U.S. patent number RE33,518 [Application Number 07/095,416] was granted by the patent office on 1991-01-15 for pressure transducer assembly.
This patent grant is currently assigned to Baxter International, Inc.. Invention is credited to Paul Anderson, Edward J. Arkans, James K. Bullock, Henrick K. Gille, Keith Gilroy, Kenneth R. McCord.
United States Patent |
RE33,518 |
McCord , et al. |
January 15, 1991 |
**Please see images for:
( Certificate of Correction ) ** |
Pressure transducer assembly
Abstract
A pressure transducer assembly is disclosed for directly
monitoring pressure in a fluid which flows through the assembly.
The assembly includes a housing defining a chamber therewithin and
having an inlet port and an outlet port in fluid-flow communication
with the chamber. An electrically insulated body element is sealed
within the chamber dividing the chamber into a first chamber and a
second chamber. The first chamber is in fluid-flow communication
with the inlet and outlet ports. The second chamber is separated
from the first chamber by a fluid-tight seal such that any fluid
present in the first chamber cannot enter the second chamber. A
pressure transducer sensor is secured in the insulated body and
exposed to the first chamber such that the sensor can determine the
pressure in a fluid in the first chamber and convert the pressure
into electric impulses. The sensor is separated from the fluid in
the first chamber by an insulating medium across which fluid
pressure can be determined. Connected to the sensor are electrical
conductors which extend through the insulated body and into the
second chamber. The second chamber provides an engagement site for
an electrical connector which can interconnect with the electrical
conductors and provide an electrical path through which the
electric impulses generated by the sensor can be transferred to a
monitor.
Inventors: |
McCord; Kenneth R. (Yorba
Linda, CA), Bullock; James K. (Burbank, CA), Gilroy;
Keith (Upland, CA), Gille; Henrick K. (Monrovia, CA),
Arkans; Edward J. (Sunland, CA), Anderson; Paul
(Tujunga, CA) |
Assignee: |
Baxter International, Inc.
(Deerfield, IL)
|
Family
ID: |
26790200 |
Appl.
No.: |
07/095,416 |
Filed: |
September 10, 1987 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
489900 |
Apr 29, 1983 |
04539998 |
Sep 10, 1985 |
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Current U.S.
Class: |
600/488; 600/561;
73/706; 73/708 |
Current CPC
Class: |
A61B
5/0215 (20130101); G01L 19/0023 (20130101); G01L
19/003 (20130101); G01L 19/0084 (20130101) |
Current International
Class: |
A61B
5/0215 (20060101); G01L 19/00 (20060101); G01L
9/00 (20060101); A61B 005/215 () |
Field of
Search: |
;128/672-675,748
;73/706,708,717,721,723,727 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2925880 |
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Jan 1981 |
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DE |
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1212264 |
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Mar 1960 |
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FR |
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1583433 |
|
Oct 1969 |
|
FR |
|
2125991 |
|
Sep 1972 |
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FR |
|
0022933 |
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Feb 1983 |
|
JP |
|
0168930 |
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Oct 1983 |
|
JP |
|
0168931 |
|
Oct 1983 |
|
JP |
|
Other References
Cobe Disposable Transducer System, Dec., 1981. .
"MPX Pressure Transducers", Motorola Inc..
|
Primary Examiner: Sykes; Angela D.
Attorney, Agent or Firm: Peterson; Gordon L.
Claims
We claim:
1. A pressure transducer assembly for monitoring pressure in a
fluid comprising:
a housing defining a chamber and having an inlet port and an outlet
port in fluid-flow communication with the chamber;
an insulated body sealed within the chamber which forms separate
first and second chambers within the housing with the first chamber
in fluid-flow communication with the inlet port and outlet
port;
a pressure transducer means secured in the insulated body and
exposed to the first chamber for determining and converting fluid
pressure within a fluid in the first chamber into electrical
impulses;
a fluid pressure responsive media covering the pressure transducer
means which is electrically non-conductive and which separates the
pressure transducer means from any fluid present in the first
chamber;
electrical conducting means connected to the pressure transducer
means and extending through the insulated body and into the second
chamber for providing electrical connection between the pressure
transducer means in the first chamber and the second chamber;
and
engagement means on the housing for providing a connection locus on
the housing for electrical wiring which can be interconnected with
the electrical conducting means.
2. A pressure transducer assembly as required in claim 1 wherein
the fluid pressure responsive media comprises silicone
elastomer.
3. A pressure transducer assembly as recited in claim 1 further
comprising tubing connecting means on the inlet and outlet ports
for connecting tubing to the housing.
4. A pressure transducer assembly as recited in claim 1 wherein the
electrical conducting means comprises a plurality of electrical
conducting metal pins electrically interconnected to the pressure
transducer means to transfer power to the pressure transducer means
and to transfer away electrical impulse signals corresponding to
determined pressures.
5. A pressure transducer assembly as recited in claim 1 wherein the
insulated body sealed within the chamber comprises a polysulfone
body.
6. A pressure transducer assembly as recited in claim 1 wherein the
pressure transducer means comprises a silicon pressure transducer
with a single piezoresistive element.
7. A pressure transducer assembly as recited in claim 6 wherein the
pressure transducer means comprises a monolithic silicon pressure
sensor employing a four-terminal resistive element formed in a
monocrystalline silicon diaphragm.
8. A pressure transducer assembly as recited in claim 1 wherein the
pressure transducer means monitors fluid pressure within the first
chamber in the range from about -50 mmHg to +300 mmHg.
9. A pressure transducer assembly as recited in claim 1 further
comprising a clear lens means on the housing extending over the
first chamber for viewing fluid and bubbles in the fluid within the
first chamber.
10. A pressure transducer assembly as recited in claim 9 wherein
the clear lens means comprises a clear dome portion on the housing
extending over at least a portion of the first chamber.
11. A pressure transducer assembly as recited in claim 1 wherein
the housing comprises a biocompatible polymeric material.
12. A pressure transducer assembly as recited in claim 11 wherein
the biocompatible polymeric material is selected from the group
consisting of polycarbonate, polypropylene, polyethylene and
polysulfone.
13. A pressure transducer assembly as recited in claim 1 further
comprising vent means on the housing and on the insulated body for
providing exposure to the atmosphere for the pressure transducer
means.
14. A pressure transducer assembly as recited in claim 13 wherein
the vent means comprises an opening extending through the housing
into the second chamber and aligned with an opening extending
through the insulated body and leading to the pressure transducer
means.
15. A pressure transducer assembly as recited in claim 1 wherein
the engagement means comprises a resilient, snap-fitting means for
connecting electrical wiring to the assembly.
16. A pressure transducer assembly as recited in claim 15 wherein
the resilient, snap-fitting means comprises an opening into the
second chamber for receiving an electric wiring connector and at
least one resilient portion of the housing for engaging an electric
wiring connector and which is deformable for releasing such an
electric wiring connector.
17. A pressure transducer assembly as recited in claim 1 further
comprising a wiring connector means which engages the electrical
conducting means in the second chamber for transmitting electric
impulses generated by the pressure transducer means along
electrical wiring to a monitoring means for displaying fluid
pressure in fluid in the first chamber.
18. A pressure transducer assembly as recited in claim 17 wherein
the electrical conducting means comprises electrical pins extending
into the second chamber and the wiring connector means comprises a
body having electrical pins engaging terminals and which slides
into the second chamber and which .[.engaging.]. .Iadd.engages
.Iaddend.the electrical pins.
19. A pressure transducer assembly as recited in claim 1 wherein
the pressure transducer means includes a temperature compensation
circuit means for determining fluid pressure at the .[.second.].
.Iadd.sensed .Iaddend.temperature of a fluid in the first
chamber.
20. A pressure transducer assembly as recited in claim 1 wherein
the inlet port and outlet port are axially aligned.
21. A disposable pressure transducer assembly for use in the
invasive monitoring of blood pressure, the assembly comprising:
a housing defining a chamber therewithin and having an inlet port
and an outlet port in fluid-flow communication with the
chamber.
an electrically insulated intervening wall in the chamber
separating the chamber into a first chamber and a second chamber
wherein the first chamber is in fluid-flow communication with the
inlet port and outlet port and the second chamber is separated from
the first chamber by a fluid-tight seal;
a pressure transducer means secured in the first chamber in a
depression on the electrically insulated intervening wall, which
pressure transducer means is exposed to the first chamber for
sensing and converting fluid pressure exhibited by a fluid in the
first chamber into electrical impulses;
an electrically nonconductive, fluid pressure responsive media
covering the pressure transducer means which separates the pressure
transducer means from direct contact with fluid present in the
first chamber;
electrical conducting means connected to the pressure transducer
means for transmitting and receiving electrical impulses from the
pressure transducer means and which extends through the intervening
wall into the second chamber to provide a pathway for electricity
between the pressure transducer means in the first chamber and the
second chamber; and
receptor means on the housing for receiving and connecting the
housing to electrical wiring means for powering the pressure
transducer means and for transferring electrical impulses generated
by the pressure transducer means and corresponding to determined
pressures.
22. A disposable pressure transducer assembly as recited in claim
21 wherein the electrically nonconductive fluid pressure responsive
media comprises silicone elastomer.
23. A disposable pressure transducer assembly as recited in claim
.[.20.]. .Iadd.21 .Iaddend.further comprising tubing connecting
means on the inlet and outlet ports for connecting tubing to the
housing.
24. A disposable pressure transducer assembly as recited in claim
21 wherein the electrical conducting means comprises a plurality of
electrical conducting metal pins electrically interconnected to the
pressure transducer means to transfer power to the pressure
transducer means and to transfer away electric impulse signals
corresponding to determined pressures.
25. A disposable pressure transducer assembly as recited in claim
21 wherein the electrically insulated intervening wall within the
chamber comprises a polysulfone wall.
26. A disposable pressure transducer assembly as recited in claim
21 wherein the pressure transducer means comprises a monolithic
silicon pressure sensor employing a four-terminal resistive element
formed in a monocrystalline silicon diaphragm.
27. A disposable pressure transducer assembly as recited in claim
21 wherein the pressure transducer means monitors fluid pressure
within the first chamber in the range from about -50 mmHg to +300
mmHg.
28. A disposable pressure transducer assembly as recited in claim
21 further comprising a clear lens means on the housing extending
over the first chamber for viewing fluid and bubbles in the fluid
within the first chamber.
29. A disposable pressure transducer assembly as recited in claim
28 wherein the clear lens means comprises a clear dome portion on
the housing extending over at least a portion of the first
chamber.
30. A disposable pressure transducer assembly as recited in claim
21 wherein the housing comprises a biocompatible polymeric
material.
31. A disposable pressure transducer assembly as recited in claim
30 wherein the biocompatible polymeric material is selected from
the group consisting of polycarbonate, polypropylene, polyethylene
and polysulfone.
32. A disposable pressure transducer assembly as recited in claim
21 further comprising vent means on the housing and on the
electrically insulated intervening wall for providing exposure to
the atmosphere for the pressure transducer means.
33. A disposable pressure transducer assembly as recited in claim
32 wherein the vent means comprises an opening extending through
the housing into the second chamber and aligned with an opening
extending through the electrically insulated intervening wall and
leading to the pressure transducer means.
34. A disposable pressure transducer assembly as recited in claim
21 further comprising a wiring connector means which engages the
electrical conducting means in the second chamber for transmitting
electrical impulses generated by the pressure transducer means
along electrical wiring to a monitoring means for displaying fluid
pressure in fluid in the first chamber.
35. A disposable pressure transducer assembly as recited in claim
34 wherein the electrical conducting means comprises electrical
pins extending into the second chamber and the wiring connector
means comprises a body having electrical pins engaging terminals
and which slides into the second chamber and which .[.engaging.].
.Iadd.engages .Iaddend.the electrical pins.
36. A disposable pressure transducer assembly as recited in claim
21 wherein the pressure transducer means includes a temperature
compensation circuit means for determining fluid pressure at the
sensed temperature of a fluid in the first chamber.
37. A disposable pressure transducer assembly as recited in claim
21 wherein the inlet port and outlet 171 are 173 ep .Iadd.port
.Iaddend.axially aligned.
38. A disposable pressure transducer assembly for invasively
monitoring blood pressure comprising:
a housing comprised of polysulfone defining a chamber therewithin,
having an inlet port and an outlet port in fluid-flow communication
with the chamber and having a first aperture opening to the
chamber;
an electrically insulated intervening wall in the chamber comprised
of polysulfone which separates the chamber into a first chamber and
a second chamber wherein the first chamber is in fluid-flow
communication with the inlet port and outlet port and the second
chamber having an opening through the housing and separated from
the first chamber by a fluid-tight seal and the first aperture
extends into the second chamber and aligns with a second aperture
extending through the electrically insulated intervening wall;
a pressure transducer means secured in the first chamber in a
depression on the electrically insulated intervening wall, which
pressure transducer means is exposed to the first chamber for
sensing and converting fluid pressure exhibited by a fluid in the
first chamber into electrical impulses;
an electrically nonconductive fluid pressure responsive media
comprising silicone elastomer covering the pressure transducer
means which separates the pressure transducer means from direct
contact with fluid present in the first chamber;
electrical conducting pins connected to the pressure transducer
means for transmitting and receiving electrical impulses from the
pressure transducer means and which extend through the intervening
wall into the second chamber to provide a pathway for electricity
between the pressure transducer means in the first chamber and the
second chamber; and
snap-fitting resilient arms on the housing which combine with the
opening through the housing into the second chamber which receives
and connects the housing to electrical wiring means for powering
the pressure transducer means and for transferring electrical
impulses generated by the pressure transducer means and
corresponding to determined pressures.
39. A disposable pressure transducer assembly as recited in claim
38 wherein the pressure transducer means comprises a monolithic
silicon pressure sensor employing a four-terminal resistive element
formed in a monocrystalline silicon diaphragm.
40. A disposable pressure transducer assembly as recited in claim
38 wherein the pressure transducer means monitors fluid pressure
within the first chamber in the range from about -50 mmHg to +300
mmHg.
41. A disposable pressure transducer assembly as recited in claim
38 wherein the pressure transducer means includes a temperature
compensation circuit means for determining fluid pressure at the
sensed temperature of a fluid in the first chamber.
42. A disposable pressure transducer assembly as recited in claim
38 further comprising a clear lens means on the housing extending
over the first chamber for viewing fluid and bubbles in the fluid
within the first chamber.
43. A disposable pressure transducer assembly as recited in claim
42 wherein the clear lens means comprises a clear dome portion on
the housing extending over at least a portion of the first
chamber.
44. A disposable pressure transducer assembly as recited in claim
38 wherein the inlet .[.por.]. .Iadd.port .Iaddend.and outlet port
are axially aligned.
45. A disposable pressure transducer assembly for invasively
monitoring blood pressure comprising:
a housing comprised of polysulfone with at least a portion of the
housing forming a dome and extending over and defining a chamber
with the housing, the housing including an inlet port and an outlet
port in fluid-flow communication with the chamber and a first
aperture opening to the chamber;
an electrically insulated intervening wall in the chamber comprised
of polysulfone which separates the chamber into a first chamber and
a second chamber wherein the first chamber is in fluid-flow
communication with the inlet port and outlet port and the second
chamber having an opening through the housing and separated from
the first chamber by a fluid-tight seal and the first aperture
extends into the second chamber and aligns with a second aperture
extending through the electrically insulated intervening wall;
a pressure transducer means secured in the first chamber in a
depression on the electrically insulated intervening wall, which
pressure transducer means is exposed to the first chamber for
sensing and converting fluid pressure exhibited by a fluid in the
first chamber into electrical impulses;
an electrically nonconductive fluid pressure responsive media
comprising silicone elastomer covering the pressure transducer
means which separates the pressure transducer means from direct
contact with fluid present in the first chamber.
electrical conducting pins connected to the pressure transducer
means for transmitting and receiving electrical impulses from the
pressure transducer means and which extend through the intervening
wall into the second chamber to provide a pathway for electricity
between the pressure transducer means in the first chamber and the
second chamber; and
snap-fitting resilient arms on the housing which combine with the
opening through the housing into the second chamber which receives
and connects the housing to electrical wiring means for powering
the pressure transducer means and for transferring electrical
impulses generated by the pressure transducer means and
corresponding to determined pressures.
46. A disposable pressure transducer assembly as recited in claim
45 wherein the pressure transducer means comprises a monolithic
silicon pressure sensor employing a four-terminal resistive element
formed in a monocrystalline silicon diaphragm.
47. A disposable pressure transducer assembly as recited in claim
45 wherein the pressure transducer means monitors fluid pressure
within the first chamber in the range from about -50 mmHg to +300
mmHg.
48. A disposable pressure transducer assembly as recited in claim
45 wherein the pressure transducer means includes a temperature
compensation circuit means for determining fluid pressure at the
sensed temperature of a fluid in the first chamber.
49. A disposable pressure transducer assembly as recited in claim
45 wherein the inlet port and outlet port are axially aligned.
.Iadd.
50. A pressure transducer assembly for monitoring pressure in a
fluid comprising;
a housing defining a chamber and having an inlet port and an outlet
port in fluid-flow communication with the chamber;
an insulated body sealed within the chamber which forms separate
first and second chambers within the housing with the first chamber
in fluid-flow communication with the inlet port and outlet port and
adapted to be filled with fluid from the inlet port;
a pressure transducer means secured on the insulated body and
exposed to pressure of fluid in the first chamber for determining
and converting fluid pressure within a fluid adapted to be in the
first chamber into electrical impulses;
temperature compensation means for compensating the sensed pressure
in the fluid based upon the temperature of the fluid and correcting
such sensed pressure;
a fluid pressure responsive media which is electrically
nonconductive and which separates the pressure transducer means
from any fluid present in the first chamber; and
an electrical conductor connected to the pressure transducer means.
.Iaddend. .Iadd.
51. A pressure transducer as described in claim 50 wherein the
insulating body has an opening extending between the first and
second chambers, said pressure transducer means is in communication
with said opening and said fluid pressure responsive media is in
said opening. .Iaddend. .Iadd.52. A pressure transducer as
described in claim 51 wherein the fluid pressure responsive media
is a polymeric material and the transducer is aligned
with the opening. .Iaddend. .Iadd.53. A pressure transducer
assembly for monitoring pressure in a fluid comprising:
a housing having an inlet port and an outlet port;
means for forming a partition within the housing to provide
separate first and second chambers within the housing with the
first chamber in fluid-flow communication with the inlet port and
outlet port and adapted to be filled with fluid from the inlet
port, said housing having a portion through which fluid in the
first chamber can be observed;
a pressure transducer carried by the partition and exposed to
pressure of fluid in the first chamber for determining and
converting fluid pressure within a fluid adapted to be in the first
chamber into electrical impulses;
a fluid pressure responsive media which is electrically
nonconductive and which separates the pressure transducer from any
fluid present in the first chamber; and
an electrical conductor connected to the pressure transducer and
extending from the pressure transducer. .Iaddend. .Iadd.54. A
pressure transducer assembly for monitoring pressure in a fluid
comprising;
a biocompatible housing having an inlet port and an outlet
port;
means for forming a partition within the housing to provide
separate first and second chambers within the housing with the
first chamber in fluid-flow communication with the inlet port and
outlet port, said housing having a portion through which fluid in
the first chamber can be observed;
said partition having an opening extending between the first and
second chambers;
a pressure transducer for sensing pressure of the fluid;
temperature compensation means for compensating the sensed pressure
in the fluid based upon the temperature of the fluid and correcting
such sensed pressure;
means for mounting the pressure transducer in said housing in
communication with said opening whereby the pressure transducer is
exposed to pressure of fluid adapted to be in the first chamber for
determining and converting fluid pressure within a fluid in the
first chamber into electrical impulses;
a biocompatible electrically nonconductive fluid pressure
responsive media in said opening for separating the pressure
transducer from any fluid present in the first chamber; and
an electrical conductor connected to the pressure transducer.
.Iaddend. .Iadd.55. A pressure transducer as described in claim 54
wherein said partition is a nonconductor of electricity between the
first and second chambers. .Iaddend. .Iadd.56. A pressure
transducer as described in claim 54 wherein the transducer is
aligned with said opening and supported by the partition. .Iaddend.
.Iadd.57. A pressure transducer assembly for monitoring pressure in
a fluid comprising:
a housing having an inlet port and an outlet port;
a source of I.V. solution;
flexible tubing connected to the source of I.V. solution and to the
inlet port;
means for coupling the outlet port to the patient;
means for forming a partition within the housing to provide
separate first and second chambers within the housing with the
first chamber in fluid-flow communication with the inlet port and
outlet port and adapted to be filled with fluid from the inlet
port, said housing having a portion through which fluid in the
first chamber can be observed;
a pressure transducer carried by the partition and exposed to
pressure of fluid in the first chamber for determining and
converting fluid pressure within a fluid adapted to be in the first
chamber into electrical impulses;
a fluid pressure responsive media which is electrically
nonconductive and which separates the pressure transducer from any
fluid present in the first chamber; and
an electrical conductor connected to the pressure transducer and
extending
from the pressure transducer. .Iaddend. .Iadd.58. A pressure
transducer assembly for monitoring pressure in a fluid
comprising:
a biocompatible housing having an inlet port and an outlet
port;
means for forming a partition within the housing to provide
separate first and second chambers within the housing with the
first chamber in fluid-flow communication with the inlet port and
outlet port and adapted to be filled with fluid from the inlet
port;
a pressure transducer carried by the partition and exposed to
pressure of fluid in the first chamber for determining and
converting fluid pressure within a fluid adapted to be in the first
chamber into electrical impulses;
a biocompatible fluid pressure responsive media which is
electrically nonconductive and which separates the pressure
transducer from any fluid present in the first chamber; and
an electrical conductor connected to the pressure transducer and
extending from the pressure transducer.
Description
BACKGROUND OF THE INVENTION
The pressure transducer assembly herein can be used in any fluid
line for which the fluid pressure within the line is to be
determined. The pressure transducer assembly herein has particular
utility for the invasive monitoring of blood pressure. In a
particular application, the pressure transducer assembly provides a
disposable pressure transducer assembly which can be used for a
single patient use and then discarded.
Invasive blood pressure monitoring as a system which provides an
accurate method for monitoring the blood pressure of a patient.
Frequently, invasive blood pressure monitoring is performed for
critically infirmed patients. Invasive blood pressure monitoring is
also performed during critical surgeries and on patients in
intensive care units and critical care units. Invasive blood
pressure monitoring is gaining acceptance in conjunction with the
care and treatment of cardiac .[.pateints.]. .Iadd.patients
.Iaddend.and for providing a technique for the constant, accurate
determination of blood pressures for such patients. Invasive blood
pressure monitoring is used with cardiac catheterization to provide
bedside cardiac and blood pressure monitoring. In invasive blood
pressure monitoring, a catheter is inserted into a patient's
circulatory system with the end of the catheter having an opening
which is open to the blood stream. In many instances, the catheter
is inserted into the circulatory system such that the proximal end
of the catheter reaches the heart in order to provide monitoring of
atrial and venous pressures. An I.V. set is generally attached to
the distal end of the catheter protruding from the patient. An I.V.
solution bag in the I.V. set assembly contains a solution which is
permitted to flow through the catheter and into the patient. The
I.V. solution extending through the catheter and into the patient
provides a fluid pathway for pressure in the patient's circulatory
system. By positioning a pressure transducer along the fluid
pathway, the blood pressure in the patient's circulatory system can
be monitored. Generally, such a pressure transducer consists of a
dome which functions as a reservoir for the I.V. fluid. The dome
includes a resilient diaphragm which attaches to an electrical
transducer. The transducer senses pressure fluctuations in the
diaphragm and converts such pressure fluctuations into electrical
impulses which are transmitted to a monitor.
The pressure transducers that are currently used in invasive
monitoring systems are relatively expensive and are generally
constructed to be reusable following sterilization. Some pressure
transducers can be reused as they are not in direct contact with
the fluid being administered but rather are adapted to be connected
to fluid reservoir domes which can be either disposable or
reusable.
It would be desirable to provide a pressure transducer in a single
integrated assembly which can provide an accurate monitoring of
fluid pressure while being inexpensive and disposable. It would
also be desirable to provide such a pressure transducer such that
the pressure in the fluid pathway is determined and converted to
electrical impulses such that the transducer need only be
electrically connected to a readout monitor or display unit for
such determined pressures.
SUMMARY OF THE INVENTION
The invention herein is directed to a pressure transducer assembly
for directly monitoring pressure in a fluid which flows through the
assembly. The assembly includes a housing defining a chamber
therewithin and having an inlet port and an outlet port in
fluid-flow communication with the chamber. An electrically
insulated body element is sealed within the chamber dividing the
chamber into a first chamber and a second chamber within the
housing. The first chamber is in fluid-flow communication with the
inlet and outlet ports. The second chamber is separated from the
first chamber by a fluid-tight seal such that any fluid present in
the first chamber cannot enter the second chamber. A pressure
transducer sensor is secured in the insulated body and exposed to
the first chamber such that the pressure transducer sensor can
determine the fluid pressure in a fluid in the first chamber and
convert the sensed fluid pressure into electric impulses. The
pressure transducer sensor is separated from the fluid in the first
chamber by an insulating medium across which fluid pressure can be
determined but electrical current cross. Connected to the pressure
transducer sensor are electrical conductors which extend through
the insulated body and into the second chamber. The second chamber
provides an engagement site for an electrical connector which can
interconnect with the electrical conductors and provide an
electrical path through which the electric impulses generated by
the pressure transducer sensor can be transferred to a monitor for
monitoring the fluid pressure within the fluid in the first
chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top plan view of the pressure transducer assembly
herein connected to an electrical connector which can form a part
of the assembly herein;
FIG. 2 is a lateral cross-sectional view of the embodiment shown in
FIG. 1 taken along lines 2--2;
FIG. 3 is a side elevational view of the pressure transducer
assembly shown in FIG. 1;
FIG. 4 is an end elevational view of the electrical connector which
connects to the pressure transducer housing assembly.
FIG. 5 is an exploded view of the pressure transducer housing
assembly and the electrical connector assembly; and
FIG. 6 is a schematic representation of a pressure transducer
assembly illustrating its utility in a technique for the invasive
monitoring of blood pressure.
DETAILED DESCRIPTION
The pressure transducer assembly herein will be described with
regard to the accompanying drawings wherein the overall assembly
and utility for the assembly is illustrated in FIG. 6. FIG. 6
schematically represents the use of the pressure transducer
assembly herein for invasive blood pressure monitoring.
In particular, the invention herein resides in the pressure
transducer housing assembly 12 shown in FIG. 1. With regard to FIG.
1, the pressure transducer assembly 10 is shown in part by the
pressure transducer housing assembly 12 which is connected to an
electrical connector assembly 14. The electrical connector assembly
is structured to enable electrical connection with the pressure
transducer assembly so as to provide power to the pressure
transducer assembly and to provide a route for electrical impulses
generated by the pressure transducer assembly.
The pressure transducer housing assembly comprises a housing 16
which defines a chamber 15 therein. The chamber 15 is divided into
a first chamber 20 and a second chamber 22 by an insulated body 24
which is sealed to the housing within the chamber 15. The insulated
body 24 is nonconductive of electricity and is constructed of a
suitable material that is compatible with the material of the
housing, which is biocompatible with the human physiology, and
which will not react with the fluid being administered to a patient
through the pressure transducer assembly. The material of the
insulated body is selected from a material which can be sealed to
the housing to provide a fluid-tight seal between the first and
second chambers. The housing can be constructed of any suitable
material which is biocompatible with the human physiology including
materials such as polycarbonate, polypropylene, polyethylene,
polysulfone and the like. A suitable material for the insulated
body member is polysulfone. The insulated body member can be
sonically welded to seal the body member within the chamber 15 and
to form and separate the first chamber 20 and the second chamber
22. Constructing the housing and presure transducer assembly of the
plastic materials described makes the assembly disposable so that
it can be discarded after a single patient use. Such materials are
inexpensive and easy to mold, such as by injection molding in large
volumes.
The first chamber 21 is in fluid-flow communication with an inlet
port 26 provided on the housing. The first chamber is also in
fluid-flow communication with an outlet port 28 provided on the
housing. The inlet and outlet ports can be hollow, cylindrically
extending portions of the housing which project from the housing to
enable the affixing of tubing (shown in FIG. 6) to the housing.
Preferably, the inlet and outlet ports are axially aligned to
provide a substantially unimpeded flow path through the housing.
The inlet port, outlet port and first chamber provide a fluid-flow
pathway through which fluid can be administered to a patient while
simultaneously permitting the monitoring of pressure waves along
the fluid pathway. The inlet port can be provided with a rotating
adapter 27 or other similar attachment means such as Linden
fittings, Luer fittings and the like whereby a catheter or tubing
can be attached to the housing in a fluid-tight seal. Similarly,
the outlet port can be provided with a rotating adapter 29 to
connect a catheter or tubing to the outlet side of the housing.
The housing can include a dome 30 which is a portion of the housing
that is structured in a dome which extends over the first chamber.
The dome is preferably constructed of a clear material such that
any fluid within the first chamber can be observed. The dome
functions as a clear lens which permits the observation of the
fluid and any bubbles which can be present in the fluid. The dome
can also function to trap, or momentarily trap, any air bubbles
which can be present in the fluid. The presence of air bubbles is
undesirable as it can provide erroneous pressure readings and it is
undesirable to introduce air bubbles to the patient.
Positioned within the first chamber is a pressure sensor such as a
silicon pressure sensor 32. In the preferred embodiment, the
pressure sensor is positioned in a depression on the insulated body
as can be readily seen from the cross-sectional view of FIG. 2. The
silicon pressure sensor is a pressure transducer which is capable
of sensing or determining a pressure in any fluid present in the
first chamber and converting such pressure to an electric impulse.
Preferably, the pressure transducer is a monolithic silicon
pressure sensor employing a four-terminal resistive element formed
in a thin monocrystalline silicon diaphragm. Acceptable silicon
pressure sensors are commercially available from Motorola, Inc.,
Sensors which can be used in the pressure transducer assembly
herein include the sensors that are disclosed in U.S. Pat. No.
4,317,126 assigned to Motorola, Inc., the entire disclosure of
which is incorporated herein by this reference. In addition to the
sensors disclosed in the U.S. Pat. No. 4,317,126 patent, a
particularly preferred silicon pressure sensor is a sensor which
includes a temperature compensation circuit for compensating the
sensed pressure in the fluid based upon the temperature of the
fluid and correcting such sensed pressure. Such a silicon pressure
sensor is commercially available from Motorola, Inc. as SPX-1001D
pressure sensors.
Covering the pressure sensor 32, as can be more readily seen in the
cross-sectional view shown in FIG. 2, is an insulating medium 34.
Insulating as used with regard to the insulating medium refers to
the nonconductance of electricity. The insulating medium 34 extends
over and completely covers the silicon pressure sensor such that
there is no electrical connection or electrical pathway between
fluid in the first chamber and the silicon pressure sensor. As seen
in FIG. 2, the term "covers" is used to mean that the insulating
medium and silicon pressure sensor are mechanically contiguous. The
insulating medium 34 comprises a material that is sufficiently
fluid-like that it transmits the pressure in the fluid to the
sensor. The insulating medium is also preferably biocompatible as
it is in contact with the fluid being administered to the patient.
A particularly preferred insulating medium is a silicone polymer,
such as a methyl silicone elastomer. Such an insulating medium
prevents electrical shock to the patient through the fluid as any
electrical current to the silicon pressure sensor is insulated from
the fluid in the first chamber by the insulating medium.
In order for the silicon pressure sensor to accurately measure the
pressure of the fluid in the first chamber, the silicon pressure
sensor is preferably vented to the atmosphere. The venting of the
silicon pressure sensor to the atmosphere is accomplished by
providing a first aperture 45 in the base of the electrical
connector which coincides and aligns with a second aperture 46 in
the housing. The second aperture in the housing opens into the
second chamber and coincides and aligns with a third aperture 48 in
the insulated body. The third aperture 48 in the insulated body
opens to the lower side of the silicon pressure sensor and thereby
provides a direct pathway to the atmosphere for the silicon
pressure sensor.
A series of electrical pins 36 extend through the insulated body 24
into the first chamber and are in electrical contact with the
silicon pressure sensor 32 through suitable circuits 37. The
portion of the pins 36 which extend into the first chamber are
completely imbedded within the insulating medium 34 and thereby
physically separated from fluid in the first chamber by the
insulating medium. The electrical pins extend through the insulated
body and into the second chamber of the housing of the pressure
transducer assembly. The electrical pins extend from the insulated
body to provide a male electrical plug which can be inserted into a
corresponding female electrical plug on the electrical connector
assembly 14 to provide electrical contact between the pressure
transducer housing assembly and the electrical connector
assembly.
In the preferred embodiment, the second chamber is open and
provides a receptor site for the electrical connector assembly.
That is, at least a portion of the electrical connector assembly
can be inserted into the second chamber to mate with the electrical
pins. The view shown in FIG. 3 of the drawing shows a view of the
pressure transducer housing assembly looking into the open second
chamber 22 wherein the insulated body 24 can be seen with the
extending electrical pins 36. In other embodiments, the electrical
pins can also extend through the sidewall of the housing to enable
connection to an electrical connector assembly.
The electrical connector assembly can be mated to the pressure
transducer housing assembly. The electrical connector assembly
includes electrical plug receptors 38 which receive the electrical
pins 36. The electrical plug receptors are connected through
suitable wiring 40 which can carry the electrical impulses
generated by the silicon pressure sensor to a suitable display unit
or monitor as is shown in FIG. 6. Such wiring can also provide
power to the pressure transducer assembly. An end view of the
electrical connector assembly 14 is illustrated in FIG. 4. The
mating of the pressure transducer housing assembly and the
electrical connector assembly is shown in an exploded view in FIG.
5. The electrical connector assembly can include a cavity 44 into
which a portion 17 of the housing 16 of the pressure transducer
housing assembly can be inserted to mate the electrical pins 36 and
electrical plug receptors 38. The electrical connector assembly can
include a projecting portion 39 which can insert into the open
second chamber of the housing. Such an arrangement provides a
relatively snug fit between the pressure transducer housing
assembly and the electrical connector assembly to prevent
inadvertent separation of the assemblies. In a preferred embodiment
of the invention, the pressure transducer housing assembly and the
housing 16 thereof can be provided with resilient snap-fitting
projections such as the resilient arm portions 42 which can be
inserted into and snap-fittingly engage suitable apertures 41 in
the body of the electrical connector assembly 14.
The electrical connector assembly provides an electrical conduit
between the pressure transducer housing assembly and a display
unit. The electrical connector assembly includes the assembly 14
and the associated wiring 40 which leads from the electrical
connector assembly to a display unit.
The utility of the pressure transducer assembly herein is
schematically illustrated in FIG. 6. In FIG. 6, a patient 50 is
catheterized with a catheter which extends into the circulatory
system. The catheter is connected at about the exit site from the
patient of flexible tubing 52 along which can be positioned a clamp
54 for occluding fluid flow through the tubing. The tubing 52 is
connected to the pressure transducer housing assembly 12 at the
outlet port. As can be seen by one having skill in the art, the
housing of the pressure transducer housing assembly can be
positioned in any manner with regard to inlet and outlet flow of
fluid as the direction of flow of any fluid through the housing
does not influence the pressure reading by the silicon pressure
sensor. The terms inlet and outlet, as used herein, are merely
arbitrarily assigned to the two ports on the housing to facilitate
the description of utility.
The inlet port of the housing is connected through suitable
flexible tubing 60 to a source of an I.V. solution such as an I.V.
bag and drip chamber 58. A clamp 54 and a fluid-flow restriction
device 62 can be positioned along the flexible tubing leading to
the pressure transducer housing assembly 12.
The electrical connector assembly 14 is interconnected to the
pressure transducer housing assembly. The wiring 40 extending
therefrom can be connected to a suitable display unit or monitor 56
can be powered by batteries or by normal alternating current.
In operation, prior to connecting the flexible tubing 52 to the
catheter which has been inserted in the patient, fluid from the
I.V. bag is permitted to flow through the tubing 60, pressure
transducer housing assembly 12, and flexible tubing 52. The
connection between the flexible tubing 52 and catheter is then made
so as to prevent the formation or inclusion of entrapped air along
the fluid-flow path. After connecting the tubing 52 to the
catheter, a complete fluid-flow path is .[.obtined.].
.Iadd.obtained .Iaddend.and with the communication of the fluid in
the pressure transducer assembly and the patient's circulatory
system, any pressure within the circulatory system is
correspondingly observed in the fluid present in the first chamber
of the pressure transducer assembly. The silicon pressure sensor
thereby observes the pressure in the fluid and transforms such
sensed pressure into electrical impulses which flow along the
wiring 40 to the display unit 56 wherein the pressure readings are
displayed for the benefit of the attendant.
* * * * *