U.S. patent application number 10/947743 was filed with the patent office on 2005-02-17 for patient support system.
Invention is credited to Chambers, Kenith W., Hanh, Barry D., Novack, Robert C., Stolpmann, James R., Williamson, Donald E..
Application Number | 20050034764 10/947743 |
Document ID | / |
Family ID | 27558919 |
Filed Date | 2005-02-17 |
United States Patent
Application |
20050034764 |
Kind Code |
A1 |
Hanh, Barry D. ; et
al. |
February 17, 2005 |
Patient support system
Abstract
A pressure control apparatus for use in a bed including a
pressurized air source, an inflatable air sack, and an
independently inflatable cell located adjacent the inflatable air
sack. A controller is operable to regulate the pressure in the air
sack and to independently alternately pressurize and vent the
inflatable cell at a selected frequency.
Inventors: |
Hanh, Barry D.; (Mount
Pleasant, SC) ; Novack, Robert C.; (Charleston,
SC) ; Williamson, Donald E.; (N. Charleston, SC)
; Stolpmann, James R.; (Charleston, SC) ;
Chambers, Kenith W.; (Charleston, SC) |
Correspondence
Address: |
Intellectual Property Group
Bose McKinney & Evans LLP
2700 First Indiana Plaza
135 North Pennsylvania Street
Indianapolis
IN
46204
US
|
Family ID: |
27558919 |
Appl. No.: |
10/947743 |
Filed: |
September 23, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10947743 |
Sep 23, 2004 |
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10190807 |
Jul 8, 2002 |
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6820640 |
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10190807 |
Jul 8, 2002 |
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09633599 |
Aug 7, 2000 |
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6415814 |
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09633599 |
Aug 7, 2000 |
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08804317 |
Feb 21, 1997 |
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6098222 |
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08804317 |
Feb 21, 1997 |
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08501274 |
Jul 17, 1995 |
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5606754 |
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08501274 |
Jul 17, 1995 |
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08350715 |
Dec 7, 1994 |
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08350715 |
Dec 7, 1994 |
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08201042 |
Feb 24, 1994 |
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08201042 |
Feb 24, 1994 |
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07898970 |
Jun 15, 1992 |
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07898970 |
Jun 15, 1992 |
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07555319 |
Jul 19, 1990 |
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5121513 |
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07555319 |
Jul 19, 1990 |
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07355755 |
May 22, 1989 |
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4949414 |
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07355755 |
May 22, 1989 |
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07321255 |
Mar 9, 1989 |
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Current U.S.
Class: |
137/487.5 |
Current CPC
Class: |
Y10T 137/7761 20150401;
Y10T 137/86421 20150401; A61G 7/05776 20130101; Y10T 137/86389
20150401; Y10S 5/915 20130101; Y10T 137/86622 20150401; Y10T
137/87217 20150401; A61G 2203/34 20130101; A61G 7/0527 20161101;
Y10T 137/2544 20150401; A61G 7/001 20130101 |
Class at
Publication: |
137/487.5 |
International
Class: |
F16K 031/12 |
Claims
1. A bed for supporting a patient, comprising: a bed frame; and an
inflatable patient support assembly supported on the bed frame, the
assembly having at least one inflatable zone including: first and
second interlaced sets of generally adjacent inflatable air sacs
defining a patient support surface, each air sac in the first set
inflating collectively with other sacs in the first set, each air
sac in the second set inflating collectively with the other sacs in
the second set, the first set of air sacs being inflated
independently relative to second set of air sacs, and a vibrational
therapy system configured to impart a vibrational force to the
patient support surface.
2. The bed of claim 1, wherein the at least one zone has first and
second sets of generally adjacent inflatable air sacs, each air sac
in the first set inflating collectively with other sacs in the
first set, each air sac in the second set inflating collectively
with the other sacs in the second set, the first set of air sacs of
the at least one zone being inflated independently relative to the
second set of air sacs of the at least one zone.
3. The bed of claim 1, further including a controller having
software to alternately inflate the first set and second set of air
sacs.
4. The bed of claim 1, wherein the vibrational therapy system
includes an impact cell.
5. The bed of claim 4, wherein the impact cell is positioned within
an air sac.
6. A bed for supporting a patient, comprising: an inflatable
patient support assembly, the assembly having: first and second
interlaced sets of generally adjacent inflatable air sacs defining
a patient support surface, and a controller including a pulsating
mode of operation where air pressures within the first set of air
sacs and the second set of air sacs are successively and
alternately pulsated, and a rotational mode of operation where the
patient support surface is laterally rotated.
7. The bed of claim 6, wherein the controller further includes a
vibrational therapy mode where a vibrational force is imparted to
the patient support surface.
8. The bed of claim 7, further comprising an impact cell in
communication with the controller and configured to provide the
vibrational force to the patient support surface.
9. The bed of claim 6, wherein the controller further includes a
pressure relief mode where the first set of air sacs and the second
set of air sacs are maintained at a substantially constant pressure
to support the patient in a relatively static condition.
10. A method of providing therapy to a patient, the method
comprising the steps of: providing an inflatable patient support
assembly having first, second, third, and fourth generally adjacent
inflatable air sacs and a controller; providing alternating
pressure therapy by inflating the first and third air sacs and at
least partially deflating the second and fourth air sacs; and
providing lateral rotation therapy by providing inflation to a
first chamber of the air sacs that is greater than the inflation
provided to a second chamber of the air sacs.
11. The method of claim 10, wherein the patient support assembly
includes a plurality of independently controlled zones, each
including first, second, third, and fourth generally adjacent
inflatable air sacs.
12. The method of claim 10, further comprising the step of
providing vibrational therapy by imparting a vibrational force to a
patient support surface defined by the air sacs.
13. A method of providing therapy to a patient including the steps
of: providing an inflatable patient support assembly having first,
second, third, and fourth generally adjacent inflatable air sacs
defining a patient support surface; providing alternating pressure
therapy by inflating the first and third air sacs and at least
partially deflating the second and fourth air sacs; and providing
vibrational therapy by imparting a vibrational force to the patient
support surface.
14. The method of claim 13, wherein the patient support assembly
includes a plurality of independently controlled zones, each
including first, second, third, and fourth generally adjacent
inflatable air sacs.
15. The method of claim 13, further comprising the step of
providing lateral rotation therapy by altering inflation levels of
the air sacs.
16. A patient support apparatus for use with a source of
pressurized air, comprising: a first support zone and a second
support zone, each support zone including a plurality of inflatable
bladders for supporting a portion of the patient, the plurality of
inflatable bladders in each support zone configured such that every
alternate bladder is coupled together in a first group and every
other alternate bladder is coupled together in a second group; a
plurality of pressure control valves, each pressure control valve
associated with a respective group of inflatable bladders, each
respective pressure control valve configured to regulate the
pressure of the respective group of inflatable bladders; and a
microprocessor configured to control the plurality of pressure
control valves such that: the first support zone is inflated to a
first reference pressure and subsequently pulsating the pressure in
the first group and the second group in the first support zone; and
the second support zone is inflated to a second reference pressure
which is substantially maintained in the first group and the second
group of the second support zone.
17. The patient support apparatus of claim 16, wherein the
microprocessor is further configured to control the pressure
control valves such that a first chamber of the air sacs have a
pressure greater than a second chamber of the air sacs.
18. The patient support apparatus of claim 16, further comprising a
vibrational therapy system controlled by the microprocessor.
19. The patient support apparatus of claim 18, wherein the
vibrational therapy system includes an impact cell.
20. The patient support apparatus of claim 19, wherein the impact
cell is positioned within an air sac.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a continuation of application Ser. No. 10/190,807,
filed Jul. 8, 2002 which is a continuation of application Ser. No.
09/633,599, filed Aug. 7, 2000, now U.S. Pat. No. 6,415,814, which
is a continuation of application Ser. No. 08/804,317, filed Feb.
21, 1997, now U.S. Pat. No. 6,098,222, which is a continuation of
application Ser. No. 08/501, 274, filed Jul. 17, 1995, now U.S.
Pat. No. 5,606,754, which is a continuation of application Ser. No.
08/350,715, filed on Dec. 7, 1994, now abandoned, which is a
continuation of application Ser. No. 08/201,042, filed on Feb. 24,
1994, now abandoned, which is a continuation of application Ser.
No. 07/898,970, filed Jun. 15, 1992, now abandoned, which is a
continuation-in-part of application Ser. No. 07/555,319, filed Jul.
19, 1990, now U.S. Pat. No. 5,121,513, which application is a
divisional application of Ser. No. 07/355,755, filed on May 22,
1989, now U.S. Pat. No. 4,949,414, which application is a
continuation-in-part Application of Ser. No. 07/321,255, filed Mar.
9, 1989, now abandoned, all the disclosures of which are
incorporated by reference herein.
BACKGROUND AND SUMMARY OF THE INVENTION
[0002] Therapeutic percussors and vibrators are known and used to
stimulate expectoration of mucous from the lungs. It has been found
that by applying undulating or vibratory action to the area of the
body adjacent to the thoracic cavity, postural draining or coughing
up of sputum is induced thereby reducing the amount of mucous that
lines the inner walls of the alveoli.
[0003] Various pneumatic and mechanical types of percussors are
known in the art. For example, U.S. Pat. No. 4,580,107 to Strom et
al. discloses a pneumatic percussor for stimulating the
expectoration of mucous. Similarly, U.S. Pat. No. 3,955,563 to
Maione discloses a pneumatic percussor useful in the therapeutic
treatment of cystic fibrosis and other lung disorders.
[0004] Low air loss patient support structures or beds are also
known in the medical field. The structures essentially consist of a
plurality of inflatable sacs disposed on a frame structure. The
patient's weight is uniformly distributed over the supporting
surface area of the inflatable sacs. Low air loss beds are known in
the art claiming therapeutic value in pulmonary and circulatory
care. Low air loss beds are also considered helpful in preventing
and treating pressure sores. Exemplary low air loss beds relating
to wound care management and prevention include the Flexicair and
Restcue beds provided by Support Systems International, Inc.
[0005] Alternating pressure low air loss beds are also known in the
art. For example, U.S. Pat. No. 5,044,029 to Vrzalik discloses a
low air loss bed having first and second sets of air bags
alternating positioned in an interdigitated fashion. Valves and
circuitry are provided for alternately changing the pressure in
each of the sets of bags to selectable maximum and minimum pressure
above and below a predetermined baseline pressure in repetitive and
cyclical fashion. Low air loss beds are also known for turning or
rotating a patient from side to side in a cyclic fashion, for
instance the Biodyne bed by Kinetic Concepts, Inc.
[0006] Support Systems International, Inc. markets the Restcue bed
having the ability to operate in a first static mode, a second
pulsation mode, and a third patient turning mode. The Restcue Bed
employs a uniquely designed inflatable sac, as disclosed in U.S.
Pat. No. 4,949,414, to operate in any one of the three modes.
[0007] Until now, the vibratory therapeutic treatment of lung
disorders, such as cystic fibrosis, has not been combined with the
benefits of low air loss technology. Previously, a patient
restricted to a low air loss bed, such as the Restcue bed, who also
required percussive chest therapy to induce mucociliary clearance
required an external mechanical or pneumatic type vibrator, such as
the Strom device. This device would be applied directly to the
patient's upper torso to loosen the mucous.
[0008] It is also known in the art to provide vibratory pads or
similar supports upon which a patient can lie or sit. U.S. Pat. No.
4,753,225 to Vogel, for example, discloses an oscillator plate on
which a body can sit, lie, or stand. The oscillator plate is made
to oscillate by sound waves. U.S. Pat. No. 4,583,255 to Mogaki et
al. discloses a massage mat having a plurality of juxtaposed air
chambers. A repeated rhythmic wave motion is induced over the
entire surface of the mat or in a local surface by repeating a
succession of feeding and discharging of compressed air into and
from the air chambers. U.S. Pat. No. 4,551,874 to Matsumura et al.
discloses a similar pneumatic massage mat.
[0009] The patient care industry has become sensitive to the rising
cost of health care in this country. Sophisticated therapy devices
such as the low air loss beds described, although very effective in
their method, can amount to significant expense if the patient
requires sustained use of the bed. The more versatile these beds
can be made, the more the expense of the bed can be spread among a
wider patient basis. For example, a low air loss bed also
incorporating a vibratory therapy mode of operation could be used
to treat a first patient suffering from pressure ulcers and a
second patient suffering from a lung disorder. The present
invention provides such a unique and versatile patient support
system and marks a significant advance in the art of low air loss
specialty hospital beds.
[0010] The accompanying drawings which are incorporated in and
constitute a part of this specification, illustrate embodiments of
the invention and, together with the description, serve to explain
the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a perspective view of a preferred embodiment of
the present invention;
[0012] FIG. 2 shows a cut-away perspective view of a preferred
embodiment of components of the present invention;
[0013] FIG. 3 illustrates a partial perspective view of a portion
of a component of an embodiment of the present invention;
[0014] FIG. 4 illustrates a partial perspective view of components
of an embodiment of the present invention;
[0015] FIG. 5 illustrates a partial cross-sectional view with the
viewer's line of sight taken generally along the lines 5--5 of FIG.
4;
[0016] FIG. 6 illustrates perspective assembly view of embodiments
of components of the present invention;
[0017] FIG. 7 illustrates a cut-away perspective view of an
embodiment of a component of the present invention;
[0018] FIG. 8 illustrates a cut-away side view of the component
like the one shown in FIG. 7;
[0019] FIGS. 9a-9d illustrate different views of a preferred
embodiment of a component of a device suitable for use in the
present invention;
[0020] FIG. 10 illustrates a perspective view of components of an
embodiment of the present invention;
[0021] FIG. 11 illustrates a schematic view of components of an
embodiment of the present invention;
[0022] FIG. 12 shows a schematic view of components of an
embodiment of the present invention;
[0023] FIG. 13 illustrates a schematic view of a components of an
embodiment of the present invention;
[0024] FIG. 14 illustrates a cut-away perspective view of a
component of the present invention as if it were taken along the
lines 14--14 in FIG. 13;
[0025] FIG. 15 illustrates a component used in an embodiment of the
present invention;
[0026] FIG. 16 illustrates an embodiment of a component of the
present invention;
[0027] FIG. 17a illustrates a cut-away perspective view of a
vibratable inflatable sac according to the present invention;
[0028] FIG. 17b illustrates another cut-away perspective view of a
vibratable inflatable sac according to the present invention;
[0029] FIG. 18 illustrates a cut-away perspective view of an
embodiment of a vibrating inflatable sac according to the present
invention;
[0030] FIG. 19a illustrates yet another embodiment of a vibratable
inflatable sac according to the invention;
[0031] FIG. 19b is a cut-away side perspective view taken along the
lines b--b of FIG. 19a and illustrates an embodiment of an
inflatable cell according to the invention;
[0032] FIG. 20 is a schematic view of the components of the
vibratory patient support system according to the present
invention;
[0033] FIG. 21 is yet another schematic view of the components of
an embodiment of the present invention;
[0034] FIG. 22 is a partial diagrammatic view of the components of
an embodiment of the present invention; and
[0035] FIG. 23 illustrates a perspective view-of a control panel
for the vibration patient support system.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] Reference now will be made in detail to the present
preferred embodiments of the present invention, examples of which
are illustrated in the accompanying drawings. As used herein, air
tightly is a relative phrase that refers to essentially no air
leakage at the operating air pressures of the present
invention.
[0037] The preferred embodiment of the modular low air loss patient
support system is shown in FIG. 1 and is generally designated by
the numeral 20.
[0038] The patient support system of the present invention
preferably includes a frame, indicated generally in FIG. 1 by the
numeral 30, having at least one articulatable section 32. The frame
carries the components of the patient support system and typically
has more than one articulatable section and preferably is mounted
on castors for ease of movement in the hospital environment. The
hydraulic lifting mechanisms for raising and lowering portions of
the frame, including the articulatable sections of the frame, are
conventional, and suitable ones are available from Hillenbrand
Industries of Batesville, Ind., sold under the Hill-Rom brand.
[0039] In accordance with the present invention, a plurality,
preferably seventeen in the illustrated embodiment (FIGS. 12 and
13), of elongated inflatable sacks are provided. As shown in FIG. 2
for example, each of the sacks 34 of the present invention
preferably has a multi-chamber internal configuration, and
preferably four chambers are provided. In one embodiment shown in
the drawings, the shape of each inflated sack is generally
rectangular and preferably has exterior dimensions thirty-two
inches long, ten and one-half inches high, and four and one-half
inches thick. The patient support surface of each sack is provided
by a top 36 which measures four and one-half inches by thirty-two
inches, and a bottom 38 (FIG. 3) is similarly dimensioned.
Depending upon their location on the patient support, the sack may
include a plurality of pin holes (not shown) to allow a small
amount of air to bleed from the sack. The diameters of the holes
preferably are about fifty thousandths of an inch, but can be in
the range of between eighteen to ninety thousandths of an inch.
Each exterior end 40 of each sack measures ten and one-half inches
by four and one-half inches, and each exterior side 42 measures ten
and one-half inches by thirty-two inches. Each sack is preferably
integrally formed of the same material, which should be gas tight
and capable of being heat sealed. The sacks preferably are formed
of twill woven nylon which is coated with urethane on the surfaces
forming the interior of the sack. The thickness of the urethane
coating is in the range of three ten thousandths of an inch to two
thousandths of an inch. Vinyl or nylon coated with vinyl also would
be a suitable material for the sack. Unless the sacks are designed
to be disposable, the material should be capable of being
laundered. Internally, the sack preferably is configured with four
separately defined chambers. As shown in FIG. 2 for example, the
internal webs 44 of each sack preferably are integral with the
outside walls of each sack, and are at least joined in airtight
engagement therewith. An end chamber 46 is disposed at an opposite
end of each sack. Each end chamber is generally rectangular in
shape with one of the narrow ends 48 formed by a portion of the top
of the sack, and the opposite narrow end 50 formed by a portion of
the bottom of the sack. As shown in FIG. 5 for example, the narrow
end of each end chamber forming a section of the sack bottom is
provided with a sack air entrance opening 52 through the bottom of
the sack.
[0040] As shown in FIG. 2 for example, each multi-chamber sack
includes a pair of intermediate chambers 54 disposed between the
end chambers. Each intermediate chamber preferably is shaped as a
right-angle pentahedron. Each intermediate chamber 54 has a base
wall 56, an altitude wall 58, a diagonal wall 60, and two opposite
triangular-shaped side walls 62. Each base wall, altitude wall, and
diagonal wall has a generally rectangular shaped perimeter. Each
base wall 56 is connected at a right angle to each altitude wall
58. Each diagonal wall 60 is connected at one edge to each base
wall and at an opposite edge to the altitude wall. The edges of
each triangular side wall are connected to oppositely disposed
edges of the base, altitude, and diagonal walls. As shown in FIG. 2
for example, each intermediate chamber is disposed within each sack
so that its diagonal wall faces toward the center of the sack and
toward the other intermediate chamber. One of the intermediate
chambers is disposed above the other intermediate chamber so that
it becomes conveniently referred to as the upper intermediate
chamber, while the other intermediate chamber becomes the lower
intermediate chamber. The altitude wall of the upper intermediate
chamber preferably is formed by a middle section of the top 36 of
the sack 34. The altitude wall of the lower intermediate chamber
preferably is formed by the middle section of the bottom 38 of the
sack 34. As shown in FIG. 1 for example, each sack preferably is
disposed to extend transversely across the longitudinal centerline
of the patient support, and the intermediate chambers are disposed
in the center of each sack. Thus, the intermediate chambers also
are disposed to extend transversely across the longitudinal
centerline of the patient support. As shown in FIG. 2 for example,
one of the intermediate chambers is disposed at least partly above
the other intermediate chamber and preferably is disposed
completely above the other intermediate chamber. Because of the
symmetrical position of each sack relative to the longitudinal
centerline of the patient support system, one of the intermediate
chambers is disposed predominately to the left side of the
centerline and has a minority portion disposed to the right side of
the centerline. Similarly, the other of the intermediate chambers
is disposed predominately to the right side of the longitudinal
centerline of the patient support and has a minority portion
disposed to the left of the centerline.
[0041] Each sack has a pair of restrictive flow passages, one
connecting each of the end chambers to the adjacent intermediate
chamber. As shown in FIG. 2 for example, preferably a single web
serves as a common wall of an end chamber and the base wall of the
adjacent intermediate chamber. As shown in FIG. 2 for example, each
restrictive flow passage can be defined by a hole 64 through the
web that is common to the intermediate chamber and the adjacent end
chamber. Hole 64 preferably is defined by a grommet having an
opening therethrough and mounted in a web that forms both the base
wall of an intermediate chamber and the vertically disposed
internal side wall of the end chamber adjacent the intermediate
chamber. The grommet is sized to ensure that the end chambers have
filling priority over the intermediate chambers and thus are the
first to fill with air and the last to collapse for want of air.
For sacks dimensioned as described above for example, a grommet
having a {fraction (1/4)} inch diameter opening has been suitable
for achieving the desired filling and emptying priority.
[0042] In further accordance with the present invention, means are
provided for supplying gas, preferably air, to each sack of the
patient support system of the present invention. As embodied herein
and shown schematically in FIG. 12 for example, the means for
supplying air to each sack preferably includes a blower 66 powered
electrically by a motor which runs on a low direct current voltage
such as 24 volts. The blower must be capable of supplying
pressurized air to the sacks at pressures as high as 30 inches of
standard water but should be capable of supplying pressures in a
preferred range of 0 to 18 inches of standard water while operating
in the blower's optimum performance range.
[0043] As shown in FIG. 12 for example, a pressure transducer 246
measures the pressure at the blower outlet. The measured pressure
signal is transmitted to a microprocessor (described hereafter) via
a blower control circuit 67 and a circuit board 150 (described
hereafter). Blower 66 preferably is controlled by voltages supplied
by a blower control circuit 67 which receives a control voltage
signal from the microprocessor via a circuit board 150. The
microprocessor is preprogrammed to compare the pressure signal
received from pressure transducer 246 to a desired pressure signal
calculated by the microprocessor. Depending upon the result of the
comparison, the microprocessor regulates the power supply to the
blower control circuit. However, the methodology used by the
microprocessor to compare the calculated pressure to the measured
pressure contains a built-in delay (preferably about three seconds)
so that the response to changes in the measured blower pressure is
not instantaneous. The deliberate time delay in the response to the
measured blower pressure assures control loop stability and
prevents unwarranted pressure fluctuations in the sacks. Otherwise,
instantaneous real time pressure corrections in response to the
blower output pressure and control valve output pressure could
cause pressure oscillations in the system.
[0044] As embodied herein and shown in FIGS. 4, 5, and 14, and
schematically in FIGS. 12 and 13, the means for supplying air to
each sack preferably further includes a support member carried by
the frame. The support member preferably is rigid to provide a
rigid carrier on which to dispose sacks 34 and may comprise a
plurality of separate non-integral sections so that a one-to-one
correspondence exists between each support member section and each
articulatable section of the frame. As shown in FIG. 14 for
example, each section of the rigid support member preferably
comprises a modular support member 68 and defines a multi-layered
plate 70. Each plate 70 preferably is thin and has a flat top
surface 72 and an opposite bottom surface, which also preferably is
flat. As shown in FIG. 14 for example, each plate has an upper
layer 74, a lower layer 76, and a middle layer 78 disposed between
the upper and lower layers. As shown partially in FIG. 4 for
example, the three layers are sealed around the edges to form two
opposed ends 80 and two opposed side edges 82 joining between the
ends.
[0045] As shown in FIGS. 4 and 13 for example, a plurality of inlet
openings 84 are defined through at least one of the side edges 82.
As shown in FIG. 13 for example, depending upon the relative
position of the modular support member, some of the modular support
members have a plurality of outlet openings 86 defined in an
opposite side edge 82. The modular support manifold of Zone IV for
example also has a plurality of outlet openings 86 defined through
the other of the side edges, while the modular support manifold of
Zone V only has inlet openings 84 defined through one of the side
edges 82, and lacks outlet openings on the opposite side edge. As
partially shown in FIG. 4 for example, the inlet openings 84 of one
plate 70 are engaged by fittings 88 and flexible hoses 90 to become
connected to the outlet openings 86 of an adjacent modular support
member.
[0046] As shown in FIGS. 5 and 14, and schematically in FIG. 13,
for example, the upper layer defines a plurality of air sack supply
openings 92 which extend through the top surface of each plate 70,
and preferably through all three layers of plate 70. As shown in
FIG. 5 for example, these air sack supply openings 92 are used to
hold a special connection fitting (described hereafter) that
connects the air sacks to a supply of controlled pressurized
air.
[0047] As shown schematically in FIG. 13 for example, at least one
of the modular support members defines a seat sack support member
94 (Zone III) and includes a plurality of pressure control valve
openings 96 defined through the lower layer 76 and extending
through the bottom surface of the plate 70. Each pressure control
valve opening 96 is configured to be connected to a pressure
control valve (described hereinafter). Each of the ten pressure
control valve openings 96 shown in FIG. 13 is schematically
represented by a circle inscribed within a box. To avoid
unnecessarily cluttering FIG. 13, only three of the pressure
control openings are provided with designating numerals 96.
Preferably, one end of a rigid elbow 98 (FIGS. 7 and 8) has a
flexible bellows (not shown) which is connected to each pressure
control valve opening 96, and the other end of the elbow is
connected to the output end of the pressure control valve. The seat
sack support member preferably includes at least one pressure
control valve opening for each pressure control valve required by
the particular configuration of the patient support system. Each
pressure control valve opening intersects with a channel (described
hereafter) for supplying air to the air sacks.
[0048] As shown in FIGS. 5 and 14, and schematically in FIGS.
11-13, for example, the layers of each plate 70 preferably combine
to define a plurality of separated enclosed channels therethrough.
In an alternative embodiment, the channels can be formed by
discrete flexible tubes. The channels are airtight and perform the
function of conduits for the transport of pressurized air from the
source of pressurized air to the air sacks. The multi-layer
construction of plate 70 allows some channels to cross one another
without intersecting, if the air flow configuration requires same.
As shown schematically in FIG. 13 for example, some channels 100
connect one of the inlet openings 84 of plate 70 to one of the
outlet openings 86 defined through the opposite side edge 82 of the
plate 70. Some of the channels 102 connect one of the inlet
openings 84 defined through one of the side edges 82 to one or more
of the sack supply openings 92 defined through the top surface of
the plate 70 of the modular support member. Each air sack supply
opening 92 communicates with at least one of the channels. Other
channels 104 include one of the pressure control valve openings
96.
[0049] As embodied herein and shown in FIGS. 2, 3 and 5 for
example, the means for supplying gas to the sacks preferably
includes a hand-detachable airtight connection, an embodiment of
same being designated generally in FIG. 5 by the numeral 106. The
connection comprises two components, one secured to the air sack
34, and the other secured to the modular support member 70. The
force required to insert one of the components into the other
component and to disconnect the components from one another is low
enough to permit these operations to be accomplished manually by
hospital staff without difficulty. Accordingly, both components of
the hand-detachable connection 106 preferably are formed of a
semi-rigid plastic material with an elastic O-ring 114 secured
within the interior of a female connection fitting 108.
[0050] As shown in FIG. 5 for example, the component secured to the
modular support member comprises an elongated female connection
fitting 108 having an exterior configured to engage airtightly with
the air sack supply opening 92 defined through the plate 70. A
plenum 93 is defined between the exterior of fitting 108 and air
sack supply opening 92. A lower end of the connection fitting
extends through the air sack supply opening 92, and a locking nut
95 screws onto this end of the fitting to secure same within the
air sack supply opening of the modular support member.
[0051] The female connection fitting 108 has an interior configured
with a hollow axially disposed coupling opening 110, preferably a
cylinder, to receive a coupling in airtight engagement therewith. A
cylindrical poppet 97 is disposed in the cylindrical coupling
opening and is configured to slide within the cylindrical coupling
opening. Poppet 97 is closed at one end, and a spring rests between
the bottom 113 of the interior of fitting 108 and the interior of
the closed end of poppet 97. The spring-loaded poppet is thereby
biased to seal off the entrance 111 of coupling opening 110.
[0052] The connection fitting further defines a fitting groove 112
completely around the interior of the fitting and preferably near
the entrance 111 of coupling opening 110. The connection fitting
also includes a resiliently deformable flexible O-ring 114 held in
the fitting groove 112. As shown in FIG. 5 for example, the
coupling cylinder 110 defined in the interior of the connection
fitting further includes a channel opening 116 defined therethrough
and in a direction normal to the axis of the coupling cylinder 110.
Because of plenum 93, the connection fitting is always disposed in
the air sack supply opening 92 so that the channel opening 116
communicates with the channel 102 that connects to the air sack
supply opening 92.
[0053] As shown in FIGS. 2, 3, 5, and 6 for example, the other
component of the hand-detachable connection includes an elongated
coupling 118 that is secured at one end to the air entrance opening
52 of the sack and extends outwardly from the sack. The coupling
has an axial opening 120 defined therethrough to permit air to pass
through same and between the interior and exterior of the sack. The
exterior of coupling 118 is configured to be received within the
interior of the connection fitting. The exterior of the coupling
has a groove 122 therearound that is configured to seat around and
seal against the deformable O-ring 114 of the connection fitting
108 therein when the coupling is inserted into the connection
fitting in airtight engagement with the fitting. Groove 122
provides a locking detent to mechanically lock and seal O-ring 114
therein.
[0054] As shown in FIG. 6 for example, the coupling is secured to
extend from the air entrance opening 52 of the air sack with the
aid of a grommet. 126 and a retaining ring 125. The grommet 126 is
heat sealed to the fabric of the air sack on the interior surface
of the air sack around the air entrance opening. The coupling
extends through the grommet 126 and the air entrance opening. A
pull tab 124 is fitted over the coupling and rests against the
exterior surface of the air sack. Alternative embodiments of pull
124 are shown in FIGS. 3 and 6 for example. A retaining ring 127 is
passed over the coupling and mechanically locks against the
coupling in air-tight engagement with the air sack. The pull tab
124, which is sandwiched between retaining ring 127 and the sack,
can be grasped by the hand of a person who desires to disconnect
the coupling from the fitting. In this way, the material of the air
sack need not be pulled during disconnection of the coupling from
the fitting. This prevents tearing of the air sack near the air
entrance opening during the disconnection of the coupling from the
fitting.
[0055] As shown in FIG. 5 for example, connection fitting 108
preferably includes a poppet 97 that is a spring loaded cylindrical
member disposed concentrically within coupling cylinder 110 so that
one end of the spring 99 rests against the closed end of the
poppet, and the other end of the spring rests against the bottom
113 of the interior of connection fitting 108. Thus, when coupling
118 is inserted into coupling cylinder 110, coupling 118 depresses
poppet 97 and connects channel opening 116 to axial opening 120 of
coupling 118. When no coupling 118 is inserted into coupling
cylinder 110, the spring forces the poppet to seal against O-ring
114 and thereby seal the coupling cylinder opening 110 at the
entrance 111 thereof near the top layer 74 of plate 70. This
permits one sack to be detached while air is being supplied to the
others without leakage of air through the coupling cylinder opening
110. The sealing effect of the poppet also prevents fluids from
entering the channels of plate 70, and this is advantageous during
cleaning of the upper surfaces of plate 70.
[0056] In keeping with the modular configuration of the patient
support system of the present invention, the means for supplying
air to each sack further preferably includes a modular manifold for
distributing air from the blower to the sacks plugged into the
modular sack support member. The modular manifold provides means
for mounting at least two pressure control valves and for
connecting same to a source of pressurized air and to an electric
power source. Because its elongated shape resembles a "log," such
modular manifold is sometimes referred to as the log manifold, and
one embodiment is designated by the numeral 128 in FIG. 10 for
example. Log manifold 128 includes an elongated main body 130 that
is hollow and defines a hollow chamber 132 within same. As shown in
FIG. 10 for example, main body 130 is shaped as a long rectangular
tube which preferably is formed of aluminum or another light weight
material such as a hard plastic or resin. As shown in FIG. 10, an
air supply hose 134, which suitably is one and one quarter inches
in diameter, carries pressurized air from blower 66 to chamber 132
of main body 130. A first end wall 136 is defined at one narrow end
of main body 130, and a second end wall (not shown) is defined at
the opposite end of main body 130. A conventional pressure check
valve 138 such as shown in FIG. 13 for example, is provided in each
end wall to permit technicians to gauge the pressure inside chamber
132.
[0057] One section of main body 130 defines a mounting wall 140 on
which a plurality of pressure control valves 162 (such as shown in
FIGS. 7 and 8 for example and described in detail hereafter) can be
mounted. A plurality of ports 142 are defined through the mounting
wall and spaced sufficiently apart from one another to permit
side-by-side mounting of pressure control valves 162. Each port 142
has a bushing 144 mounted therein. The bushing is configured to
receive and secure a valve stem 146 (FIG. 8) of a pressure control
valve 162. As shown in FIG. 7 for example, valve stem 146 typically
has one or more O-rings 148 engage with bushing 144 to form an
airtight connection that nonetheless is easily detachable and
engageable, respectively, by manual removal and insertion of the
pressure control valve. This permits easy removal and replacement
of the valve and reduces repair time and inoperative time for the
patient support system as a whole.
[0058] The log manifold further includes a circuit board 150
preferably mounted on the exterior of the main body adjacent the
mounting wall 140. As shown in FIG. 10 for example, an electrical
connector 152 is provided for receiving a direct current power line
to furnish electric power to operate circuit board 150. The circuit
board includes a plurality of electrical connection fittings
defined therein. Each electrical connection fitting 154 or plug
outlet is preferably disposed in convenient registry with one of
the ports 142 defined in the mounting wall. Electrical connection
fittings 154 receive an electrical connector, e.g., plug 156, of a
pressure control valve 162 to transmit electrical power and signals
thereto to operate the various electrical components of the
pressure control valve. In addition, a plurality of fuses 158 are
provided on circuit board 150 to protect circuit board 150 and
components connected thereto, such as a microprocessor 160
(described hereinafter), from electrical damage. As shown in FIG.
10 for example the fuse receptacles are on the exterior of the log
manifold 128 to provide technicians with the unobstructed access
that facilitates troubleshooting and fuse replacement.
[0059] In further accordance with the patient support system of the
present invention, means are provided for maintaining a
predetermined pressure in the sacks. The predetermined pressure is
kept at a constant predetermined value for each of a number of
groups of sacks in the standard mode of operation or may be
constantly varying over time in a predetermined sequence in yet
other modes of operation of the patient support system of the
present invention. As embodied herein and shown schematically in
FIG. 12 (in which electrical connections are shown in dashed lines
and pneumatic connections are shown in solid lines, in both cases
arrows indicate the direction of electrical or pneumatic flow) for
example, the means for maintaining a predetermined pressure
preferably includes a programmable microprocessor 160 and at least
one and preferably a plurality of pressure control valves 162, each
of the latter preferably monitored by a pressure sensing device
(not shown in FIG. 12 separately from valves 162).
[0060] As embodied herein and shown in FIGS. 7 and 8 for example,
the means for maintaining a predetermined pressure in the sacks
includes a pressure control valve 162. Preferably, a plurality of
pressure control valves are provided, and each valve 162 can
control the pressure in a plurality of sacks 34 by means of being
connected to a gas manifold (such as modular support member
channels 100, 102, 104) which carries air from the pressure control
valve to each of the sacks.
[0061] Each pressure control valve includes a housing 164, which
preferably is formed of aluminum or another light weight material.
As shown in FIG. 8 for example, an inlet 166 is defined through one
end of the housing for receiving air flow from a source of
pressurized air. An outlet 168 is also defined through the housing
for permitting the escape of air exiting the pressure control
valve. An elongated valve passage 170 is defined within the housing
and is preferably disposed in axial alignment with the inlet. The
passage has a longitudinal axis that preferably is disposed
perpendicularly with respect to the axis of the valve outlet, which
is connected to the valve passage. The valve housing further
defines a chamber 172 disposed between the inlet and a first end
174 of the valve passage. The pressure control valve includes a
piston 176 disposed in the chamber. The piston is displaceable in
the chamber to vary the degree of communication through the chamber
that is permitted between the valve inlet and the valve passage.
The piston preferably is formed of a hard polymeric or resinous
material such as polycarbonate for example. The pressure control
valve further includes an electric motor 178 that preferably is
mounted outside the housing and near the chamber.
[0062] The pressure control valve preferably includes means for
connecting the motor to the piston in a manner such that the
operation of the motor causes displacement of the piston within the
chamber. As embodied herein and shown in FIG. 8 for example, the
connecting means preferably includes a connecting shaft 180 that
has one end non-rotatably secured to the rotatable shaft 182 of the
motor 178. Connecting shaft 180 has its opposite end non-rotatably
connected to one end of the piston. As shown in FIG. 9b for
example, piston 176 has a groove 183 disposed diametrically through
one end of the piston to non-rotatably secure the end of connecting
shaft 180 therein. Chamber 172 preferably is cylindrical and has
its longitudinal axis disposed perpendicularly relative to the
longitudinal axis of the valve passage. The piston preferably is
cylindrical and rotatably displaceable in the chamber with a close
clearance between the piston and the chamber so as to minimize any
passage of air thereby. One end of the piston has a cam stop 181
which engages a stop (not shown) in chamber 172 to restrict piston
176 from rotating 360 degrees within chamber 172. As the motor
shaft 182 rotates, the connecting shaft 180 and piston 176 are
rotatably displaced relative to the chamber. As shown in FIG. 8 for
example, the piston has a flow slot 184 extending radially into the
center of the piston so that depending upon the position of this
slot 184 relative to the inlet and the passage, more or less flow
is allowed to pass from the inlet 166, through this slot 184, and
into the passage 170. Thus, the position of the piston within the
chamber determines the degree of communication that is permitted
through the chamber and the degree of communication permitted
between the valve passage and the valve inlet. This degree of
communication effectively regulates the pressure of the air
delivered by the valve.
[0063] As shown in FIGS. 9a, 9b, 9c, and 9d for example, piston
slot 184 preferably is configured to result in a linear
relationship between the air flow permitted through the valve and
the rotation of the piston. As shown in FIG. 9d for example, piston
slot 184 preferably comprises three distinctly shaped sections. The
section designated 185 is closest to the surface of the piston and
is formed as a spheroidal section. The intermediate section is
designated 187 and is formed as a semi-cylinder. The section
extending deepest into the center of the piston is designated 189
and is formed as an elongated cylinder with a spherical end.
[0064] As shown in FIGS. 7 and 8 for example, the pressure control
valve further preferably includes a pressure transducer 186 that
communicates with the valve passage to sense the pressure therein.
Preferably, the pressure transducer is mounted to the valve
housing. An opening 188 is defined through the housing opposite
where the outlet is defined. The pressure transducer has a probe
(not shown) adjacent the opening to permit the transducer to sense
the pressure in the valve passage. The pressure transducer converts
the pressure sensed in the valve passage into an electrical signal
such as an analog voltage, and this voltage is transmitted to an
electronic circuit (described hereafter as a circuit card) of the
valve.
[0065] As shown in FIG. 7 for example, the pressure control valve
further includes an electronic circuit 190 which is mounted to the
exterior of the housing on a circuit card 192. The valve circuit
contains a voltage comparator network and voltage reference chips
for example. The valve circuit controls the power being provided to
the valve motor. The circuit card is connected to the valve
pressure transducer and receives the electrical signals transmitted
from the transducer corresponding to the pressure being sensed by
the transducer in the valve passage. The circuit card receives a
reference voltage signal from a microprocessor (described
hereinafter) via circuit board 150. The microprocessor sends an
analog-voltage signal to the valve circuit 190 via circuit board
150. The valve circuit compares this signal to the one from the
pressure transducer and computes a difference signal. The valve
circuit controls the valve motor 178 to open or close the valve
according to the magnitude and sign (plus or minus) of the
difference voltage signal.
[0066] As shown in FIG. 7 for example, the pressure control valve
further includes an electrical lead 194 that is connected at one
end (not shown) to the valve circuit card 192 and terminates at the
other end in a plug 156. This plug can be connected into a plug
outlet such as the electrical connection fitting 154 on the log
manifold 128 and thus is consistent with the modular construction
of the present invention.
[0067] As shown in FIG. 7 for example, the pressure control valve
further defines a dump outlet hole 196 through the valve housing in
the vicinity of the valve chamber. As shown in FIG. 8 for example,
a dump passage 198 is defined through the valve piston and is
configured to connect the dump hole to the valve passage upon
displacement of the piston such that the dump hole becomes aligned
with the dump passage of the piston.
[0068] As shown in FIG. 1 for example, a microswitch 199 is
disposed near the hydraulic controls for changing the elevation of
the patient support. When a control handle 201 is placed in the CPR
mode of operation, microswitch 199 is activated, and the
microprocessor turns off the blower and signals all of the valves
to align the dump passage of the piston with the dump hole. This
causes the rapid deflation of all of the air sacks and places the
support into a condition suitable for performing a cardiopulmonary
resuscitation (CPR) procedure on the patient.
[0069] As shown in FIG. 16 for example, the control panel of the
present invention has a button for SEAT DEFLATE. When the operator
presses the SEAT DEFLATE button, the microprocessor activates the
two pressure control valves which control the pressure in the sacks
supporting the seat zone (Zone III shown in FIGS. 12 and 13 for
example) of the support system. The microprocessor signals the
pressure control valves controlling the seat zone to align their
pistons' dump passages with the dump holes in the valve housings in
order to permit all of the air in the sacks in the seat zone to
escape to the atmosphere through the dump holes. As shown in FIG. 8
for example, when the valve pistons are aligned in this manner, the
valve inlets are blocked by the pistons and thus prevented from
communicating with the valve passages and valve outlets.
[0070] As shown in FIG. 8 for example, a conventional pressure
check valve 138 preferably is mounted in a manual pressure check
opening 200 defined through the housing of each pressure control
valve. As shown in FIG. 9, a conventional pressure check valve 138
also preferably is inserted into the end walls of log manifold 128.
As shown in FIG. 15 for example, check valve 138 has a head 202
with a port 204 defined therethrough for receiving a probe of a
pressure measuring instrument (not shown). A collapsible bladder
flange 206 extends from head 202 to the opposite end of check valve
138. The bladder flange extends through the pressure check opening
200 in the housing of the pressure control valve. A slit 208 is
formed axially through the collapsible bladder flange and connects
to port 204. The bladder flange is resiliently collapsible around
slit 208 to prevent passage of air therethrough. The probe of the
measuring instrument is hollow and is inserted through port 204
until the probe parts the flange 206 to open the collapsible slit
208. This allows the probe to access the pressure in the control
valve or chamber of the log manifold, as the case may be. Check
valve 138 preferably is formed of a flexible material such as a
soft plastic or neoprene rubber. One supplier of such check valves
is Vernay Labs of Yellow Springs, Ohio 45387.
[0071] As embodied herein and shown schematically in FIG. 12 for
example, the means for maintaining a predetermined pressure
preferably includes a programmable microprocessor 160. The
microprocessor preferably has parallel processing capability and is
programmed to operate the pressure control valves in conjunction
with the blower to pressurize the sacks according to the height and
weight of the patient. The height and weight information is
provided to the microprocessor by the operator. This is
accomplished by providing the desired information via a control
panel 210 such as shown in FIG. 16 for example. The height of the
patient is displayed on a digital readout 212 in either inches or
centimeters, and the weight of the patient is displayed on a
separate digital readout 214 in either pounds or kilograms.
[0072] As shown in FIGS. 12 and 13 for example, five pressure zones
or body zones preferably include a head zone (Zone 1 or I), a chest
zone (Zone 2 or II), a seat zone (Zone 3 or III), a thigh zone
(Zone 4 or IV), and a leg and foot zone (Zone 5 or V). Each body
zone is supplied with pressurized air from the blower via two
separate pressure control valves. In one configuration of the air
flow path from the blower to the sacks, one of the pressure control
valves controls air supplied to the chambers of each sack on one
side of the patient support system for each body zone, and the
other pressure control valve controls the air to the chambers on
the side of each sack on the opposite side of the patient support
system. In yet another configuration of the air flow path from the
blower to the sacks, one of the pressure control valves controls
the air supplied to all of the chambers of every alternate sack in
a body zone, and the other pressure control valve controls the air
supplied to all of the chambers in the remaining alternate sacks in
the body zone.
[0073] The microprocessor is programmed to set the reference
pressure of each pressure control valve of each body zone into
which the patient support system has been divided for purposes of
controlling the pressure supplied to air sacks 34 under particular
portions of the patient. Based upon the height and weight of the
patient, the microprocessor is preprogrammed to calculate an
optimum reference pressure for supporting the patient in each body
zone. This reference pressure is determined at the valve passage
where the pressure transducer of each pressure control valve is
sensing the pressure. The circuit card 192 performs a comparison
function in which it compares the reference pressure signal
transmitted to it from microprocessor 160 via circuit board 150 to
the pressure which it has received from the pressure transducer.
Depending upon the difference between this signal received from the
valve's pressure transducer and the calculated desired signal
corresponding to the preset reference pressure, the valve circuit
192 signals the valve motor to open or close the pressure control
valve, depending upon whether the pressure is to be increased or
decreased. This process continues until the desired reference
pressure is sensed by the pressure transducer of the pressure
control valve. The microprocessor has parallel processing
capability and thus can simultaneously supply each of the pressure
control valves with the reference pressure for that particular
control valve. Moreover, the speed of each of the microprocessor
and valve circuits greatly exceeds the time in which the motors of
the pressure control valves can respond to the signals received
from the valve circuits. Thus, in practical effect the motor
response times limit the frequency with which the pressure control
valves can be corrected.
[0074] Moreover, the reference pressure calculated by the
microprocessor also can depend upon other factors such as whether
one or more articulatable sections of the frame is elevated at an
angle above or below the horizontal. Another factor which can
affect the microprocessor's calculation of the reference pressure
for the particular zone is whether the patient is being supported
in a tilted attitude at an angle below the horizontal and whether
this angle is tilted to the left side of the patient support system
or the right side. Still another factor is whether the patient is
lying on his/her side or back.
[0075] Yet another factor that can affect the reference pressure
calculated by the microprocessor is whether the patient comfort
adjustment buttons 216 have been manipulated via the control panel
to adjust the pressure desired by the patient in a particular zone
to a pressure slightly above or slightly below the reference
pressure that the microprocessor is preprogrammed to set for that
particular zone under the other conditions noted, including,
elevation angle, side lying or back lying, and tilt attitude. As
shown in FIG. 16 for example, each body support zone has a
triangular button 216 pointing upward and a triangular button 216
pointing downward. Depression of the upward button 216 increases
the reference pressure that the microprocessor calculates for that
particular zone. Similarly, the depression of the downward pointing
button 216, decreases the reference pressure that the
microprocessor calculates for that particular zone. The range of
increase and decrease preferably is about twenty percent of the
reference pressure that is calculated for the standard mode of
operation in each particular zone. This permits the patient to
change the pressure noticeably, yet not so much as to endanger the
patient by producing a condition that is either over-inflated or
under-inflated for the sacks in a particular zone. Moreover, the
20% limitation also can be overridden by pressing the OVERRIDE
button shown in FIG. 16. The override function can be cancelled by
pressing the RESET button shown in FIG. 16.
[0076] One form of sack pressure algorithm which is suitable for
use by the microprocessor to calculate the reference pressures for
different configurations of the patient support system of the
present invention is as follows:
Pressure=C.sub.1 x Weight+C.sub.2 x Height+C.sub.3
[0077] Table 1 provides parameters suitable for several elevation
configurations, patients lying on his/her back, side lying, and all
five zones. For example, the constants C1, C2 and C3 for each zone
are the same for elevation angles 0 degrees through 29 degrees with
the patient lying on his/her back. The values of C1, C2 and C3 for
side lying are the same for elevation angles of 0.degree. through
29.degree..
1 TABLE 1 Elevation Angle Zone C1 C2 C3 0.degree.-29.degree. I
0.00473 0.04208 -1.27789 back lying II 0.02088 -0.01288 1.73891 III
0.03688 -0.10931 7.33525 IV 0.00778 -0.01828 2.21268 V 0.00316
0.00482 0.61751 30.degree.-44.degree. I 0.00857 0.02056 -0.22725
back lying II 0.02230 0.03996 3.32860 III 0.01971 0.08197 -0.68941
IV 0.00554 0.03495 0.38316 V 0.00303 0.01883 -0.12248
45.degree.-59.degree. I 0.00152 0.02889 0.11170 back lying II
0.01349 -0.02296 3.06615 III 0.03714 0.01023 3.37064 IV 0.01014
0.09399 -3.39696 V 0.00298 -0.00337 1.40102 60.degree. and above I
0.00571 -0.00976 1.77230 back lying II 0.01165 0.02598 -0.20917 III
0.01871 0.04853 4.35063 IV 0.02273 0.06610 -2.94674 V 0.00291
0.00292 0.99296 SL I 0.01175 0.00548 0.43111 (Side Lying) II
0.03276 0.03607 -1.78899 0.degree.-29.degree. III 0.03715 -0.10824
8.22602 IV 0.01091 -0.00336 1.48258 V 0.00146 0.02093 -0.15271
[0078] The weight of the patient is supported by the surface
tension of the air sack as well as the air pressure within the
sack. Thus, values of C1, C2, and C3 can vary with air sack
geometry or the properties, such as stiffness, of the materials
used to form the air sacks Different air sack geometries may
provide more or less stiffness in the air sack.
[0079] Typically, a ribbon cable 218 electrical connector (FIG. 10)
connects circuit board 150 to microprocessor 160. Circuit board 150
receives analog signals from microprocessor 160 and distributes
same to the valve circuit card 192 of each particular pressure
control valve 162 for which the signal is intended. In addition, in
some embodiments, circuit board 150 can return signals from the
individual pressure control valve circuitry 190 to the
microprocessor. The voltage signals from the microprocessor cause
the valve circuit card 192 to operate the motor of the pressure
control valve to expand or contract the valve opening to attain a
reference pressure, which the microprocessor is preprogrammed to
calculate. The valve circuit compares the reference signal received
from the microprocessor to the signals received from pressure
transducer 186 of the pressure control valve. In effect, this
enables the support system of the present invention to monitor the
air pressure in the valve passage 170 near the valve outlet 168,
which is the location where the sensing probe of the pressure
transducer is disposed to sense the pressure supplied to the air
sack through the pressure control valve.
[0080] In further accordance with the present invention, there is
provided means for switching between different modes of
pressurizing the sacks. As embodied herein and shown schematically
in FIGS. 11, 12 and 13 for example, the mode switching means
preferably includes at least one flow diverter valve 220 and
preferably includes a plurality of flow diverter valves 220. The
number of flow diverter valves depends upon the number of different
pressure zones desired for the patient support system embodiment
contemplated. A pressure zone includes one or more sacks or sack
chambers which are to be maintained with the same pressure
characteristics. In some instances, it is desired to have opposite
sides of the sack maintained at different pressures. This becomes
desirable for example when the rotation mode of the patient support
system is operated. In other instances it becomes desirable to have
the pressure in every other sack alternately increasing together
for a predetermined time interval and decreasing together for a
predetermined time interval. This becomes desirable for example
when the patient support system is operated in the pulsation mode
of operation.
[0081] As shown in FIG. 13 for example, each flow diverter valve
preferably is mounted within a modular support member 68, and more
than one diverter valve 220 can be mounted in a modular support
member such as the seat sack support member 94. However, other sack
support members 68, such as the head sack support member shown in
FIG. 13 for example, may lack a diverter valve. Each diverter valve
preferably is mounted between the top and bottom surfaces of each
plate 70. As shown schematically in FIG. 11 for example, each
diverter valve has a first flow pathway 222 with a first inlet 224
at one end and a first outlet 226 at the opposite end. Each
diverter valve further includes a second flow pathway 228 with a
second inlet 230 at one end and a second outlet 232 at the opposite
end. The flow pathways are mounted and fixed on a rotating disk
234, also referred to as a switching disk 234, that rotates about a
central pivot 236.
[0082] The so-called switching disk is rotatable for the purpose of
changing the path defined by the inlets and outlets. As shown in
solid lines in FIG. 11 for example, first flow pathway 222 connects
channel A with channel B, and second flow pathway connects channel
C with channel D. Thus, a first inlet 224 of first pathway 222 is
connected to channel A and a first outlet 226 of first pathway 222
is connected to channel B. Similarly, a first inlet 230 of second
pathway 228 is connected to channel D and a first outlet 232 of
second pathway 228 is connected to channel C. In the solid line
configuration shown schematically in FIG. 11, both sides of every
alternate sack are connected together and thus maintained at the
same pressure by a pressure control valve connected to the sacks
via pressure control valve openings 96. This is the configuration
for the so-called pulsation (P) mode of operation.
[0083] As shown by the dotted line configuration of the flow
pathways, when the switching disk is rotated 90 degrees
counterclockwise to the dotted line position (R), the first flow
pathway connects channel A to channel C, and the second flow
pathway connects channel B to channel D. Thus, first inlet 224 of
first pathway 222 is connected to channel C, and second inlet 230
of second pathway 228 is connected to channel B. First outlet 226
of first pathway 222 becomes connected to channel A, and second
outlet 232 of second pathway 228 becomes connected to channel D. In
the dotted line configuration shown in FIG. 11, one side of all of
the sacks are connected together and thus can be maintained at a
common pressure, and the other side of all of the sacks are
connected together and also can be maintained at a common pressure.
This is the configuration for the so-called rotation (R) mode of
operation.
[0084] The use of the diverter valves by the present invention
enables the support system to be operated in either a pulsation
mode of operation or a rotation mode of operation with a minimum
number of valves and air flow conduits. The diverter valve allows
the air flow paths of the support system to be reconfigured between
two distinctly different ways of connecting the pressurized air
source through the pressure control valves to individual air sacks
of the patient support system.
[0085] The patient support system of the present invention can be
operated to automatically rotate the patient, i.e., turn the
patient to one side or the other, at preset intervals of time.
Referring to the control panel shown in FIG. 16, the patient
support system of the present invention can be set to operate in a
rotational mode by pressing the SET UP button followed by pressing
the MODE SELECTION button until the ROTATION indicator is lit. Then
the rotation section of the control panel becomes illuminated and
can be operated. The operator selects the amount of time that the
patient is to be maintained in a right-tilted position, or a
horizontal position, or a left-tilted position. To accomplish this
for the horizontal position for example, the operator activates the
horizontal button 238 followed by activating the TIME button. This
manipulation enters the time interval during which the patient
support is to maintain the patient supported in the horizontal
position. This interval of time is displayed on a digital readout
239. To set the time that the patient is to spend in the
right-tilted position, the operator presses the right button 240
followed by the TIME button. Again, the time interval which the
patient is to be maintained tilted to the right is displayed
digitally on readout 239. A similar procedure is followed to set
the time spent in the left-tilted position.
[0086] In addition, right button 240 allows the operator to select
the attitude of the patient in the right-tilted s position. There
are a number of illumination bars disposed above the right button.
Each illumination bar corresponds to a different attitude to which
the patient can be tilted to the right. The operator selects the
desired attitude by continuously pressing the triangular buttons
above and below id right button 240 until the bar adjacent the
desired attitude is illuminated. For example, the maximum attitude
of tilt requires the operator to continue pressing the downward
pointing triangular button beneath right button 240 until the
lowermost bar above the right button is lit. The same procedure is
followed to set the attitude for the left-tilted position.
[0087] Moreover, as shown schematically in FIG. 12 for example, the
angle of elevation of the head and chest section of the patient
support is monitored by an elevation sensing device 242, which
sends signals to the circuit board 150 of the modular valve
mounting manifold 128. FIG. 12 illustrates electrical signaling
pathways by dashed lines and pneumatic pathways by solid lines. The
arrows at the ends of the dotted lines indicate the direction of
the electrical signals along the electrical pathways. The elevation
sensing device detects the angle at which the head and chest
section has been positioned, and supplies a corresponding signal to
the microprocessor via circuit board 150. Examples of suitable
elevation sensing devices are disclosed in U.S. Pat. Nos. 4,745,647
and 4,768,249, which patents are hereby incorporated in their
entireties herein by reference. If this elevation information from
the sensing device 242 indicates that the angle of articulation
exceeds 30 degrees, the microprocessor configures the pressure
profile to a standard mode of operation and thus cancels any
rotation or pulsation that may have been selected by the operator.
The rotation mode is cancelled to avoid torquing the patient's
body. The pulsation mode is cancelled because the elevation of the
patient above 30 degrees reduces the ability to float the patient
in the sacks in the seat zone during pulsation of the three sacks
therein. Thus, the "bottoming" of the patient during pulsation at
elevation angles above 30 degrees is avoided. Upon reduction of the
articulated angle below 30 degrees, the microprocessor does not
automatically resume either pulsation or rotation but requires any
mode other than the standard mode to be reset.
[0088] In accordance with the present invention, the control over
blower 66 preferably includes a blower control circuit which
controls the power supplied to blower 66. Microprocessor 160
provides a blower control voltage to blower control circuit 67
which controls the power supply to blower 66 according to this
blower control voltage signal received from microprocessor 160. A
pressure transducer 246 measures the pressure preferably at the
blower and communicates a signal corresponding to the measured
blower pressure to the microprocessor 160 via blower control
circuit 67 and circuit board 150.
[0089] Microprocessor 160 has a blower control algorithm which
enables microprocessor 160 to calculate a desired reference
pressure for the blower. The blower control algorithm preferably
calculates this blower reference pressure to be 3 to 4 inches of
standard water higher than the highest pressure in the air sacks.
Typically, the seat zone (Zone III) has this highest pressure for a
given height and weight setting (provided by the operator to the
microprocessor) regardless of the elevation of the head and chest
sections and whether the patient is lying on his/her side or back.
However, a patient with abnormal body mass distribution (which
could be caused by a cast for example) may require the highest sack
pressure in one of the other zones. If Zone III has the highest
sack pressure, as the elevation angle increases, the sack pressure
in Zone III increases, and the reference pressure for the blower
also increases to equal 3 to 4 inches of standard water above the
pressure of the sacks in Zone III.
[0090] Microprocessor 160 stores the signal from transducer 246
corresponding to the measured blower pressure in the microprocessor
memory, which is updated preferably only once every three seconds.
Microprocessor 160 calculates the reference blower pressure about
four times each second and compares it to the stored measured
pressure about once each second. If the measured pressure is more
than about one inch of standard water higher than the reference
pressure calculated by microprocessor 160, microprocessor 160
decreases the control voltage by an increment of {fraction (1/256)}
of the maximum control voltage signal that microprocessor 160 is
programmed to provide to blower control circuit 67. This maximum
voltage corresponds to the maximum output of blower 66. If the
measured blower pressure is more than about one inch of standard
water lower than the reference pressure, then microprocessor 160
increases the control voltage signal by an increment of {fraction
(4/256)} times the maximum control voltage. The increase or
decrease, if any, occurs about once each second. Pressure deficits
are of a greater concern, and thus correction of such deficits
occurs four times faster than correction of excess pressures. The
pressure changes resulting from the blower control sequence occur
no more frequently than once each second and are no greater than
{fraction (1/256)} of the maximum pressure for decreases and
{fraction (4/256)} times the maximum pressure for increases.
Moreover, the microprocessor's three second delay in updating the
measured pressure used in the calculations assures that changes in
the measured pressure that have very short durations will not lead
to pressure instability because of control loop exacerbation of
short-lived pressure fluctuations. This three second time interval
can change depending upon the pressure dynamics and control
dynamics of the system.
[0091] The selection of the rotation mode of operation on control
panel 210 causes the microprocessor to signal the diverter valves
to align their pathways for rotational operation of the support
system. Once the parameters of operation in the rotation mode have
been inputted, the microprocessor recalculates an optimum reference
pressure for each pressure control valve. The microprocessor
determines the appropriate tilt reference pressure based upon the
height and weight of the patient and the angle of tilt selected by
the operator. This is accomplished such that the pressure in the
low pressure side of the sack and the pressure in the high pressure
side of the sack average out to the pressure that would be set for
the same sacks in the normal mode of operation, i.e., without any
rotation. Thus, the average pressure over the entire sack during
the rotational mode of operation is the same as it would be in the
non-rotational modes of operation.
[0092] The operator initiates the rotation by pressing the RUN
button on panel 210 in FIG. 16 for example. When the operator
presses the RUN button, the microprocessor adjusts the pressure
control valves 162 to set the new tilt reference pressure in the
end and intermediate chambers on the side of the support system to
be tilted. This results in a reduction in the pressure in the end
and intermediate chambers of the tilted sides of the sacks in each
body zone. The microprocessor operates the control valve to prevent
this low sack pressure from falling below 1 to 2 inches of standard
water, because this is the minimum pressure needed to keep the end
chamber inflated while the weight of the patient is squeezing out
air from the intermediate chamber. The microprocessor also raises
the pressure in the end and intermediate chambers on the opposite
side, i.e., non-tilted side of the sacks of the support system. The
increase in pressure in the chambers of the untilted side of the
support system is needed to compensate for the loss in pressure in
the chambers on the tilted side of the support system. The
additional pressure allows the patient to be supported in the
tilted position as comfortably as in the non-tilted position. The
pressure increase in the chambers of the non-tilted side of the
sacks is preferably sufficient so that the average pressure between
the two sides of each sack equals the pressure in this sack when
the patient is supported thereon in a non-tilted position. In other
words, one-half of the sum of the pressure in the high side of the
sack and the low side of the sack is equal to the normal base line
pressure of this particular sack in a non-tilted mode of operation,
i.e., when both sides of the sack are at this same base line
pressure.
[0093] In accordance with the present invention, a method is
provided for turning the patient on a low air loss patient support
system as in the present invention. As embodied herein, the turning
method includes the step of grouping all of the sacks 34 into at
least two body zones that correspond to at least two different
zones of the patient's body. Each zone of the patient's body is
preferably supported by one or more sacks in one of the two body
zones. Preferably five body zones are involved.
[0094] The next step in the method for turning a patient is to
pressurize all of the sacks according to a first pressure profile
that provides each sack in each body zone with a respective first
air pressure. This first air pressure has been chosen so as to
provide a first respective level of support to that portion of the
patient's body supported by the sacks in that body zone. The level
of support is predetermined depending upon the height and weight of
the patient and calculated accordingly by the microprocessor. The
height and weight data also affect the respective first air
pressure that is chosen for the sacks in that particular body
zone.
[0095] The terms "pressure profile" are used to refer to the fact
that the pressure in each body zone may be different because of the
different support requirement of that particular body zone. If the
individual pressures in the sacks of all the body zones were to be
represented on a bar graph as a function of the linear position of
the sacks along the length of the patient support, a line
connecting the tops of the bars in the graph would depict a certain
profile. Hence the use of the term "pressure profile" to describe
the pressure conditions in all of the sacks at a given moment in
time, either when the pressures are changing or in a steady state
condition.
[0096] The next step in turning the patient involves separately
controlling the air pressure that is supplied to each side of each
of the sacks. This preferably is accomplished by supplying the
chambers on one side of the sacks in each body zone via a first
pressure control valve and supplying the chambers on the other side
of the sacks via a separate pressure control valve, and connecting
each pressure control valve to a four-way diverter valve. The
diverter valve can then be configured to ensure that the air
pressure being supplied to the chambers on one side of each sack is
being controlled by one of the pressure control valves, and the
pressure being supplied to the chambers on the other side of the
sack of a particular zone is being supplied through a separate
pressure control valve.
[0097] The next step in turning the patient involves lowering the
pressure in the chambers on the side of the sacks to which the
patient is to be tilted. Specifically, the pressure must be lowered
in the chambers of one side of the sacks from a first pressure
profile, previously established, to a predetermined second pressure
profile. The second pressure profile is predetermined according to
the height and weight of the patient and also according to the
attitude to which the patient is to be tilted. The greater the
angle below the horizontal to which the patient is to be tilted,
the lower the predetermined second pressure profile.
[0098] Another step in the method of turning the patient requires
raising the pressure in the chamber on the side of the sacks that
is opposite the side to which the patient is being tilted. This
involves raising the pressure in the chamber of the non-tilted side
of each of the sacks to a predetermined third pressure profile. The
raised pressure profile in the non-tilted sacks compensates for the
lower pressure profile in the side of the sacks to which the
patient has been tilted. When the overall pressure being supplied
to support the patient has been reduced in half of the sack, as
occurs during tilting, that portion of the patient's body in that
particular body zone would not be maintained at the desired level
of support without increasing the pressure in the non-tilted side
of the sack.
[0099] The operator begins by lowering the pressure in one side of
the all of the sacks until the patient has been tilted to the
desired attitude of tilt beneath the horizontal. As this is
occurring, the microprocessor is increasing the pressure in the
non-tilted sacks such that one-half of the sum of the pressure in
the tilted sacks plus the pressure in the untilted sacks equals the
base line pressure of the sacks before the tilting procedure began.
In the case just described, the base line pressure corresponds to
the pressure in the sack at the first pressure profile. Preferably,
the raising and lowering of the pressures in the chambers of
opposite sides of the sacks occurs practically simultaneously.
Since preferably the microprocessor has parallel processing
capability and thus can control each of the pressure control valves
simultaneously, the speed with which the tilting is effected (or
any other pressure changes in the sacks) is primarily limited by
the flow restrictions in the pneumatic circuit, which is primarily
a function of the air sack volume and the pressure level in the
sacks.
[0100] In further accordance with the present invention, the
patient is maintained in the selected tilted position for a
predetermined length of time. At the end of this predetermined
length of time, which is clocked by the microprocessor, the patient
is returned to the horizontal position by simultaneously increasing
the pressure in the side of the sacks to which the patient
previously had been tilted while decreasing the pressure in the
non-tilted side of the sacks until the pressure in both sides of
the sacks returns to the first predetermined pressure profile. The
changes in pressure from low to high or from high to low preferably
occurs over a time interval of about three minutes. This is done to
reduce the likelihood that the patient will experience any
uncomfortable sensation during these pressure changes.
[0101] In still further accordance with the present invention, the
method of turning a patient can maintain the patient in the
horizontal position for a predetermined interval of time. At the
end of this predetermined interval of time, the patient then can be
tilted to the side of the patient support system that is opposite
the side to which the patient had been tilted prior to being
maintained in the horizontal position. Moreover, the amount of time
which the patient spends in a particular position, namely,
left-tilted, horizontal, and right-tilted, can be preselected so
that the patient can be maintained in one of the three positions
for however long is deemed therapeutic.
[0102] It is during the turning, i.e., rotation or tilting, mode of
operation that the grommet which defines the hole 64 connecting
each intermediate chamber 54 with each end chamber 46 of each sack
34 plays a particularly important role. As the pressure control
valve controlling the side of the sack to which the patient is to
be tilted begins to close and reduce the pressure being supplied to
this side of these sacks, the weight of the patient above the
depressurizing intermediate chamber 54 squeezes the air from the
intermediate chamber through the grommet and into the end chamber
46 to compensate for the reduced pressure being supplied to the end
chamber via the pressure control valve. Thus, the reduction in
pressure initially serves to deflate the intermediate chamber while
maintaining the end chamber as fully inflated as before the
pressure control valve began to reduce the pressure supplied
thereto. The pressure in the end chamber of course is being
reduced. However, the end chamber remains completely inflated,
unlike the connecting intermediate chamber which is being squeezed
by the weight of the patient that no longer is being supported by
the same level of air pressure as was present when the sacks were
being maintained according to the first pressure profile that was
first set to maintain the patient in the horizontal position atop
the sacks. Moreover, since the end chamber remains inflated, it
acts as a passive constraint to prevent the patient from rolling
past the end chamber and off of the patient support.
[0103] To operate the support system of the present invention in
the pulsation mode, the operator pushes the SET UP button on the
control panel illustrated in FIG. 16 for example. Then the operator
presses the MODE SELECTION button until the PULSATION indicator
illuminates. When the PULSATION indicator is illuminated, the
pulsation section of the control panel also becomes illuminated.
The microprocessor immediately signals the diverter valves to align
their pathways for the pulsation mode of operation. In the
pulsation alignment of the diverter valves, the channels of the
modular support members connect alternately adjacent air sacks.
This results in two sets of sacks which can be operated at two
separate and opposite patterns of pressurization. As shown in FIG.
16 for example, the operator selects the time interval for a
complete pulsation cycle by pressing the TIME button. The time
interval for each pulsation cycle is displayed in a digital readout
244 above the TIME button. The operator selects the degree of
depressurization in the phase of the pulsation cycle in which the
pressures in alternating sacks are lowered while the pressures in
the other sacks are increased according to the amount that the
pressures in the first group of alternating sacks have been
lowered. The operator accomplishes this selection by pressing one
of the two triangular shaped buttons beneath the light bars next to
the MAX-MIN scale to illuminate the light bar adjacent the desired
level of depressurization. Once the parameters of operation in the
pulsation mode have been inputted, the microprocessor begins
calculating a pulsation reference pressure for each pressure
control valve. This pulsation reference pressure depends upon the
degree of depressurization selected by the operator and the height
and weight of the patient. Preferably, the microprocessor maintains
the pressures in adjacent sacks such that one-half of the sum of
the pressures in the adjacent sacks equals the base line pressure
for a sack in that zone at the elevation angle, if any, and taking
into account whether the patient is side lying or back lying. The
operator initiates the pulsation of the sacks by pressing the RUN
button on panel 210 in FIG. 16 for example.
[0104] In further accordance with the present invention, a method
is provided for periodically relieving the pressure of the patient
support system against the patient's body. This method preferably
is accomplished by pulsating the pressure in the sacks of the low
air loss patient support system having a plurality of sacks
disposed transversely across the length of the support system. The
pressure in a first group of sacks comprising every alternating
sack is depressurized relative to the remaining sacks, which are
provided with an increase in pressure. The pressure differential
between the two separate sacks is maintained for a predetermined
interval of time. At the end of this time interval, the pressure
profiles switch so that the other set of alternating sacks becomes
depressurized while the first set of alternating sacks receives a
slight increase in pressure. This opposite pressurization condition
is also maintained for a predetermined interval of time, whereupon
the cycle repeats itself until the pulsation mode of operation is
discontinued.
[0105] Prior to the initiation of the pulsation mode of operation,
all of the sacks in the patient support will be maintained at a
first pressure profile according to the height and weight of the
patient, the various angles of inclination of any of the
articulating sections of the frame, and any tilt angle imposed upon
the sacks. However, preferably, the pulsation method will not be
operated in conjunction with any tilting of the patient, and thus
activation of the pulsation method automatically discontinues
operation in the tilting mode.
[0106] The steps of the method for pulsating the pressure in the
sacks of the low air loss patient support system include
configuring the air supply means of the patient support to define
two separate groups of alternating sacks. A first group of sacks
includes either every odd number sequenced sack in order from one
end of the patient support to the opposite end of the patient
support or every even number sequenced sack. For purposes of this
description, the first of the two groups of sacks will be chosen to
be the odd number sequenced sacks. In a preferred embodiment, the
sacks are further grouped into body zones to support the patient's
body at a predetermined pressure for all of the sacks in the body
zone. Thus, all of the sacks in a particular body zone will be
pressurized at the same first pressure, and accordingly the
individual first pressure will be applied to all of the sacks in
each body zone. This step of configuring the sacks is preferably
accomplished by configuring a plurality of diverter valves to
connect every alternating sack in a body zone.
[0107] The next step includes reducing the air pressure being
supplied to the sacks in the first group. This is accomplished as
the microprocessor controls the pressure control valve of this
first group to attain a second pressure profile. The second
pressure profile corresponds to a decreased pulsation reference
pressure calculated by the microprocessor when the degree of
depressurization was selected by the operator. The microprocessor
controls the pressure control valves supplying air to the sacks in
the first group until the decreased pulsation reference pressure
has been attained by the sacks in this first group.
[0108] The next step occurs simultaneously with the first step and
includes supplying air pressure to the sacks in the second of the
two groups, namely, the group including every even number sequenced
sack in order from one end of the patient support to the opposite
end of the patient support, at a third pressure profile. This third
pressure profile corresponds to an increased pulsation reference
pressure which the microprocessor calculated for each pressure
control valve controlling the sacks in the second group for each
individual body zone. This increased pulsation reference pressure
also has been calculated by the microprocessor depending upon the
degree of depressurization selected by the operator.
[0109] This third pressure profile is designed to compensate for
the loss of pressurization by the first group of sacks so that the
patient support can continue to maintain the patient at the same
level of horizontal support during the depressurization of the
first group of sacks. In other words, while the pressures in the
alternate groups of sacks are changing, the vertical height of the
patient above the floor is not changing significantly from what it
was prior to the onset of the pulsation mode of operation. Thus,
the microprocessor maintains the pressures in the two groups of
sacks such that one-half the sum of the second and third pressure
profiles equals the first pressure profile.
[0110] The two steps involving the changes in pressurization of the
two groups of sacks, occur simultaneously over a first time
interval.
[0111] The method for pulsating the pressure in the sacks further
includes the step of maintaining the second and third pressure
profiles being supplied to the two groups of sacks during a second
interval of time. This is accomplished by the microprocessor
controlling the pressure control valves to maintain the increased
or decreased pulsation reference pressures calculated by the
microprocessor for the respective group of sacks over the time
interval selected by the operator.
[0112] After the predetermined lower pressure has been maintained
for the sacks in the one group for the second interval of time, the
next step is to increase the pressure being supplied to this one
group during a third interval of time until each sack in this one
group attains a higher individual pressure corresponding to the
third pressure profile. At the same time that the sacks in the
first group of sacks are attaining the higher individual pressure,
the pressure being supplied to the sacks in the other of the two
groups is being decreased to the lower pressure corresponding to
the second pressure profile. The pressure in the other of the two
groups is decreased until the predetermined lower pressure is being
provided to each individual sack in this other group. The pressure
decreases over this third interval of time.
[0113] Finally, the third pressure profile in the one group and the
second pressure profile in the other group are maintained during a
fourth interval of time.
[0114] Preferably, all of the first, second, third, and fourth
intervals of time are of equal duration. However, in some
embodiments of the method of pulsating the sacks of the present
invention, the first interval of time preferably equals the third
interval of time, and the second interval of time preferably equals
the fourth interval of time.
[0115] In yet another embodiment of the method of pulsating the
sacks of the present invention, not only are the first and third
time intervals equal to each other as well as the second and fourth
time intervals being equal to each other, but the first and third
time intervals are shorter than the second and fourth time
intervals. In other words, the time which the sacks spend
alternately changing pressures is less than the time during which
the sacks remain at the steady state higher or lower pressures.
Similarly, in yet another embodiment of the method of pulsating the
sacks of the present invention, the second and fourth time
intervals can be equal to each other and shorter than the first and
third time intervals, which also are equal to each other.
[0116] In accordance with the present invention and as illustrated
in the figures in general, particularly FIGS. 17 through 23, a
vibratory patient support system 300 is provided. Vibratory patient
support system 300 includes rigid support frame 30, as described,
and a plurality of inflatable sacs 34 supported upon support frame
30. Each sac 34 has an upper support surface 36 whereby a plurality
of sacs 34 forms a patient support surface. Vibratory patient
support system 300 further includes means for pressurizing and
maintaining sacs 34 at a predetermined pressure. These means have
already been described in detail. Vibrating means A separate from
the pressurizing and maintaining means are provided for vibrating
at least a portion of the patient support surface at a
predetermined therapeutic frequency. In a preferred embodiment,
zone 2 (FIG. 13) contains vibrating means A. The plurality of sacs
34 are maintained at their predetermined pressure while the portion
of the patient support surface is simultaneously vibrated at a
predetermined frequency within the specified frequency range. Means
are further provided for variably controlling vibrating means
A.
[0117] The vibratory patient support system 300 may be similar to
the low air loss patient support system previously described with
the addition of vibrating means A for vibrating at least a portion
of the low air loss patient support system. In a preferred
embodiment of system 300, inflatable sacs 34 are disposed
transversely across support frame 30, as depicted generally in FIG.
1. As also previously described in detail, support frame 30 is
preferably articulable in sections with at least one section
corresponding to the general area of a patient's chest. In a
preferred embodiment, vibrating means A are disposed within at
least one inflatable sac 34 which is located in the section
corresponding to the general area of the patient's chest.
[0118] Vibrating means A may be external to inflatable sacs 34 or
disposed internal to at least one sac 34 as depicted generally in
FIGS. 17 through 22. However, it is within the scope of the present
invention to include external vibrating means, such as a mechanical
vibrator for vibrating a portion of the patient support surface at
a predetermined therapeutic frequency. Vibrating means A may
include, for example, an internal fluid or air system, a pulsating
air or fluid system, or any suitable motive means for vibrating the
patient support system.
[0119] Additionally, the vibratory patient support system of the
present invention is not limited to a low air loss configuration.
Inflatable sacs 34 may comprise low air loss sacs but, this is not
a requirement of the invention.
[0120] A multi-modal low air loss patient support system has
already been described. The multi-modal system includes means for
pressurizing inflatable sacs 34 in a first constant pressure mode,
means for pressurizing inflatable sacs 34 in a second pulsation
mode, and means for pressurizing inflatable sacs 34 in a third
turning mode. In a preferred embodiment of vibratory patient
support system 300 according to the invention, vibrating means A
are included with the multi-mode low air loss patient support
system as described. In this embodiment, vibratory patient support
system 300 is switchable from any one of the modes of operation of
the low air loss configuration described to any other mode of
operation with vibrating means A being independently actuable and
controllable from any one of the modes of operation. The modes of
operation of the low air loss configuration system have already
been discussed in detail in the specification and need not be
repeated.
[0121] Vibrating means A and the means for variably controlling
vibrating means A according to the invention preferably includes an
operator interface means, such as control panel 308 as shown in
FIG. 23 or other suitable operator interface component. Control
panel 308, or like interface component, may be included as part of
the control panel depicted in FIG. 16, or comprise a singular
component. The means for variably controlling vibrating means A may
include means for selecting from a first percussion mode and a
second vibration mode. In the percussion mode, vibrating means A
vibrates the patient support surface at a predetermined frequency
in a range of, for example, 1 to 5 hz. In the vibration mode,
vibrating means A vibrates the patient support surface at a
predetermined frequency within a range of 6 to 25 hz, for example.
The frequency ranges of the modes can obviously be tailored to
desired frequency ranges. Means are further provided to allow the
operator to select any combination of frequency, amplitude, and
duration of the vibrating therapy.
[0122] Control panel 308 depicted in FIG. 23 is merely a
representation of what a suitable user-friendly control panel for
use with the present invention may resemble. Control panel 308 or
operator interface can comprise any suitable means or interface
component. For example, a LED display may be used providing the
operator with a menu for selecting the vibrational mode, frequency,
amplitude, and duration of vibrating therapy.
[0123] The relationship of circuit board 150, microprocessor 160,
and blower control 67 has already been described in detail. The
means for variably controlling vibrating means A preferably
comprises an interface with microprocessor 160 and circuit board
150. Microprocessor 160 includes software means for controlling the
frequency of vibrating means A through power distribution board
150. This relationship is depicted generally in FIGS. 20 through
22. The means for varying the amplitude or magnitude of frequency
of vibrating means A includes an interface with blower control unit
67. This relationship will be described in more detail below.
[0124] Vibrating means A according to the invention may comprise a
pneumatic vibrating system or means B, as in FIGS. 20 and 21
generally. The motive force for pneumatic vibrating system B is a
pressurized air source, preferably the same pressurized air source
used with the means for pressurizing and maintaining sacs 34 at a
predetermined pressure. For example, the source of pressurized air
could be blower 66. As shown in FIGS. 20 and 21 in particular,
blower 66 supplies air to valves 162 through manifold 128 for
pressurizing and maintaining sacs 34 at their predetermined
pressure. As indicated by the broken lines in the figures, the
pressurized air source for pneumatic vibrating system B may be via
manifold 128 or directly from blower 66. In an alternative
embodiment, pneumatic vibrating system B may employ its own
separate source of pressurized air, for instance a separate blower
66 or other suitable source of pressurized air. This separate
source of air may include, for example, a connection to the
hospital service air system, an external pressurized air control,
or other external source.
[0125] Pneumatic vibrating system B may further comprise at least
one inflatable cell 304. Cell 304 may be disposed within at least
one inflatable sac 34, as shown particularly in FIGS. 17 through
19b, or disposed external to sac 34 generally adjacent the upper
surface thereof. Inflatable cell 304 is disposed within sac 34
generally at the top thereof to lie just beneath upper surface 36
of sac 34. In the embodiments depicted in FIGS. 17a, 17b, and 18,
inflatable cell 304 is completely separate from sac 34 and
supported within sac 34 by, for instance, internal slings 306 upon
which inflatable cell 304 rests. Slings 306 are heat sealed or
otherwise adhered to the sides 42 of sac 34. Any appropriate
retaining means for maintaining cell 304 in position within sac 34
may be used but, flexible slings 306, or like devices, are
preferred in that they will give with the changing shape and volume
of sac 34.
[0126] In one preferred arrangement, cell 304 comprises a tubular
pod which extends generally lengthwise within sac 34, as shown in
FIGS. 17a and 17b. Alternatively, a plurality of individual
inflatable cells or pods 304 may be disposed within sac 34 as
depicted in FIG. 18. It should be understood that any arrangement
of inflatable cells 304 within sac 34 is within the scope of the
invention.
[0127] As described, each inflatable sac 34 has an upper surface
36. Preferably, inflatable cells 304 are disposed within sac 34
just below surface 36 so that when inflatable cells 304 are rapidly
inflated and vented, they impart a vibrational force to upper
surface 36. Thus, the frequency of the vibrational forces imparted
to the patient support surface depends upon the frequency
inflatable cells 304 are alternately inflated and vented.
Alternatively, cells 304 may be external to sac 34 and still impart
vibrational forces to the patient support surface.
[0128] FIG. 19a depicts another preferred embodiment of inflatable
cells 304. In this embodiment, inflatable cell 304 is not
completely separate from sac 34 but, the top of cell 304 is also
upper surface 36 of sac 34. In other words, inflatable cell 304 and
sac 34 share the same upper surface. In this embodiment, internal
slings 306 are not required. In this embodiment, a diaphragm 316
may also be provided within each inflatable cell 304, as shown
particularly in FIGS. 19a and 19b. Diaphragm 316 rest just below
upper surface 36 and forms the top of pressurizable portion 313 of
inflatable cell 304. Above pressurizable portion 313, there is a
space 311 within which diaphragm 316 expands and contracts. Ports
303 are provided into space 311 so that the relative pressure
within space 311 equalizes with the pressure of internal chamber
320. Diaphragm 316 is precisely arranged within cell 304 beneath
upper surface 36 so that when cell 304 is pressurized, diaphragm
316 expands and "snaps" against upper surface 36. Upon venting cell
304, diaphragm 316 contracts or returns to its original position.
Due to ports 303, the pressure in space 311 equalizes with that in
internal chamber 320, thereby aiding diaphragm 316 in returning to
its original position. With this embodiment, the vibrational forces
imparted to upper surface 36 are enhanced by the action of the
diaphragm 316 within inflatable cell 304.
[0129] Means are further provided for connecting inflatable cells
304 to the source of pressurized air. Preferably, device 322 is
provided similar to the hand detachable air-tight connection 126
for supplying pressurized air to sacs 34, as previously described.
However, any suitable air-tight connection can employed as device
322. Flexible tubing or other like material may be used to convey
the pressurized air internally through sac 34 to inflatable cell
304. When inflatable cells 304 are disposed within a
multi-chambered sac 34, as illustrated in FIGS. 18 and 19a, the
flexible tubing, if disposed internal to sac 304, may pass through
internal walls 44. In this case, air-tight seals or grommets 315
are provided to ensure the air-tight integrity of the internal
chambers of sac 34.
[0130] Pneumatic vibrating system B according to the present
invention may also include controllable valve means C disposed
between the source of pressurized air or blower 66 and inflatable
cell 304. Valve means C operate to alternately supply pressurized
air from the pressurized air source to inflatable cell 304 and to
vent pressurized air from inflatable 304 at a predetermined
frequency. In this manner, inflatable cell 304 expands and
contracts thereby pneumatically vibrating just below upper surface
36 of sac 34, thereby imparting vibrational forces to the patient
support surface.
[0131] Controllable valve means C may comprise solenoid valves 314,
310, and 312 as shown in FIGS. 20 and 21. In the embodiment of FIG.
21, three-way solenoid valve 314 is utilized. Three-way solenoid
valve 314 operates to alternately pressurize inflatable cell 304
and vent cell 304 to atmosphere. Solenoid valve 314 is powered
through circuit board 150 with the frequency of operation of valve
314 being controlled through appropriate software in microprocessor
160. The frequency of operation of valve 314, or the rate valve 314
pressurizes and vents cell 304 is controlled and may be varied
through interfacing with microprocessor 160.
[0132] Controllable valve means C may comprise conventional timer
control circuits with relay outputs for controlling the frequency
of operation of the solenoid valves. In this embodiment, the timer
control circuit need not be interfaced with microprocessor 160.
Preferably though, appropriate software is embodied in
microprocessor 160 for controlling the valves.
[0133] The software for control of controllable valve means C may
be embodied in an appropriate chip carried within microprocessor
160. The control of solenoid valves through appropriate software
and power distribution boards is well-known to those skilled in
solid state electronic control systems and need not be described in
detail here. In summary though, an operator may interface with
microprocessor 160 through, for instance, control panel 308 of FIG.
23, to establish the vibrational mode and frequency of valve 314.
Depending on the operator's commands, microprocessor 160 generates
a control signal for valve 314 through power distribution board
150. The control signal and power to operate valve 314 is routed
through circuit board 150 to solenoid valve 314. In an alternative
embodiment not depicted in the figures, other routing and power
distribution systems may be employed for controlling controllable
valve means B. For instance, a separate microprocessor and power
distribution board may be utilized for independently controlling
solenoid valve 314. The frequency, sequencing, and amplitude of the
vibrational forces may be controlled with the software and
microprocessor 160 by, for example, varying the frequency and
timing of the valve operations.
[0134] As embodied in FIG. 20, controllable valve means C according
to the invention may comprise two-way solenoid valves 310, 312.
Valves 310 and 312 may operate in opposite phase to alternately
pressurize and vent inflatable cells 304. First solenoid valve 310
is signaled to open thereby allowing pressurized air into
inflatable cells 304 while second solenoid valve 312 is
simultaneously signaled to close. Valve 310 then shuts stopping the
flow of pressurized air to cell 304 while second solenoid valve 312
simultaneously opens venting cell 304. In an alternative
embodiment, valves 310 and 312 may open and close with a
predetermined time delay there between so that a time lag exists
between pressuring and venting of cells 304. As described above,
control of solenoid valves 310 and 312 is through microprocessor
160 and circuit board 150.
[0135] It should be understood that the solenoid valves 310, 312,
and 314 are only examples of suitable controllable valves for use
with the vibrating therapy system of this invention. Other values
or valve configurations are suitable and within the scope of this
invention. For instance, a spool valve or solenoid diaphragm type
valve may also be utilized.
[0136] Means are also preferably provided for controlling the
amplitude or magnitude and sequence of vibrational forces imparted
to upper surface 36. This may be accomplished by, for instance,
varying the source of pressurized air to cells 304 or the timing of
the pressurization of the cells. In the embodiment of the invention
depicted in the figures, blower 66 supplies air to inflatable cell
304. The magnitude or amplitude of vibrational forces of cell 304
can be varied by controlling the speed of blower 66 through blower
control circuit 67. Preferably, an operator interface is provided
by, for example, control panel 308, for varying the output of
blower 66.
[0137] It is a desirable feature of the vibrational therapy device
according to the present invention that vibrating means A, for
example, pneumatic vibrating system B, be separately actuable and
controllable in any of the modes of operation of the patient
support system. If vibratory patient support system 300 of the
present invention includes the low air loss patient support system
described earlier, it is desired to be able to actuate and control
vibrating means A so as not to interfere with or affect the
operational mode of the low air loss system. For example, it may
desired to actuate vibrating means A while the low air loss patient
support system is simultaneously rotating the patient from side to
side. Additionally, it may only be necessary to actuate vibrating
means A for only brief periods of time at preselected intervals. In
this manner, it is desired to have a timing control circuit, within
microprocessor 160 for example, for establishing and controlling
the period of operation of vibrating means A regardless of the mode
of operation of the low air loss patient support configuration.
[0138] In further accordance with the present invention, a
vibratable inflatable sac 318 is provided. Vibratable sac 318 may
be utilized, for example, with other sacs in a inflatable patient
support system, such as a low air loss patient support bed. As
illustrated in FIGS. 17a and 17b, vibratable sac 318 comprises at
least one internal chamber 320 and preferably, a plurality of
internal chambers as illustrated in FIG. 17b. Means 126 are
provided for connecting internal chamber 320 to a source of
pressurized air so that vibratable sac 318 can be pressurized and
maintained at a predetermined pressure. Pneumatic vibrating means B
are carried internal to sac 318 and disposed within internal
chamber 320 generally near the top thereof just below upper surface
36 of sac 318. Means 322 are provided for connecting vibrating
means B to a source of pressurized air so that vibrating means B
can be alternately pressurized and vented at a predetermined
frequency thereby imparting a therapeutic vibrational force to the
upper surface 36 of sac 318. In one preferred embodiment of
vibratable inflatable sac 318 according to the present invention,
pneumatic vibrating means includes an inflatable cell or pod 304
disposed within internal chamber 320 just below upper surface 36,
as already described.
[0139] It will be apparent to those skilled in the art that various
modifications and variations can be made in the present invention
without departing from the scope or spirit of the invention. Thus,
it is intended that the present invention cover the modifications
and variations of this invention provided they come within the
scope of the appended claims and their equivalents.
* * * * *