U.S. patent number RE36,000 [Application Number 08/437,964] was granted by the patent office on 1998-12-22 for adhesive pulse oximeter sensor with reusable portion.
This patent grant is currently assigned to Nellcor Puritan Bennett Incorporated. Invention is credited to Russell DeLonzor, David B. Swedlow, Jessica Warring.
United States Patent |
RE36,000 |
Swedlow , et al. |
December 22, 1998 |
Adhesive pulse oximeter sensor with reusable portion
Abstract
A pulse oximeter sensor that is designed to surround an
appendage of the patient, such as a finger, toe or foot is
disclosed. The sensor has a reusable member which preferably
includes a photodetector. A disposable, flexible member preferably
contains the photoemitter and can be wrapped around the patient's
appendage to secure it to the appendage and the reusable member.
When secured, the photoemitter and photodetector end up on opposite
sides of the appendage. The disposable member connects to the
reusable member to establish electrical contact. The reusable
member is connected to a cable which can be plugged into a sensor
monitoring system.
Inventors: |
Swedlow; David B. (Danville,
CA), DeLonzor; Russell (Union City, CA), Warring;
Jessica (Millbrae, CA) |
Assignee: |
Nellcor Puritan Bennett
Incorporated (Hayward, CA)
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Family
ID: |
27083629 |
Appl.
No.: |
08/437,964 |
Filed: |
May 10, 1995 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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600541 |
Oct 19, 1990 |
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Reissue of: |
741290 |
Aug 6, 1991 |
05209230 |
May 11, 1993 |
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Current U.S.
Class: |
600/454;
356/41 |
Current CPC
Class: |
A61B
5/02427 (20130101); A61B 5/6826 (20130101); A61B
5/6838 (20130101) |
Current International
Class: |
A61B
5/024 (20060101); A61B 005/02 () |
Field of
Search: |
;128/633,637,664,665
;606/13 ;356/39-41 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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671279 |
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Oct 1963 |
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CA |
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0019478 |
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Nov 1980 |
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EP |
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0284943 |
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Oct 1988 |
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EP |
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2348992 |
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Apr 1974 |
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DE |
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WO8909566 |
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Oct 1989 |
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WO |
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Primary Examiner: Casler; Brian L.
Attorney, Agent or Firm: Rothwell, Figg, Ernst &
Kurz
Parent Case Text
BACKGROUND OF THE INVENTION
This is a continuation-in-part of patent application Ser. No.
07/600,541, filed Oct. 19, 1990, now abandoned.
Claims
What is claimed is:
1. A sensor for attaching to a patient for electrooptical
measurement of blood characteristics, comprising:
a reusable member including a first electronic means for emitting
or detecting electromagnetic radiation;
conducting means, connected to said reusable member, for
electrically connecting said first electronic means to an external
sensor monitoring system;
a disposable, flexible member including a second electronic means
for detecting electromagnetic radiation emitted by said first
electronic means or emitting electromagnetic radiation to be
detected by said first electronic means;
means for removably coupling said flexible member to said reusable
member to provide a connection between said second electronic means
and said conducting means; and
means for securing said disposable, flexible member and reusable
member to said patient.
2. The sensor of claim 1 wherein said means for securing comprises
an adhesive on said disposable, flexible member.
3. The sensor of claim 1 wherein said second electronic means is at
least one photoemitter.
4. The sensor of claim 1 wherein said means for removably coupling
comprises a tail extending from said disposable, flexible member
having at least one exposed first electrical conductor, at least
one exposed second electrical conductor extending from said
reusable member, and a bridge means connected to said reusable
member and extending across said second electrical conductor for
allowing said tail to be inserted between said bridge means and
said second conductor.
5. The sensor of claim 4 wherein said tail includes resilient means
for applying force between said second conductor and said bridge
means to hold said tail in place.
6. The sensor of claim 1 wherein said reusable member comprises a
rigid housing and a deformable means, attached to said housing, for
securely gripping and complying to an appendage of said
patient.
7. The sensor of claim 1 wherein said second electronic means
comprises a red light photoemitter and an infrared
photoemitter.
8. The sensor of claim 7 wherein said first electronic means
comprises a photodetector.
9. The sensor of claim 1 wherein said means for securing attaches
said sensor to an appendage of said patient so that said first
electronic means is on an opposite side of said appendage from said
second electronic means.
10. The senor of claim 1 further comprising a black coating on said
flexible member around said second electronic means.
11. The sensor of claim 1 further comprising:
an electrostatic screen adjacent said first electronic means;
and
a thin film covering said first electronic means and at least a
portion of said electrostatic screen, said film being transparent
over said first electronic means and opaque over said portion of
said electrostatic screen.
12. A sensor for attaching to an appendage of a patient for
electrooptical measurement of blood characteristics,
comprising:
a reusable member including a first electronic device for emitting
or detecting light;
conducting means for electrically connecting said first electronic
device to an external sensor monitoring system;
a disposable, flexible member including a second electronic device
for detecting light emitted by said first electronic device or
emitting light to be detected by said first electronic device;
a tail extending from said disposable, flexible member having at
least one exposed first electrical conductor, at least one exposed
second electrical conductor extending from said reusable member,
and a bridge connected to said reusable member and extending across
said second electrical conductor to allow said tail to be inserted
between said bridge and said second conductor;
means for securing said disposable, flexible member to said
appendage and said reusable member so that said first electronic
device is on an opposite side of said appendage from said second
electronic device.
13. The sensor of claim 12 wherein said means for securing
comprises an adhesive on said disposable, flexible member.
14. The sensor of claim 12 wherein said second electronic device is
a photoemitter.
15. The sensor of claim 12 wherein said tail includes resilient
means for applying force between said second conductor and said
bridge to hold said tail in place.
16. A sensor for attaching to an appendage of a patient for
electrooptical measurement of blood characteristics,
comprising:
a reusable member including a photodetector;
conducting means, connected to said reusable member, for
electrically connecting said photodetector to an external sensor
monitoring system;
a disposable, flexible member including at least one photoemitter
for emitting light to be detected by said photodetector;
means for removably coupling said flexible member to said reusable
member to provide a connection between said photoemitter and said
conducting means; and
an adhesive coating on said disposable, flexible member for
securing said disposable, flexible member to said appendage and
said reusable member so that said photodetector is on an opposite
side of said appendage from said photoemitter.
17. A sensor for attaching to an appendage of a patient for
electrooptical measurement of blood characteristics,
comprising:
a reusable member including at least one photodetector, said
reusable member including a rigid housing and a deformable means,
attached to said housing, for securely gripping and complying to
said patient's appendage;
conducting means, connected to said reusable member, for
electrically connecting said photodetector to an external sensor
monitoring system;
a disposable, flexible member including a red light photoemitter
and an infrared photoemitter for emitting light to be detected by
said photodetector;
a tail extending from said disposable, flexible member having at
least one exposed first electrical conductor;
at least one exposed second electrical conductor extending from
said rigid housing;
a bridge connected to said rigid housing and extending across said
second electrical conductor to allow said tail to be inserted
between said bridge and said second conductor;
resilient means, coupled to said tail, for applying force between
said second conductor and said bridge to hold said tail in place;
and
an adhesive coating on said disposable, flexible member for
securing said disposable, flexible member to said appendage and
said reusable member so that said photoemitters are on an opposite
side of said appendage from said photodetector. .Iadd.
18. A sensor for attaching to a patient for electrooptical
measurement of blood characteristics, comprising:
a disposable, flexible member having a plurality of conductors
disposed on a substrate and including at least one electronic means
for emitting or detecting electromagnetic radiation, said at least
one electronic means being connected to at least one of said
conductors disposed on said substrate;
conducting cable means for electrically connecting said electronic
means to an external sensor monitoring system;
means for releasably connecting said flexible member conductors to
said conducting cable means to provide a connection between said
electronic means and said conducting cable means; and
means for securing said flexible member to said
patient..Iaddend..Iadd.19. The sensor of claim 18, wherein said
means for securing comprises an adhesive connected to said
substrate..Iaddend..Iadd.20. The sensor of claim 18, wherein said
at least one electronic means is a photoemitter..Iaddend..Iadd.21.
The sensor of claim 18, wherein said at least one electronic means
is a photodetector..Iaddend..Iadd.22. The sensor of claim 18,
wherein an end of said conducting cable means opposite said
releasably connecting means is adapted to be connected to an
oximeter monitor..Iaddend..Iadd.23. The sensor of claim 18, wherein
said blood characteristics include arterial oxygen
saturation..Iaddend..Iadd.24. The sensor of claim 18, wherein said
substrate is elongated and flexible..Iaddend..Iadd.25. The sensor
of claim 18, wherein said plurality of conductors, include a
plurality of contacts on a surface of said substrate which can be
connected to said releasably connecting means for electrically
connecting said conducting cable means to said at least one
electronic means..Iaddend..Iadd.26. The sensor of claim 18, wherein
said plurality of conductors comprise a plurality of conductive
traces disposed on said substrate..Iaddend..Iadd.27. The sensor of
claim 26, wherein said traces comprise printed traces..Iaddend.
Description
This invention relates to sensors for use with noninvasive pulse
monitors such as plethysmographs or pulse oximeters.
A plethysmograph is a pulse monitor The plethysmograph sensor
shines light into the patient's tissue, and the light transmitted
through the tissue is received by a photodetector. The
photodetector generates electrical signals corresponding to the
transmitted light levels and transmits the signals to a monitor for
processing. Arterial blood will absorb some of the light, with more
light being absorbed when there is more blood. Thus, changes in the
amount of transmitted light are related to pulses of arterial blood
in the illuminated tissue.
A pulse oximeter is a device for noninvasively determining the
oxygen saturation of arterial blood. The pulse oximeter sensor
shines light at two different wavelengths (one in the red range,
the other in the infrared range) through a portion of the patient's
blood-perfused tissue. The red and infrared light transmitted
through the tissue is detected by a photodetector. The amount of
light absorbed varies with the amount of oxygen in the blood, and
varies differently for red and infrared light. The pulse oximeter
monitor computes blood oxygen saturation based on the changes in
the two detected light levels between two points in time.
There are several types of sensors for plethysmographs and pulse
oximeters. One is a surface sensor in which the light emitter and
the photodetector are mounted on the same sensor face. The sensor
is attached to the patient with both the light emitter and the
detector on the same side of the patient's appendage (e.g., on the
patient's forehead). This type of sensor detects light reflected
back from the tissue, rather than light transmitted through an
appendage. The signal detected will thus be weaker in most cases.
The sensor is typically attached with a strap, headband or tape
over the sensor, or an adhesive pad between the sensor and the
skin.
Another type of sensor is a clamp design, such as that described in
U.S. Pat. No. 4,685,464. The durable sensor described in that
patent has deformable pads creating conforming tissue contacting
surfaces to which the emitters and photodetector are secured. The
deformable pads are disposed in a hinged rigid housing that clips
on the patient like a clothes pin. This relies on a clamping force
to secure the sensor to the patient. The force of the sensor
against the patient's tissue could reduce the flow of blood to that
region. This exsanguination of the tissue beneath the sensor
adversely affects pulse detection and analysis by suppressing the
pulse in that portion of the tissue. As a result, the sensor site
must typically be checked or moved every four hours to insure
adequate perfusion. Because of its relatively large mass, however,
the clamp design is more susceptible to signal-distorting motion
artifact, i.e., differential motion between the sensor and the
patient.
A third sensor design is described in U.S. Pat. No. 4,830,014. The
conformable sensor described in that patent has emitters and a
photodetector mounted in the same side of a flexible web. The web
wraps around a portion of the patient's tissue (such as a finger)
so that the light from the emitters must travel through the tissue
before reaching the detector. The web attaches to the skin with an
adhesive surface on the emitter and detector side of the web.
Because of its relatively low mass and the adhesive, this sensor
adheres closely to the patient's skin and minimizes the effects of
motion artifact. In addition, its flexibility and use of adhesive
to secure it minimizes the exsanguination caused by rigid sensors.
Thus the sensor site typically only needs to be checked every eight
hours. Conformable sensors, however, are typically restricted to
one application due in part to a decrease in adhesive effectiveness
with each application and in part to difficulties in cleaning and
sterilization for reuse. Replacement of the sensor after only one
use can make pulse oximetry expensive.
SUMMARY OF THE INVENTION
The present invention provides a pulse oximeter sensor that is
designed to surround an appendage of the patient, such as a finger,
toe or foot. The sensor has a reusable member which preferably
includes a photodetector. A disposable, flexible member preferably
contains the photoemitter and can be wrapped around the patient's
appendage to secure it to the appendage and the reusable member.
When secured, the photoemitter and photodetector end up on opposite
sides of the appendage. The disposable member connects to the
reusable member to establish electrical contact. The reusable
member is connected to a cable which can be plugged into a sensor
monitoring system.
In the preferred embodiment, the flexible member is a flexible
adhesive web with arms extending laterally from a central portion.
The reusable member is preferably a rigid housing with a deformable
pad for contacting the appendage.
To attach the sensor to the patient, the flexible web is adhesively
attached to one side of the patient's appendage, and the rigid
housing is placed on the other side directly opposite the flexible
web. The arms extend around the appendage to adhesively hold the
conformable pad of the rigid housing against the appendage. By
reducing the mass of the sensor and by adhesively attaching the
emitters to the skin, this configuration minimizes motion artifact
by reducing the relative movement between the sensor and the
patient's skin experienced by previous clamp-type sensors. In
addition, the flexible web and conformable surface of the rigid
housing minimize exsanguination of the tissue beneath the sensor.
Since the sensor relies on adhesion to secure it to the patient,
the sensor site should not need to be checked as often as for a
clamping-type sensor.
After use, the flexible web may be separated from the rigid
housing, the rigid housing cleaned, and a new flexible web attached
to the rigid housing. The fresh adhesive on the new flexible web
provides a more reliable bond between the sensor and the patient
than the adhesive on the previously-used web. In addition, since
the flexible web covers four out of the five surfaces of the
patient's appendage (including, when worn on the finger, the
cuticle and subungual region), one time use of the flexible portion
of the sensor minimizes cross-contamination between patients when
the sensor is reused. Furthermore, because a portion of the sensor
may be cleaned and reused, this new sensor design reduces the cost
of using flexible sensors.
The electrical connection between the flexible web and the rigid
housing is preferably made with a tab extending from the flexible
web having conductive traces printed on it which connect to the
photoemitter. The conductive traces are inserted into a channel in
the back of the housing which is covered by a bridge. Underneath
the bridge are a series of electrical contacts for making
connection with the conductive traces. The tab contains an internal
resilient foam which is compressed as it is inserted between the
housing and the bridge, and exerts an outward force to maintain the
tab in place and create an electrical connection between the
conductive traces and the contacts.
For a fuller understanding of the nature and advantages of the
invention, reference should be made to the ensuing detailed
description taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a sensor according to the present
invention;
FIG. 2 is a perspective view of the sensor of FIG. 1 showing the
flexible web being wrapped around a finger; and
FIG. 3 is a perspective view of the separated disposable and
reusable members of FIG. 1 illustrating how the connection is
made.
DETAIL OF THE PREFERRED EMBODIMENT
FIG. 1 shows a sensor 10 according to the present invention. Sensor
10 consists of a flexible, disposable webbing 12 and a reusable
housing 14. Housing 14 includes a rigid portion 16 and a deformable
pad 18. A patient's finger 20, shown in phantom, is shown placed on
top of deformable pad 18.
Flexible web 12 includes a photoemitter 22, which preferably
includes two photoemitters, one for red light and one for infrared
light. A photodetector 24 is included in deformable pad 18. A
copper grid 23 is disposed over photodetector 24. A transparent
window 25 covers photodetector 24. All or substantially all of the
portion of window 25 extending beyond photodetector 24 is colored
black. In addition, a black area 29 is printed on the underside of
foam layer 28. Grid 23, photodetector 24 and photoemitter 22 are
electrically connected to a sensor monitoring system through
conductors in a cable 26 connected to housing 14.
Grid 23 is a Faraday shield (electrostatic screen) connected to
ground for reducing interference. The thin window 25 extends over
the copper grid so that the grid will not bulge out pad 18. Before
the black coating was added, shift errors in the data values were
noticed. The black coating eliminated these errors. The reason is
not certain, but the coating over the window may prevent
reflections from most of the copper, while the black coating on the
foam layer 28 may prevent light from being shunted through the foam
layer to the detector, bypassing the finger.
Webbing 12 has a top foam layer 28 with an adhesive surface. Before
use, this adhesive layer is covered with protective plastic (not
shown), which is peeled off for use.
FIG. 2 illustrates how the flexible webbing 12 is bent over and
attached to finger 20. A first arm 30 of the flexible web is
wrapped around the side of housing 14 and will continue to be
wrapped around its bottom in the direction of arrow 32. Similarly,
the other arm 34 will be wrapped around finger 20 and housing 14.
As can be seen, photoemitters 22, shown in phantom, are now on top
of the finger, directly opposite photodetector 24, which is not
visible in this view. As can be seen, only the bottom of finger 20
contacts deformable pad 18. At least the top of the finger will be
adhered to by web 12. The sides and front may also be adhered to,
depending on the shape of the finger and how the sensor is
attached. The top is the portion which is most important to be
adhering, since it contains the photoemitter which should not move
relative to the finger. This provides a secure connection which
reduces motion artifacts and puts the disposable, flexible portion
in contact with most of the surfaces of the finger so that it is
exposed to more contamination than the reusable portion.
FIG. 3 illustrates the electrical connection between flexible web
12 and rigid housing 14. FIG. 3 shows adhesive layer 28 partially
peeled back from a web base 36. In between web base 36 and adhesive
layer 28, an elongate plastic substrate 38 is placed, with a series
of conductive traces 40 on its top surface. Two conductive traces
connect to photoemitters 22, and two connect to a calibration
resistor 55, described below. Elongate plastic substrate 38 forms a
tail 42. Web base 36 can be just large enough to hold tail 42 to
adhesive layer 28, as shown, or could conform to the shape of
adhesive layer 28. Web base 36 has an adhesive surface for holding
tail 42 to layer 28.
A compressible foam member 44 is placed between the halves of tail
42. In the preferred embodiment, the foam is made of Poron foam
from Roger's Corp. A pair of tabs 46 extend from the top half of
the tail having the conductive traces. The tabs and the foam member
provide part of the attachment mechanism as explained below.
A channel 48 is formed on the bottom side of the rigid housing 16,
opposite deformable pad 18. A series of electrical contacts 50
(shown in phantom) are located in the channel. The contacts are
covered by a bridge 52 extending across the housing. A pair of
grooves 54 are formed in the channel. The grooves are slightly
larger than the tabs 46 on the flexible web.
To connect the flexible web to the rigid housing, the tail 42 of
the flexible circuit is inserted into the space beneath bridge 52.
As the tail moves forward, the plastic foam 44 compresses. As the
tail's tabs 46 move over the channel's grooves 54, the spring
action of the foam pushes the tabs into the grooves. The tabs and
grooves ensure that the flexible circuit is not inserted too far
and prevent inadvertent removal of the flexible circuit. The spring
action of the foam also pushes one set of contacts against the
other to enhance the electrical connection. In addition, the
scraping action of one set of contacts against the other during
insertion and withdrawal of the flexible circuit will help remove
any oxidation or debris on the contacts. To remove, the tabs are
lifted out of the grooves by pulling the flexible web away from the
housing and the tail is withdrawn from the space beneath the
bridge.
Cable 26 contains 6 wires. Two are connected to calibration
resistor 55 through two of contacts 50 and conductive traces 40.
Two are connected to photoemitters 22 through the other two of
contacts 50 and conductive traces 40. The remaining two wires are
connected to photodetector 24.
In the preferred embodiment, the plastic substrate is formed from
white, substantially opaque polyester. White nylon may also be
used, or a clear plastic. The adhesive may be white, with a clear
window for the photoemitters.
The preferred embodiment of the sensor according to this invention
includes an encoding/decoding system such as that described in U.S.
Pat. No. 4,621,643. The flexible web supports an encoding resistor
55 in electrical communication with the monitor. As explained in
that patent, the value of the resistor is selected to match the
wavelengths of the red and infrared LED's. That patent also
describes the necessary sensor monitoring electronics.
In an alternative embodiment, the sensor's photodetector may be
mounted in the flexible web with the emitters and the encoding
resistor mounted in the rigid housing.
In the preferred embodiment, the rigid housing is made from
injection molded polycarbonate. Alternatively, injection molded ABS
plastic may be used. U.S. Pat. No. 4,685,464 contains additional
details on construction of a rigid housing and deformable pad
including the placement of the photodetector.
As will be understood by those familiar with the art, the present
invention may be embodied in other specific forms without departing
from the spirit or essential characteristics thereof. For example,
the compression effect of foam 44 could be obtained instead by
making bridge 52 a spring-action clip, which is opened by holding
one end down during insertion and then released, with a spring on
the clip holding the tab in place. Other variations in the way
electrical contact is made are also possible. Instead of the
adhesive layer, the flexible portion could be attached to the
finger and rigid housing using velcro or other securing mechanisms.
The flexible web could be made of foil or other color materials
than white or clear. The sensor could be a surface sensor, with
adhesive for reducing motion artifact on the disposable portion.
Accordingly, the disclosure of a preferred embodiment of the
invention is intended to be illustrative, but not limiting, of the
scope of the invention which is set forth in the following
claims.
* * * * *