Note: Descriptions are shown in the official language in which they were submitted.
132381~
~his ~8 a div1sion o~ Canadian patent appl~cation ~erial
No. 565,509 ~iled by applicant on April 29~h, 1988.
Back~round of th~ InvQntlon
Thls invention relates to a disposable cassette
having a pumping chamb~r therein and with a controlled
positlve displac~ng pump driving apparatus for use wlth
the cassette, for performing intravenous or
intra-arterial infusions. More particularly, it
pertains to disposable cagsettes which include an
exposed flexible diaphragm forming one wall of the pump
chamber and adapted to be engaged by a plunger or piston
member driven and controlled by the driver apparatus to
pump fluid t~rough the cassette. ~
In recent years there has been a increasing use
of positive displacement fluid infusion pumping devices
for delivery fluids intravenously or intra-arterially to
patients in hospitals or other patient care locations.
These have to a large extent replaced the time-honored
gravity flow control systems, primarily due to their
much greater accuracy in delivery rates and dosages, the
relative sophistication in permittinq a flexible and
controlled feed from multiple liquid sources, and
particulàrly their ~bility to control with precision the
amount of dangerous drugs delivered to a patient over a
given period of time.
A typical positive displacement infusion pump
system includes a pump driver device and a disposable
cassette. The disposable cassette, which is adapted to
be used only for a single patient and for one fluid
delivery cycle, is typically a small plastic unit having
an inlet and an outlet respectively connected through
flexible tubing to the fluid supply container and to the
patient receiving the infusion. The cassette includes a
1323811
pumping chamber w~th the flow of fluid through the
chamber being controlled by a plunger or pi~ton
a~t~vated in a controlled manner by the dr~ver device.
For example, the cassette chamber may have one wall
thereof formed by ~ flexible diaphragm which is
reciprocated by the plunger in th~ driver to cause fluid
to flow. The pump driver device includes the.plunger or
piston for controll~ng the flow of fluid into and out of
the pumping chamber in the cassette, and it also
includes control mechanisms to assure that the fluid i5
delivered to the patient at a pre-set rate, ~n a
pre-determined manner, and only for a particular
pre-selected time or total dosage. The pump driver
device may also include pressure sensing and oth~r
liquid flow monitoring devices as well as - valving
members for opening and closing various passages in the
cassett~ including the inlet and outlet passages of the
pumping chamber.
SummarY of the I vention
The present inventlon pertains to a mechanism
for actuatinq a plunger-type slideable valve on a valving
device, comprises a moveable support associated with the
mechanism for holding the valving device; a moveable
gripping means on the mechanism for gripping the valve;
and a linking means between the moveable support and the
gripping means to transmit the movement of the support to
the gripping member whereby the valving device can be
placed in the moveable support, the gripping member can
engage the valve and slide the valve as the moveable
support is moved, the linking means transmitting the
movement of the moveable support to the gripping means to
slide the valve.
13238~
--3--
Brief Descri~tion of the Drawinq
FIG. 1 is a perspective view of a pumping
cassette of the present invention along with selected
portions of a driver to drive the pump cassette; -
FIG.. 2 i5 a plan view of the cassette of thepresent invention with one face broken away;
. FIG. 3 is a cross section taken along the plane
of line 3-3, of FIG. 2;
FIG. 4 is a cross section taken along the plane
of line 4-~ of FIG.~:
FIG. 5 is a perspective view of the cassette of
the present invention along with the flow regulator
shutoff assembly of a driver mechanism used to operate
the cassette of the present invention;
FIG. 6 is a detailed view partially in section
of the cassette mounted in a door of a driver having a
regulator s~utoff assembly; . ..
FIGS. 7-9 are detailed views of the regulator
shutoff assembly of a driver employed to operate the
cassette of the present invention:
FIG. 10 illustrates the air-in-line detection
system of the cassette of the present invention;
FIG. 11 is a cross section taken along the
plane of line 11 of FIG. l;
13~38~l
-4-
FIG. 12 is a sectional view of an acoustic
coupling employed ~n the air-in-line detection system of
the present invention;
FIG. 13 i8 a front elevation of a portion of
the front panel on the driver employed to drive the
cassette of the present invention shown with the .
cassette door removed;
FIG. 14 is a cross section taXen along the
plane of line 14-14 of FIG. 13 showing a cassette of the
present invention in phantom;
FIG. 15 is a detailed perspective view of the
cassette primary and secondary inlet actuator drive
assembly of the present invention;
FIG. 16 is a detailed front elevational view of
the cassette primary and secondary inlet actuator drive
assembly of the present invention:
FIGS. 17-19 are detailed side elevational views
of the cassette inlet and outlet actuator drive assembly
of the present invention;
FIG. 20 is a detailed side elevational view of
the pumping chamber inlet and outlet actuator drive
assembly of the present invention;
FIG. 21 is a detailed plan view of the pumping
chamber inlet and outlet actuator drive assembly of the
present invention.
FIGS. 22 A-C are schematic views of various
positions of the positioning flag for the cassette inlet
and outlet actuator drive assembly;
FIGS. 23 A-C are schematic views -of various
positions of the positioning flag for the pumping
chamber inlet and outlet actuator drive assembly.
FIG. 24 is a graphical representation of the
pumping sequence of the cassette driver of the present
invention: and
FIG. 25 is a schematic of the operating system
1323~
-5-
of the cassette dr~ver of the present invention.
Detailed Descri~tlon of the Preferred Embodiment
I. PumPin~ Cassette
A pumping cassette 10 of the present ~nvention
is illustrated in FIGS. 1-4. It includes a rigid face
member 12 and a rigid back member 14 with an elastomeric
member 1~ positioned ~etween. Face member 12 has
plunger opening 18 with elastomeric member 16 extending
across the opening. Behind plunger opening 18 in back
member 14 i8 an enlarged recess 20, which forms a~
pumping chamber 22. To pump flu~d from chamber 22, a
plunger 24 (FIG. 1) reciprocates into and out of opening
18 urging the diaphragm across opening 18 into and out
of chamber 22. As plunger 24 is urged against the
diaphragm,--a pumpin~ chamber outlet valve actuator 26 i8
opened while the pumping chamber inlet valve actuator 28
is closed so that fluid is forced from chamber 22 out of
the cassette outlet 30. After the plunger has expelled
a measured amount of fluid from pumping chamber 22,
valve actuator 26 closes, and valve actuator 28 opens.
Plunger 24 is withdrawn from chamber 22, whereupon
liquid is drawn into pumping chamber 22 from primary
cassette inlets 64 (FIG.3). As will be explained in
qreater detail below, cassette 10 further includes
air-in-line detection means 34 in the fluid path between
primary cassette inlet 64 and pumping chamber 22, and
air-in-line detection means 36 the fluid path between
pumping chamber 22 and cassette outlet 30. Detection
means 34 and 36 can be used to detect whether air is
being drawn into the system and whether the valves in
the cassette are working properly to prevent fluid from
flowing at an uncontrolled rate through the cassette.
Face member 12 is preferably molded from rigid
plastic such as polycarbonate. Face member 12 has a
132381~
-6-
generally flat exterior face 38-flat with the exception
of a semi-c~rcular guard member 40 for air-in-line
detection means 34, a sem~-circul8r guard member ~2 for
air-in-line detection means 36, and a cylindrical
housing 4~ for a flow control regulator 46. The
interior face 46 of face member 12 is flanged, having a
peripheral pair of flanges 48 and 50, which extend
completely around the peripheral face member 12 toward
back member 14. Flanges 48 and 50 are spaced from each
other and receive between them a peripheral flange 52 of
the elastomeric member 16.
Interior face 46 of face member 12 also
includes flanges 56 on either side of the fluid path
through cassette 12 in the outline of the fluid path
(see FIG. 2) which pinch or retain elastomeric member 16
against the interior face 54 of back member 14 to
prevent fluid from leaking out of the fluid path into
other areas within cassette, not part of the fluid
path. The details of the fluid path are described below.
Face member 2 also includes valve actuator
openings. A primary cassette inlet valve actuator
opening 62 is located adjacent primary cassette inlet 64
to allow a finger-like primary inlet actuator 66 to
regulate the flow of fluid into the cassette. Inlet
actuator 66 extends through opening 62 and is
selectively moved inwardly of opening 62 to urge a
portion of the elastomeric member 16 across the fluid
path and against the inside surface of back member 14 to
block the flow of fluid into cassette 10 from inlet 64.
The inlet actuator opening 62 and the portion of
elastomeric member 16 adjacent opening 62 form a primary
cassette inlet valve.
A secondary cassette inlet actuator opening 58
i8 located ad;acent a secondary cassette inlet 32.
opening 58 permits a secondary inlet actuator 60 to urge
~323811
--7--
a portion of elastomer~c member 16 across the fluid path
and against the inside surface of back member 14 80 as
to block the flow of f luid f rom secondary inlet opening
32 into the cassette.- Inlet actuator opening 58 an~ th~
portion o elastomeric member 16 adjacent opening 58
form a secondary cassette inlet valve. Primary inlet 64
and secondary inlet 32 can be connected to primary and
secondary sources of fluid. Actuators 66 and 60 are
used to select wh~ch fluid is pumped by cassette 10 at
any given moment, if two liquids are being pumped to the
patient at a given time. Alternatively, if one liquid
is being administered, the liguid container is connected
to primarily inlet 6~, and the primary cassette inlet
valve is opened while the secondary cassette inlet valve
is closed during fluid administration. The mechanism
used to drive inlet actuators 66 and 60 is described
below.
A pump chamber inlet actuator opening 68 (FIGS.
1 and 3) is located upstream of the fluid path leading
to pump chamber inlet 70 (FIG. 2) which is positioned at
the bottom of pump chamber 22. Actuator opening 68
allows actuator 28 to urge a portion of elastomeric
member 16 adjacent opening 68 across the fluid path
leading into pump chamber 22 to block the flow of fluid
into pump chamber 22 from cassette inlets 32 and 62 and
to block the flow of fluid from pump chamber 22 back
through cassette inlets 32 or 62. Pump chamber inlet
actuator opening 68 and the portion of elastomeric
member 16 adjacent opening 68 form a pump chamber inlet
valve.
A pump chamber outlet actuator opening 72
(FIGS. 1 and 4) is provided through face member 12 to
allow a pump chamber outlet actuator 26 to urge a
portion o elastomeric member 16 across the fluid path
leading from pump chamber outlet 74 (FIGS. 2 and 4) to
1323811
selectively block the flow of fluid from chamber 22 out
of outlet 7~. Opening 72 and the portion of elastomeric
member 16 adjacent opening 72 form a ~ump chamber outlet
valve.
As shown in connection with inlet actuator 28
in FIG. 3, back member 14 has a concave, circular valve
seat 75 opposite each actuator opening 58, 62, 68, and
72. Each val~e actuator 26, 28, 60, and 66 has a
rounded end so that when a valve actuator is urged
inwardly through an actuator opening, a portion of the
elastomeric member 16 will be urged into a valve seat
75, insuring that flow is blocked when an actuator is
actuated.
Face member 12 further includes a pressure
sensor opening 76 which allows a rod-like extension 78
of a pressure sensor 77 (FIG. 14) associated with the
pump cassette driver (not shown) to contact a pressure
detection section 80 (FIG. 4) of elastomeric member 16
positioned over a pressure chamber 82 in back member
14. Thus, the pressure of fluid being pumped from
pumping chamber 22 can be monitored. If the pressure is
excessive, it may be a sign that the needle in the
patient's arm attached to the end of a tube 84 connected
to outlet 30 has been blocked. This pressure detection
system can also be employed to check the integrity of
the valving of the pump chamber 22 at its inlet and
outlet as will be described beiow. Finally, this
pressure detection system can be used to monitor the
patient's blood pressure, as will be discussed below.
Back member 14 is also made of a rigid,
polymeric material preferably polycarbonate. Back
member 14 includes a peripheral 1ange 86 (FIGS. 3 and
4) in which peripheral flange 48 of face member 12 nests.
Flanges 48 and 86 are secured together in a sealed
fashion by welding, gluing and the like.
:
~323~1
g
As indicated previously, back member 14
includes cassette inlets 64 and 32. Secondary inlet 32
~s provided with a luer taper 33 and thread-like flanges
35 to accept a luer cap for capping inlet 32 when only
one l~quid is to be pumped, or connecting to a luer lock
tubing connector when two liquids are to be pumped.
Back member 14 also includes a recess 20 which forms
pumping chamber 22 and a recess 82 which forms a
pressure detection chamber. A reservoir recess 88 is
also provided in back member 14 to form a reservoir 90
(FIGS. 2 and 3) when the unit is assembled.
Reservoir 90 has an inlet 92 at the top of
reservoir 90, and an outlet 94 above the bottom 96 of
reservoir 93. When the cassette is initially primed
with liquid prior to pumping, the cassette is inverted
from the position shown in FIB. 2 so that the air in the
fluid path between cassette inlets 32 and 62 and pumping
chamber inlet 70 is displaced with liquid with the
exception of the air trapped between the bottom 96 and
outlet 94 of drip chamber 90. This trapped volume of
air 93 rises to t~e top of drip chamber 90 when the
cassette is returned to its upright pumping position
shown in FIGS. 2 through 4. The function of trapped air
93 will be explained below.
Reservoir 90, pressure detection chamber 82,
and pumping chamber 22 form portions of the fluid path
between cassette inlets 32 and 62 and cassette outlet
30. The remaining portions of the fluid path are also
formed on the inside surface 54 of back member 14. An
inlet passage 104 (FIGS 3 and 17) connects primary inlet
64 to an opening 105 (FIG. 3) inside of the cassette.
Secondary inlet 32 is connected with an opening 103 in
cassette 10 by an inlet passage 102 ~FIGS 2 and 10).
Fluid from openings 103 and 105 combine in a channel 106
~FIGS. 2 and 3), formed between membrane 16 and bac~
132~81~
.. .. . . . ..
--10--
member 14 and flows in~o air-in-line detection means 3~,
which will be described in detail below. From
air-in-line detection means 34, the fluid flows through
reservoir lnlet 92 into reservoir 90. From reservoir
90, the fluid enters a passage 108, valved at its lower
end by pump chamber inlet valve actuator 28, into .
pumping chamber 22 through pumping chamber in.let 70. A
short channel 110 valved by pump chamber outlet valve
actuator 28 connects pump chamber outlet 74 to pressure
detection chamber 82. The 1uid flows through pressure
detect~on chamber 82 into air-in-line detection means
36. From air-in-line detection means 36, fluid flows
through a channel 112 which leads to flow control
regulator 45.
sefore flowing out of cassette outlet 30, the
fluid flows through flow control regulator 45, disclosed
in U.S. Patent No~ 4,703,775 filed April 25, 1986
ent~tled Liquid Flow ~egulator by Giovanni Pastrone,
and U.S. Patent No. 4,552,336, entitled "Liquid Flow
Regulator~.
AS disclosed in U.S. Patent No. 4, 703, 775,
flow regulator 45 includes a plunger 47 and a
cylindrical housing 44. Plunger 47 and housing 44 are
configured to allow plunger ~7 to be threaded inwardly
of housing 44 to reduce or prevent the flow of fluid
through regulator 45, or to be threaded outwardly of
cylindrical housing 44 to increase or allow fluid to
flow through regulator 45. With this controlled inward
and outward threading of plunger 47 in housing 4~,
plunqer 47 can be used to regulate manually the flow of
1323811
fluid through the cassette when the cassette ~ 6 not
mounted in a driver, permitting regulated gravity flow
of fluid from the I.V. solution container to the
patient. Thus, when the patient i8 being transported,
say in an ambulance, an l.V. set w~th the cassette of
the present invention can be employed without the
cassette driver to regulate flow of I.V. solution to the
patient. But, when the patient arrives at the hospital,
the cassette can be mounted on a cassette driver
described in more detail below to regulate the flow of
fluid more precisely than with the manual gravity method
described above.
Also as described in more deta~l in the afore-
said U.S. Patent No. 4,703,775, flow regulator plunger 47
is adapted to be pushed inwardly into or pulled outwardly
of cylindrical housing 44 to allow rapid movement between
on and off positions.
IT. Flow ~equlator Shutoff Assemblv
~ he cassette driver mechanism includes a flow
regulator shutoff assembly 114 (FIGS. 5-9) to pull
plunger 47 rapidly-outward into the open position when
the cassette is mounted in the driver, and to push
plunger 47 inward into the "off" position when the
cassette i8 removed from the driver. Flow regulator
shutoff assembly 114 includes a gripper bracket 116
having two downwardly depending arms 118, 118' joined a
bight portion 120 at their upper ends. Pivotally
mounted between arms 118, 118' is a chevron-shaped
depressor member 122. Depressor member 122 is pivotally
mounted to and between arms 122 by a pin 124. Depressor
member 122 is also pivotally mounted about a pin 126
which is fixedly mounted on the chassis 128 of the
cassette driver assembly.
Also mounted between arms lla and 118' is a cam
130 which i8 fixedly mounted on a rotatable shaft 132.
1323811
I -12-
Cam 130 has cam surfaces 134 and 134' which engage
corresponding cam surfaces 136 and 136~ on the inslde of
depressor member 122. Cam 130 further includes a
driv~ng pin 138 which extends through 130 to engage the
lower ends of arms 118 and 118' in a manner to be
described below. `
Flow regulator shutoff assembly 114 further
includes a slotted pivot arm 140 wh~ch is fixedly secure
to rotatable shaft 132 which in turn i6 mounted on
chassis 128 so as to allow shaft 132 to rotate freely
about its longitudinal axis but to restrain it from
translational movement in horizontal or vertical
directions. Pivot arm 140, therefore, will pivot in
tandem with cam 130.
Pivot arm 140 has a slot 142 in which a roller
144 is free to slide. Roller 144 is mounted on the
driver door 146 in which cassette 10 is mounted when in
the driver. The driver door 146 is pivotally mounted on
a pin 148 which is also fixedly secure to chassis 128 of
the driver.
As can be seen in FIG. 6, when driver door 146
is open, pivot arm 140 is in a substantially horizontal
position with roller 144 at the distal end 150 of slot
142. When door 146 is pivoted to the vertical, closed
position shown in FIG. 5, roller 144 travels in slot 142
and forces pivot arm 140 to rotate in a counterclockwise
position from the position shown in FIG. 6 to the
position shown in FIG. 5 where roller 144 is in the
proximal end 152 of slot of 142. As pivot arm 140
pivots from the substantially horizontal position shown
in FIG. 6 to the substantially vertical position shown
in FIG. 5, it rotates shaft 132 since pivot arm 140 is
fixedly attached to shaft 132. As shaft 132 rotates in
a counterclockwise position, it forces cam 130 to do
likewise. As cam 130 rotates counterclockwise (FIG.7),
13238~ 1
-13-
the ends of driving pin 138 engage the lower ends of
arms 118, forcing gripper bracket 116 to pivot about pin
124. In addition, the counterclockwise rotation o cam
130 forces depressor member 122 to pivot about pin 126.
The counterclockwise rotation of cam 130 forces cam
surface 134 against cam surface 136 to urge depressor
member to rotate in a clockwise direction about pin 126
until cam surface 134' engages cams surface 136' as
shown in FIG. 7.
When door 146 is opened again (i.e., pivoted
toward the position shown in FIG. 6), pivot arm 140
pivots from the substantially vertical position shown in
FIG. 5 toward the substantially horizontal position
shown in FIG. 6, forcing cam 130 to rotate
clockwise(FIG. 8). As cam 130 rotates clockwise,
driving pin 138 releases the lower ends of arms 118, and
a spring lS0 between gripper bracket 116 and depressor
member 122 urges gripper bracket 116 to pivot clockwise
about pin 124 to return to the position of FIG. 6.
As cam 130 rotates clockwise as shown in FIG.
8, cam surface 134~'- engages cam surface 136' to force
depressor member 122 to pivot in a clockwise direction
about pin 126 to return to the position of FIG. 6 from
position of FIG. 7, the position of FIG. 8 being an
intermediate position between the positions of FIGS. 6
and 7.
The lower ends of arm 118 include gripper
fingers 152. When cassette 10 is mounted in the door
and the door is pivoted toward the closed position, the
knob 49 (FIG. 6 - 9) of plunger 47 passes beneath the
ends of fingers 152 to a position adjacent to the lower
end of depressor member 122. As cam 130 drives gripper
bracket 116 and depressor member 122 toward the "closed"
position of FIG. 7, fingers 152 trap knob 49 between
fingers 152 and the lower end of depressor member 122
1~23811
and pull plunger 47 outwardly of cylindrical housing 44
to open th~ flow regulator 45 completely.
Conversely, when door 146 is pivoted from the
closQd position toward the opened, roller 144 forces
pivot arm 140 to rotate cam 130 in a counterclockwise
direction which allows fingers 152 to move away from the
lower end of depressor member 122 to release knob 49
from flow regulator shutoff assembly 114. As knob 49 is
being released, cam 130 pivots depressor member 122 such
that the lower end of depressor member 122 depresses or
urges plunger 47 inwardly of housing 44 (see FIGS. 8 and
9) so that flow regulator 45 is closed and prevents
fluid from flowing through the cassette. When the door
is fully opened (FIG. 6), the flow regulator is off, and
the cassette can be removed. It is important that the
flow regulator be turned off before the cassette is
removed otherwise, fluid would flow through ~he cassette
in an uncontrolled fashion under the force of gravity.
As can be seen, when cassette 10 is mounted in
the cassette driver and driver door 146 is closed, flow
regulator 45 is opened completely by shutoff assembly
114. However, when door 146 is opened to remove
cassette 10 from the driver, shutoff assembly closes
flow regulator 45 to prevent fluid from flowing through
the cassette an an uncontrolled rate. After the
cassette is removed, plunger 47 can be manually threaded
outwardly of regulator 45 to allow fluid to be
administered to the patent at a controlled rate, if
desired.
As indicated above, flow regulator shutoff
assembly 114 opens flow regulator 45 completely when
cassette 10 is mounted on door 146 and door 146 is
closed. To prevent fluid from flowing through the
cassette at an uncontrolled rate before plunger 24
begins pumping fluid, pumping chamber inlet valve
` ` 1323811
-15-
actuator 28 and/or pumping chamber outlet valve actuator
26 are positioned before pumping begins so as to block
flow of fluid through the cassette, as shown in FIG.
14. Accordingly, before the cassette is placed in the
cassette driver mechanism, the flow of liquid ~s
controlled manually by flow regulator ~5 at a rate set
by medical personnel. This manual rate can range from
zero to the maximum gravity flow rate through the
cassette. When the cassette is placed in the driver
mechanism, however, flow regulator 45 is opened
completely, but valve actuators 26 and/or 28 stop fluids
from flowing through the cassette until the cassette
driver pumping sequence and rates are selected by
medical personnel. Finally, when the cassette is
removed from the cassette driver mechanism, flow
regulator shutoff assembly 114 shuts off flow regulator
45 until flow regulator 45 can be reset manually by
medical personnel at the desired rate if such reset is
desired.
III. Air-In-Line Detection SYstem
As previously indicated, the air-in-line
detection system includes an air-in-line detector 34
located in the fluid path between cassette inlets 32,
64, and drip chamber go. The air-in-line detection
system also includes an air-in-line detector 36
positioned in the fluid path between pressure detection
chamber 82 and flow regulator 45. Air-in-line detectors
34 and 36 are substantially identical to each other.
The air-in-line detection system also includes
a pair of ultrasonic detectors mounted on the cassette
driver - an ultrasonic detector 154 (FIG. 1) for
air-in-line detector 34, and an ultrasonic detector 156
for air-in-line detector 36. Ultrasonic detector 154 is
identical to ultrasonic detector 156. Therefore, only
air-in-line detector 34 and ultrasonic detector 154 will
. . .
.q
-16- 1~238~1
be described in any detail. Furthermore, they are
de~cribed in U.S. Patent No. 4,821,558 entltled
Ultra~onic Detector.
Air-in-line detector means 34 includes a pocket
158 formed integrally as part of elastomer~c member 16
~see FIGS. 3, 10 and 11). Pocket 158 extends through an
opening 160 ~FIG. 11) in face member 12 and projects
outwardly beyond the surface of face member 12.
Pocket 158 has a hollow recess 162 in it which is formed
between two sidewalls 164 and 164' and an arcuate
endwall 166. A f inger 168 projects from the inner
surface of back member 14 into recess 162 and fits
interferingly between sidewalls 164 and 164', but does
not contact endwall 166. Thus, an arcuate fluid passage
170 (see FIGS. 3 and 11) is formed between the inside
surfaces of endwall 166 and the perimeter of finger 168
which forms part of the fluid path through the
cassette. Fluid passage 170 allows the fluid flowing
through the cassette fluid path in the cassette to loop
outwardly from the surface of face member 12 so that any
air in the fluid path can be detected by ultrasonic
detector 154 ~or 156) outside of the cassette. Guard
member 40 (FIGS. 3 and 11) covers and protects the
outside of endwall 166 to prevent endwall 166 from being
crushed or damaged. Ultrasonic detectors 154 and 156
are mounted on a cassette driver, a nondisposable item,
whereas the cassette is inexpensive and disposable after
each use.
Ultrasonic detector 154 (see FIGS. 1, 10 and
12) includes two mirror housing portions 172 and 174.
Housing member 172 is generally L-shaped and i5 joined
to the mirror imaged L-shaped housing 174 at the bottom
of the L's so as to form a U-shaped housing assembly
-17- ~323811
with a recess 176 between the arms of the U adapted to
receive air-in-lin~ detector 3~. On one side of recess
176, housing portion 172 has an opening 178, whlle on
the other sidQ of recess 176, housing portion 174 has an
opening 180. Housing members 172 and 174 are hollow,
each containing a passage 182 for the necessary
electrical contacts. Positioned in opening 17~ is an
ultrasonic generator 184, facing an ultrasonic receiver
186 positioned in opening 180. Ultrasonic generator 184
is positioned directly across recess 176 from ultrasonic
receiver 186.
Elastomeric poc~et 158 has two resilient lobes
187, 187' ~FIGS. 1 and 11) which extend outwardly from
~idewalls 164, 164' in opposite directions. The width
of pocket 158 between lobes 187, 187' is somewhat less
than the width of recess 176 between ultrasonic
generator 184 and ultrasonic receiver 186 so that lobes
187 and 187' are compressed inwardly toward each other
when air-in-line detection means a4 is inserted into
ultrasonic detector 154 as shown in FIG. 10. This
insures that there will be good acoustic contact between
ultrasonic generator 184 and pocket 158 and between
ultrasonic receiver 18~ and pocket 158. Thus, an
ultrasonic signal can be transmitted across fluid
passage 170 when air-in-line detection means 34 is
inserted into recess 176. The transmission of
ultrasonic sound between ultrasonic generator 184 and
~ultrasonic receiver 186 is greatly enhanced when a
liquid is present in passage 170. But when air is
present in passage 170, the transmission of ultrasonic
sound through fluid passage 170 is attenuated. This
difference in ultrasonic sound transmission is detected
by ultrasonic receiver 186. When air is present, the
electrical signal generated by ultrasonic receiver 186
decreases. Ultrasonic detector 154 (and 156) is coupled
-18- i3238~1
to a microprocessor 233 (FIG. 25) which rece~ves an
amplified ~ignal generated by ultrasonic receiver 186
and subsequently amplified. Microprocessor 233 ls
prefera~ly a 63B03R Hitachi microprocessor. When the
signal received by processor 233 from receiver 186
decreases, an alarm 2~1 ~FIG. 25) i8 sounded by
processor 233 to stop the pumping of fluid through-the
cassette if the cassette is in the fluid delivery
cycle. Thus, when a container of medical fluid is
connected either to cassette inlets 32 or 64 is emptied,
any air drawn into the cassette from the empty
containers will be drawn through air-in-line detector
34, and the presence of that air will be detected by
ultrasonic detector 154. Alarm 2~1 and/or nurse call
242 is then sounded, and the cassette driver is stopped
to prevent further pumpinq. If ultrasonic detector 15
malfunctions and does not detect the presence of air,
the air pumped will be detected by ultrasonic detector
156. Likewise, if there is an air leak in the system
between the fluid container and the outlet of the
cassette before the fluid container is emptied, any air
drawn into the system will be detected by one or the
other ultrasonic detectors 154 or 156 through
air-in-line detectors 34 and 36. Other functions of the
air-in-line detection system will be explained in the
"Operation" section below.
Further details of the air-in-line detection
system of the present invention can be found in the
aforementioned patent No. 4,821,558.
IV. Plunqer 24
Plunger 24 and its operation is described in
detail in U.S. Patent 4,639,245 entitled ~luid Infusion ~m~
Driver'.
~ -19-
i32381~
V. Valve Actuator Assembl~es
As indicated previously, valve actuators 60 and
66 operate the secondary and primary cassette ~nlet
valve, and valve actuators 26 and 28 operate the pumping
chamber inlet and outlet valveæ. Sim~lar mechanisms are
employed to operate each of these pairs of valve
actuators. The valve actuator assembly 188 drives valve
actuators 60 and 66 ~IGS. 15-19). Valve actuator
assembly 188 includes a first bracket 190 which drives
valve actuator 66. First bracket 190 includes two arms
194 and 196 which are spaced from and perpendicular to
each other, and ~oined to each other by a bight portion
198. First bracket 190 is pivotally mounted on the
chassis 128 of the driver by a pivot pin 200 which is
located at the proximal ends of arms 194 and 196 joined
by portion 198 so that arms 194 and 196 pivot about a
common pivot point when operated as described below.
Valve actuator 66 is pivotally secured to the distal,
free end of arm 194. The distal, free end of arm 196 is
driven by a cam 201 as described below.
Valve actuator assembly 188 also includes a
second bracket 192 with two spaced, perpendicular arms
202 and 203, which are joined to each other by a bight
portion 204. Second bracket 192 is pivotally mounted to
chassis 128 by a pivot pin 20s which is located at the
ends of arms 202 and 203 joined by bight portion 204.
f The free end of arm 202 is pivotally connected to valve
actuator 60. The free end of arm 203 engages cam 201
described below.
A primary spring 206 biases brackets 190 and
192 around pins 200 and 205 such that arms 196 and 203
are urged toward cam 201. One end of spring 206 is
r d~
-20- 1323811
connected to a tab 207 which extends from bight port~on
198. The other end of primary spring 206 is connected
to a tab 208 which extends from the proximal end of arm
202. Tabs 207 and 208 generally extend toward cam 201
so that spring 206 will bias arms 196 and 203 toward cam
201.
A secondary spring 209 is attached to and
between bight portions 198 and 204 to urge arms 196 and
203 away from cam 201 in the event that primary spring
206 breaks. However, secondary spring 209 is weaXer
than primary spring 206 such that when the two springs
are operable, arms 196 and 203 will be urged toward cam
201. If primary spring 206 breaks, secondary spring 209
will urge brackets 190 and 192 to pivot around pins 200
and 205 such that arms 196 and 2-3 pivot away from cam
201. The distal end of arm 196 includes a flag portion
191 ~FIGS. 17 and 18) which passes through an optical
switch 193 in the event of primary spring breakage.
When optical switch 193 is tripped,;a signal is relayed
to processor 233 which stops the driver immediately and
sounds alarm 241 and/or nurse call 242. A stop 195 is
positioned adjacent cam 201, and brackets 190 and 192
have stop tabs 197 and 199 which project from the
proximal ends of arms 196 and 203. If primary spring
206 ~reaks, brackets 190 and 192 will pivot around pins
200 and 205 until stop tabs 197 and 199 contact stop 195
before which point flag portion 191 would have passed
through switch 193.
As shown in FIG 17-19, actuators 60 and 66 are
elongated rods. As indicated previously, the proximal
ends of actuators 60 and 66 are pivotally connected to
arms 194 and 202 of brackets 190 and 192, respectively.
The distal ends of actuators 60 and 66 are supported in
openings 250 and 251 (FI~S. 13 and 17-19) in the front
panel 252 of the driver.
-21-
132~
Cam 201 is circular in shape and ~8
eccentrlcally mounted on a motor shaft 210. Shaft 210
is operated by a stepper motor 211 (FIG. 16). When
cassette 10 is placed in driver door 146 and the driver
door is closed to ~ts vertical position, cam 201 is
moved to the position where both valve actuators 60 and
66 are fully extended (FIG. 17) toward cassette 10 so as
to close the primary and secondary cassette inlet
valves. Specifically, valve actuators 60 and 66 urge
elastomeric member 16 across the fluid passages leading
from inlets 103 and 105 into the cassette. When a
liquid is to be pumped through primary cassette inlet
64, primary inlet actuator 66 is retracted by the
clockwise rotation of cam 201 by motor 211 from the
position shown in FIG. 17 to the position shown in FIG.
18. Cam 201 engages arm 196 of bracket 190 and urges
bracket 190 to pivot clockwise about pivot pin 200
against the bias of spring 206. As bracket 190 pivots
about pivot pin 200, arm 194 retracts actuator 66,
thereby allowing liguid to flow through primary cassette
inlet 64 through opening 105.
When cam 201 is in the position as shown in
FIG. 1 with the primary cassette inlet valve open, the
secondary inlet actuator 60 remains in the extended
position, urging elastomeric member 16 across the fluid
passage from inlet 103 (FIG. 18) into the cassette.
Secondary inlet actuator 60 is held in the extended
position by the bias of primary spring 206. When cam
201 is in the position shown in FIG. 18, arm 203 does
not contact it. ~rimary spring imparts a clockwise bias
to second bracket 192 which urges actuator 60 into the
closed position shown in FIG. 18. Since cassette 10 is
in a fixed position in the driver door 146 when cassette
10 is mounted in the driver, cassette 10 acts as a stop
to prevent arm 203 from contacting cam 201 when primary
1323811
inlet actuator 66 ~s retracted as 8hown ~n FIG. 18.
When fluid is to be pumped through secondary
cassette inlet 32, motor 211 is reversed and turns cam
201 counterclockwise from the position shown in FIG. 18
to the position shown in FIG. 19 where cam 201 engages
arm 203 of second bracket 192 and pivots bracket 192
counterclockwise about pivot pin 205. When arm 202 o~
bracket 192 pivots counterclockwise, valve actuator 60
is retracted allowing fluid to flow through opening 103
into the cassette. When the secondary cassette inlet is
open, the primary cassette inlet remains closed because
primary cassette inlet actuator 66 remains in the
extended position under the bias of primary spring 206.
When cam 201 is in the position as shown in FIG. l9, arm
196 of first bracket 190 no longer contacts cam 201
because cassette 10 operates as a stop against clockwise
rotation of bracket 190 under the bias o spring 206
when cam 201 is in that position. This keeps the
secondary cassette inlet closed while the primary inlet
is open.
It can be seen, therefore, that cassette inlet
valve actuator assembly 188 allows the following
possible cassette inlet valve positions: (1) both the
primary and secondary cassette inlet valves closed; (2)
the primary inlet valve open and the secondary inlet
valve closed; and (3) the secondary cassette inlet valve
open and the primary cassette inlet valve closed. In
normal operation, valve actuator assembly 188 does not
permit both the primary and secondary cassette inlet
valves to be open simultaneously.
A second valve actuator assembly 212 is used to
operate pumping chamber outlet and inlet valve actuators
26 and 28 (FIGS. 20-21). Pumping chamber outlet valve
actuator 26 is operated by a first bracket 213 which is
pivotally mounted on a pivot pin 214 on chassis 128.
-23- 1323~1
First bracket 213 has two spaced, perpendicular arms 215
and 216 fixedly secured and integrally formed with a
bight portion 217. The proximal end of arm 215 is
pivotally secured to pivot pin 214, and the distal end
of arm 215 is pivotally secured to actuator 26. The
proximal end of arm 216 is pivotally mounted to pivot
pin 214, and the distal end of arm 216 is urged toward a
cam 218 described below by a spring 219. One end of
spring 21g is attached to a tab 220 which extends from
the proximal end of arm 216. The other end of spring
219 is attached to a tab 221 raised from chassis 128.
Spring 219, therefore, biases first bracket 213 such
that arm 216 will be urged toward a cam 218.
Valve actuator assembly 212 also includes a
second bracket 222 pivotally mounted abou~ pivot pin
214. Second bracket 222 includes a first arm 223, the
proximal end o which is pivotally secured to pin 214,
and the distal end of which is pivotally secured to the
proximal end of valve actuator 28.; Second bracket 222
also includes a second arm 224, the proximal end of
which is pivotally secured about pin 214, the distal end
of which is free to be engaged by cam 218. Arms 223 and
224 are perpendicular to each other and fixedly joined
to each other by a bight portion 225. Second bracket
222 further includes a tab 225 _which extends from the
proximal end of second arm 224. The free end of tab 225
is attached to one end of a spring 226 which biases arm
224 toward cam 218. The other end of spring 226 is
attached to a tab 227 which is raised from chassis 128.
Cam 218 is eccentrically mounted on a motor
shaft 228 operated by a stepper motor 229. As cam 218
is driven by motor 229 in counterclockwise from the
position shown in FIG. 20, cam 218 engages arm 216,
forces first bracket 213 to pivot counterclockwise about
pin 214, and causes valve actuator 26 to retract against
24 i 3 2 38 ~ 1
th~ bias of spring 219. When valve actuator 26 is
ret~acted, the pumping chamber outlet valve ~s opened.
When cam 218 is driven counterclockwise against aem 216,
arm 224 of bracket 222 rema~ns stationary, and spring
226 will force valve actuator 28 to remain extended
against the pumping chamber inlet valve, ~eeping pumping
chamber inlet valve closed. As cam 218 is driven by
motor 229 in a clockwise from the position shown in FIG.
20, it engages arm 224, pivots bracket 222, and forces
valve actuator 28 to retract against the bias of spring
226, opening the pumping chamber inlet valve. When cam
218 is driven counterclockwise against arm 224, arm 216
of bracket 213 remains stationary, and spring 219 will
force valve actuator 26 to remain extended against the
pumping chamber outlet valve, keeping the pumping
chamber outlet valve closed. It can be seen that valve
actuator assembly 212 permits both the pumping chamber
inlet and outlet valves to be closed, or allows only one
of them to be opened at a time. More importantly, valve
actuator assembly 212 prevents both the pumping chamber
inlet and outlet valves from being opened simultaneously
so that fluid cannot flow through the cassette at an
uncontrolled rate under the force of gravity during the
pumping cycle.
The proximal ends of actuators 26 and 28 are
pivotally connected to brackets 213 and 222, as
indicated above. The distal ends of actuators 260 and
28 are supported in openings 254 and 256 ~FIGS. 14 and
15) in front panel 252. Since valve actuator assemblies
188 and 212 are driven by separate motors 211 and 229,
and since plunger 24 is driven by a motor separate from
stepper motors 211 and 229, the three motors must be
operated in a synchronized fashion, and the positions of
each during the operations of the cassette driver must
be monitored.
-2s- 13~3~1 1
To monitor the position of cam 201 of valve
actuator assembly 188 (and hence monitor the position of
valve actuators 60 and 66), a flag 230 is fixedly
mounted on cam 210. Flag 230 is thin, pie-shaped strip
of metal with a small notch 231 on its radial edge. As
cam 201 moves counterclockwise from the position shown
in FIG. 18 to the position shown in FIG. 19, motor 211
takes a set number of steps, preferably 24 steps. Notch
231 is not centered on the radial edge of flag 230, but
is offset to one side. Valve actuator assembly 188
further includes an optical switch 232 through which the
radial edge of flag 230 passes as cam 201 moves from
position shown in FIG. 18 to the position shown in FIG.
19 and bac~ again during its normal operation. Optical
switch 232 passes a beam of light across the space
through which flag 230 passes. Flag 230 breaks the beam
of light as it is passing through, except for notch 231
which allows light to pass when notch 231 passes through
switch 232. Optical switch 232 is coupled to
microprocessor 233 (FIG. 25) to relay to microprocessor
233 whether light is being transmitted or whether it is
being blocked by flag 230. Microprocessor 233 also
controls stepper motor 211 such that as the stepper
motor 211 moves stepwise- clockwise or counterclockwise,
the microprocessor can determine whether cam 201 is out
of position. For instance, as flag 230 passes through
switch 232 as it moves from the position shown in FIG.
18 to the position shown in FIG. 19, there will be a
fairly large number o steps in which light is
transmitted across switch 232 before flag 230 breaks the
optical beam and prevents light from being transmitted.
As flag 230 continues its movement towards position
shown in FIG. 19, there will be a small number of steps
during which the radial edge portion 234 (FIG. 23A)
counterclockwise of notch 231 prevents the passage of
1323~ 11
-26-
light. Then, notch 231 will pass through optical switch
232, allowing light to pass for a small number of steps,
whereupon the larger radial edge portion 235 passes
through switch 232 for a fairly large number of ~teps of
motor 211. This is followed by a fairly large number of
steps where l~ght passes across switch 232 after portion
235 passes through switch 232.
It can be seen that as cam 201 moves from
position shown in FI6. 18 to the position shown in FIG.
19, there will be a pattern of a short number of steps
when portion 234 passes through switch 232 followed by a
short number of steps in which notch 231 passes through
switch 232 and a longer period of time in which portion
235 passes through notch 232. This repeated
dark/light/dark pattern is correlated by microprocessor
233 to the position where cam 201 should be during its
cycle. If motor 211 is not "in synch" with the
preprogrammed dark/light/dark values in microprocessor
233, microprocesser 233 can advance~or retard motor 211
the appropriate number of steps to synchronize the
positions of valve actuators 60 and 66 with the
positions where they should be during driver operation.
Similarly, in valve actuator assembly 212, cam
218 has a flag 236 attached to it. Flag 236 is
generally pie shaped, having a radial edge with a notch
237 in it. An optical switch is positioned so that flag
236 passes through it as flag 236 moves from the
position shown in FIG. 22(B) where valve actuator 26 is
retracted to the position shown in FIG. 22(C) where
valve actuator 28 is retracted. Notch 237 is likewise
offset to provide a small radial edge portion 239 and a
large radial edge portion on either side of notch 237.
Thus, when flag 236 moves from the position shown in
FIG. 22(C) to the position shown in FIG. 22(C), switch
238 will detect a short period of darkness as radial
-27- 1~23~1~
edge portion 239 passes, a short period of light when
notch 237 passes, and a long period of darkness as
portion 240 passes through switch 238. Microprocessor
233 is coupled to optical switch 238 such that the
periods of light and darkness can be correlated stepwise
to the number of steps taken by stepper motor 229
between the positions of FIGS. 22(C) and 22(B).
Therefore, as flàg 236 moves back and forth between
these two positions opening and closing the pumping
chamber inlet and outlet valves, microprocessor 233 can
compare the actual position of cam 218 (and hence the
positions of valve actuators 26 and 28) with the
desired, preprogrammed position to 0ither advance or
retard stepper motor 229 appropriately Not only are the
positions of cams 201 and 218 monitored during the
pumping cycle, but the positions of the cams are checXed
before pumping begins. After the cassette is placed in
door 146 and the doors closed, motor 211, for instance,
will drive cam 201 back and forth ;between the position
shown in FIGS. 18 and 19 while optical switch 232 checks
the actual position of flag 230, and microprocessor 233
will stop stepper motor 211 once it is determined that
cam 201 is in the proper position to begin the pumping
sequence. In the case ~here only a single fluid is to
be pumped, for instance, that position will be when
valve actuator 56 is retracted and valve actuator 60 is
extended (FIG. 18).
Similarly, during this pre-pumping check, motor
229 will move flag 236 and cam 218 back and forth
between the positions of FIGS. 22(B) and (C) to position
the pumping chamber inlet and outlet valve actuators 26
and 28 in their appropriate positions to begin the
pumping cycle, namely, with both valve actuators 26 and
28 fully extended, (i.e., the positions shown in FIGS.
20, and 22tA). Thus, the pumping chamber inlet and
-28-
1323~1
outlet valves can be checked according to the procedure
described below. Once microprocessor 233 verifies that
flag 236 is in the proper pos~tion, the valve checking
sequences and pumping sequences described below can
commence.
Plunger 24 ~s also operated with a stepper
motor tnot shown). An optical flag is also attached to
the plunger stepper motor shaft so that an optical
switch (not shown) and microprocessor 233 monitor and
position plunger 24 before and during the pumping cycle
to æynchronize plunger 24 with the operation of
actuators 26, 28, 60, and 66.
VI o~eration
When pumping only one liquid at a time, the
liquid container with the liquid to be pumped is
connected to primary cassette inlet 64, and the
secondary cassette inlet 32 is closed with a luer-type
loc~ing cap (not shown). The cassette is primed with
fluid by opening regulator 45 and initially inverting
the cassette from the position shown in FIG. 2 to purge
the fluid path between the cassette inlets and the
pumping chamber of air (except, of course, for the
trapped volume 100). The pumping chamber and the fluid
path beyond it are purged of air by returning the
cassette to the upright position of FIG. 2. Regulator
45 is then either closed or set manually to a desired
flow rate until the cassette is mounted in the cassette
driver. Once the cassette is mounted in the driver, the
flow regulator shutoff assembly 114 automatically opens
regulator 47 and the cassette valves are tested as
described below.
Once the cassette inlet valve actuators 60 and
66, pumping chamber inlet and outlet valve actuators 26
and 28, and plunger 24 are properly synchronized as
described above, air-in-line detector 34 and pressure
~ ~3~3.1
detection chamber 82 are used to test whether valve
actuators 26, 28, 60, and 66 are cooperating with the
disposable cassette 10 to prov~de adeguate valving of
fluid in the cassette. The sequence for such testing i8
~llustrated in Fig. 24. To test the inlet and outlet
valves of pumpinq chamber 22, inlet valve actuator 28
and outlet valve actuator 26 are extended into openings `
68 and 72, respectively to block flow of fluid into and
out of pumping chamber 22 (Step A FIG. 24). With valve
actuators 26 and 28 in the extended positions, plunger
24 is urged against elastomeric member 16 across plunger
opening 18 to pressurize pumping chamber 22 (Step B).
Plunger 24 is held in this position for the "WAIT"
period (Step C), pressurizing chamber 22 for a short
period of time, whereupon outlet valve actuator 26 is
retracted to allow pressurized liguid to escape pumping
chamber 22, while inlet valve actuator 28 is held in its
"extended" position (Step D). When outlet valve
actuator 26 is released (Step D), the pressurized liquid
within chamber 22 surges into pressure detection chamber
82, producing a pressure pulse or spike in chamber 82.
When the pumping chamber inlet and outlet valves are
functioning properly, the magnitude of this pulse will
be constant from cassette-to-cassette. However, when a
cassette with poorly functioning pumping chamber inlet
and/or outlet valves is encountered, the pressure pulse
produced within chamber 82 during this valve test
procedure will be noticeably lower because a certain
amount of pressurized liquid from chamber 22 will have
leaked past either the pumping chamber inlet or outlet
valves during the "WAIT" period. If the pressure pulse
produced by this test procedure in pressure detection
chamber 82 is lower than expected, it is assumed that
the pumping chamber inlet and/or outlet valves are
functioning improperly so that the cassette is
.
-30-
1323811
rejected.
The magnitude of the spi~e is detected by pres-
sure sensor 77 which ~g coupled to microprocessor 233.
The details of the operation of pressure sensor 77 are
described in U.S. Patent No. 4,950,244 entitled PRESSURE
SENSOR ASSEMB~Y FOR DISPOSA~E PUMP CASSETTE filed by
Fellingham et al. Microprocessor 233 compares the value
of the signal generated by sensor 77 to a stored value.
If the stored value ~ 9 significantly greater, micro-
processor 233 will sound an alarm 241 and a nurse call
242 and the pump driver will not function unless a new
cassette is used.
The pump chamber inlet and outlet valve test
procedure described above is first done automatically by
the cassette driver immediately after the cassette is
installed. Thereafter, the same test procedure can be
done periodically during fluid delivery to insure the
continuing integrity of the pumping chamber inlet and
outlet valves during fluid delivery.
The test procedure is performed periodically in
the fashion illustrated in FIG. 24, steps A-E. The
pumping chamber inlet valve is closed (step A) while the
pumpinq chamber outlet valve is closed. Chamber 22 is
pressurized by extending plunger 24 a short distance
into chamber 22 (step B). The plunger is held for the
"WAIT" period (step C~. The pumping chamber outlet
valve is opened and the pressure spiXe detected in
chamber 22 (step D). If the pressure spiXe is of
sufficient magnitude, plunger 24 extends further into
chamber 22, (step E) to displace the rest of the fluid
in chamber 22 and pump it into the patient. The pumping
chamber outlet valve is closed (last part of step E),
and the inlet valve is opened ~step F) while the plunqer
is retracted to fill the pumping chamber with liquid.
Once it is initially established that the
pumping chamber inlet and outlet valves are working
properly, air-in-line detector 3~ can be used to
establish whether the cassette inlet valves associated
132381 1
-31-
with primary cassette inlet 64 and secondary cassette
inlet 32 are working properly. To test the cassette
inlet valves, the pumping chamber outlet valve i8 closed
and the pumping chamber inlet valve is open ~end of step
E). At the same time, the two inlet valves are closed
(step G), and plunger 24 pressurizes pump chamber 22
(step H). The system is then held pressurized for a
short period of time (step I). If either of the two
cassette inlet valves leak, liquid will flow out of the
primary cassette inlet 64 or secondary cassette inlet
32. This reverse displacement of fluid will be
accompanied by the movement of trapped air 100 in drip
chamber 90 upwardly into air-in-line detector 34 as
shown in FIG. 3. Ultrasonic detector 154 will detect
this presence of air, and relay this to microprocessor
233 which sounds alarm 241 and nurse call 242. Thus,
the cassette will be rejected. If the primary and
secondary cassette inlet valve are good, plunger 24 is
retracted (step J) for the "normal cycle" (step X) of
fluid delivery described below.
In the "normal cycle" pumping sequence with
only one liquid being administered. The pumping chamber
inlet valve is closed and the pumping chamber outlet is
opened whereupon plunger 24 is urged through opening 18
against elastomeric member 16 to displace the fluid from
pumping chamber 22 out cassette outlet 30 to the
patient. The amount of fluid during the fluid delivery
stroke is controlled precisely by operating plunger 24
with a conventional stepping motor. By operating
plunger 24 with a stepper motor, the displacement of
plunger 24 against elastomeric member 16 can be
controlled precisely for each delivery stroke by
advancing the stepper motor the same number of steps for
each delivery stroke such that a constant volume of
fluid is displaced from pumping chamber 22 for each
stroke.
~`
` -32- 132381 ~
To refill pumping chamber 22 for the next
delivery stroke, the pumping chamber outlet valve is
closed, the pumping chamber inlet and the primary
cassette inlet valves are opened, and then plunger 24 i8
retracted the same number of steps it was advanced
during the previous fluid delivery stroke. Since both
the pumping chamber inlet valve and the primary cassette
inlet valve are opened, fluid will be drawn from the
fluid container connected to the primary cassette inlet
as plunger 24 is retracted stepwise. Once plunger 24 is
retracted to its starting or "home" position, the
pumping chamber inlet and the primary cassette inlet
valves are closed and the pumping chamber outlet valve
is opened for the next stepwise fluid delivery stroke of
plunger 24. The fluid delivery stroke is then repeated
followed by the pumping chamber refill retraction stroke
by plunger 24 with the pumping chamber inlet and outlet
valves appropriately valving the flow of fluid on
delivery and refill. As can be seen, the pumping of
fluid when a single fluid is being pumped is fairly
simple and straightforward.
However, multiple fluid delivery is also
possible. When two liquids are to be pumped, the
container containing the primary liquid is connected to
the primary cassette inlet 64._ The secondary liquid
container is connected to the secondary cassette inlet
32 by removing the luer lock cap on inlet 32 and
connecting ~he secondary fluid container to inlet 32
with a luer connector. The valving of the pumping
chamber inlet and outlet valves during fluid delivery
and pumping chamber refill strokes are the same durin~ a
two-fluid delivery as with the single fluid delivery
procedure described above. ~owever, the cassette inlet
valving is different. During single fluid delivery, of
course, the secondary cassette inlet valve is always
~33~ 1323811
closed and only the primary inle~ valve is open during
the refill of the pumping chamber. However, when
pumping two fluids, the primary and secondary cassette
inlet valves are each open~d and closed for selected
periods of time during the pumping chamber refill
stroke. For instance, if the two fluids are to be mixed
in a fifty-fifty proportion, the primary caæsette inlet
valve is opened during the first half of the total
number of strokes comprising the pumping chamber refill
stroke of plunger 24. During the first half of the
retraction stroke of plunger 24, the secondary cassette
inlet valve is closed. However, during the second half
of the retraction/refill stroke of plunger 24, the
secondary cassette inlet valve is opened while the
primary cassette inlet valve is closed. Since plunger
24 is controlled stepwise, it is possible to ascertain
exactly when to switch the two cassette inlet valves
from open to closed and vice versa to achieve the
desired proportioning of the two flu?ds.
Often, however, the primary fluid is a diluent
such as saline solution whereas the secondary fluid is a
concentrated drug. In such situations, a fifty-fifty
mixture may ~e undesirable, so the secondary cassette
inlet valve may be opened only 10 to 20 percent of the
steps during the pumping chamber refill stroke of
plunger 25 while the primary cassette inlet valve is
opened 80 to 90 percent of the steps comprising the
refill stroke of plunger 24.
It can be seen, therefore, that virtually any
desired concentration of secondary fluid in primary
fluid can be delivered to the patient using the cassette
and driver of the present invention simply by operating
inlet actuator 60 and 66 in sequence and in tandem with
plunger 24 during the pumping chamber refill stroke as
described above. Because cassette inlet actuators 60
i323811
and 66 cannot be simultaneously retracted as described
above (i.e., one is always extended closing its cassette
inlet valve), one cannot get grav~ty flow between the
primary and secondary fluid containers through the
cassette.
As indicated pr~viously, pressure sensor 77 and
pressure detection chamber 82 are employed to detect
whether the pumping chamber inlet and outlet valves are
functioning properly. However, once the pumping chamber
inlet and outlet valves are checked for proper
functioning, pressure sensor 77 and pressure detection
chamber 82 can also be used to monitor the patient's
blood pressure. During a pumping chamber filling stroke
of plunger 24 (e.g. step F in FIG. 24), the pumping
chamber outlet valve is closed such that the pressure of
the fluid in the fluid path from the pumping 'chamber
outlet valve to the patient ~s at the patient's blood
pressure. Thus, real time measurements of the patient's
blood pressure can be taken through the cassette. The
patient's blood pressure is stored in memory 243.
During the operation of cassette 10, microprocessor will
compare the patient's blood pressure to previously
recorded values of the same patient's pressure. If the
patient's blood pressure drops or increases dramatically
over time, microprocessor 243 will sound alarm 241
and/or nurse call 242 to alert medical personnel.
Pressure sensor 77 is also used to detect
occlusions in the line leading from the cassette outlet
to the patient. When plunger 24 is extended during the
fluid delivery stroke, the pressure in pressure chamber
82 is monitored by sensor 77 and microprocessor 233. If
the pressure is excessive, it indicates the patient line
has been wholly or partially occluded. Microprocessor
sounds alarm 241 and nurse call 242.
Air-in-line detector 154 and 156 are also
~35~ 13 23 81 ~
interfaced with microprocessor 233 (FIG. 25) so that
microprocessor 233 will stop the driver and sound alarm
241 and nurse call 242 if air i8 d~tected in th~
cassette or if detector 154 detects a bad inlet valve.
A ~DC/LED display 244 (FIG. 25) is also
interfaced wi~h microprocessor 244 so that input or
output values of delivery rates, delivery volumes, `
patient blood pressure and the like can be displayed to
an operator. Li~ewise, message codes can be displayed
to tell the operator why an alarm has been sounded.
A keyboard 2~5 is provided to input values of
delivery rates, delivery volumes, patient blood
pressure, concentration and the like. Microprocessor
233 can be programmed to deliver a given volume of
primary or secondary fluid over a desired period of
time, for instance. It is also programmed to set the
concentration of secondary liguid in primary solution
when two liquids are simultaneously delivered.
An AC/DC power supply 246 is provided and
includes a battery charger to continuously monitor and
charge batteries provided in the driver for operation
without AC current. In the event of battery failure,
alarm 241 is sounded.
Finally, a dataway 247 is provided to allow a
printer or other display to be connected to the driver
to get data printouts of patient blood pressure over
time, and fluid delivery times, volumes and rates.
While one embodiment has been disclosed and
described, other embodiments will become apparent to
those of ordinary skill in the art. Such embodiments
are to be construed within the ambit of the claims which
follow, unless by their terms, the claims expressly
state otherwise.
.
