Note: Descriptions are shown in the official language in which they were submitted.
a7~34
The presen-t invention relates to a novel flexible
diaphragm valve used in systems and equipment sets for
the administration of medical liquids to a patient. This
application is a divisional application of Canadian
Application Serial No. 346,461, filed February 26, 1980.
The parenteral administration of medical liquids
to patients is a long established practice. Liquids
including amino acids, blood, dextrose, electrolytes, and
saline are commonly administered to patients over prolonged
periods of time. Generally, these liquids are administered
from a glass bottle or plastic bag suspended above the
patient and containing 250 - 2,000 ml. of the liquid. Such
prolonged infusions commonly are administered at a flow
rate of 10 - 150 ml./hr,
Frequently, the patient must receive an additive
or secondary liquid while the prGlonged infusion is being
administered. Preferably, this secondary liquid should be
administered through the same hypodermic needle to avoid
unnecessary pain and trauma to the patient of additional
venipuncture. To avoid dilution and incompatability
problems r it is also preferred that the flow of the primary
liquid employed in the prolonged infusion be temporarily
interrupted, the secondary liquid administered and the
flow of the primary liquid resumed. Generally, the
secondary liquid will be administered at a flow rate of
50 - 250 ml./hr.
.
mb/
~970~
Back~round Art
Abbott Laboratories, North Chicago, Illinois
manufactures a y-type set for the sequential administra-
tion of primary and secondary liquids. These VENOSET (trade mark)
piggyback sets allow the prolonged infusion of a primary
li~uid to be t~mporarily halted by means of a backcheck
valve in the primary liquid flow path to administer a
secondary liquid without the need for a new venipuncture.
Them, when the secondary liquid has been depleted, the
backcheck valve automatically opens to resume flow of
the primary liquid. An important characteristic of this
system is that the secondary liquid container must be
suspended at a higher height than the primary liquid con-
tainer to establish the liquid pressure differential that
closes the backcheck valve in the primary liquid flow pathO
A similar system is disclosed in U. S. Patent
3,886,937 granted June 3, 1975 to D. Bobo, et al., as-
signed to American Hospital Supply Corp., and entitled
"Medical Administration Set for Dispensing Plural Medioal
Liquids", Another similar system is disclosed in U. S.
Patent 4,105,029 granted August 8, 1978 to R. Virag,
assigned to Baxter Travenol and entitled "Intravenous
Solution Set ~aving An Air Access Site and Constricted
Inner Diameter Portionn.
An inherent disadvantage of the above-mentioned
prior art medical liquid administration systems is that
they each resume the flow of primary liquid at the rate
the secondary liquid had been flowing. Because the pre-
ferred flow rate of the secondary liquid is generally
greater than the preferred flow rate of the primary
liquid, when the primary liquid resumes flow at that rate~
the patient can be administered an excessive amount of
primary liquid, unless the flow rate of the primary liquid
is adjusted to the preferred primary liquid flow rate soon
after the flow of primary liquid resumes.
A remedy to the above~described disadvantage
would appear to be provided by simply incorporating flow
7~
control devices into both the primary and secondary liquid
flow paths. ~Iowever, while this remedy does provide dual
flow rates for the primary and secondary liquids, it is
unacceptable. That is, hecause the common tube of the
y-set must be able to accommodate both flow rates, when
the primary liquid is flowing at a slower rate than the
secondary liquid was, there will be an unfilled volume or
void in the common tube. To fill that void, air will be
drawn into the common tube from the depleted secondary
container. That air will then be drawn into the patient
by the weight of the primary liquid, thereby causing a
serious embolism and perhaps, the patient's death.
Accordingly, it will be apparent that an efficacious
system for the sequential administration of medical liquids
at dual flow rates would be advantageous to the medical
profession.
Disclosure of Invention
The present invention relates to a novel flexible
diaphragm valve which may be used as the air barrier in
the secondary liquid flow path of a system for administration
of medical liquids. The diaphragm is substantially
impervious to air and liquid to insure that no air is drawn
from the secondary container when the secondary liquid is
depleted.
Specifically, the invention relates to a valve for
controlling the flow of liquid in a conduit, the valve
comprising: a housing divided into first and second chambers
by an air and liquid impermeable, flexible diaphragm, the
first chamber having an air vent through the housing, and
mb/-'~ - 3 ~
7(~4
the second chamber llaviny an ai.r vent through the housing
and means associated therewith to prevent the flow of
liquid therethrough, an inlet to be connected to the
conduit for the entrance of liquid into the second chamber,
and an outlet to be connected to the conduit for the exit
of liquid from the second chamber, which the outlet is
normally closed to air and liquid by the diaphragm, whereby
liquid entering through the inlet under sufficient pressure
to fill the second chamber will contact and exert pressure
against substantially all of the second chamber side of
the flexible diaphragm and hydrostatically lift the flexible
diaphragm away from the outlet to thereby allow the liquid
to exit from the valve until the liquid no longer fills
the second chamber, whereupon -the flexible diaphragm will
return ~.o its normal position to again close the outlet
to air and liquid.
Brief Description of the Drawings
Other objects and attendant advantages will become
obvious to those skilled in the art by reading the
following detailed description in connection with the
accompanying drawing, wherein like reference characters
designate like or corresponding parts throughout the
several figures thereof and wherein:
FIG~RE 1 is a schematic block diagram of the
efficacious system for the sequential administration of
medical liquids at dual flow rates contemplated by this
invention;
mbJcb
~ 7~ ~
FIGURE 2 - 5 are front elevation views of four
medical liquid administration equlpment sets embodying
the system of FIGURE l;
FIGURE 6 is a front elevational view of one em-
. 5 bodiment of the efficacious equipment sets for the sequen-
tial administration of medical liquids at dual flow rates
contemplated by this invention;
FIGURE 7 is a front elevational view of another
embodiment of the equipment sets contemplated by this
invention;
FIGURE B is a front elevational view of an al-
ternate version of part of the set of FIGURE 7;
FIGURE 9 is a front elevational view of one em_
bodiment of the efficacious equipment sets for the sequen-
tial administration of medical liquids at dual flow rates
contemplated by this invention;
FIGURE 10 is a front elevational view in cross-
section of the flexible diaphragm valve depicted in FIG-
URE 9;
FIGURE 11 is a front elevational view of another
embodiment of the efficacious equipment sets for the se-
quential administration of medical liquids at dual flow
rates contemplated by this invention;
FIGURE 12 is a front elevational view in cross-
section of the flexible diaphragm valve depicted in FIG-
URE 11; and
FIGURE 13 is a front elevational view in cross-
section of an altern~te embodiment of the flexible dia-
phragm valve of FIGURE 12.
Best Mode for Carrying Out
Referring to the drawings, there is shown in
FIGURE 1, a schematic block diagram of the basic elements
of the gravitational flow system for the sequential ad-
ministration of medical liquids at dual flow rates.
~9'7(~
The diagram depicts a primary liquid container
11 that contains a primary medical liquid to be admin-
istered to a patient for a prolonged period of time. The
diagram also depicts a secondary liquid container 13 that
contains a secondary medical liquid to be administered
to the patient for a relatively short period of time,
during which time the administration of the primary liquid
will be temporarily interrupted. As shown in the sets of
FIGURES 2 and 5, containers 11 and 13 can be glass bottles,
plastic flexible bags, or any other suitable container.
Primary container 11 and secondary con~ainer 13
are connected in fluid communication to a conventional
hypodermic needle 15 through a primary tube 17, a second-
ary tube 19, and a common tube 21. Thus, the primary
liquid flow path from primary container 11 to needle 15
comprises primary tube 17 and common tube 21~ Likewise,
the secondary liquid flow path from secondary container
13 to needle 15 comprises secondary tube 19 and common
tube 21.
The distal end of primary tube 17 is in fluid
communication with primary container 11, preferably by
means of a piercing pin 23 inserted into a puncturable
closure of container 11. Piercing pin 23 can have an
integral drip chamber 25, and when container 11 is a
glass bottle, as shown in the set of FIGURE 2, an inte-
gral filtered air vent 27. Such piercing pins, drip
chambers and air vents are well known in the medical prac-
tice and need not be more fully explained here.
The proximal end of primary tube 17 is joined
in fluid communication to the distal end of common tube
21, preferably by a y-tube 29, it being understood that
the primary, secondary and common legs of y-tube 29
constitute a portion of the primary, secondary and
common tubes 17, 19 and 21, respectively. Primary tube
17 has a primary flow control 31 intermediate its ends
for independent adjusting the rate of flow of the primary
liquid through the primary flow path. Preferably, as
shown in FIGURES 2 - 5, primary flow control 31 can be
~ ~ ~9~
a roller clamp. However, it can be any other adjustable
device that will reliably maintain a desired primary
liquid flow rate.
The proximal end of primary tube 17 is joined
in fluid communication to the distal end of common tube
21, preferably by a y-tube 29, it being understood that
the primary, secondary and common legs of y-tube 29 con-
stitute a portion of the primary, secondary and common
tubes li, 19 and 21, rQspectively.
As shown in FIGURES 6 and 7, primary tube 117
may have a portion 130 having a constricted or reduced
inner diameter for restricting the flow of primary liquid
through primary tube 117 to a predetermined rateO As
shown in FIGURE 7, primary tube 117 also includes a por~
tion 131 joined in parallel to constricted portion 130 by
y-tubes 132. Portion 131 has a substantially larger inner
diameter than reduced portion 130 and, accordingly, does
not affect the flow rate of primary liquid through pri-
mary tube 117. Portion 131 has slide clamp 134 that pre- 1
vents or permits primary liquid to flow through portion
131.
Alternatively, as shown in FIGURE 8, portions
130 and 131 can be provided with a common clamp 134a.
Clamp 134a is designed so that when it is slid to open con-
stricted portion 130, portion 131 will be closed and vice
versa. Returning to Figures 1-5, Primary tube 17 includes
a primary valve 33 between its proximal end and primary
flow control 31. Primary valve 33 allows primary liquid
to flow from primary container 11 whenever the height of
the primary liquid is greater than or equal to the height
of the secondary liquid in the system of FIGURE 1~
Further, primary valve 33 prevents the flow of primary
liquid from primary container 11 whenever the height of
the primary liquid is less than the height of the second-
ary liquid in the system.
While primary valve 33 has been shown in the
sets of FIGURES 1 - 5 as being spaced from the proximal
en~ of primary tube 17, it will be readily apparent that
primary valve 33 can be incorporated into the primary leg
of y-tube 29, if so ~esired. For example, primary valve
33 can be a co~ventional, one-way, backcheck valve
mounted within the primary leg of y-tube 29.
The distal end of secondary tube 19 is in fluid
communication with secondary container 13, preferably,
by means o a piercing pin 35 inserted into a puncturable
closure of container 13. Piercing pin 35 can have an
integral drip chamber 37, and when container 13 is a glass
bottle, as shown in FIGURE 2, an integral, filtered air
vent 39. The proximal end of secondary tube 19 is joined
in fluid communication to the distal end of common tube
21, preferably, by a y-tube 29.
An air barrier 41 and secondary flow control 43
are located in the secondary liquid flow path. Preferably,
as shown in FI~URES 2 - 5, secondary flow control 43 can be
a roller clamp. ~owever, it can be any other adjustable
device that can reliably maintain a desired secondary
liquid flow rate.
As shown in FIGURES 1 - 5, air barrier 41 is lo-
cated in secondary tube 19, which is its preferred loca-
tion. However, air barrier 41 can be located in common
tube 21, if so desired. Likewise, for increased relia-
bility of the system, a plurality of air barriers 41 can be
located in either the secondary tube 19, common tube 21, or
both. Further, while air barrier 41 is shown spaced from
the proximal end of secondary tube 19, it will be readily
apparent that air barrier 41 can be incorporated into the
secondary or common tube leg of y-tube 29.
As shown in the set of FIGURE 2, air barrier 41
comprises a housing 44 having an inlet and outlet in fluid
communication with secondary tube 19 and constitutes` a
portion of it. Housing 44 is filled with a hydrophilic
membrane filter 45 which is impermeable to air when wet.
The hydrophilic filters can be formed from materials such
as a cellulose acetate material produced by the Millipore
Filter Corporation of Bedford, Massachusetts or the
Sartorius-Membranfilter GmbH of Weender Landstr, West
Germany.
-- 8 --
37~
The housing of each se~ shown in FIGURES 2 -
5 also includes an air vent tube 47 having a slide clamp
49 and a filtered opening 50. Alternatively, opening 50
can be filtered by a hydrophobic membrane filter which
is permeable by air, but not liquids. The hydrophobic
filters can be ~ormed of polyfluorotetraethylene, hexa-
fluoropropylene/tetrafluoroethylene copolymer, or other
suitable materials. One such filter is made of Gelman
ANH-450 material made by Gelman Instruments of Ann Arbor,
Michigan. ~hen such a hydrophobic filter is used, slide
clamp 49 can be eliminated.
Each embodiment of the system of FIGURE 1 shown
in FIGURES 2 - 5 includes a slide clamp 51 near the-distal
end of secondary tube 19 and a slide clamp 52 near the
proximal end of common tube 21.
The air barrier 41 shown in the set of FIGURE 3
comprises a housing 53 that is substantially transparent
and has graduations 55 on its sidewall that in~icate the
- amount of liquid contained therein. Housing 53 has an ~l
inlet and outlet in fluid communication with secondary
tube 19 and constitutes a portion of it. The outlet
from housing 53 is covered by a hydrophilic membrane
filter 45. In the set of FIGURE 3, secondary tube 19 in-
cludes a drip chamber 55 on the proximal side of air
barrier 41.
The air barrier 41 shown in the sets of FIGURES
4 and 5 comprises a housing 63 that has an inlet and out-
let in fluid communication with secondary tube 19 and
constitutes a portion of it. The outlet from housing 63
has a float valve 65 which floats away from the outlet
when liquid is present in housing 63, but seats or closes
over the outlet when no liquid is present. It will be
apparent to those skilled in the art that numerous other
conventional mechanical valves can be employed to perform
the function of float valve 65, so long as the valve forms
a barrier impermeable by air when no liquid is present in
the housing 63O
As seen in FIGURES 9 and 11, air barrier 241 and
secondary ~low control 240 are located in the secondary
liquid flow path. Preferably, as shown in FIGURES 7 and
9, secondary flow control 240 can be a roller clamp. How-
ever, it can be any other adjustable device that can re-
liably maintain a desired secondary liquid flow rate.
As shown in FIGURES 9 - 11, an air barrier 241
is located in secondary tube 219. While air barrier 241
is shown near the proximal end of secondary tube 219, it
will be readily apparent that air barrier 241 can be more
distally located on secondary tube 219, or incorporated
into the secondary tube leg of y-tube 229, if so desired.
As shown in the set of FIGURE 9, air barrier
241 comprises a valve housing 242 having an inlet 243 and
outlet 244 in fluid communication with secondary tube 219
and constitutes a portion of it. As best seen in FIGURE
10, housing 242 is divided into two chambers 246, 247 by
an air and liquid impermeable, flexible diaphragm 248.
Diaphragm 248 is, preferably, made of elastomeric material,
such as natural or silicone rubber. Diaphragm 248 can
also be made of thermoplastic materials, such as poly-
ethylene. As shown in FIGURE 10, diaphragm 248 can be
captured between halves of housing 242. Alternatively,
diaphragm 248 can be insert-molded into a single piece
housing.
Chamber 246 has an air vent 250 through housing
242 by which ambient air can enter and exit. Chamber 247
has an air vent 252 through which ambient air can enter
and exit. Air vent 252 is covered by a hydrophobic mem-
brane 254 which is permeable by air, but not liquids. Thehydrophobic filter can be formed of polyfluorotetraethylene,
hexafluoropropylene/tetrafluoroethylene copolymer, or other
suitable materials. One such filter is made of Gelman
ANH-450 (trade mark) material made by Gelman Instruments of
Ann Arbor, Michigan.
As seen in FIGU~E 10, outlet 244, preferably, ex-
tends into chanber 247 a substantial distance and its inner
-- 10 --
end 256 forms a seat on which flexible diaphragm 248 is nor-
mally seated to close outlet 244 to air and liquid.
As shown in the set of FIGURE 11, air barrier
241 comprises a valve housing 262 having an inlet 243 and
outlet 244 in fluid communication with secondary tube 219
and constitutes a portion o~ it. As best seen in FIGURES
12 and 13, housing 26Z is divided into two chambers 246,
247 by an air and liquid impermeable membrane 248. Cham-
ber 246 has an air vent 250 covered by a hydrophobic mem-
lQ 'brane 264~ Alternatively, as shown in FIGURE 13, air
vent 250 can include a tube 265 having a filtered end
266 and a slide clamp 267 which can be slid to open vent
250 to the passage of air and closed to prevent the pas-
sage of liquid.
Housing 262 has a port 268 therethrough and open-
ing into'chamber 246. As seen in FIGURE 11, port 268 is
connected in fluid communication to primary tube 217 by a
'pilot tube 269,-preferably, by means of a y-tube 270.
Pilot tube 269 has a slide clamp 271 thereon for controll-
ing the flow of liquid through pilot tube 269. When slide
clamp 271 is open, primary liquid can enter housing 262 to
further bias flexible membrane 48 to its normally closed
position. The entering primary liquid forces air from
chamber 246 through vent 250. However, the primary liquid
is prevented from flowing through vent 250 by hydrophobic
membrane 264. When the alternative'embodiment of FIGURE
5 is used, slide clamp 265 must also be open to enable
liquid to enter chamber 246 and slide clamp 271 can be
eliminated, if so desired.
As shown in FIGURES 12 and 13, chamber 247 of
housing 262 has an air vent 252 covered by a hydrophobic
membrane 254. Alternatively, vent 252 can include a tube
having a filtered end and a slide clamp similar to that
of vent 250, is so desired. The inner end 256 of outlet
244 from chamber 247 is provided a plurality of protru-
sions to form a plurality of seats on which flexible dia-
phragm 248 can seat. Preferably, the plurality of pro-'
trusions are formed by a plurality of concentric rings of
~ .
-- 11 --
~ 9 70 ~
unequal heights, the height of the respective rings de-
creasi.ny in a direction from the perimeter of inner end
256 toward its center.
In the set of FIGURE 4, primary tube 17 includes
a primin~ tube 67 having a slide clamp 69 that controls
the flow of primary liquid through priming tube 67. Prim-
ing tube 67 is joined in parallel to the main branch o~
primary tube 17 by y-tubes 71, 72 located on each side
of primary control means 31. As will be more fully ex
plained in the following paragraphs, priming tube 17
allows primary control means 31 to remain at its preferred
adjustment while the set of FIGURE 4 is being primed or
backprimed at a higher flow rate.
Primary flow control 31 is shown on the distal
side of primary valve 33 in FIGURES 1 - 5. It has been
found that for pressure differentials of the magnitude
occuring in the system o~ this invention, location of pri
- mary flow control 31 on the proximal side of primary valve
33, for most of the preferred settin~s of primary flow
control 31, results in a greater pressure being exerted
in primary valve 33 by primary liquid than by secondary
liquid. As a result, primary valve 33 remains open, as
if the height o~ primary liquid were greater than or
equal to the height of secondary liquid in the system.
Surprisingly, it has been found that when
primary flow control 31 is located on the distal side of
primary valve 33, as shown in FIGURES 1 - 5, certain em-
bodiments of primary valve 33 might not remain closed as
expected whenever the height of primary liquid is less
than the height of secondary liquid in the system. This
unexpected opening results from the reaction force on
primary valve ~3 caused by primary liquid that cannot
flow up~wardly past primary flow control 31 when primary
valve 33 initially closes. This reaction force reopens
valve 33 and keeps it open.
It has been found that this unexpected opening
of primary valve 33 can be obviated by the inclusion in
primary tube 17 of a chamber 75 for a compressible mass.
97~
As shown in ~IGUR~ 5, chamber 75 is located between primary
flow control 31 and primary valve 33 and provides a cush-
ion or ~pring for relieving pressures ont the distal side
of primary valve 33 whenever valve 33 closes in response
to the height of primary liquid being less than the
height of secondary liquid in the system. Although pri-
mary valve 33 and chamber 75 are shown as separate units
in FIGURE 5, it will be apparent that they can be combined
into one unit, if so desired.
As shown in the set of FIGURE 5, chamber 75 has
a housing with an inlet and outlet in fluid communication
with primary tube 17. ~owever, it is contemplated that
chamber 75 can have only one opening in communication
with primary tube 17. That is, chamber 75 may have a
single opening transverse to the normal flow of liquid
through primary tube 17 so that primary liquid only flows
in or out of its single opening when reverse flow pres-
sures exist on the distal side of primary valve 33.
Generally, the compressible mass of chamber 75
will be air and its housing will be a rigid opaque plas-
tic. However, it is contemplated that the compressible
mass of chamber 75 can be a sponge or other flexible
solid materials, as well. Further, the housing of cham-
ber 75 can be a flexible material which is compressible
by the primary liquid to expand chamber 75, if so desired.
For simplicity, the equipment sets embodying the
system of FIGURE 1 have been depicted and described as
integral units of FIGURES 2 - 5. It-is apparent, however,
that the sets can be manufactured and assembled in sub-
sets of the entire set and that each subset will accord-
ingly be provided such resealable closures, piercing means,
adapters, etc. as are necessary to permit their easy
assemblage into the complete set at an appropriate time.
It will also be apparent that each of the several compo-
nents of the sets of FIGURES 2 - 5 can be interchanged or
combined in combinations other than those specifically
depicted.
- 13 -
Operation_o ~ y~
As depicted in FIGURES 2 - 5, primary container
11 is suspended in space at a height above the patient
by means of a hook 77 and stand 79. It will be apparent
that other means for suspending the containers of this
invention are well known.
- To insure that all the air that might be forced
into the patient has been removed from the set, the set
is initially primed by first closing all slide clamps
49, 51, 52 and 69, if presen~. Piercing pin 23 is then
inserted into the resealable closure of primary container
11. Primary flow control 31 and secondary ~low control
43 are fully opened. Slide clamp 52 is opened to allow
primary liquid to flow through the primary liquid flow
path and force all the air therefrom that might be forced
into the patient. If chamber 75 is present in primary
tube 17, a substantial volume of air will remain therein.
Slide clamp 52 is then closed.
In FIGURES 9 - 13, if inlet 243 to air barrier
241 is closed by a resealable closure at this time, second-
ary tube 219 will have been backprimed whiie primary tube
217 was being primed. When secondary tube 219 is back-
primed, chamber 247 will be flooded so that all of dia-
phragm 248 will be contacted by primary liquid that will
hyddrostatically lift diaphragm 248 from outlet 244 to
fully open the valve. As primary liquid enters chamber
247, diaphragm 248 will flex away from outlet 244 and air
will be expelled through air vent 252 in chamber 247 and
air vent 250 in chamber 246. However, hydrophobic mem-
brane 254 will prevent the flow of liquid through vent 252.
Clamp 49 on air vent 47 of air barrier 41 is
then opened to allow primary liquid to flow into, or back-
prime, secondary ~low path 19 and force all the air from
air barrier 41. Slide clamp 49 is then closed. Alterna-
tively, if the set is fully assembled, slide clamp 51 can
be opened to allow primary liquid to force air out of the
entire secondary tube 19. Slide clamp 51 is then closed.
- 14 -
~ 3'~ ~
During the initial priming of secondary tube
19, it is advan~ageous to hold secondary tube 19 at a
height well below primary container 11. When secondary
tube 19 has been primed, it is secured in a convenient
place until its subsequent use.
Common tube 21, which preferably has an adapter
at its proximal end open to the flow of liquid therefrom,
is next connected to needle 15, which will generally have
been already inser~ed into a vein of the patient. Slide
clamp 52 will then be opened to allow primary liquid to
flow th~ough the primary liquid flow path to the patient's
vein. Primary flow control 31 is then adjusted to a set-
ting that will provide the desired flow rate for a pro-
longed infusion of primary liquid into the patient,
generally 10 - 150 ml./hr. As is well known in the medi-
cal practice, that flow rate can be visually observed by
viewing and counting drops passing through the primary
drip chamber 25.
In the set of FIGURE 6, flow control device 143
can be alllowed to remain fully open, so that the flow
rate of primary liquid through primary tube 117 will be
determined solely by the constricted or reduced inner
diameter of portion 130~ Alternatively, or in the sets
of FIGURES 7 or 8, whenever portion 131 is open to the
flow of liquid therethrough, flow control 143 is then
adjusted to a setting that will provide the desired flow
~ate for a prolonged infusion of primary liquid into the
patient, generally 10 - 150 ml./hr. As is well known in
the medical practice, that flow rate can be visually ob-
served by viewing and counting drops passing through theprimary drip chamber 25. If the sets of FIGURE 9 are being used, slide
clamps 267 and/or 271 are opened to allow primary liquid
to enter chamber 246 of valve housing 262. If this
pilot liquid enters chamber 246 before secondary tube
219 is fully bac~primed, it will not be possible to back-
prime secondary tube 219 as the weight of the liquid will
prevent membrane 248 from lifting away from outlet 244. It
~ ~t~
will be apparent that none of the pilot liquid entering
chamber 246 through pilot tube 269 will be administered to
the patient.
Secondary flow control 243 is then adjusted to a
desired flow rate, typically 50 - 250 ml./hr., for the
secondary liquid, which will flow until the secondary
container 213 is depleted. It will be apparent that the
initial liquid flowing from secondary tube 219 will be the
primary liquid with which it was primed.
When the height of primary liquid in the sets
of FIGVRES 9 - 11 becomes greater than the height of the
secondary liquid, primary valve 233 will immediately open
and allow primary liquid to flow from the primary con-
tainer at the flow rate to whieh primary flow control 31
is adjusted. The primary flow rate is independent of the
secondary flow rate. In those instances where it is less
than or equal to the secondary flow rate, both primary
and secondary liquid will flow through common tube 221,
until air reaches air barrier 241 in the secondary tube.
Then only primary liquid will enter common tube 221. Air i
barrier 241 then prevents air from being drawin into common
tube 221 and eventually to the patient's vein.
Diaphragm 248 of valve housing 242 shown in FIGURE
9 will now seat against outlet 244 because of its own
weight and elastic memory. Air will re-enter chamber 246
through air vent 250 as diaphragm 248 seatC. Secondary
liquid will remain in chamber 2~7 at a level just below
diaphragm 248~ As primary liquid flows through common
tube 221 on the proximal side of diaphragm 248, it will
create a reduced pressure that will tend to draw dia-
phragm 248 into outlet 244 even further. In addition,
diaphragm 248 of housing 262 will be further biased against
outlet 244 by the weight of the primary liquid present in
chamber 246, when that valve is employed.
When secondary container 213 becomes depleted
of secondary liquid, it can be left empty until another
secondary liquid is to be administered. When another
secondary liquid is to be administered, the secondary
- 16 -
~ 370 ~
piercing pin 235 is merely removed from secondary contain-
er 213 and inserted into a new secondary liquid container.
The pilot liquid must be drained from chamber 246, if
present. The secondary tube 219 must then be backprimed,
as when the secondary container was administered.
The set of FIGURE 3 can be employed to admini-
ster a specific dose of secondary liquid to the patient by
closing secondary tube slide clamp 51 when the desired
amount of secondary liquid is in the calibrated cylinder
53. Air vent slide clamp 49 is then opened to allow the
secondary liquid to flow from cylinder 53. However,
while calibrated cylinder 53 is depicted at a lower
height than primary container 11, in FIGURE 3, once
secondary tube slide clamp 51 is closed, calibrated
cylinder 53 must be raised to a height substantially
above primary container 11, otherwise concomitant flow
of the primary and secondary liquids will occur.
When the height of primary liquid in the system
of FIGURE 1, as depicted in the sets of FIGURES 2 - 5,
becomes greater than the height of the secondary liquid,
primary valve 33 will immediately open and allow primary
liquid to flow from the primary container at the flow rate
to which primary ~low control 31 is adjusted. The primary
flow rate is independent of the secondary flow rate. In
those instances where it is less than or equal to the
secondary flow rate, both primary and secondary liquid
will flow through common tube 21, until air reaches air
barrier 41 in the secondary tube. Then only primary
liquid will enter common tube 21. Air barrier 41 then
prevents air from being drawn into common tube 21 and
eventually to the patient's vein.
When primary container 11 becomes depleted of
primary liquid, the primary piercing pin 23 is merely re-
moved therefrom and inserted into the resealable closureof a new primary container, which is then suspended in
place of the previous container. If primary container
11 had become empty, it will be necessary to reprime
the entire system as when the first primary container
was administered.
When secondary container 13 becomes depleted
of secondary li~uid, it can be left empty until another
secondary liquid is to be administered. When another
secondary liquid is to be administered, the secondary
piercin~ pin 35 is merely removed from secondary contain-
er 13 and inserted into a new secsndary liquid container.-
The secondary tube 19 must then be backprimed, as when
the first secondary container was administered~
Having described the invention in specific de-
tail and exemplified the manner in which it may be carried
into practice, it will now be readily apparent to those
skilled in the art that innumerable variations, applica-
tions, modifications and extensions of the basic prin-
ciples involved may be made without departing from the
sphere or scope.
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