Note: Descriptions are shown in the official language in which they were submitted.
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Disclosure ;
This invention relates to a dialysis apparatus and
more particularly to a peritoneal dialysis apparatus. This
application is a divisional of our co-pending Canadian Patent
Application No. 198,505 filed April 30, 1974.
Peritoneal dialysis is a well known medical
procedure ~or removing impurities from the blood stream. It
is accomplished by introducing a suitable dialysis fluid
into the peritoneal cavity and then withdrawing the fluid after
a suitable period of time. During the time that the dialysis
fluid is in the peritoneal cavity, impurities in the blood
stream are drawn through the walls of the blood vessels on the
abdominal wall and in the viscera, and through the peritoneum
membrane against which they lie through the osmotic effect of
the dialysis fluid. The entire procedure may take up to 36
hours since the dialysis fluid must be replaced from time to
time as the concentration of impurities in it increase.
Heretofore, peritoneal dialysis has been done in hospitals
because of th~ high risk of infection and because trained
; 20 personnel need to be available to perorm the procedure.
According to one aspect, the invention relates to a
dialysis apparatus comprising first and second means for
regulating the flow of dialysis fluid through said apparatus,
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each of said means being movable between a first position
where it permits the flow of dialysis fluid and a second position
where it stops the flow of dialysis fluid, said regulating
means being coupled to each other so that when one of said
regulating means is in its first position the other regulating
means is in its second position, energizable means for
alternately moving each of said regulating means between
their first and second positions, first and second timers
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corresponding to said first and second regulating means, each
of said timers being energized when the regulating means
corresponding thereto permits flow to control the time length
of said flow, and means coupling said first and second timers
to each other and to said energizable means so that when the
time on one of said timers runs out, said other timer is
: reset and begins to operate and said energizable means is ~.
energized to move said regulating means to their alternate
I positions.
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The invention can best be described by referring
to the attached drawings wherein a presently preferred form of
the invention is illustrated and wherein:
Figure 1 is a schematic drawing of a preferred form
of the apparatus.
Figure 2 is a sectional view of the means for con-
trolling the flow of fluid through the apparatus.
Figure 3 is a sectional view taken along line 3-3
of Figure 2.
Figure 4 is a sectional view taken along line 4-4
of Figure 2. ~-
Figure 5 is a perspective view of a portion of the
apparatus illustrated in Figure 1 for weighing fluid discharged
from the peritoneal cavity.
Figure 6 is a perspective view of a portion of the
apparatus shown in Figure 1 which is used for heating the
dialysis liquid.
Figure 7 is a sectional view taken along line 7-7
of Figure 6.
Figure 8 is a schematic view of the circuitry for
operating the apparatus.
Figure 9 is a drawing graphically portraying the
operation of the apparatus.
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Now referring to the drawing for a detailed descrip~
tion of the invention, a peritoneal dlalysis apparatus is schemat-
ically illustrated by the numeral 10 in Figure 1.
The apparatus 10 comprises a container 14 in which
a supply of dialysis fluid is stored for use as needed, a means
16 for metering and heating the dialysis fluid after it is dis-
pensed from container 14, a catheter (schematically) 18, a means
for detecting discharge of fluid from the patient 20, a means for
receiving fluid discharged from the apparatus 22 and a means for
controlling the flow of dialysis fluid through the apparatus 24.
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A pump or other positive driving means may be used ,
to move the fluid through the apparatus. However, its construc-
` tion is greatly simplified and its reliability is substantially
increased by relying on the force of gravity.
Accordingly, the components of the apparatus are
supported by a suitable means indicated schematically by numeral
21 at successively lower heights than the preceding components.
The successive components in the apparatus may be interconnected
by suitable resilient flexible plastic conduits. A typical
plastic is commercially available and is sold as tubing under the
trademark "TYGON". '~
The container 14 may be of any convenient size.
Preferably it should contain enough dialysis fluid to enable a
complete dialysis procedure to be performed and should be con-
structed so that the dialysis fluid can be kept sterile. An out-
let 25 in the bottom of the container connects it with the rest of
the apparatus. Fluids used in peritoneal dialysis are commercially
available and are well known to those skilled in the art. A
typical fluid is sold under the trademark "DIANEAL" by Travenol
Laboratories.
The means for metering and heating the dialysis
fluid 16 is best seen in Figures 6 and 7. It includes an outer
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housing 26 which may be of any convenient shape. A heating unit
is supported in housing 26 by a plurality of fasteners 28. It
comPrises front and rear thermally conductive plates 30 and 32
which are arranged in spaced parallel relation to each other.
Each of plates 30 and 32 supports a heating element 34 and 36.
The heating elements cover a substantial area of plates 30 and 32
to rapidly bring the plates to the desired temperature. A collap-
sible sterile bag 35 which may be made from "TYGON" is supported
within housing 26. A typical means for supporting the bag may in-
clude suspending it from a rod 36 which is slipped through a `
sleeve along one edge of the bag. The bag 35 may have any
convenient volume. However it is preferred that the volume be
about two liters since introduction and discharge of this
volume of fluid into the peritoneal cavity at intervals during
the procedure achieves satisfactory results. A bag of reduced
volume may be selected when the patient is a child.
The plates 30 and 32 are connected in a circuitwhich enables them to bring the dialysis fluid in bag 35 to a
temperature of about 30 C. The circuit which will be described
herein includes a thermal switch 38 in contact with the bag 35.
An outlet 39 in the bottom of the bag connects it to the rest
of the apparatus. Since the bag 35 is collapsible it can be
filled and emptied without exposing its contents to the air.
The catheter 18 may be permanently implanted in the
patient or it may be a disposable catheter. Both types of cathe-
ters are well known and are commercially available for use in
peritoneal dialysis.
The means for detecting discharge of fluid from the
patient 20 can best be seen in Figure 5. It may be mounted to
a support frame (not shown) by a bracket 44. The bracket sup-
ports a pin 46 which serves as a fulcrum for an elongated lever
arm 48. A collapsible bag 50 for collecting fluid discharged
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from the patient is supported at one end of lever arm 48. The
other end of lever arm 43 is connected to a counterweight such
as spring 52. A second bracket 53 on the support frame carries
a microswitch 54 so that the operator of the microswitch is in
contact with the lower surface of lever arm 48.
The volume of bag 50 may be about three liters so
that if any fluid has collected in the peritoneal cavity, it
also will be discharged along with the dialysis fluid. The !
counterweight is selected so that microswitch 54 is closed
until a sufficient volume of fluid, preferably about 1500 grams,
is collected in bag 50. At 1500 grams, the force of the counter-
weight is overcome and the lever arm 48 rotates about pin 46
to open microswitch 54. The microswitch is connected to an
alarm signal in a manner which will be explained herein.
Normally, microswitch 54 is closed. However, if at
a predetermined interval microswitch 54 is still closed, the
alarm is activated to notify the patient that the expected
quantity of fluid has not drained from the peritoneal cavity.
The means for receiving fluid discharged from the
apparatus 22 may comprise any convenient receptacle such as a
disposable bag. In the alternative it could be a conventionàl
drain.
The container 14 is connected to both the means for
heating and metering dialysis fluid 16 and the inlet of catheter
18. To this extent a length of tubing 60 is connected between
the bottom opening 25 in container 14 and an arm of a "T" 62.
Another length of tubing 64 is connected between the second arm
of the "T" 62 and the opening 39 in the means for heating and ;
metering dialysis fluid 16. The third arm of "T" 62 is con-
nected by a length of tubing 66 to the catheter 18.
The outlet of the catheter 18 is connected to both
the means for detecting discharge of fluid from the patient 20
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and the means for receiving discharged fluid 22. To this extent
a length of tubing 70 is connected between the catheter 18 and
one arm of a "T" 72. Another length of tubing 74 is connected
between a second arm of "T" 72 and the bag 50. The third arm
of "T" 72 is connected to the means for receiving discharged
fluid 22 by a length of tubing 76. ~:
The lengths of tubing 60, 66, 70 and 76 pass through
control means 24.
From Figure 1 it is apparent that the control means
24 may comprise first and second valves 80 and 82. First valve
80 selectively opens and closes tubes 60 and 70. Second valve
82 selectively opens and closes tubes 66 and 76. The valves
regulate the flow of fluid through the apparatus.
When valve 80 is open and valve 82 is closed, the
fluid in container 1~ is permitted to flow through tubes 60 and . :
64 into the heating and metering means 16. Simultaneously,
fluid is drained from the patient through the catheter 18 and
tubes 70 and 74 into bag 50.
When valve 82 is open and valve 80 is closed, fluid :
flows from the heating and metering means through tubes 64 and
66 into catheter 18 and thence into the patient. Simultaneously,
fluid is drained from the bag 50 through conduits 74 and 76 into
the discharge receiving means 22.
Thus, by controlling the duration of time for which
the valves 80 and 82 are opened and closed and by regulating the
volume of dialysis fluid which can be stored in the heating and
metering means 16, an efficient, safe peritoneal dialysis appara-
tus is achieved. Significantly, it should be noted that bag 50
is provided on the downstream side of the patient in order to
detect an in5ufficient drainage of fluid from the peritoneal
cavity.
The control means 24 is illustrated in Figures 2-4.
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It comprises a housing 86 which rotatably supports a shaft 88 in
bearings 89. The shaft 88 is connected by way of a clutch 90 to
the output shaft 92 of a motor 94. Output shaft 92 is rotatably
supported by bearing 95.
Shaft 88 supports cams 100 and 102 which operate
!
valves 80 and 82 respectively, and cam 104 which operates micro-
switches 108 and 110. Cams 100 and 102 have profiles that corres-
pond to Figure 9 wherein it is seen that each valve 80, 82 opens
slowly and closes quickly. The microswitches 108 and 110 are
supported by housing 86 so that their operators can be displaced
into a notch formed in the cam 104 (see Figure 8). ~ence rotation
of cam 104 through a complete revolutlon causes each microswitch
to be tripped once. The cams 100 and 102 are supported on shaft
88 so that they are 180 out of phase with respect to each -
other. Thus, when one of valves 80 and 82 is open, the other
is closed. As will be explained in greater detail herein,
the power to motor 94 is supplied through microswitches 108 and
110. When the switch operators fall into the notch in the cam,
the motor 94 is stopped. This positions the valves 80 and 82
in accordance with the configuration of cams 100 and 102 until
the motor is energized through the microswitch whose operator
is not in the notch.
Each valve includes a stem 114 with a cross bar 118
at one end and, if deslred, a roller 120 at its other end. Each
valve stem 114 includes a radially directed flange 122 near
roller 120.
The valve stems 114 are supported in apertures 123
formed in a support member 124 mounted in housing 86. Each of
valve stems is biased toward its respective cam 100, 102 by a
spring 126 which bears against the flange 122.
A plate 130 is supported in spaced relation from
the front wall of housing 86 by a suitable hinge 132. Suitable
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latching means such as member 134 may be provided for retaining
plate ].30 in the position illustrated in Figure 2.
Plate 130 supports a housing 138 having the appear-
ance of a frame with a central opening 139. The housing 138 is
comprised of two separate members 140, 142 which have grooves
in which the tubes can be received. When the members 140, 142
are assembled the tubes are held in the position illustrated
in Figures 2 and 4. Thus, tubes 60 and 70 are positioned so ;
that they can be pinched closed by valve 80. Tubes 66 and 76
are positioned so that they can be pinched closed by valve 82.
A layer of relatively soft backing material 148
such as foam rubber, felt or the like is secured to plate 130
adjacent tubes 60, 70, 66 and 76.
Suitable means is provided for selectively energiz- ;
ing motor 94 at predetermined intervals during the dialysis
treatment. The motor causes shaft 88 to rotate with the result
that the tubes 60 and 70, and 66 and 76 are alternately pinched
and released to permit fluid to flow through the apparatus.
The energization means for the motor comprises the
circuit illustrated schematically in Figure 8.
The circuit comprises timers 150A, 150B and 150C,
a two-position lztching relay 156, and alarm signal 158 and a
counter 160.
Additionally, the circuit includes the heating plates
34 and 36, thermal switch 38, switch 54, motor 94 and
switches 108 and 110.
The circuit is energized by closing on-off switch
162. Switch 164, which may be called the fill switch, is opera-
tive when closed to cause the dialysis fluid in bag 34 to enter
the patient by way of catheter 18. Switch 166, which may be
called the drain switch, is operative when closed to cause the
dialysis fluid in the patient to be discharged therefrom into
bag 50.
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On-off switch 162 may be a two-position push but-
ton switch. When the switch is "OFF" a circuit is completed
across terminals 170 and 172. When the switch is "ON" a circuit
is completed across terminals 174 and 176. Eill switch 164 may
be a push button switch which is biased to a normally "OPE~"
position. However, when the push button is momentarily "CLOSED"
a circuit is enabled across terminals 180 and 182.
Drain switch 166 may be a push button switch of the
same type as switch 164 in that it is biased to a normally "OPEN"
position. In its "OPEN" position it enables a circuit across
terminals 186 and 138~ When this switch is momentarily "CLOSED"
a circuit is enabled across terminals 190 and 192.
Timers which may be used satisfactorily in the in-
vention are identified commerclally as Singer Industrial Timers,
Type GTD, 30 minutes. These timers may be set to run for a -
maximum time of 30 minutes. Each timer 150A, 150B and 150C is
essentially the same. Thus, the same part in each timer is
identified by the same reference numeral with the different
times being distinguished by the letters "A", "B" and "C"
following the numerals,
The following description will suffice for all
timers 150. Each timer includes a switch 196 which is comprised ;
of contacts 198 and 200 and throw 202. It also includes a
timer motor which is connected by an electrically energized
clutch to throw 202.
The timer motor runs continuously as long as power
is applied to motor terminal 204.
The clutch is energized as long as power is applied
to clutch terminzl 206. Every time the clutch is energized, the
timer is reset to the maximum time thereon (this feature is an
aspect of the particular timer identified herein).
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Both the timer motor and the clutch are connected
to common terminal 208. While the motors are connected to the
throws by the clutches, the throws 202 engage contacts 198 in
each switch 196. ~hen each timer has run out, the throws
202 move from contacts 198 to contacts 200.
Relay 156 includes three separate but interconnected
single throw switches. In each switch the throw, 210, 212
and 214, repectively is movable between first and second contacts
210A and 210B, 212A and 212B and 214A and 214B.
The throws are shifted by energizing coil "Ll" or
"L2". Energization of coil "Ll" completes a circuit through con-
tacts 210A, 212A and 214A. Energization of coil "L2" completes
a circuit through contacts 210B, 212B and 214B. The throws
remain in engagement with the contacts until the other coil
("Ll" or "L2") is energized, then they shift.
The source of electromotive force 221~ which may be
an ordinary electrical outlet, is connected by way of fuse 223
to terminals 170 and 174 on on-off switch 162.
The circuit is designed so that when the apparatus
is shut off the relay throws are at rest on contacts 210A, 212A
and 214A. Therefore the apparatus always starts on that portion
of its cycle which permits fluid to be drained from the patient
into bag 50. The mechanism by which this occurs is explained
herein.
Upon the closing of on-off switch 162 on terminals
174 and 176 a number of circuits are completed or enabled from
the source of power 221 and fuse 223. These circuits permit
fluid to be discharged from the patient for a predetermined
interval as will be explained herein.
Thus, a circuit is completed to motor 94 from on-
off switch terminal 176 by way of lines 220, 222 and through
switch 108. A circuit is completed to thermal switch 38 and
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heater plates 34, 36 by way of linea 220, 224, 226, 228 and
230.
The motors and clutches on timers 150B and 150C are
energized and the timers begin to wind down by virtue of circuit
through drain switch 166 and relay 156. The circuit includes
lines 224, terminals 190, 186 and 188, line 232, relay contact
214A and line 234.
The motor and clutch of timer 150C is energized by ~ ;
way of lines Z34 and 236 and line 238 which is connected to timer '
10 motor terminal 204C and clutch terminal 206C.
Switch 196C receives power by way of lines 234, 240
and throw 202C. Since throw 202C is touching contact 198C, a
circuit is completed by way of line 242 to the motor terminal
204B in timer 150B. An indicator lamp may be connected to
line 242 to indicate when the timer motor is energized. Clutch
terminal 206B receives power from line 236 by way of line 244.
The motor 94 causes shaft 88 to rotate in the direc-
tion indicated by the arrow in Figure 8 until the operator of
switch 108 falls into the notch in cam 104. This opens the cir~
cuit to the motor thereby halting the rotation shaft 88. By vir-
tue of the positions of cams 100 and 102 on shaft 88 they have
been rotated to the position illustrated in Figure 2 where
valve 80 is open and valve 82 is closed. As illustrated in
Figure 1, when the valves are in this configuration dialysis
fluid is permitted to drain from container 14 to the heating
and metering means 16 and at the same time fluid is permitted
to drain from the patient by way of catheter 18 into the bag 50.
If for some reason, cam 104 is not in the position
illustrated when on-off switch 162 is closed and switch 108 is
30 open, the motor 94 will not operate since the valves 80 and 82
will be in the correct positions to permit fluid to be drained
from the patient.
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Timer 150C is set to run for a shorter time than
timer 150B. Timer 150C cooperates with switch 54 to indicate
that fluid is draining from the patient at an adequate rate.
To this extent a circuit is normally enabled through switch 54
by way of contact 200C in timer 150C, line 254, switch contact
256 and line 258 to alarm 158. But when the weight of fluid in
bag 50 reaches 1500 grams, or any predetermined weight deemed
desirable, the thrown in switch 54 is moved to contact 260.
With the foregoing in mind, when timer 150C runs
out, as for example fifteen minutes after it is energized, throw
202C moves to contact 200C. If the predetermined quantity of ~
fluid is not in bag 50, the circuit through alarm 158 is com- ~ -
pleted by way of line 254, contact 256 and line 258. The alarm
158 may be visible, audible or a combination of both, provided
it alerts the patient to the fact that inadequate drainage
from the body is taking place. Since there is no power in
line 242, the motor in timer 150B is stopped. Thus, the
apparatus remains in the drain portion of the cycle and the
alarm 158 remains energized until the apparatus is shut off
or the fill switch 164 is depressed.
If an adequate amount of fluid is in bag 50 when
timer 150C runs out, the alarm is bypassed and power to motor
terminal 204B is achieved by way of line 254, contact 260 and
line 242.
Assuming that there has been adequate drainage
to bag 50, when the time on timer 150B runs out, throw 202B
moves to contact 200B to start filling the patient with dialysis
` fluid. This energizes coil "L-2" in relay 156 by way of lines
226, 264, throw 202B, contact 200B, lines 266 and 268. Coil
"L2" moves all of the throws in the relay clockwise so that
circuits are completed to terminals 210B, 212B and 214B.
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Simultaneously with the energization of coil "L2"
counter 160 is energized by way of lines 266, 270 and 272.
~ence a count is taken on each time the circuit shifts to
cause dialysis fluid to enter the patient.
Clockwise movement of the relay throws 210, 212 and `
214 completes or enables a number of circuits. ~-
A circuit is completed to motor 94 through line 222 9
relay contact 212B and through switch 110. The switch is closed
since the notch in cam 104 is now adjacent switch 108. The motor ~
rotates shaft 88 until the operator on switch 110 falls into the -
notch whereupon the motor stops rotating the shaft. At this
point valves 80 and 82 are in the positions illustrated in
Figure 1 wherein fluid is permitted to fill the patient by
way of catheter 18 from the heating and metering means 16 and
the fluid in bag 50 is permitted to be discharged to the drain
means 22
The motor and clutch on timer 150A are energized
and the timer begins to wind down by way of a circuit through re-
lay throw 214, relay contact 214B and line 276. Line 276 i5 con-
nected to motor terminal 204A and clutch terminal 206A. An
indicator lamp may be coupled to motor terminal 204 to indicate
that the motor is energized.
The throw 202A in switch 196A is on contact 198A
while the timer is running. When the time on timer 150A runs
out, after, for example 30 minutes, throw 202A shifts to contact
200A to complete a circuit through coil "Ll" by way of line 280,
relay throw 202A and lines 282, 284 and 286.
Energization of coil "Ll" shifts all the relay
- throws in relay 156 counterclockwise so that they engage contacts
~30 210A, 212A and 214A. This completes a circuit through timer
1503 and timer 150C so that the cycle is repeated as described
above. In the event that timer 150C should run out before an
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adequate amount of fluid is received in bag 50, alarm 158 will
be energized.
When time 150B runs out the relay 156 shifts and
the motor 94 is energized to rotate shaft 88 to permit dialysis
fluid to again fill the patient. At the same time, timer 150A
is energized.
Significantly, it should be noted that the timers
are reset to the maximum time thereon each time they are ener- `
gized. In timers 150A and 150B the maximum ~ime is externally
adjustable. To this extent, they may be mounted on a panel
and have knobs extending therefrom for that purpose.
On the other hand, timer 150C is designed to be -
non-adjustable. Thus, it may be set at the factory. It is pref-
erably permanently mounted within an enclosing structure so that
it cannot be tampered with by the user.
At any time in its cycle the apparatus may be shut
down by moving switch 162 to the "OFF" position so that it com- ;
pletes a circuit across terminals 170 and 172.
If the relay throws are in their clockwise positionS
when on-off switch 162 is moved to its "OFF" position J a cir-
cuit is completed to coil "Ll" from terminals 170 and 172 by
way of line 290, relay contact 210B, and lines 2929 284 and
286. This moves the throws counterclockwise which then opens
the circuit from on-off switch 162 since relay contact 210A is
not connected to the rest of the circuit.
:
If, on the other hand, the relay is closed on con-
;~ tact 210A~ moving switch 162 to its "OFF" position so that it
completes a circuit across terminals 170 & 172 it merely shuts
down the apparatus.
The apparatus can be switched from the drain cycle
` to the fill cycle or from the fill cycle to the drain cycle by
depressing fill switch 164 or drain switch 166 respectively.
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For example, if the apparatus is draining fluid
from the patient and it is desired to switch it to fill the ~ ;
patient, switch 164 is depressed momentarily to complete
a circuit across terminals 180 and 182. This completes a cir- -~
cuit from the source of electromotive force through contacts
174 and 176, line 220, through switch 164 by way of ter-minals
180 and 182, and line 294. Counter 160 is energized by way
of lines 294 and 272. Coil "L2" is energized by way of lines
294, 270, and 268. When coil L2 is energized, it shifts the ,
throws (they are in their counterclockwise position when fluid is
draining from the patient). This completes a circuit to relay
contact 212B and a circuit to relay contact 214B so that
circu~ts are c~leted throu~h s~ntc~h 110 to n~tor 94 ~d ~o ti~r m~tor -~
and clutch terminals 206A and 204A in~r 150A. Shaft 88
rotates until switch 110 opens thereby de-energizing motor 94.
~ This opens valve ~2 to fill the patient from the metering and
- heating means 22.
When the time on timer 150A runs out, throw 202A
moves to contact 200A. This completes a circuit from terminal
176 in on-off switch 162 to coil "Ll" by way of line 280,
throw 202AJ contact 200A and lines 282, 284 and 286. Energiza-
., ",~
;~ tion of coil "Ll" shifts the relay throws counterclockwise to ~
energize and reset timers 150B and 150C and motor 94 (through ~,
switch 108) to start the drain portion of the cycle.
The drain cycle continues as explained above with
both timers 150C and 150B being energized. If timer 150C runs
:.
out before an adequate amount of fluid is in bag 50 an alarm is
sounded.
On the other hand, if an adequate amount of fluid
is in bag 50 when timer 150B runs out, the relays are again
thrown and the fill portion of the cycle takes over.
If the apparatus is in the fill portion of its
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cycle and it is desired to shift it to the drain portion~ switch
166 is depressed momentarily to complete a circuit across termin-
als 190 and 192. This completes a circuit to coil "Ll" by way
of terminal 192 and lines 296 and 286. Energization of coil
"Ll" shifts the relay throws counterclockwise to complete
circuits to relay contacts 212A and 214A so that circuits
are completed to motor 94 and to timers 150B and 150C. In this `;
regard, the circuit components assume the same configuration
that they have when on-off switch 162 is moved to its "ON"
position as described in detail above.
From the foregoing it is apparent that at any part
of its cycle the apparatus can be shifted to the opposite part
of the cycle.
In order to use the apparatus described, each of
the components of the apparatus, namely container 1~, metering -
and heating means 16, the patient and catheter 1~ 7 the fluid
detecting means 20 and the fluid receiving means 22 are ar-
ranged so that each component has a higher elevation than the
component following it so that the natural tendency of the
dialysis fluid in container 14 is to flow through the apparatus.
The sequence of operation of the apparatus is shown
in Figure 9. The apparatus can go through a complete cycle in
up to one hour. Up to thirty minutes can be used to fill the
patient and up to thirty minutes can be used to drain
.~ the patient. The duration of the fill and drain intervals
, .
are controlled by timers 150A and 150B. Since the timers are
- externally adjustable these periods can be varied as desired.
The motor 9~ is energized at the end of each fill
and each drain interval. The motor i8 selected so that each
time it is energized shaft 88 rotates through half a turn in
about thirty seconds. As explained earlier the motor is
energized at the end of each fill and drain interval. Cams 100
17
and 102 are profiled to enable valves 80 and 82 to gradually
open over each thirty second interval of shaft rotation, but to
close abruptly. This i5 SO that the dialysis fluid does not
surge or drip through the tubing. During each thirty second
period of cam rotation, the positions of valves 80 and 82 are -;
reversed, and, due to cam 104, one of microswitches 108, 110
is opened while the other is closed.
A commercial embodiment of the invention would com-
~10 prise sufficient dialysis fluid in container 14 to discharge
a two liter dose of dialysis fluid into the patient every
half hour with the succeeding half hour being consumed in with- ~;
drawing the dialysis fluid. Thus, the heater bag acts as a
measuring device in order to control the amount of fluid being
introduced to the peritoneal cavity in any given time.
It is contemplated that with the present apparatus
a complete dialysis can be achieved in a period of about 10 ~- -
hours as opposed to an interval of 36 to 72 hours as in present
procedures.
The substantial reduction in time is achieved by
virtue of the fact that the dialysis fluid is changed rather ~'
rapidly.
Thus, it is a well known fact that in an osmotic
process, as thefluids on each side of the membrane approach
equilibrium, the rate of exchange across the membrane decreases.
Thus, it is advantageous to change the dialysis fluid as the
rate of transfer across the peritoneal membrane begins to
slacken.
This can readily be done with the present apparatus
by merely externally adjusting the time available Oll timers 150A
and 150B.
At the same time since the presence of an attendant
is not necessary in order to change the fluid in container 14,
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a sufficient amount of fluid in order to perform the entire
dialysis may be made available at one time~ It is contemplated
that an adequate amount of fluid to satisfactorily dialyze an
adult patient would be about 20 liters. Thus, over a period of
10 hours, at a rate of 2 liters per cycle, the entire quantity
of fluid would be consumed.
Significantly, at the end of each cycle of the ap-
paratus, the fluid discharged from the peritoneal cavity is
weighed in order to assure that the patient is draining properly.
In the event that inadequate drainage is taking place, a suitable
alarm is activated.
A further safety device is present by virtue of the
fact that when the apparatus is initially turned on, as by
pushing switch 162 to close a circuit across terminals 174 and
176, the apparatus automatically starts on a drain cycle. Thus,
there is no possibility that two liters of dialysis fluid would
~ be iII the patient as two additional liters are being introduced.
- Finally, it should be noted that the apparatus al-
` ways shuts off in the drain position.
While the invention has been described with respect
, to one preferred embodiment thereof, it is apparent that many
other forms and embodiments will be obvious to those skilled in
- the art in view of the foregoing description. Thus, the
scope of the invention described herein should not be limited
by that description but, rather, only by the scope of the claims
....
~ appended hereto.
.
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~ 30
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