U.S. patent application number 12/145596 was filed with the patent office on 2009-12-31 for blood pressure cuff apparatus and system.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. Invention is credited to JOHN CLEMMONS, BRUCE ARNOLD FRIEDMAN.
Application Number | 20090326394 12/145596 |
Document ID | / |
Family ID | 40941051 |
Filed Date | 2009-12-31 |
United States Patent
Application |
20090326394 |
Kind Code |
A1 |
CLEMMONS; JOHN ; et
al. |
December 31, 2009 |
BLOOD PRESSURE CUFF APPARATUS AND SYSTEM
Abstract
A pressure cuff is disclosed herein. The pressure cuff includes
a sleeve and a cuff bladder. The cuff bladder defines a bladder
length of 9.2+/-2.1 centimeters and a bladder width of 24.6+/-4.2
centimeters. The bladder length and bladder width dimensions
provide precise non-invasive blood pressure measurements when the
pressure cuff is applied to a forearm having a circumference in the
range of 27 to 37 centimeters.
Inventors: |
CLEMMONS; JOHN; (TAMPA,
FL) ; FRIEDMAN; BRUCE ARNOLD; (TAMPA, FL) |
Correspondence
Address: |
PETER VOGEL;GE HEALTHCARE
20225 WATER TOWER BLVD., MAIL STOP W492
BROOKFIELD
WI
53045
US
|
Assignee: |
GENERAL ELECTRIC COMPANY
SCHENECTADY
NY
|
Family ID: |
40941051 |
Appl. No.: |
12/145596 |
Filed: |
June 25, 2008 |
Current U.S.
Class: |
600/499 ;
600/495 |
Current CPC
Class: |
A61B 5/02233
20130101 |
Class at
Publication: |
600/499 ;
600/495 |
International
Class: |
A61B 5/02 20060101
A61B005/02 |
Claims
1. A pressure cuff comprising: a sleeve; and a cuff bladder
comprising a bladder length of 9.2+/-2.1 centimeters and a bladder
width of 24.6+/-4.2 centimeters; wherein the bladder length and
bladder width dimensions provide precise non-invasive blood
pressure measurements when the pressure cuff is applied to a
forearm having a circumference in the range of 27 to 37
centimeters.
2. The pressure cuff of claim 1, wherein the sleeve is generally
rectangular.
3. The pressure cuff of claim 1, wherein the sleeve is generally
arcuate shaped.
4. The pressure cuff of claim 1, wherein the cuff bladder is
generally rectangular.
5. The pressure cuff of claim 1, wherein the cuff bladder is
generally arcuate shaped.
6. The pressure cuff of claim 1, wherein the sleeve comprises a
hook and loop fastening mechanism.
7. The pressure cuff of claim 1, wherein the sleeve comprises two
or more layers that are generally impermeable to air and are fused
together in a manner adapted to form the cuff bladder.
8. The pressure cuff of claim 1, wherein the cuff bladder is
retained by the sleeve.
9. A pressure cuff comprising: a sleeve; and a cuff bladder
comprising a width ratio range of 0.25 to 0.34 and a length ratio
range of 0.66 to 0.91; wherein the bladder length ratio range and
bladder width ratio range provide optimal non-invasive blood
pressure measurement precision when the pressure cuff is applied to
a patient's forearm.
10. The pressure cuff of claim 9, wherein said cuff bladder
comprises a bladder length of 9.2+/-2.1 centimeters and a bladder
width of 24.6+/-4.2 centimeters
11. The pressure cuff of claim 9, wherein the sleeve is generally
rectangular.
12. The pressure cuff of claim 9, wherein the sleeve is generally
arcuate shaped.
13. The pressure cuff of claim 9, wherein the cuff bladder is
generally rectangular.
14. The pressure cuff of claim 9, wherein the cuff bladder is
generally arcuate shaped.
15. The pressure cuff of claim 9, wherein the sleeve comprises two
or more layers that are generally impermeable to air and are fused
together in a manner adapted to form the cuff bladder.
16. A system comprising: a blood pressure monitor; and a pressure
cuff pneumatically coupled with the blood pressure monitor, said
pressure cuff comprising: a sleeve; and a cuff bladder retained by
the sleeve, said cuff bladder comprising a bladder length of
9.2+/-2.1 centimeters and a bladder width of 24.6+/-4.2
centimeters; wherein the bladder length and bladder width
dimensions provide precise non-invasive blood pressure measurements
when the pressure cuff is applied to a forearm having a
circumference in the range of 27 to 37 centimeters.
17. The system of claim 16, wherein the sleeve is generally
rectangular.
18. The system of claim 16, wherein the sleeve is generally arcuate
shaped.
19. The system of claim 16, wherein the cuff bladder is generally
rectangular.
20. The system of claim 16, wherein the cuff bladder is generally
arcuate shaped.
Description
BACKGROUND OF THE INVENTION
[0001] The subject matter disclosed herein relates to a blood
pressure cuff apparatus adapted for use on a patient's forearm, and
a system comprising the blood pressure cuff apparatus.
[0002] Conventional non-invasive blood pressure (NIBP) monitoring
systems generally inflate a pressure cuff above the patient's
systolic pressure and measure oscillations in the cuff as the cuff
is deflated. The pressure cuff is wrapped around the patient's
upper arm and secured thereto with a fastening mechanism such as,
for example, a hook and loop fastening mechanism. After wrapping
and securing the pressure cuff, a cuff bladder is inflated with air
to apply a variable amount of pressure. In order to maximize the
precision with which a NIBP monitoring system estimates a given
patient's blood pressure, the pressure cuff must be properly sized
relative to the patient's upper arm.
[0003] Conventional pressure cuffs and cuff bladders each comprise
length and width dimensions that define a generally rectangular
shape. The pressure cuffs are sized by selecting length and width
cuff bladder dimensions in proportion to a target patient's upper
arm circumference. One problem is that the upper arm circumference
of an obese patient becomes so large that it is difficult to
properly fit. More precisely, in order to maintain the desired
proportionality, the width of the pressure cuff becomes so large
that it extends from the upper arm beyond the patient's elbow. When
a pressure cuff is applied in this manner, the accuracy of the
resultant blood pressure estimate is potentially greatly
diminished. Another problem is that subcutaneous adipose tissue in
the upper arm of an obese patient can interfere with NIBP
measurements thereby potentially introducing a source of error.
BRIEF DESCRIPTION OF THE INVENTION
[0004] The above-mentioned shortcomings, disadvantages and problems
are addressed herein which will be understood by reading and
understanding the following specification.
[0005] In an embodiment, a pressure cuff includes a sleeve and a
cuff bladder. The cuff bladder defines a bladder length of
9.2+/-2.1 centimeters and a bladder width of 24.6+/-4.2
centimeters. The bladder length and bladder width dimensions
provide precise non-invasive blood pressure measurements when the
pressure cuff is applied to a forearm having a circumference in the
range of 27 to 37 centimeters.
[0006] In another embodiment, a pressure cuff includes a sleeve and
a cuff bladder. The cuff bladder defines a width ratio range of
0.25 to 0.34 and a length ratio range of 0.66 to 0.91. The bladder
length ratio range and bladder width ratio range provide optimal
non-invasive blood pressure measurement precision when the pressure
cuff is applied to a patient's forearm.
[0007] In another embodiment, a system includes a blood pressure
monitor, and a pressure cuff pneumatically coupled with the blood
pressure monitor. The pressure cuff includes a sleeve and a cuff
bladder retained by the sleeve. The cuff bladder comprises a
bladder length of 9.2+/-2.1 centimeters and a bladder width of
24.6+/-4.2 centimeters. The bladder length and bladder width
dimensions provide precise non-invasive blood pressure measurements
when the pressure cuff is applied to a forearm having a
circumference in the range of 27 to 37 centimeters.
[0008] Various other features, objects, and advantages of the
invention will be made apparent to those skilled in the art from
the accompanying drawings and detailed description thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a schematic diagram of a non-invasive blood
pressure monitoring system attached to a patient in accordance with
an embodiment;
[0010] FIG. 2 is a schematic diagram of a pressure cuff in
accordance with an embodiment; and
[0011] FIG. 3 is a schematic diagram of a pressure cuff in
accordance with another embodiment.
DETAILED DESCRIPTION OF THE INVENTION
[0012] In the following detailed description, reference is made to
the accompanying drawings that form a part hereof, and in which is
shown by way of illustration specific embodiments that may be
practiced. These embodiments are described in sufficient detail to
enable those skilled in the art to practice the embodiments, and it
is to be understood that other embodiments may be utilized and that
logical, mechanical, electrical and other changes may be made
without departing from the scope of the embodiments. The following
detailed description is, therefore, not to be taken as limiting the
scope of the invention.
[0013] Referring to FIG. 1, a non-invasive blood pressure (NIBP)
monitoring system 10 attached to a patient 12 is shown in
accordance with an embodiment. The NIBP monitoring system 10
includes a pressure cuff 14 pneumatically coupled with a NIBP
monitor 16 via the flexible tubes 18, 20. The pressure cuff 14
includes a cuff bladder 22. For purposes of this disclosure, the
term bladder should be defined to include an inflatable pocket or
chamber. The NIBP monitor 16 includes a pump 24 adapted to inflate
the cuff bladder 22, and one or more valves 26 adapted to deflate
the cuff bladder 22. The NIBP monitor 16 also includes a pressure
transducer 30 operable to sense or identify pressure pulses at the
portion of the limb to which the pressure cuff 14 is attached. A
controller 32 converts the pressure pulse data from the pressure
transducer 30 into blood pressure data in a known manner.
[0014] The NIBP monitor 16 is configured to measure mean arterial
pressure (MAP), systolic blood pressure (SYS), and/or diastolic
blood pressure (DIA) by inflating the pressure cuff 14 to a
supra-systolic pressure level and measuring oscillations under the
cuff 14 as the cuff 14 is deflated. For purposes of this
disclosure, the term "oscillation" refers to a measurable pressure
level pulse produced by a change in volume of an artery under the
pressure cuff 14.
[0015] There are several problems with implementing an upper arm
pressure cuff on an obese patient as will be described in detail
hereinafter. For purposes of this disclosure, the term "obese"
should be defined to include a body mass index (BMI) within the
range of 30 to 40. The term body mass index refers to a patient's
weight divided by the square of their height
(BMI=weight/height.sup.2). A first problem with implementing an
upper arm pressure cuff on an obese patient is related to the fact
that upper arm circumference tends to increase as BMI increases.
Accordingly, an upper arm cuff geometry adapted to accommodate an
obese patient's upper arm circumference may be constrained by the
length of the upper arm or extend beyond the elbow. A second
problem with implementing an upper arm pressure cuff on an obese
patient is related to the fact that the upper arm of an obese
patient can include excess subcutaneous adipose tissue that can
interfere with NIBP measurement precision.
[0016] As a solution to the previously described problems, the
pressure cuff 14 is adapted for use on a patient's forearm rather
than their upper arm. For purposes of a NIBP acquisition site, the
forearm provides several advantages over the upper arm including
the following: the forearm has a smaller range of circumferential
variation among patients; and generally includes less subcutaneous
adipose tissue. Accordingly, the pressure cuff 14 enables the
precise NIBP measurement of patients for whom conventional upper
arm cuffs are not well suited such as, for example, obese patients
or muscular patients with highly developed upper arms.
[0017] Pressure cuffs adapted for use on a patient's upper arm are
generally sized by selecting length and width cuff bladder
dimension in proportion to the target patient's upper arm
circumference. This cuff geometry proportionality will hereinafter
be described in terms of a width ratio defined as bladder width
divided by target limb circumference, and a length ratio defined as
bladder length divided by target limb circumference.
[0018] As an example, a pressure cuff with a 14.25 centimeter
bladder width and a 27.75 centimeter bladder length is
appropriately sized for a patient having an upper arm circumference
in the range of 23.0 to 33.0 centimeters. As another example, a
pressure cuff with a 17.50 centimeter bladder width and a 33.00
centimeter bladder length is appropriately sized for a larger
patient having an upper arm circumference in the range of 31.0 to
40.0 centimeters. As yet another example, a pressure cuff with a
21.25 centimeter bladder width and a 40.00 centimeter bladder
length is appropriately sized for an even larger patient having an
upper arm circumference in the range of 38.0 to 50.0 centimeters.
The first exemplary pressure cuff would yield a width ratio range
of 0.43 to 0.62 and a length ratio range of 0.84 to 1.21, the
second exemplary pressure cuff would yield a width ratio range of
0.44 to 0.56 and a length ratio range of 0.83 to 1.06, and the
third exemplary pressure cuff would yield a width ratio range of
0.43 to 0.56 and a length ratio range of 0.80 to 1.05. The
previously described length and width ratios have been determined
empirically over time to improve the precision of upper arm NIBP
measurements and are well known to those skilled in the art.
[0019] Initial experiments conducted using upper arm cuffs on the
forearm resulted in BP measurements that were in error by 11.5 mmHg
for systolic and 8.2 mmHg for diastolic when compared to invasive
pressure measurements. As is known to those skilled in the art,
invasive blood pressure measurements are directly acquired from
within the patient's vascular system such as with a catheter, and
are generally regarded as the most accurate means for measuring
blood pressure. These results indicated that the width and length
ratios commonly used for upper arm cuffs could not be applied to
blood pressure measurements on the forearm.
[0020] Research was conducted to identify other cuff bladder
geometries that may yield more accurate results when applied to the
forearm. More precisely, a design of experiments was performed
using a variety of different cuff bladder sizes and shapes in order
to correlate forearm cuff bladder geometry with resultant NIBP
measurement precision. The precision of the NIBP measurements
acquired using a forearm pressure cuff was established relative to
invasively acquired blood pressure measurements. Blood pressures in
peripheral vessels such as the radial artery differ from central
blood pressures. These differences are due to reflections from the
peripheral vascular bed.
[0021] The design of experiments indicated that a pressure cuff
comprising a cuff bladder having a 9.2 centimeter width and a 24.6
centimeter length yielded a high degree of precision when applied
to a patient having a forearm circumference in the range of 27 to
37 centimeters. In order to maintain consistency, the circumference
of the forearm was measured at a point one centimeter below the
medial crease of the elbow. The 27 to 37 centimeter forearm
circumference range was selected to include a high percentage of
obese patients, however, this circumference range may also include
forearm circumferences of patients falling within other patient BMI
ranges. Therefore, although the pressure cuff 14 is particularly
well adapted for use with obese patients having a forearm
circumference in the range of 27 to 37 centimeters, it should be
appreciated that the pressure cuff 14 may also be appropriate for
other patient BMI ranges and other forearm circumference
ranges.
[0022] The forearm pressure cuff geometry identified by the design
of experiments (i.e., 9.2 centimeter width and a 24.6 centimeter
length) yields a width ratio range of 0.25 to 0.34 and a length
ratio range of 0.66 to 0.91. This forearm pressure cuff geometry
identified by the design of experiments comprises very different
width ratio ranges and length ratio ranges, and provides greatly
improved NIBP measurement precision, as compared to conventional
upper arm cuff geometries applied to the forearm. It should
therefore be appreciated that by conducting the design of
experiments and identifying specific optimized cuff dimensions for
a range of forearm circumferences, it is now possible to
non-invasively measure the blood pressure of obese patients with a
high degree of precision.
[0023] The design of experiments also indicated that a cuff bladder
having a width variation of +/-2.1 centimeters and a length
variation of +/-4.2 centimeters yields an adequate degree of
precision when applied to a patient having a forearm circumference
in the range of 27 to 37 centimeters. Accordingly, based on the
results of the design of experiments, a pressure cuff bladder
comprising a 9.2+/-2.1 centimeter width and a 24.6+/-4.2 centimeter
length should be considered to be optimized for purposes of
obtaining a precise NIBP measurement when applied to a patient
having a forearm circumference in the range of 27 to 37
centimeters.
[0024] Referring to FIG. 2, a schematic illustration of the
pressure cuff 14 is shown in accordance with an embodiment. The
pressure cuff 14 comprises a flexible, non-distensible sleeve 34
and the cuff bladder 22. The sleeve 34 is flexible such that it may
be conveniently wrapped around a patient's limb, and
non-distensible such that it generally does not expand or swell in
response to pressure. According to one embodiment, the sleeve 34
comprises two or more layers that are impermeable to air and are
fused together near their peripheral edges in a manner adapted to
form the cuff bladder 22. According to another embodiment, the cuff
bladder 22 is a separate component retained by the sleeve 34. The
sleeve 34 is generally rectangular defining a sleeve end 36 and a
generally opposite sleeve end 38. The cuff bladder 22 is also
generally rectangular, and defines a bladder length L.sub.1 and a
bladder width W.sub.1.
[0025] The sleeve 34 is preferably long enough to be wrapped around
a patient's forearm such that the sleeve ends 36, 38 overlap each
other by an amount necessary to secure the pressure cuff 14.
According to one embodiment, the sleeve 34 comprises complementary
hook and loop type fastening portions 40, 42 adapted to retain the
pressure cuff 14 on the patient's forearm. As previously described,
based on the results of the design of experiments, the bladder
length L.sub.1 is 9.2+/-2.1 centimeters and the bladder width
W.sub.1 is 24.6+/-4.2 centimeters such that optimal NIBP
measurement precision is maintained when the pressure cuff 14 is
applied to a patient having a forearm circumference in the range of
27 to 37 centimeters.
[0026] Referring to FIG. 3, a schematic illustration of a pressure
cuff 44 is shown in accordance with an embodiment. The pressure
cuff 44 comprises a flexible, non-distensible sleeve 46 and a cuff
bladder 48. The sleeve 46 is flexible such that it may be
conveniently wrapped around a patient's limb, and non-distensible
such that it generally does not expand or swell in response to
pressure. According to one embodiment, the sleeve 46 comprises two
or more layers that are impermeable to air and are fused together
near their peripheral edges in a manner adapted to form the cuff
bladder 48. According to another embodiment, the cuff bladder 48 is
a separate component retained by the sleeve 46.
[0027] The sleeve 46 is generally arcuate shaped, and comprises
radial inner and outer edges 50, 52 that define an angle .alpha..
The sleeve 46 also comprises a sleeve end 54 and a generally
opposite sleeve end 56. The cuff bladder 48 is generally arcuate
shaped, and comprises radial inner and outer edges 58, 60 that
define an angle .beta.. The cuff bladder 48 defines a bladder
length L.sub.2 and a bladder width W.sub.2. According to one
embodiment, angle .alpha. is approximately 48.1 degrees, and the
angle .beta. is approximately 23.4. As shown in FIG. 3, the bladder
length L.sub.2 is defined at the middle of the bladder 48 as
measured along the bladder width W.sub.2.
[0028] The generally arc shape of the sleeve 46 forms a generally
conical shape when the sleeve ends 54 and 56 are engaged in the
manner described hereinabove with respect to the pressure cuff 14
(shown in FIG. 2). This conical shape conforms more closely to that
of a typical obese patient's forearm and may therefore provide a
better fit. As previously described, based on the results of the
design of experiments, the bladder length L.sub.2 is 9.2+/-2.1
centimeters and the bladder width W.sub.2 is 24.6+/-4.2 centimeters
such that optimal NIBP measurement precision is maintained when the
pressure cuff 44 is applied to a patient having a forearm
circumference in the range of 27 to 37 centimeters.
[0029] This written description uses examples to disclose the
invention, including the best mode, and also to enable any person
skilled in the art to practice the invention, including making and
using any devices or systems and performing any incorporated
methods. The patentable scope of the invention is defined by the
claims, and may include other examples that occur to those skilled
in the art. Such other examples are intended to be within the scope
of the claims if they have structural elements that do not differ
from the literal language of the claims, or if they include
equivalent structural elements with insubstantial differences from
the literal language of the claims.
* * * * *