also relates to a method of
conducting dialysis. The invention also relates to a
sensing system for detecting ammonium in a dialysate.
Background
Kidneys are vital organs of the human tasis
system. Kidneys act as a natural filter in the body which
remove toxic metabolic wastes such as urea from the blood.
Kidney failure or malfunction may lead to an lation
of toxins and to an imbalanced electrolyte level in the
blood, which may result in undesirable repercussions that
are hazardous to an individual's health.
Renal dysfunction and/or failure and, in particular,
end-stage renal disease, may cause the body to lose the
ability to adequately remove toxic waste in the blood and
restore the optimal level of electrolytes in the blood,
within physiological ranges. Dialysis is commonly used to
replace inadequate kidney on by removing toxic
waste.
For the past few years, the predominant form of
dialysis used for patients with end-stage renal disease
(ESRD) is hemodialysis. Hemodialysis involves the use of
an extracorporeal system for the removal of toxins
directly from the patient's blood by passing a large
amount of the t's blood through a filtering unit or
er. Hemodialysis treatment lly lasts several
hours and must be performed under medical supervision
three to four times a week, which significantly decrease a
patient's mobility and quality of life. Furthermore, as
hemodialysis is performed periodically rather than on a
continuous basis, patient health deteriorates as soon as a
ment cycle” in which contaminants are removed has
been ted.
The other form of dialysis used for ts with
kidney failure is peritoneal dialysis, most ly
d in the following two techniques: "continuous
ambulatory peritoneal dialysis" (CAPD) and "automated
peritoneal dialysis" (APD). In CAPD, fresh dialysate is
infused into the patient's abdominal (peritoneal) cavity
where, by means of diffusion, metabolic waste and
electrolytes in the blood are exchanged with the dialysate
across the peritoneal membrane. To allow sufficient
diffusion of the electrolytes and lic waste to
occur, the dialysate is retained in the abdominal
(peritoneal) cavity for a couple of hours before removal
and replacement (of the spent dialysate) with fresh
dialysate. Major drawbacks of continuous ambulatory
peritoneal dialysis are a low level of toxin clearance,
and the need to continuously e the spent dialysate,
which can be arduous for the patient and disruptive to
his/her daily activities.
To address this problem, s have been designed
that reconstitute used / spent dialysate from alysis
and/or peritoneal dialysis as opposed to discarding it.
However, current devices that reconstitute used / s pent
dialysate have several associated disadvantages including
complex set up procedures and difficulties in maintaining
the sterility of components. A further disadvantage is
that current devices often require a plurality of fluid
connections, which ses the risk of introducing
biological ination and reduces sterility of the
device. In addition several components must be disposed
of either daily, weekly or monthly adding another layer of
complexity to the operation of such devices. In addition,
the flow system of known regenerating dialysis devices
requires a plurality of pumps, which in turn undesirably
increases the overall size, weight and power consumption
of the device.
Accordingly, there is a need to provide a is device
that overcomes or at least ameliorates one or more of the
disadvantages described above. There is also a need to
provide a dialysis device t compromising on the
size, weight and power consumption of the device.
Furthermore, an ideal artificial kidney should simulate a
normal kidney by providing continuous metabolic and fluid
control, removal of toxins, and unrestricted patient
m. As mentioned above, alysis, continuous
ambulatory peritoneal dialysis (CAPD), automated
peritoneal dialysis (APD) and “24/7” wearable, peritoneal-
based artificial kidneys (WAK) are some methods that help
renal failure patients to remove metabolic waste. Some of
these methods, e.g. the “24/7” wearable, peritoneal-based
artificial kidneys (WAK), provide optimal nce of
uremic toxins by continuously regenerating the dialysate
using sorbent cartridge technology.
Methods utilizing t cartridge technology typically
require a safety ism to monitor the exhaustion of
the sorbent. Before or when the sorbent is ted or
does not function well, users need to replace the
cartridge to prevent ing toxins back to the patient.
One common approach is to monitor the ammonium
concentration of the rated dialysate to check that
it is under a safe level.
However, there are difficulties in dialysis
ammonia/ammonium detection. A known method of monitoring
the regenerated peritoneal dialysate um
concentration in-line is to orate an
ammonia/ammonium sensor directly onto the dialysate liquid
line. In other words, the sensing system is part of the
dialysate flow. However, this method requires the
a/ammonium sensing system to maintain its sterility
at all times, as well as function well. Also, there may be
patibility . Further, the sensing system has
to be compatible with liquid phase applications.
Currently, many liquid phase applications of sensing and
monitoring ammonia/ammonium level have their drawbacks and
limitations. As such, they are unsuitable for use in
peritoneal dialysis.
Besides ly incorporating an ammonia/ammonium sensor
in the regenerated dialysate liquid line, it is possible
to incorporate a sensor beside the liquid dialysate to
monitor the ammonium concentration. For example, US
2007/0161113 A1 and A2 disclose an optical
ammonia detecting device where an ammonia sensitive
material is placed directly adjacent to a liquid flow path
containing regenerated dialysate. The components for the
optical detection device are placed adjacent to the
ammonia sensitive material, together with the electrical
accessories for data processing and signal detection.
However, due to the close proximity of the ammonia sensing
material to the hydrophobic ne, the electrical
accessories are disposed very close to the dialysate line.
This approach also requires a closed “opaque casing” to
prevent any external light erence, which increases
cturing complexity. Electrical accessories for data
processing and signal detection are relatively bulky.
Accordingly, urization of portable and wearable
peritoneal is devices is difficult. Additional
drawbacks of this concept may also include:
Disposable/single use for the ammonia sensing
material/part;
Need for patients to assemble the cartridge for
use;
Very or direct contacting sensor causes
potential diasylate ng leading to a biocompatibility
concern
Possible improper assembly may cause inaccuracy
Detection methods and systems disclosed in other
publications have several drawbacks such as non-
biocompatibility, assembly difficulties (e.g. improper
assembly may cause inaccuracies), bulkiness, single-use
ammonia sensing components and sterility concerns.
Accordingly, there is also a need to provide a sensing
system for detecting ammonium in a dialysate that
overcomes or at least rates one or more of the
disadvantages described above.
Summary
Definitions
The following words and terms used herein shall have
the meaning indicated:
The term "sorbent" as used herein broadly refers to a
class of als characterized by their ability to
adsorb and/or absorb the desired matter of interest.
The term "non-toxic" as used herein refers to a
substance that causes little to no adverse reactions when
present in the human body.
The term "contaminants" in the context of this
specification, means any constituents, typically toxic
constituents, within a ate that are generally
l to human health and which are desirable to be
removed in a dialysate detoxification process. Typical
contaminants include, but are not limited to ammonium,
phosphates, urea, creatinine and uric acid.
The term "biocompatible" as used herein refers to the
property of a al that does not cause adverse
biological reactions to the human or animal body.
The term "upstream" as used herein refers to a
localization within the flow path, relative to a point of
reference, and in direction opposite to that of the
dialysate flow. The term "downstream" as used herein
refers to a localization within the flow path, relative to
a point of reference, and in direction of the dialysate
flow.
The term "crack-pressure" as used herein refers to
the point at which the internal pressure of a pneumatic
system triggers the opening of a valve.
The term "regenerate" as used herein refers to the
action of detoxifying dialysate by removal of uremic
toxins.
The term "reconstitute" as used herein refers to the
action of converting regenerated dialysate to essentially
the same state and chemical composition as fresh
peritoneal dialysate prior to dialysis.
The term "outflow mode" as used herein refers to the
flow of ate from the patient's body through a
t. The flow is referenced from the patient's body.
The term "inflow mode" as used herein refers to the
flow of the dialysate from a sorbent to the patient's
body. The flow is referenced to the patient's body.
The term “fluid” as used herein refers to a liquid or
a gas.
Throughout this disclosure, certain embodiments may
be sed in a range format. It should be understood
that the ption in range format is merely for
ience and brevity and should not be construed as an
ible limitation on the scope of the disclosed
ranges. Accordingly, the description of a range should be
considered to have specifically disclosed all the possible
sub-ranges as well as individual numerical values within
that range. For example, description of a range such as
from 1 to 6 should be considered to have specifically
disclosed sub-ranges such as from 1 to 3, from 1 to 4,
from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc.,
as well as individual s " within that range, for
example, 1, 2, 3, 4, 5, and 6. This applies regardless of
the breadth of the range
The word “substantially” does not exclude
“completely” e.g. a composition which is “substantially
free” from Y may be tely free from Y. Where
necessary, the word “substantially” may be d from
the definition of the ion.
Unless specified otherwise, the terms "comprising"
and "comprise", and grammatical variants thereof, are
intended to represent "open" or "inclusive" language such
that they include recited elements but also permit
inclusion of additional, unrecited elements.
As used herein, the term "about", in the context of
concentrations of components of the formulations,
typically means +/- 5% of the stated value, more lly
+/- 4% of the stated value, more typically +/- 3% of the
stated value, more typically, +/- 2% of the stated value,
even more lly +/- 1% of the stated value, and even
more typically +/- 0.5% of the stated value.
Certain embodiments may also be described broadly and
generically herein. Each of the narrower species and
subgeneric groupings g within the generic disclosure
also form part of the disclosure. This includes the
generic description of the embodiments with a proviso or
negative limitation removing any t matter from the
genus, regardless of whether or not the excised material
is specifically recited herein.
Disclosure of Optional Embodiments
It is an object of the present invention to substantially
overcome or at least ameliorate one or more disadvantages
of the prior art.
One aspect of the present ion provides a sensing
system for detecting a substance in a dialysate The
sensing system may include a hydrophobic barrier capable
of allowing the substance in the dialysate to equilibrate
to a gas; a or capable of detecting the gas; an
interface disposed between the hydrophobic barrier and the
detector and configured to allow fluid communication of
the gas; and one or more delivery mechanisms capable of
transporting the gas from the hydrophobic barrier to the
detector.
In one ment, the one or more delivery mechanisms
provides a driving force capable of orting the gas
from the hydrophobic barrier to the detector.
In one embodiment, the driving force circulates the gas
within the interface. In a further embodiment, the
driving force moves the gas back and forth within the
interface.
In one embodiment, the sensing system may further include
electronic control means configured to control the g
force.
In one embodiment, the one or more delivery isms may
include a carrier gas.
In one embodiment, the interface is about 1cm to 50cm in
length.
In one embodiment, the nce is ammonium and the gas
is ammonia gas.
In one embodiment, the hydrophobic barrier may be capable
of separating the ammonium in the dialysate from the
ammonia gas in the ace.
In one embodiment, the substance is a volatile organic
compound used for the detection of l ions.
In one embodiment, the hydrophobic barrier may be a
degasser barrier.
In one embodiment, the hobic barrier may be a
bacteria filter.
In one embodiment, the hydrophobic barrier is in direct
contact with the dialysate.
In one ment, the interface may include one or more
ammonia gas compatible materials.
In one embodiment, the ace may be a non-porous
material.
In one embodiment, the interface may include condensation
reduction means within the interface.
In one embodiment, the system may further include an
electronic processor electrically connected to the
detector, the electronic processor configured to obtain
readings from the or, process the readings and/or
trigger an alarm when the readings exceed a predetermined
threshold.
An alternate aspect of the present invention provides a
dialysis device that includes: the sensing system as
described above; and a sorbent cartridge. The detector may
be an ammonia detector that is capable of detecting
ammonia gas. The amount of detected ammonia gas may
provide an indication of the exhaustion of the sorbent
cartridge.
In one embodiment, the dialysis device may be a peritoneal
dialysis device.
In one embodiment, the dialysis device may be a
hemodialysis device.
An ate aspect of the present invention es a
method of detecting ammonium in a dialysate. The method
may include the steps of providing a hydrophobic barrier
capable of ng ammonium in the dialysate to
equilibrate to ammonia gas; ing a detector capable
of detecting ammonia gas; ing a channel n the
hydrophobic barrier and the detector, and configuring the
channel to allow fluid communication of the ammonia gas;
and providing one or more delivery mechanisms capable of
transporting the ammonia gas from the hydrophobic barrier
to the detector.
Brief Description of Drawings
The accompanying drawings illustrate a disclosed
embodiment and serve to explain the principles of the
disclosed embodiment. It is to be understood, however,
that the drawings are designed for purposes of
illustration only, and not as a tion of the limits
of the invention.
Fig. 1a is a schematic diagram of one embodiment of the
disclosed dialysis device.
Fig. 1b is a schematic diagram of one ment of the
disclosed dialysis device, wherein the flow of the
dialysate is toward the e chamber from the
peritoneal cavity.
Fig. 1c is a schematic diagram of one embodiment of the
disclosed is device, n the flow of the
ate is from the storage chamber to the peritoneal
cavity.
Fig. 1d is a schematic m of one embodiment of the
disclosed dialysis .
Fig 1e is a schematic diagram of one embodiment of the
disclosed dialysis device.
Fig 1f is a schematic diagram of one embodiment of the
disclosed dialysis device.
Fig. 2a is a schematic m of an alternative
embodiment of the disclosed dialysis device, wherein the
flow of the dialysate is toward the storage chamber from
the peritoneal cavity.
Fig. 2b is a schematic diagram of the embodiment of Figure
2a, wherein the flow of the dialysate is from the storage
chamber toward the peritoneal cavity.
Fig. 3 is a graphic representation of the flow control of
the dialysate according to an embodiment of the present
disclosure.
Figs. 4a-d are a cross nal views of a prototype of a
disposable housing in ance with an embodiment of the
present disclosure.
Fig. 5 is a perspective view of a prototype of one
embodiment of the dialysis device disclosed herein.
Fig. 6 is a schematic diagram of one embodiment of the
disclosed disposable housing comprising a discrete
additive dispensing means.
Fig. 7 is a schematic diagram of one embodiment of the
disclosed dialysis device comprising a discrete additive
dispensing means in locking ment with a disposable
housing in accordance with the disclosure.
Fig. 8 is a cross sectional view of a sealed connector of
the additive dispensing means in accordance with the
disclosure.
Fig. 9 is a cross sectional view of a sealed connector of
the additive dispensing means in ance with the
disclosure.
Fig. 10 is a cross sectional view of an embodiment of an
additive dispensing means in accordance with the
disclosure.
Fig. 11 is a cross sectional view of an embodiment of an
ve dispensing means in accordance with the
disclosure.
Fig. 12a-c is a cross sectional view of an embodiment of
an automatic dispensing system in accordance with the
disclosure.
Fig. 13 is a graphic representation of the voltage drop of
a rechargeable y versus dialysis time in a dialysis
device in accordance with the disclosure.
Fig. 14 is a graphic representation of the voltage drop of
a rechargeable battery versus is time with constant
pumping in a device in accordance with the disclosure.
Fig. 15 is an ment of a degasser in a device in
accordance with the disclosure.
Fig. 16 is an embodiment of a fibrin trap in a device in
accordance with the disclosure.
Fig. 17 is an embodiment of a power-connecting switch in
accordance with the disclosure.
Fig. 18 is a schematic of an a sensing system
according to an embodiment of the invention.
Fig. 19 is a schematic of another ammonia sensing system
according to an embodiment of the invention.
Fig. 20 is a schematic of a r ammonia sensing system
according to an embodiment of the invention.
Figs 21a-21d provide schematics of four example
configurations of embodiments of the ammonia g
system.
Figs 22a and 22b rate the dialysate in-flow and
dialysate out-flow phases of the embodiment of the ammonia
sensing system shown in Fig. 21a.
Fig. 23 shows one example of a timing diagram for a
control method implemented for the embodiment of the
ammonia sensing system shown in Fig. 21a.
Figs. 24(a) and (b) are graphs showing the results
obtained from one example embodiment of the present
invention using an electrical ammonia or.
Fig. 25 is a schematic of a controller system for an
ammonia g system according to an embodiment of the
invention, in fluid communication with a disposable
sorbent cartridge of a is device.
In the figures, like numerals denote like parts.
Detailed Description of the Embodiments
Referring to Fig 1a, there is shown one embodiment of
the disclosed dialysis device (200).
The dialysis device comprises a disposable housing
(10) having a flow path in the form of conduit (20), a
controller in the form of a control housing (30) for
controlling the operation of the disposable housing (10).
In this figure the disposable housing (10) and control
housing (30) are not operably connected to each other.
The able housing (10) and control housing (30)
se interface means in the form of a conduit
connector (40a) disposed on said control housing (30) and
(40b) disposed on the disposable housing (10) capable of
connecting the control housing and the disposable housing.
The disposable g (10) and control housing (30) are
t into operative engagement when the conduit
connector (40a) is brought into locking engagement with
conduit connector (40b) The conduit (20) of the
able housing (10) is fluidly sealed from the control
housing (30) and conduit tor (40a,40b).
The dialysis device comprises a le dialysate
tube (50) which is capable of being in fluid communication
with the peritoneal cavity (60) and a conduit (20). The
dialysis device further ses a e chamber (70)
located in a rigid compartment (180). The storage chamber
(70) comprises a deformable diaphragm (71) integrally
formed in one of the walls of the storage chamber (70).
The deformable diaphragm (71) is in fluid communication on
one side with the dialysate conduit (20) and, on another
opposite side, in fluid communication with a pressure
r (80). When the disposable housing (10) and
control housing (30) are operably coupled to each other,
the conduit connector (40a,40b) fluidly couples the
pressure chamber (80) of the disposable housing (10) to a
pump (90) located in the control housing (30).
The pump (90) is ured to actuate the deformable
diaphragm (71), by inducing a pressure change in the
pressure chamber (80) which deforms the deformable
diaphragm (71) and thereby moves dialysate within said
dialysate conduit (20).
Check valves (100,101,102,103) are disposed along the
conduit (20) and are configured to, in the outflow mode,
allow the dialysate to flow from the peritoneal cavity
(60) to the storage chamber (70), and in the inflow mode
allow the dialysate to flow from the storage chamber (70)
to said sorbent zone (110) for l of contaminants
therein, and further permit the dialysate substantially
free of said contaminants to flow back to the peritoneal
cavity (60).
The able housing is also provided with an
enrichment module (120), for dispensing a preselected
amount of an ment solution into the dialysate, in
fluid communication with the conduit (20) via a conduit
(130). The enrichment module is also in fluid
communication with an enrichment solution reservoir (121).
The pump (90) is in fluid communication with a deformable
membrane (72) of the enrichment module 120 via conduit
connector 0b), when the disposable housing (10) and
control housing (30) are in operable engagement.
An ammonia sensor (140) is also provided downstream
of the sorbent zone (110) to detect any ammonia in the
ate. Ammonia is ed by the ammonia detector
(141) when the able housing (10) and control housing
(30) are ly d to each other.
A degasser in the form of a hydrophobic membrane
(150) is also located downstream of the sorbent zone. The
external side of the hydrophobic membrane (150) is in
fluid communication with a vacuum pump (151) via the
conduit connector (40a, 40b) when the control housing and
disposable housing are operably coupled.
Referring now to Fig 1b, there is the embodiment of
Fig. 1a showing the disposable housing (10) and control
g (30) operably coupled with each other, ing
in an outflow mode, wherein the flow of the dialysate is
toward the e chamber (70) from the peritoneal cavity
(60) of a patient. The pump (90) es the deformable
diaphragm (71), by inducing negative pressure in the
pressure chamber (80). The ve re in the
re chamber (80) deforms the deformable diaphragm
(71) by biasing the deformable diaphragm (71) in the
direction of arrow A and thereby moves dialysate from said
peritoneal cavity (60) of the patient into the dialysate
conduit (20) via bubble trap (51). The dialysate flows to
the storage chamber (70) through check valve (100). A
pressure sensor (170) is located in operable communication
with the pump (90) to establish a preselected negative
pressure within the pressure chamber (80) and to ine
if the pressure of the dialysate being withdrawn from the
peritoneal cavity (60) is within a safe limit.
The pump (90) operates intermittently under the
control of the pressure sensor (170) to maintain the
ve pressure in the pressure chamber (80) within a
preselected range. Once the storage chamber (70) is full
of dialysate, this is detected by the pressure sensor
(170), triggering the inversion of the pump direction and
thus converting the system to an inflow mode.
The pump 90 is also in fluid communication with a
diaphragm (72) integrally formed in a wall of said
enrichment module (120). At the same time as the storage
chamber (70) is actuated under negative pressure, the
enrichment module (120) is also actuated under negative
pressure by the pump (90), such that a predetermined
amount of an ment solution is withdrawn from an
enrichment solution reservoir (121) though check valve
(103) into the enrichment module (120). Check valve (102)
ensures that no dialysate is awn into the enrichment
module (120) from the conduit (20).
Referring to Fig 1c, the flow system of Figure 1b is
shown in the inflow mode, wherein the flow of the
dialysate is from the storage chamber (70) to the
peritoneal cavity (60). Once the storage r (70) is
full, the pump (90) actuates the deformable diaphragm
(71), by inducing positive pressure in the pressure
r (80).
The positive pressure in the pressure chamber (80)
deforms the deformable diaphragm (71) by biasing the
deformable diaphragm (71) in the direction of arrow B and
thereby moves dialysate from the storage chamber (70) and
check valve (100) closes preventing dialysate from
returning to the peritoneal cavity (60) before being
treated to remove contaminants.
The pressure sensor (170) monitors the pressure in
the pressure chamber (80) to ensure that the pressure of
the dialysate being returned to the peritoneal cavity (60)
in the inflow mode is within a safe limit.
The dialysate flows from the storage chamber (70)
into the sorbent zone (110) through check valve (101).
The regenerated dialysate from the t zone (110) then
flows past a degasser in the form of a hydrophobic
membrane (150). The external side of the membrane is
subjected to negative re by a vacuum pump (151) to
aid the removal of gas generated during the dialysis
procedure. The dialysate then flows through an ammonia
sensor (140) which monitors the level of ammonia in the
rated dialysate, to ensure that the ammonia level
does not exceed a safe limit, prior to returning to the
neal cavity (60) of a patient. Ammonia is detected
by the a detector (141).
The regenerated dialysate then flows past an
enrichment module (120). In the inflow mode, the pump
(90) actuates the diaphragm (72) of the enrichment module
(120), which has previously been primed with a volume of
enrichment solution from the enrichment solution reservoir
(121), under positive pressure. As the ment module
(120) is actuated, check valve (103) closes to ensure that
the enrichment solution does not flow back into the
enrichment solution reservoir (121). The enrichment
module (120) then dispenses a preselected amount of
enrichment solution containing desired substances, such as
electrolytes, osmotic agents, nutrients, medication and
the like, into the dialysate conduit (20) through check
valve (102) and conduit (130).
The regenerated dialysate then flows back to the
peritoneal cavity (60) through the bubble trap (51) and
flexible dialysate conduit (50).
As in the outflow mode, the pump (90) is operated
intermittently under the control of the pressure sensor
(170) to maintain the ve pressure in the pressure
chamber (80) within a preselected range. Once the e
chamber is empty of dialysate, the pressure sensor (170)
detects this and inverts the pump direction and converts
the system to the outflow mode to repeat the dialysis
cycle.
Referring to Fig 1d, there is presented an
alternative embodiment of the dialysis device according to
the disclosure. The dialysis device (200) works in
essentially the same way as the device described in Figs
1a-c. The regenerated dialysate from the sorbent zone
(110) flows past a degasser in the form of a hydrophobic
membrane (150). The external side of the ne is
subjected to ve pressure by a vacuum pump (151) in
fluid communication with the hydrophobic membrane to aid
the removal of gas generated during the is
procedure. Differing from 1a-c, the gas vented from the
dialysate is then passed through an ammonia sensor (140)
located in the control g (30). The ammonia sensor
monitors the level of ammonia in the gas vented from the
dialysate to ensure that the ammonia level does not exceed
a safe limit, prior to returning the dialysate to the
peritoneal cavity (60) of a patient.
Referring to Fig 1e, there is shown an alternative
embodiment of the dialysis device according to the
disclosure. The dialysis device (200) works in
essentially the same way as the device described in Figs
1a-c. However, the pump (90) also subjects the
hydrophobic membrane (150) via the t connector (not
shown) and valve (104) to negative pressure during an
outflow mode (where dialysate is received from a patient’s
peritoneal cavity (60) via a le dialysate tube
(50)). Valve (104) ensures that no gas is introduced into
the dialysate path via the hydrophobic ne (150)
during an inflow mode, when the pump (90) subjects the
pressure chamber (80) to positive pressure. Ammonia gas
released from the dialysate is then detected by the
ammonia sensor (140).
Referring to Fig 1f, there is shown an alternative
embodiment of the dialysis device according to the
disclosure. The dialysis device (200) works in
essentially the same way as the device described in Figs
1a-c. However, the pump (90) is in fluid communication
with both the pressure chamber (80) and the enrichment
module (120) via a single connection (41) in the
disposable housing (10). The pump (90) also subjects the
er in the form of a hydrophobic membrane (150) to
negative pressure during an outflow mode (where dialysate
is received from a patient’s peritoneal cavity (60) via a
le dialysate tube (50)). During an inflow mode the
pump (90) subjects the pressure chamber (80) to positive
pressure. Valve (104) ensures that no gas is introduced
into the dialysate path via the hydrophobic membrane (150)
during an inflow mode, when the pump (90) subjects the
pressure chamber (80) to positive pressure. Ammonia gas
released from the dialysate is then detected by the
ammonia sensor (140).
Referring to Fig 2a, there is presented an
ative embodiment of the flow system (201) in
accordance with the present sure wherein the flow of
the dialysate is toward the e chamber (70) from the
peritoneal cavity (60), i.e. outflow mode. The pump (90)
actuates the deformable diaphragm (71), by ng
negative pressure in the re chamber (80). The
negative pressure in the pressure chamber (80) deforms the
deformable diaphragm (71) by biasing the deformable
diaphragm (71) in the direction of arrow A and thereby
moves dialysate from said peritoneal cavity (60) of the
t into the dialysate conduit (20) via bubble trap
(51). The dialysate flows to the storage chamber (70)
d in a rigid compartment (180) through check valve
(100). A re sensor (170) is located in operable
communication with the pump (90) to establish a
preselected negative pressure within the pressure chamber
(80) and to determine if the pressure of the dialysate
being withdrawn from the peritoneal cavity (60) is within
a safe limit.
The pump (90) operates intermittently under the
control of the pressure sensor (170) to maintain the
negative pressure in the pressure chamber (80) within a
ected range. Once the storage chamber (70) is full
of dialysate, this is ed by the pressure sensor
(170) which inverts the pump direction and converts the
system to an inflow mode.
An enrichment module (120) is ed in fluid
communication with the conduit (20) via a conduit (130).
The enrichment module (120) is configured to be actuated
by a syringe pump (91) in the inflow mode.
Referring to Fig 2b, the flow system of Figure 2a is
shown in the inflow mode, wherein the flow of the
dialysate is from the storage r (70) to the
peritoneal cavity (60). Once the storage chamber (70) is
full, the pump (90) es the deformable diaphragm
(71), by inducing positive pressure in the pressure
chamber (80). The positive pressure in the pressure
chamber (80) deforms the deformable diaphragm (71) by
biasing the deformable diaphragm (71) in the direction of
arrow B and y moves dialysate from the storage
chamber (70) and check valve (100) closes preventing
dialysate from returning to the peritoneal cavity (60)
before being treated to remove contaminants.
The pressure sensor (170) monitors the pressure in
the pressure chamber (80) to ensure that the pressure of
the dialysate being returned to the peritoneal cavity (60)
in the inflow mode is within a safe limit.
The ate flows from the e chamber (70)
into the sorbent zone (110) h check valve (101).
The regenerated dialysate from the sorbent zone (110)
flows past a degasser in the form of a hydrophobic
membrane (150) located upstream of a check valve (105).
The presence of check valve (105) results in a positive
pressure gradient across the hydrophobic membrane which
permits the l of any unwanted gas emitted during the
dialysis operation. The dialysate then flows through an
ammonia sensor (140) which monitors the level of ammonia
in the regenerated dialysate, to ensure that the ammonia
level does not exceed a safe limit, prior to returning to
the peritoneal cavity (60) of a patient.
The regenerated dialysate then flows past an
enrichment module (120). In the inflow mode, the syringe
pump (91) actuates the ment module (120), which
contains a volume of enrichment solution under positive
pressure. The enrichment module (120) then ses a
ected amount of enrichment solution containing
desired substances, such as electrolytes, osmotic agents,
nutrients, medication and the like, into the dialysate
conduit (20) via conduit (130). The syringe pump (91)
only operates in the inflow mode.
The regenerated dialysate then flows back to the
peritoneal cavity (60) through the bubble trap (51) and
flexible dialysate conduit (50).
As in the outflow mode, the pump (90) is operated
intermittently under the control of the pressure sensor
(170) to maintain the positive pressure in the pressure
chamber (80) within a preselected range. Once the storage
chamber is empty of dialysate, the pressure sensor (170)
detects this and inverts the pump direction and converts
the system to the outflow mode to repeat the dialysis
cycle.
Fig. 3, shows a graphic entation of the flow
control of dialysate in an embodiment of the dialysis
device according to the present sure. The phases of
the flow control in Fig. 3 are separated into “outflow,
w” and “dwell”.
In an outflow mode, a negative actuating pressure is
produced by a pump, which is operated intermittently under
the control of a pressure . As can be seen in Fig.
3, the negative re in the pressure r is
maintained within the limits of a preselected upper and
lower pressure. Unobstructed flow of dialysate is
indicated by uous ) relief of (negative)
pressure during the off-times of the pump. The
measurement of the time which passes during the pressure
relief (tR - relaxation time) may be used to estimate the
effected fluid flow speed. When the storage chamber is
full of dialysate, the pressure cannot be relieved anymore
and the pressure becomes static for a period of time (tS –
static time). This is detected by a pressure sensor,
which triggers the reversal of the pump to an inflow mode.
The average "outflow" flow rate is equal to the volume of
the storage chamber ("tidal volume") divided by the time
required to fill the storage chamber completely. This
rate is dependent on the choice of preselected pressure
limits and can be modified accordingly.
During the inflow mode a positive actuating pressure
is produced by the pump. The dialysate contained in the
storage chamber is subsequently forced through the sorbent
zone of the device and is then returned to the patient.
The pump is operated intermittently, such that the
positive pressure is regulated between ected upper
and lower pressure limits. The fluid in the storage
chamber is forced through the t cartridge, thereby
ing the (positive) pressure. The duration of this
relief can be used to estimate the flow rate (tR -
relaxation time). When the pump chamber is empty, the
pressure cannot be relieved anymore and the pressure
becomes static for a period of time (tS – static time),
indicating completion of the w" phase. The average
"inflow" flow rate equals the volume of the storage
chamber divided by the time required to complete "inflow".
Fig. 3 also shows a wait time or “dwell” time (tW).
This period is used to control the overall fluid exchange
rate: overall flow rate equals storage r volume
(tidal volume) divided by the total cycle time (tC =
outflow + inflow + dwell). For example, if a specific
overall ge rate is desired, then the system can use
the dwell time as a flexible wait time until the desired
total cycle time has passed.
Fig. 4a shows a ype disposable housing (400) in
accordance with an embodiment of the present sure.
Fig. 4b shows a cross sectional view of the disposable
housing taken along axis A-A of Fig. 4a. The disposable
housing comprises an enclosure (401) ng an or
(402) for receiving a control housing (not shown) via a
conduit connector (403). The disposable housing comprises
a rigid compartment (404) defining a pressure chamber
(405) in which a storage chamber (406) is disposed. The
storage chamber has a deformable diaphragm (420)
integrally formed in a wall f. The storage r
(406) is in fluid communication with a sorbent zone (407),
via a fluid channel (416).
The sorbent zone (407) comprises a check valve (409,
see Fig. 4c and 4d) in fluid communication with a degasser
in the form of a hydrophobic membrane (410).
Fig. 4c provides a cross-sectional view of the
t module along axis C-C of Fig. 4a. An enrichment
module (411) is in fluid communication with an enrichment
solution reservoir (412) via a check valve (413). The
enrichment module (411) is also in fluid ication
with the conduit of dialysate via check valve (414).
Fig. 4d provides a cross-sectional view of the
sorbent module along axis D-D of Figure 4a. The
regenerated dialysate exits the disposable housing via
check valve (409) and outlet (415).
In use during an outflow mode, the control housing
(not shown) is located in the interior (402) of the
disposable housing (400, see Fig. 4a and 4b). The pump in
the control housing actuates the deformable agm
(420) located in the wall of the storage chamber (406),
via the conduit connector (403, see Fig. 4b) by
transmitting pump fluid from the conduit connector (403)
thereby inducing negative re in the pressure chamber
(405). The negative pressure in the pressure chamber
(405) moves dialysate from the peritoneal cavity of the
patient into the storage chamber (406) through check valve
(408). At the same time as the storage chamber (406) is
actuated under negative pressure, the enrichment module
(411, see Fig. 4c) is also actuated under negative
pressure by the pump such that a predetermined amount of
an enrichment solution is withdrawn from an enrichment
solution reservoir (412) though check valve (413) into the
enrichment module (411).
In use during the inflow mode once the storage
chamber (406) is full, the pump actuates the deformable
diaphragm (420) located in the wall of the storage chamber
(406) via the conduit connector (403) by transmitting
fluid to the conduit connector (403) and thereby inducing
ve pressure in the pressure chamber (405). The
positive pressure in the re chamber (405) moves
dialysate from the storage chamber (406) and check valve
(408) closes preventing dialysate from returning to the
neal cavity before being treated to remove
contaminants. Dialysate flows from the storage r
(406) into the sorbent zone (407) through channel (416).
The regenerated dialysate exiting from the sorbent zone
(407) flows past a hydrophobic membrane (410) to remove
any unwanted gas emitted during the dialysis operation.
The degassed dialysate then flows past an enrichment
module (411), a check valve (409) and exits the disposable
housing via tube connector (415).
In the inflow mode, the pump also es the
enrichment module (411) under positive pressure and check
valve (413) . The enrichment module (411) dispenses
a preselected amount of enrichment solution containing
desired substances, such as electrolytes, osmotic agents,
nutrients, tion and the like, into the dialysate
through check valve (414). The dialysate is then returned
to the peritoneal cavity via a check valve (409) and a
tube connector (415).
Referring now to Fig. 5, there is shown a picture of a
prototype of one ment of the entire flow system
disclosed herein, with a disposable housing (500) and the
control housing (510).
Referring to Fig 6, there is shown one embodiment of a
disposable housing (601) having a flow path in the form of
conduit (20). The disposable housing (601) comprises a
flexible dialysate tube (50) which is capable of being in
fluid communication with the peritoneal cavity (60) and a
conduit (20). The dialysis device further ses a
storage chamber (70) located in a rigid compartment (180).
The storage chamber (70) comprises a deformable agm
(71) integrally formed in one of the walls of the e
chamber (70). The deformable diaphragm (71) is in fluid
ication on one side with the dialysate conduit (20)
and, on another opposite side, in fluid communication with
a pressure chamber (80).
The pump (670) is ured to actuate the deformable
diaphragm (71), by inducing a pressure change in the
pressure chamber (80) which deforms the deformable
diaphragm (71) and y moves dialysate within said
ate conduit (20).
Check valves (100,102,103,105) are disposed along the
conduit (20) and are configured to, in the outflow mode,
allow the dialysate to flow from the peritoneal cavity
(60) to the storage chamber (70), and in the inflow mode
allow the dialysate to flow from the storage chamber (70)
to said sorbent zone (110) for removal of contaminants
therein, and further permit the dialysate substantially
free of said contaminants to flow back to the peritoneal
cavity (60).
The disposable housing is also provided with a discrete
enrichment module (620), for dispensing a preselected
amount of an enrichment solution into the ate. The
enrichment module is not in fluid communication with the
dialysate flow path in this figure. The ment module
comprises an enrichment solution reservoir (621), a
ner in the form of a bag manufactured from a
biocompatible material for holding the enrichment solution
(not shown). The enrichment module (620) is provided with
a connector (622) adapted for fluid communication with the
dialysate conduit (20) of the disposable housing (601).
The connector (622) is sealed prior to insertion into the
disposable housing to maintain the sterility of the
enrichment solution in the ment module (620). The
disposable housing is provided with a male connector (623)
of complementary configuration to the connector (622)
located on the enrichment module (620). When in mating
engagement (see Figure 7) the male connector (623) serves
to break the seal of the connector (622) to form a fluid
connection between the enrichment reservoir (621) in the
enrichment module (620) and the dialysate conduit (20) of
the disposable g (601).
The disposable housing (601) also comprises an ment
pump (660) for adding a predetermined amount of enrichment
solution to the dialysate conduit (20).
A degasser in the form of a hydrophobic membrane (150) is
also located downstream of the sorbent zone (110). The
external side of the hydrophobic membrane (150) is in
fluid communication with air ts (630 and 631).
A hydrophilic membrane (610) is disposed in the degasser
compartment, in the dialysate flow path and directly
ream of the hydrophobic degasser membrane (150).
The hydrophilic membrane (610) serves as a barrier to
prevent gas, particles and bacteria contained in the
dialysate exiting the sorbent zone (110) from reaching the
peritoneal cavity (60). The membrane also es a
backpressure facilitating the venting of gas through the
degasser membrane (150).
Referring to Fig 7, there is shown an embodiment of
the disclosed dialysis device (700). The dialysis device
comprises a disposable housing (601) having a flow path in
the form of conduit (20), a controller in the form of a
control housing (690) for controlling the operation of the
disposable housing (601). The disposable housing (601)
and l housing (690) comprise ace means in the
form of conduit connectors (691a, 691b, 691c) that connect
the control housing (690) and the disposable housing
(601). The disposable housing (601) and control housing
(690) are brought into operative engagement when the
conduit connectors are brought into locking engagement.
The t (20) of the disposable g (601) is
y sealed from the control housing (690) and conduit
connectors (691a, 691b, 691c).
The dialysis device (700) comprises a flexible
ate tube (50) which is capable of being in fluid
communication with the peritoneal cavity (60) and a
conduit (20). The dialysis device r comprises a
storage chamber (70) located in a rigid tment (180).
The storage chamber (70) comprises a deformable diaphragm
(71) integrally formed in one of the walls of the storage
chamber (70). The deformable diaphragm (71) is in fluid
communication on one side with the dialysate conduit (20)
and, on another opposite side, in fluid communication with
a pressure chamber (80). When the disposable housing
(601) and control housing (690) are ly coupled to
each other, the conduit connector (691a, 691b, 691c)
y couples the pressure chamber (80) of the
able housing (601) to an air pump (670) located in
the control housing (690).
The air pump (670) is configured to actuate the
deformable diaphragm (71), by inducing a pressure change
in the re chamber (80) which deforms the deformable
diaphragm (71) and thereby moves dialysate within said
dialysate conduit (20).
Check valves (100,102,103,105) are ed along the
conduit (20) and are configured to, in the outflow mode,
allow the dialysate to flow from the neal cavity
(60) to the storage chamber (70), and in the inflow mode
allow the dialysate to flow from the storage chamber (70)
to said sorbent zone (110) for removal of contaminants
therein, and r permit the dialysate substantially
free of said contaminants to flow back to the peritoneal
cavity (60).
In this figure the discrete enrichment module (620),
is located in the disposable housing (601). The connector
(622) of the ment module (620) is in mating
engagement with the male connector (623) of the disposable
housing to form a fluid connection between the enrichment
reservoir (621) in the enrichment module (620) and the
dialysate conduit (20) of the disposable housing (601).
The disposable housing (601) also ses an
enrichment pump (660) for adding a predetermined amount of
enrichment solution to the dialysate conduit (20).
The enrichment pump (660) is a fixed displacement pump
comprising a diaphragm (661) in fluid communication with
the air pump (670). The air pump (670) exerts a positive
or a negative air pressure to the diaphragm (661) of the
enrichment pump (660) and the deformable diaphragm (71) of
the storage chamber (70), functioning as pneumatic pump
for cycling dialysate h the dialysate conduit (20)
at the same time. On one side of the diaphragm (661) in
the enrichment pump (660) is an air compartment which
fluidly connects to the air pump (670), and the other side
is the enrichment solution tment ting to the
enrichment reservoir (621) reservoir via the mated
connectors (622,623). When the enrichment solution
compartment is subjected to negative pressure enrichment
solution is drawn from the enrichment reservoir (621).
When a positive pressure is applied to the air
compartment, the enrichment solution is forced out of the
enrichment pump (660) into the dialysate conduit (20).
A degasser in the form of a hydrophobic membrane (150) is
also located ream of the sorbent zone (110). The
external side of the hydrophobic membrane (150) is in
fluid communication with air conduits (630 and 631). In a
normal dialysis operation, air conduit (630) is an outlet
to the ammonia sensor (140) and air conduit (630) is in
fluid ication with the air pump (670). During
ing, the air pump (670) in the control housing (690)
exerts a negative pressure to remove any gas from the
ate in the dialysate conduit (20). A check valve
(680) prevents external air from entering air conduit
(630).
A hydrophilic membrane filter (610) downstream of the
hydrophobic ne (150) prevents gas, particles and
bacteria contained in the dialysate from reaching the
peritoneal cavity (60). The membrane (610) also produces
a backpressure facilitating the venting of gas through the
hydrophobic membrane (150).
Figures 8a and 8b show an embodiment of a sealed connector
(622) in accordance with the present invention. The
connector (622) on the ment module (620) is provided
with a plug (800) that can be dislodged by the connector
(623) located on the disposable housing (601). In figure
8b the connector (622) on the enrichment module is brought
into mating engagement with the connector (623) on the
disposable housing (601) to dislodge the plug (800).
Figures 9a and 9b show an embodiment of a sealed connector
(622) in accordance with the present invention. The
connector (622) on the enrichment module (620) is provided
with a plug (800) that can be pierced by the tor
(623) located on the disposable housing (601). In figure
8b the connector (622) on the enrichment module is t
into mating engagement with the tor (623) on the
disposable housing (601) to pierce the plug (800).
s 10a and 10b show the embodiment of a sealed
connector of Figure 9a and 9b. The connector (622) on the
enrichment module (620) is provided with a plug (800) that
can be d by the connector (623) located on the
disposable housing (601). In figure 10b the connector
(622) on the enrichment module is brought into mating
engagement with the connector (623) on the disposable
g (601) to pierce the plug (800). The enrichment
module is a rigid container for holding the additive
solution, comprising a sponge (1001) located at an end of
the container in communication with a connector (622).
The sponge facilitates delivery of the enrichment on
from the enrichment reservoir (621) to the dialysate
conduit (20).
Figure 11 shows another embodiment of a container in the
enrichment module (620). In this figure the container is
in the form of a resiliently deformable bottle (1101).
The bottle on the left hand side is full of enrichment
on. The bottle on the right hand side of the figure
is depleted.
Figure 12a shows a cross-sectional view of the enrichment
pump (660). The enrichment module (620) comprises an
enrichment reservoir (621) in fluid communication with the
enrichment pump (660) via the mated connectors (622 and
623). The enrichment pump (660) is provided with a
agm (661) which defines an air chamber (662) in
fluid communication with the air pump (not shown) and an
enrichment on chamber (663) in fluid communication
with the enrichment oir (621).
Figure 12b shows a close up view of figure 12a in an
outflow cycle. When the air pump exerts a negative
pressure beyond 50 mmHg, in the dialysate outflow cycle,
enrichment solution is drawn from the enrichment reservoir
(621) into the enrichment solution chamber (663) of the
enrichment pump (660).
Figure 12c shows the enrichment pump (660) in an inflow
cycle. In the inflow cycle when a positive pressure
greater than 200 mmHg is exerted in the air chamber (662),
the enrichment solution chamber (663) will be emptied and
a fixed volume of enrichment solution, VEP, will flow to
and merge with the ate in the dialysate conduit via
outlet (1201).
Figures 13 and 14 show the results of battery tests on a
dialysis device in accordance with the disclosure. The
purpose of the experiment was to ine the minimum
capacity of the battery that is needed to support the
operation of a high ty dialysis cartridge for at
least 12 hours. Based on an average power consumption of
153mA of the system, for a 12 hour operation, the minimum
battery capacity needed would be at least 1836mAh. Thus,
to retain at least 80% of the battery capacity over a
year, the minimum y needed will be 2203mAH. This is
according to the retentive specifications of the battery,
where the y capacity will drop to 80% of its overall
ty when its operation cycle is more than 300 cycles
(1836mAh x 120%). To determine the actual usage duration
for the system, 2 tests were performed using an 11.1V,
2250mAH, Lithium Polymer y.
Test #1:
Taking a representative operation scenario for a normal
flow control, where the pump is being turned ON and OFF to
maintain at either 400mmHg (Inflow) or -100mmHg (Outflow),
without a relaxation of the re, the result showed
that a 2250mAh capacity battery was able to support the
mentioned operation for 18Hrs before it was shut down by
the firmware at 10.5V. Figure 13 shows the graph showing
the voltage drop of the battery versus the operation time
in this experiment.
Test #2:
In the second test, assuming the worst case scenario that
the pump is constantly ON for the whole inflow and outflow
cycle operation, the results show that the battery can
last for 14.5Hrs before it was shut down by the firmware
at 10.5V. Below is the graph showing the voltage drop of
the battery versus the operation time in this experiment.
Figure 15a shows an exploded view of a degasser (1501) in
accordance with the sure. The degasser comprises a
gas vent means in the form of two hydrophobic membranes
(1502) and (1503). The hobic membranes are arranged
in parallel on either side of a hydrophilic membrane
(1504). Each hydrophobic membrane (1502 and 1503) is
located adjacent to air vents (1505 and 1506). The
degasser is also provided with air inlets/outlets (1507
and 1508) and a dialysate outlet (1509). The hydrophilic
membrane is curved to facilitate the flow of gas in the
dialysate to the hydrophobic nes and subsequently
the air vents to remove gas from the dialysate in the
dialysate conduit of the dialysis device. In use a 4
micro paper filter seals the top of the sorbent zone in
the dialysis device and is covered by the degasser. The
hydrophilic ne is located adjacent to the paper
filter by a spacer (not . The hydrophilic membrane
reduces sorbent powder leakage from the t zone and
paper filter and also acts as a bacterial filter.
Referring to Figure 15b, in a normal dialysis operation, a
first air outlet (1507) is in fluid communication with an
ammonia sensor and a second air outlet (1508) is in fluid
communication with a ing exhaust via another
connecting air-port (not shown). When detecting for
ammonia gas presence in the case of sorbent cartridge
exhaustion, heric air flows through a throttle
valve, or any stable flow constrained , in the
controller, allowing a controlled amount of air to flow
through the first air outlet (1507), to an air conduit
above the hydrophobic membranes, and flow out from the
other end of the air conduit to the second air outlet
(1508), and circulate to an a sensor in the
controller. During degassing, the air pump in the
controller exerts a negative pressure to remove any gas,
in particular CO2, in the air conduit via the first air
outlet (1507) back to an exhaust in the controller.
ing to Figure 16, an exploded view of a fibrin
trap (1601) is shown. During dialysis, it is possible
that dialysate will contain some small amount of fibrin.
The trap comprises an inlet valve (1602) and a filter (not
shown) located opposite the inlet valve (1602). The inlet
valve is in the form of a resiliently deformable disk
hinged on a stud (1605) such that the hinge is located
away from the dialysate flow into the trap and thus will
not catch on any fibrin t in the dialysate. In use
the dialysate enters the trap through an inlet (1604) and
passes through the disk valve (1602). The disk valve is
located on a stud . During an outflow mode, the
disk valve (1602) is closed against the inlet (1604)
preventing the flow of dialysate from the sorbent zone to
the patient. The dialysate that enters the sorbent zone
may comprise fibrin. The fibrin is prevented from
entering the sorbent zone by the filter (1603) and is
ore retained in the trap .
Figure 17A shows a power-connecting switch in accordance
with an embodiment of an invention. The switch (1701) is
located in the controller (1702). The switch is in an
open condition when the controller (1702) is not d
to a disposable housing. A resiliently deformable
material, in the form of a rubber tube (1703), is located
in a channel (1704), immediately adjacent to the switch
(1701).
A pin (1705) is located on a breakable frame (1706) on the
able housing (1707), which is of complementary
configuration to the channel (1704) located on the
controller (1702). When the disposable housing and
controller are coupled together, the pin (1705) is
received in the channel (1704) and the frame is deformed
and broken (1708) by the controller (1702) (Figure 17B).
The pin (1705) when located in the channel (1704) exerts a
positive compressing force on the rubber tube (1703) which
closes the switch (1701). The frame continues to urge the
pin toward the rubber tubing to actuate the switch (1701)
into a closed condition (Figure 17B). The switch (1701)
now electrically connects the battery (not shown) to the
controller to permit the dialysis device to be used by a
patient. The fractured frame (1706) can no longer hold
the pin (1705) rigidly upright for the pin (1705) to get
inserted into the channel (1704) on the controller (1702)
again.
Applications
It is an age of the device that as the flow path is
fluidly sealed from the controller the sterility of the
device can be maintained by daily al of disposable
housing.
It is a further advantage of the dialysis device that a
single connector between the disposable housing and
controller is required, thus reducing the complexity of
setting the device up for operation.
It is a further age that the size of the dialysis
device according to the disclosure can be icantly
reduced relative to other dialysis devices.
It is a r advantage that the device according to the
disclosure is energy efficient.
It is an age of the device according to the
disclosure that as the fluid displacement means is
integrally formed with a wall of the e chamber this
s the pumping mechanism of the dialysis device to be
shared by the e r thereby permitting a
reduction in the size of the disposable housing. This is
further advantageous as it permits the construction of a
more portable and unobtrusive device to be used by a
It is a further advantage that the connector between the
disposable housing and the controller is fluidly sealed to
prevent biological or chemical contamination of the
device. It is an age of the device that, as the
flow path is fluidly sealed from the controller, the risk
of biological and/or al contamination of the
ate by the controller is significantly reduced.
It is a further advantage of the device that as only one
pump and only one interface connector is required this
reduces the requirement for additional pumps and
connections and thus results in a significant reduction in
the size of the dialysis device ve to known dialysis
devices.
It is a further advantage of the device of the disclosure
that as only one pump is required to activate a storage
chamber, an additive dispensing means and a gas vent
means, this further permits miniaturization of the device
and enhances portability and energy efficiency.
It is a further advantage that as only one pump is
required to activate the storage chamber, the additive
dispensing means and the gas vent means, there is a
significant reduction in the complexity of the device
which results in a decrease in manufacturing costs
relative to known dialysis devices.
It is a further age of the device that the pressure
sensor can also be used to measure a patient's
intraperitoneal pressure, without onal pressure
sensors.
Further embodiments of the present invention seek to
provide a biocompatible and remote ammonia g system
for peritoneal dialysis and ialysis. The sensing
system can advantageously monitor a dialysate’s ammonium
level continuously in a safe manner, while overcoming the
challenges of orting a limited amount of ammonia gas
to the ammonia sensing system. The sensing system is
capable of monitoring the regenerated dialysate ammonium
concentration from a remote distance, so as to function as
a safety mechanism for a dialysis device. The sensing
system according to example embodiments is especially
suitable for miniaturized le and le dialysis
devices.
The inventors have recognized that miniaturized portable
and wearable peritoneal dialysis devices require some
specific application conditions such as: (i) g the
ammonia sensing part away from the dialysate line to
maintain the dialysate’s sterility, (ii) keeping the
ammonia g components away from the hydrophobic
membrane to facilitate sorbent exchange, and ease of
designing and assembling the controller and disposable
dialysis housing, and (iii) making the dialysis device as
portable and wearable as possible.
However, providing the above-mentioned specific
application conditions pose several challenges. First, a
limited amount of ammonia gas is generated at the
hydrophobic barrier when the regenerated dialysate reaches
its safe margin ammonium level. Second, delivering the
d amount of ammonia gas to the a sensing
system (which may be in a remote on) and detecting
its presence can be difficult.
To transport a limited amount of ammonia gas to the
ammonia sensing system, the gas connection conduits have
to be ammonia gas compatible, which means the materials
should not react with or adsorb ammonia gas nor release
any ammonia gas or any similar chemicals.
To facilitate transportation of the limited amount of
ammonia gas, gas transportation at the interface between
the hobic r and the ammonia detector has to be
controlled. Additional means, including but not limited to
ucing extra driving forces to deliver gas to the
ammonia detector, can enhance the gas transport
ency. This can increase the sensitivity of the
remote ammonia sensing system.
Fig. 18 is a schematic of a sensing system 1800, according
to an embodiment of the invention. The sensing system 1800
may include a gas “generator” 1802, a detector capable of
detecting the generated gas 1804, an interface (e.g. a
gas conduit or channel) 1806 between the gas generator
1802 and the detector 1804, and an electrical system
ing an appropriate set of firmware (not shown). In
one embodiment, the sensing system 1800 is designed to
sense ammonia gas. In this embodiment, the gas generator
1802 is an a gas generator, and the detector 1804 is
an ammonia/ammonium detector.
While the sensing system 1800 described above, and the
various ate embodiments of sensing systems described
below are described in terms of ammonia detection, it is
understood that other types of gasses may also be detected
using the sensing systems bed. By way of example
and not tion, the systems may be configured to
detect volatile c compounds (VOC) such as acetone or
other biomarkers used for the detection of medical
conditions, CO2 O2, SO2, HCN, NOx, etc. As discussed below,
A dialysate flows into a liquid line 1808 at point 1809
and is passed through a sorbent cartridge comprising toxin
removers 1812. The dialysate flows out after toxin removal
at point 1810. The ammonia gas generator 1802 is in direct
contact with the dialysate liquid flow coming from the
toxin remover 1812.
The ammonia gas generator 1802 is the part where ammonia
gas (NH3) crosses a hydrophobic barrier, such as, but not
limited to a hydrophobic ne, a hollow fiber, etc,
and enters the gas phase. a (NH3) is in a pH
dependent equilibrium with ammonium (NH4+) in the
ate. The ammonia gas generator 1802 is disposed at a
point that is distal the ammonia detector 1804. The terms
“ammonia” and ium” may be used interchangeably in
the following description, e.g. “ammonia/ammonium
detector”. In an example embodiment, the ammonium (NH +) in
the dialysate equilibrates to ammonia gas (NH3). Although
the “detector” is configured to detect ammonia gas, the
concentration of NH4+ in the dialysate is proportional to
the NH3 gas generated. Thus, the “detector” can also be
thought of as an ammonium detector. Accordingly, in the
ption, the two terms are to be taken as
substantially equivalent.
In an embodiment, the ammonia gas generator 1802 may be a
hydrophobic barrier. The hydrophobic barrier is in direct
contact with the regenerated dialysate liquid flow. When
there is ammonium present in the dialysate, the ammonium
can equilibrate on the hobic er barrier to
generate ammonia gas. In one example embodiment, the
hydrophobic barrier is a degasser membrane or degasser
fabric / resin. In another embodiment, the hydropho bic
barrier is a bacteria filter.
In an embodiment, the ammonia detector 1804 is capable of
ing the presence of ammonia gas in the ammonia gas
generator 1802 of the hydrophobic barrier, which reflects
the ammonium tration in the regenerated dialysate on
the other side of the hydrophobic barrier (at the liquid
phase side of the hydrophobic r).
Various types of ammonia sensors may be used,
including chemical sensors (e.g. chemical sensitive
materials and matrix, pH sensitive colorimetric materials,
etc.), electrical sensors (e.g. semiconductor based
s, nano-particles, nano-wires and carbon nano-tubes,
graphene sensors, etc.), biological sensors and their
combinations and/or derivatives thereof. The terms
“sensor” and “detector” may be used interchangeably in the
ption and are to be taken as substantially
equivalent.
In an embodiment, the interface 1806 is a channel
configured to allow fluid communication of the ammonia gas
from the ammonia gas generator 1802 (at the gas phase side
of the hydrophobic barrier) to the ammonia gas or
1804 which is at a remote position. Materials used for the
channel are preferably neutral or basic (i.e. ammonia-gascompatible
) and rous. Ammonia-gas-compatible
als neither adsorb nor release any ammonia gas or
other similar chemicals. Non-porosity of the ace
material advantageously minimizes unnecessary physical
adsorption of the d amount of ammonia gas. Suitable
materials for the channel include, but are not limited to:
metals, polytetrafluoroethylene (PTFE) (“Teflon”),
polyvinyl chloride (PVC), acrylonitrile butadiene
styrene (ABS), polyethylene (PE), and polypropylene (PP).
In another embodiment, sensitivity of the ammonia sensing
system can be enhanced by optimizing the dimensions (e.g.
length, thickness, etc.) of the gas channel. In one
example embodiment, the l is about 1cm to about 50cm
in length.
In an embodiment, transportation of the ammonia gas to the
ammonia gas detector may be enhanced by reducing liquid
condensation within the interface. Since ammonia gas can
be easily dissolved in a neutral s liquid, a
reduction of liquid condensation in the interface channel
advantageously enhances ammonia gas transfer.
In an example embodiment, to enhance ortation of the
a gas, a heat isolation barrier may be used to
reduce the heat loss and to keep the system temperature as
constant as possible so as to minimize condensation. By
way of example and not limitation, the heat isolation
barrier may be a carrier bag having thermal isolation
padding for storing the wearable dialysis device. In yet
another embodiment, introduction of suitable ammonia-gascompatible
water absorbers within the gas channel
ageously absorb any potential condensation droplets.
Suitable water adsorbers include, but are not limited to:
alkaline or neutral materials, e.g. soda lime, cellulose
and its derivatives based polymers, etc.
In a r embodiment, an a-gas-compatible gas
adsorber may be used within the channel to minimize
interference and to enhance the sensitivity of the ammonia
g system. Suitable adsorbers e, but are not
limited to: alkaline or neutral materials, e.g. soda lime,
cellulose and its derivatives based polymers, etc.
Ammonia gas that has passed beyond the ammonia detector
1804 may be exhausted at point 1814 using suitable means
known to persons skilled in the art.
In an example embodiment, the remote ammonia sensing
system comprises a delivery ism/medium capable of
orting the ammonia gas from the point that is distal
the detector to the detector. In other words, the medium
facilitates transportation of the generated ammonia gas
from the hydrophobic barrier along the interface to the
ammonia sensor/detector. The medium can be chosen from a
list of gases, and electrical or magnetic field.
In one example embodiment, the gas is circulated around
the gas phase side of the hydrophobic barrier to
facilitate transportation of the ammonia gas from an
immediate position to a remote position of the gas phase
side of the hydrophobic r. The circulated gas
delivers the ammonia gas to the ammonia detector. In this
embodiment, an extra pump may be used to provide an extra
driving force.
Fig. 19 is a schematic of an ammonia sensing system 1900
using gas circulation, according to an embodiment of the
ion. The system 1900 includes a pump 1950 e
of providing an extra driving force. A dialysate flow
path 1908 is separated from a gas flow path 1906 by an
ammonia gas generator 1902. An ammonia detector 1914,
check valve 1952, and the pump 1950 are operably connected
to the gas flow path 1906. The pump 1950 provides a
driving force to circulate the ammonia gas and other
degassed gas mixture around the gas flow path 1906. A
one-way pump may be used, together with the check valve
1952 to create a unidirectional flow of gas around the gas
flow path 1906. The circulation configuration also has an
age over the back and forth pump configuration in
that only the delivery medium with highest concentration
of a gas from the generator is pushed to the
detector. This configuration may thus e a higher
sensitivity for the system.
In r ment, the degassed gas is moved back and
forth within the gas loop to deliver the ammonia gas to
the remote position of ammonia detector. In this
embodiment, an extra two-way pump may be used to provide
the driving force. Fig. 20 is a schematic of an ammonia
sensing system 2000 with providing reciprocating (back and
forth movement) of the gas, according to an embodiment of
the invention. The system 2000 includes a pump 2050
capable of providing an extra driving force. A dialysate
flow path 2008 is separated from a gas flow path 2006 by
an ammonia gas generator 2002. An ammonia detector 2014,
and the pump 2050 are operably connected to the gas flow
path 2006. The pump 2050 may be a two-way pump to move
the gas back and forth within the gas flow path 2006. In
this embodiment, an advantage that the back and forth
motion of the gas provides over the circulation type pump
is that, when the gas is pushed over the hydrophobic
barrier, it helps to ameliorate any potential microliquid-droplets
blocking the barrier. This configuration
produces less sation in experimental configurations
compared to the ation configuration. In this
embodiment, the back and forth motion of the gas has one
advantage over the circulation type pump. When the gas is
pushed over the hydrophobic barrier, it helps to
ameliorate any potential micro-liquid-droplets blocking
the barrier. This configuration produces less condensation
in experimental configurations compared to the circulation
configuration.
In yet another embodiment, an external gas may be used as
the delivery/carrier gas to deliver the ammonia gas to the
remote position of the ammonia or. In this
embodiment, the external gas may be introduced to the gas
loop via the main pump 2150 (see figs. 20). This is more
clearly rated in Fig 25. During the inflow phase of
the whole system, the system firmware controls the motion
of the valve 2506. Since the main system is under positive
pressure, a controlled portion of gas is released into the
gas interface via valve 2504, and uently reaches the
generator 2562 (hydrophobic barrier). Suitable external
gases include, but are not limited to: air or en.
Four example configurations of embodiments of the system
are illustrated in Figures 21(a) to (d). All four
configurations comprise a dialysate flow path 2108 being
ted from a gas flow path 2106 by an ammonia gas
generator 2102. An ammonia detector 2114, check valves
1952a/b, a valve 2154, and a pump 2150 are operably
ted to the gas flow path 2106. In some embodiments,
the valve 2154 may be a switch concept valve coupling with
or without an e, a solenoid valve, or other types of
valves know to those of skill in the art.
In more detail, the gas connection pattern of the first
configuration (i.e. Fig. 21(a)) was optimized to
illustrate the dialysate in-flow and dialysate out-flow
phases as shown in Figs. 22(a) and (b) respectively.
During the in-flow phase, the valve 2154 is connected. The
gas flows through the ammonia sensor 2114 and check valve
2152a; and ammonia gas is exhausted from the gas flow path
2106. During the out flow phase, the valve 2154 is
disconnected. The gas flows through the ammonia sensor
2114 and check valve 2152b; and exits the gas flow path
2106 via valve 2150 back to the dialysis device.
In more detail, the gas tion pattern of the first
configuration (i.e. Fig. 21(a)) was optimized to
illustrate the dialysate in-flow and dialysate out-flow
phases as shown in Figs. 22(a) and (b) respectively. In
Fig. 22a, during the w phase, the main operational
system is under positive pressure. The firmware connects
valve 2154. The gas flows from pump 2150 to the gas
l 2106. The transport medium reaches the a
gas generator 2102 first, then through the gas interface
2103 (which is between the generator 2102 and the detector
2114) to the ammonia sensor 2114.
During the out flow phase, the main system is under
negative re and the firmware disconnects valve 2154.
No external gas goes into the gas channel. The gas channel
is evacuated by the main pump 2150. The degassed gas
passes the gas interface and reach ammonia/ammonium
detector. Due to the fact that the gas channel pressure is
lower than the external pressure of the system, the gas
further moves to the valve 2152b rather than valve 2152a.
The gas flows through the valve 2152b to the main system
exhaust (Fig. 25 2158) via the main pump 2150.
A combination of the above isms may be used to
facilitate transportation of the ammonia gas from the
point that is distal the detector to the detector. For
example, a carrier gas comprising nitrogen may be used in
ction with a two-way pump. In other applications,
an alternate carrier gas including, but not limited to
air, and/or other gases may be used.
When using a delivery/carrier gas, either a continuous or
intermittent gas pattern can be used. The amount of
delivery gas within the gas conduit is preferably
optimized. Too little delivery gas may not produce
sufficient g forces to transport the ammonia gas to
the ammonia detector. On the other hand, too much delivery
gas flow may dilute the d amount of ammonia gas,
possibly resulting in the ammonia gas concentration
falling out of the detection limit of the ammonia
detector. By optimizing the ry gas flow, the ammonia
gas is transported to the ammonia detector within the
desired time. In one example embodiment, the gas flow
range is about 2 - 50ml/min, and/or 5 - 200ml/strok e. An
optimized result in the embodiment is about 5 - 25m l/min
and/or 30 - 70ml/stroke.
The continuous carrier gas n, after proper
optimization, is theoretically more efficient in gas
delivery. However, it consumes relatively more power and
may need an extra pump to drive the carrier gas.
The intermittent r gas pattern requires less power,
and can use the main gas pump 2512 of the dialysis
controller device 2500 (see Figure 25) to release the
required amount of carrier gas into the system at the
required time points.
In an embodiment, an electronic control means and
processor (i.e. the electrical system and firmware)
controls the g force for the ortation of
ammonia gas to a remote position and to function as an
automated controller. A suitable set of firmware may
include the timing control for opening and closing of the
valve in the gas flow path so as to r the ammonia
gas from the gas generator to the ammonia detector,
synchronizing the ammonia sensor read-back with the valve
timing control, determination of the gradient and/or
comparison with a pre-determined threshold for the ammonia
signal, and activation of the alarm system.
Fig. 23 shows one timing m for a control method
implemented for the first configuration (i.e. Fig 21(a)).
In every cycle, there are two distinct phases – an out
flow phase and an in flow phase. During the in flow phase,
the gas path is opened from time t1 to t2. At time t3, the
reading from the ammonia sensor is obtained. The l
method is installed in the controller firmware. The
l is implemented during the inflow phase when the
pressure difference between the internal cartridge and the
degasser channel is more significant and stable than the
outflow phase. A high pressure gradient is more favorable
for the penetration of ammonia gas through the membrane
into the interface of the gas tor and the ammonia
gas detector.
In some embodiments a pressure gradient of 10-760mmHg is
possible. A pressure gradient of 50-200mmHg may be
preferred for some embodiments. In other embodiments, the
t1-t2 interval may be 0-30s. In a preferred embodiment 1-
10s may be used. In other embodiments, t3 can be t2+(1
second or more) to the end of the cycle. In a preferred
embodiment, t3 is t2+ 0 seconds).
Two ent methods may be used to determine the a
signal level. The first method is to directly obtain the
gs from the ammonia detector after the settling time
of the ammonia signal. The second method is to use the
minimum or maximum value of the ammonia signal readings
which are obtained at a ermined rate (e.g. 1Hz)
during the inflow phase.
If no ammonium or a safe level of ammonium is present in
the regenerated dialysate (i.e. the t cartridge
functions well and is yet to be exhausted), the
equilibrium of ammonium and ammonia gas over the
hydrophobic r hardly generates any ammonia gas on
the gas phase of the hydrophobic membrane. When the
delivery gas ism is triggered, the degassed gas and
the inner delivery gas are transported to the ammonia
detector. The ammonia detector does not react to this gas
mixture and the processed sensor signal remains within the
safe range. The gradient of the ammonia signal is
calculated from the readings of two consecutive flow
cycles except for the first cycle where no gradient of the
signal is available. No high concentration ammonia gas or
system malfunction alarm is triggered.
If the ammonium level in the regenerated dialysate
approaches the safety margin (i.e. the sorbent cartridge
malfunctions or is about to be exhausted), the
ammonium/ammonia equilibrium over the hydrophobic barrier
causes ammonia gas to be present in the gas phase over the
hydrophobic barrier. When the delivery gas mechanism is
triggered, the delivery gas transports the ammonia gas
along the gas channel to the ammonia detector. The ammonia
detector reacts with the ammonia gas and generates an
alarm signal. The gradient of the ammonia signal is
calculated from the readings of two consecutive flow
cycles. The alarm may be configured to activate when the
ammonia signal reading exceeds a pre-determined threshold
and the signal gradient is positive (i.e. indicating an
increase in the amount of ammonium/ammonia in the system).
Figs. 24(a) and (b) are graphs showing the results
ed from one example embodiment of the present
invention using an electrical a or. In Fig.
24(a), as the level of ammonia in the system rises over
time (as reflected by the increase in concentration of
ammonia (in mM) from the ammonia assay ), the signal
of the ammonia sensing part of the ammonia detector
increases correspondingly. In an ment, an alarm can
be configured to trigger when a predetermined signal level
is reached. In Fig. 24(b), as the level of a in the
system rises over time (as reflected by the increase in
concentration of ammonia (in mM) from the ammonia assay
result), the readings obtained from the a
sensor/detector se correspondingly. With respect to
both Figures 24(a) and 24(b), the right y-axis reflects
the actual ammonia concentration in mM, while, the left yaxis
is a value that is directly proportional and related
to the voltage of the analogue signal from the sensor.
Fig. 25 is a schematic of a ller system 2500
according to an embodiment of the invention, in fluid
communication with a disposable sorbent cartridge 2550 of
a dialysis . The disposable sorbent cartridge 2550
comprises a toxin er 2552, a UF bag 2554, storage
module/pneumatic pump 2556, infusate pump 2558, infusate
reservoir 2560, degasser/sterile filter 2562, and check
valves 2564. The disposable sorbent cartridge 2550 is
ted to a patient’s peritoneal cavity 2580 via
connector 2582. Pinch clamps 2584 may be used on
appropriate fluid lines. The workings and/or connections
of the components in the disposable sorbent cartridge 2550
are not relevant for the current purpose of understanding
the connection of the disposable sorbent cartridge 2550 to
the ammonia sensing system 2500 according to an embodiment
of the invention.
The controller system 2500 comprises an ammonia detector
2502, check valves 2504, valves 2506/2508/2510, a pump
2512, a pressure sensor 2514, a safety screen 2516, and an
exhaust means 2518. In one embodiment, the safety screen
2516 may be, by way of example and not limitation, a 5µm
metal screen.
In this embodiment, the system 2500 is a controller system
the system 2500 es the ammonia sensing system as
described above, including an a gas generator 2562 a
gas interface 2590, an a detector 2502, check valves
2504a-c, and one more valves 2506, which is connected to
2504c. The ammonia sensing system is part of the main
controller system plus a part of a disposable cartridge
which can be used in the portable dialysis system.
After passing through the er 2562 in the able
sorbent cartridge 2550, the dialysate passes through the
dialysate line 2570 and is re-constituted with the
te concentrate in 2560 by the infusate pump 2558,
then returned to the patient via the valve 2564, pinch
clamp 2584 and connector 2582. The ammonia gas
equilibrated over the generator (hydrophobic barrier 2561)
is transported to the ammonia detector 2502 via the
interface/channel 2590. After passing through the ammonia
detector 2502, the gas mixture is exhausted through check
valve 2504a during the inflow phase, or is exhausted
through check valve 2504b, 2510, 2512, 2508, 2516 and 2518
during the outflow phase.
ments of the present invention provide several
advantages. The ammonia gas detector is separated from the
ammonia gas generator and located at a remote position. In
other words, the a gas detector is spatially
isolated from the liquid line, advantageously maintaining
the dialysate’s sterility. Additionally, the system
provides for ease of assembly in disposable or partially
disposable s.
Furthermore, the ammonia g system with integrated
degassers, sterile filters, and/or other functional
hydrophobic barriers (acting as the ammonia gas
tor), and pump system allows a compact system
design.
The integrated gas transport mechanism/medium between the
ammonia gas generator and ammonia gas detector
advantageously improves the sensitivity of the sensing
system, such that a limited amount of ammonia can be
detected.
Furthermore, using appropriate controller firmware with
suitable detection algorithms, the a sensing system
can be fully ted.
The biocompatible and remote ammonia sensing system
according to embodiments of the ion as described
above may be incorporated into a dialysis device. The
dialysis device may be a peritoneal dialysis device or a
hemodialysis device.
An embodiment of the t invention also relates to a
method of detecting ammonium in a dialysate, comprising
the steps of: providing a detector capable of detecting
ammonia gas; and providing a channel configured to allow
fluid communication of the ammonia gas; wherein the
channel is disposed between the detector and a point
distal the detector; the point being where ammonium in the
dialysate equilibrates to form ammonia gas.
In yet another embodiment of the invention, the
biocompatible and remote ammonia sensing system according
to embodiments of the ion as described above may be
modified to detect other fluids (e.g. other gases present
in a dialysate). By way of example and not limitation, the
systems may be ured to detect volatile organic
compounds (VOC) including, but not limited to acetone, CO2
O2, SO2, HCN, NOx, etc.
It will be nt that various other modifications and
adaptations of the invention will be nt to the
person skilled in the art after reading the foregoing
sure without departing from the spirit and scope of
the invention and it is intended that all such
cations and adaptations come within the scope of the
appended claims.
Claims (19)
1. A sensing system for detecting a substance in a dialysate, comprising: a hydrophobic barrier capable of allowing the substance in the dialysate to equilibrate to a gas; a detector capable of detecting the gas; an ace disposed between the hydrophobic barrier and the detector and configured to allow fluid communication of the gas between the hydrophobic barrier and the or; and one or more delivery isms e of transporting the gas from the hydrophobic barrier h the interface to the detector, wherein the one or more delivery mechanisms allow the gas to move either back and forth within the interface, or forth to the detector, and wherein the substance is ammonium and the gas is ammonia gas, and the gas is in a pH dependent equilibrium with the substance in the dialysate.
2. The sensing system as claimed in claim 1, wherein the one or more delivery mechanisms provides a driving force e of transporting the gas.
3. The sensing system as claimed in claim 2, wherein the driving force circulates the gas within the interface.
4. The sensing system as claimed in any one of claims 2 to 3, further comprising electronic control means configured to control the driving force.
5. The sensing system as claimed in any one of the preceding claims, wherein the one or more delivery mechanisms comprise a carrier gas.
6. The sensing system as claimed in any one of the preceding claims, wherein the interface is about 1cm to 50cm in length.
7. The sensing system as claimed in claim 1, wherein the hobic barrier is capable of separating the ammonium in the dialysate from the ammonia gas in the interface.
8. The sensing system as claimed in any one of claims 1-6, wherein the substance is a volatile c compound used for the detection of medical conditions.
9. The sensing system as claimed in any one of the preceding claims, wherein the hydrophobic r comprises a degasser
10. The sensing system as claimed in any one of the preceding claims, wherein the hydrophobic barrier comprises a ia filter.
11. The sensing system as claimed in any one of the preceding claims, wherein the hydrophobic barrier is in direct contact with the dialysate.
12. The sensing system as claimed in any one of the preceding claims, wherein the interface ses one or more a gas compatible materials.
13. The sensing system as claimed in any one of the preceding claims, wherein the interface ses a rous material.
14. The sensing system as claimed in any one of the preceding claims, n the interface comprises condensation reduction means within the interface.
15. The sensing system as claimed in any one of the preceding claims, further comprising an electronic processor electrically connected to the detector, the electronic processor configured to obtain readings from the detector, process the readings and/or trigger an alarm when the readings exceed a predetermined threshold.
16. A dialysis device comprising: the sensing system as claimed in any of the preceding claims; and a sorbent dge, wherein the detector is an ammonia detector that is capable of detecting ammonia gas, and wherein the gradient of the amount of detected ammonia gas provides an indication of the exhaustion of the sorbent cartridge.
17. The dialysis device as d in claim 16, wherein the dialysis device ses a peritoneal dialysis .
18. The dialysis device as claimed in claim 16, wherein the dialysis device comprises a hemodialysis device.
19. A method of ing ammonium in a dialysate, comprising the steps of: providing a hydrophobic barrier capable of allowing ammonium in the dialysate to equilibrate to ammonia gas; providing a detector capable of detecting ammonia gas; disposing an interface between the hydrophobic barrier and the or, and configuring the channel to allow fluid ication of the ammonia gas between the hydrophobic barrier and the detector; and providing one or more delivery mechanisms capable of transporting the ammonia gas from the hydrophobic barrier through the interface to the detector, wherein the one or more delivery mechanisms allow the ammonia gas to move either back and forth within the ace, or forth to the detector, and wherein the ammonia gas is in a pH ent equilibrium with the ammonium. Temasek Polytechnic By the Attorneys for the Applicant SPRUSON & FERGUSON Per: WO 70172
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/SG2011/000395 WO2012067585A1 (en) | 2010-11-15 | 2011-11-08 | Dialysis device and method of dialysis |
SGPCT/SG2011/000395 | 2011-11-08 | ||
PCT/SG2012/000425 WO2013070172A1 (en) | 2011-11-08 | 2012-11-08 | Sensing system for detecting a substance in a dialysate |
Publications (2)
Publication Number | Publication Date |
---|---|
NZ623899A NZ623899A (en) | 2016-09-30 |
NZ623899B2 true NZ623899B2 (en) | 2017-01-05 |
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