U.S. patent application number 12/563207 was filed with the patent office on 2010-01-14 for self-contained compression device with pneumatic bladder and method.
This patent application is currently assigned to TYCO HEALTHCARE GROUP LP. Invention is credited to Malcolm Bock, Jesse E. Denson, Steve Nardi, Scott Wudyka.
Application Number | 20100010405 12/563207 |
Document ID | / |
Family ID | 38780824 |
Filed Date | 2010-01-14 |
United States Patent
Application |
20100010405 |
Kind Code |
A1 |
Nardi; Steve ; et
al. |
January 14, 2010 |
SELF-CONTAINED COMPRESSION DEVICE WITH PNEUMATIC BLADDER AND
METHOD
Abstract
Apparatus and methods for cyclically compressing the limb of a
patient to improve blood flow in the limb. In one embodiment, a
compression device includes a compressive section sized and shaped
for extending around a portion of the limb for applying compressive
pressure and a housing operatively connected to the compressive
section. The housing includes first and second housing members
movable relative to each other between contracted and expanded
positions. A non-pneumatic mechanical actuator is provided in the
housing for cyclically moving the first and second housing members
from their contracted position to their expanded position to apply
compressive pressure to the limb portion. At least one pneumatic
bladder is positioned for distributing the compressive pressure
over a surface of the limb portion.
Inventors: |
Nardi; Steve; (Taunton,
MA) ; Denson; Jesse E.; (Lincoln, RI) ;
Wudyka; Scott; (Leominster, MA) ; Bock; Malcolm;
(Medfield, MA) |
Correspondence
Address: |
TYCO HEALTHCARE - EDWARD S. JARMOLOWICZ
15 HAMPSHIRE STREET
MANSFIELD
MA
02048
US
|
Assignee: |
TYCO HEALTHCARE GROUP LP
Mansfield
MA
|
Family ID: |
38780824 |
Appl. No.: |
12/563207 |
Filed: |
September 21, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11533524 |
Sep 20, 2006 |
7618384 |
|
|
12563207 |
|
|
|
|
Current U.S.
Class: |
601/152 |
Current CPC
Class: |
A61B 5/026 20130101;
A61B 5/024 20130101; A61B 17/1325 20130101; A61H 11/00 20130101;
A61H 23/02 20130101; A61B 5/6829 20130101; A61B 5/6828 20130101;
A61B 17/1355 20130101; A61B 5/6824 20130101 |
Class at
Publication: |
601/152 |
International
Class: |
A61H 7/00 20060101
A61H007/00 |
Claims
1. A self-contained compression device for cyclically compressing
the limb of a patient to improve blood flow in the limb, the
compression device comprising: a compressive section sized and
shaped for extending generally circumferentially around a portion
of the limb for applying compressive pressure to the limb portion;
and a module operatively connected to and carried by the
compressive section for cyclic expansion and contraction in
generally radial directions with respect to said limb portion
between a contracted condition in which the module has a first
dimension for relaxing pressure on said limb portion, and an
expanded condition in which the module has a second dimension
greater than said first dimension for compressing the limb portion;
said module comprising the combination of at least one pneumatic
bladder and at least one non-pneumatic mechanical device, said at
least one non-pneumatic mechanical device being operable to apply a
force in a generally radial direction with respect to said limb
portion for moving said module toward its expanded condition to
apply compressive pressure to said limb portion, and said at least
one pneumatic bladder being positioned for distributing said
compressive pressure over a surface of the limb portion.
2. A compression device as set forth in claim 1, wherein said
non-pneumatic mechanical device comprises opposing platens and one
or more springs between the platens for urging the platens away
from one another.
3. A compression device as set forth in claim 2, wherein said
compression device comprises an annular band having a pocket, and
wherein the module is received in the pocket.
4. A compression device as set forth in claim 3, wherein the module
is removable from the pocket for re-use with another disposable
annular band.
5. A compression device as set forth in claim 2, wherein the module
comprises a battery-powered pump for inflating the pneumatic
bladder.
6. A compression device as set forth in claim 1, wherein said
non-pneumatic mechanical device comprises opposing housing members
defining an interior housing space, and a motor-operated actuator
between the housing members in the interior housing space for
moving the housing members away from one another to expand the
module, said pneumatic bladder being located outside the interior
housing space.
7. A compression device as set forth in claim 6, wherein said
compression device comprises an annular band having a pocket, and
wherein the module is received in the pocket.
8. A compression device as set forth in claim 7, wherein the module
is removable from the pocket for re-use with another disposable
annular band.
9. A compression device as set forth in claim 1, wherein said
mechanical device is seated on the at least one pneumatic
bladder.
10. A self-contained compression device for application to a limb
of a patient for use in a compression therapy to improve blood flow
to the heart, the compression device comprising: a compression
section sized and shaped for extending generally circumferentially
around a portion of the limb, said compressive section including a
pocket; a mechanical device in said pocket for cyclically applying
compressive pressure to the limb portion; a pneumatic bladder in
the pocket for distributing said compressive pressure over a
surface of the limb portion; and a sensing device associated with
the pneumatic bladder for sensing a characteristic of said
compression therapy and for outputting a signal indicative of said
characteristic.
11. The compression device as set forth in claim 10, wherein said
characteristic comprises one or more of the following: pressure of
the contents of the bladder; temperature of the patient; pulse of
the patient; blood flow of the patient; and oxygen level of the
patient.
12. The compression device as set forth in claim 10, wherein said
mechanical device comprises a module operable for cyclic expansion
and contraction in generally radial directions with respect to said
limb portion between a contracted condition in which the module has
a first dimension for relaxing pressure on said limb portion and an
expanded condition in which the module has a second dimension
greater than said first dimension for compressing the limb portion,
the module comprising at least one non-pneumatic mechanical
actuator operable to apply a force in a generally radial direction
with respect to said limb portion for moving the module toward its
expanded condition.
13. A method of using a compression system to cyclically compress
portions of a limb of a patient to improve blood flow in the limb,
said compression system comprising a compressive unit having zones
corresponding to different portions of a limb, and at least two
modules each comprising a housing including first and second
housing members movable relative to each other between a contracted
position in which the housing has a first dimension and an expanded
position in which the housing has a second dimension greater than
said first dimension, said module comprising the combination of at
least one pneumatic bladder and at least one non-pneumatic
mechanical device, said at least one non-pneumatic mechanical
device being operable to apply a force in a generally radial
direction with respect to said limb portion for moving said module
toward its expanded condition, said method comprising the steps of:
applying the compressive unit to a limb such that the compressive
unit extends circumferentially around the limb and the zones of the
unit correspond with said limb portions to be cyclically
compressed; operatively connecting the at least two modules to said
compressive unit such that the modules are positioned in respective
zones of the compressive unit with the pneumatic bladders of the
modules adjacent respective limb portions; and causing said housing
members to move cyclically between said expanded and contracted
positions for cyclically applying compressive pressure to said limb
portions in a manner such that said compressive pressure is
distributed over surfaces of respective limb portions by the
pneumatic bladders.
14. A method as set forth in claim 13, further comprising the step
of sensing the zone in which each module is located when the
modules are positioned on the compressive unit.
15. A method as set forth in claim 13, further comprising
synchronizing operation of the modules to cyclically compress the
limb portions.
16. A method as set forth in claim 13, wherein said operatively
connecting step comprises removably connecting said at least two
modules to said compressive unit.
17. A method as set forth in claim 16, wherein said operatively
connecting step comprises placing the modules in respective pockets
of the compressive unit.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional of U.S. patent application
Ser. No. 11/533,524, filed Sep. 20, 2006, which is hereby
incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] This invention relates generally to compression therapy, and
more particularly to devices which enhance blood flow to avoid
circulation problems, such as deep vein thrombosis (DVT).
[0003] Cyclical compression of a body part (e.g., leg) is
beneficial to a person who has a blood circulation problem
involving poor venous return to the heart. Many devices on the
market and in the prior art provide compression by using one or
more pneumatic bladders that encircle the leg or other limb(s). The
bladders are inflated in a predetermined sequence and to a
prescribed pressure at timed intervals. The device that controls
the inflation typically employs an air pump or compressor and a
number of valves that operate to direct the flow of air to the
bladders. Conventional products use a bladder-filled sleeve wrapped
around the limb and a tube that connects the bladder(s) to a
controller device that resides separately from the patient such as
on the footboard of a bed, on the floor, or on a night stand. If
the patient must move, the device must be removed. In addition,
while the device is on the patient, it is possible that tubes
become entangled in the patient's limbs and/or become a nuisance or
safety hazard to caregivers and visitors who may be close to the
bed.
[0004] There is a need, therefore, for an improved compression
device.
SUMMARY OF THE INVENTION
[0005] In general, a compression device of this invention is
self-contained and used for cyclically compressing the limb of a
patient to improve blood flow in the limb. The compression device
comprises a compressive section sized and shaped for extending
generally circumferentially around a portion of the limb for
applying compressive pressure to the limb portion, and a housing
operatively connected to and carried by the compressive section.
The housing includes first and second housing members movable
relative to each other between a contracted position in which the
housing has a first dimension for relaxing pressure on the limb
portion, and an expanded position in which the housing has a second
dimension greater than the first dimension for compressing the limb
portion. A non-pneumatic mechanical actuator is provided in the
housing for cyclically moving the first and second housing members
from their contracted position to their expanded position to apply
compressive pressure to the limb portion. The at least one
pneumatic bladder is positioned for distributing the compressive
pressure over a surface of the limb portion.
[0006] In another aspect, the compression device comprises a
compression section sized and shaped for extending generally
circumferentially around a portion of the limb. The compressive
section includes a pocket that contains a mechanical device for
cyclically applying compressive pressure to the limb portion, and a
pneumatic bladder for distributing such compressive pressure over a
surface of the limb portion. A sensing device associated with the
pneumatic bladder is provided for sensing a characteristic of a
compression therapy and for outputting a signal indicative of the
characteristic.
[0007] In yet another aspect, this invention is directed to a
method of using a compression system to cyclically compress
portions of a limb of a patient to improve blood flow in the limb.
The compression system comprises a compressive unit having zones
corresponding to different portions of a limb, and at least two
modules each comprising a housing including first and second
housing members movable relative to each other between a contracted
position in which the housing has a first dimension and an expanded
position in which the housing has a second dimension greater than
the first dimension. The module comprises the combination of at
least one pneumatic bladder and at least one non-pneumatic
mechanical device. The at least one non-pneumatic mechanical device
is operable to apply a force in a generally radial direction with
respect to the limb portion for moving the module toward its
expanded condition. The method comprises the steps of: applying the
compressive unit to a limb such that the compressive unit extends
circumferentially around the limb and the zones of the unit
correspond with the limb portions to be cyclically compressed;
operatively connecting the at least two modules to the compressive
unit such that the modules are positioned in respective zones of
the compressive unit with the pneumatic bladders of the modules
adjacent respective limb portions; and causing the housing members
to move cyclically between their expanded and contracted positions
for cyclically applying compressive pressure to the limb portions
in a manner such that the compressive pressure is distributed over
surfaces of respective limb portions by the pneumatic bladders.
[0008] Other objects and features will be in part apparent and in
part pointed out hereinafter.
BRIEF DESCRIPTION OF THE DRAWING
[0009] FIG. 1 is an elevational view of a compression device of
this invention as applied to the limb of a patient (shown in
phantom) and showing first and second housing members of the device
in a contracted position;
[0010] FIG. 2 is a view similar to FIG. 1 showing the housing
members in an expanded position for compressing the limb;
[0011] FIG. 3 is a perspective view of the housing in its
contracted condition;
[0012] FIG. 4 is a view similar to FIG. 3 but with the housing
members exploded to show an actuator inside the housing;
[0013] FIG. 4a is an exemplary block diagram of a control system
for controlling operation of one or more compression devices of
this invention;
[0014] FIG. 5A is an end view of the housing in a contracted
position with a portion of the side wall broken away to show a
spring arrangement urging the housing toward its contracted
condition;
[0015] FIG. 5B is a view similar to FIG. 5A but showing the housing
in an expanded condition;
[0016] FIG. 6 is a schematic view of the actuator and the housing
members in their contracted position;
[0017] FIG. 7 is a view similar to FIG. 6 but showing the housing
members in their expanded position;
[0018] FIG. 8 is a perspective view showing the compression device
applied to a limb of a patient;
[0019] FIG. 9 is a view showing three compression devices of a
system of this invention applied to the limb of a patient;
[0020] FIG. 10 is a view showing a different embodiment of a
compression system comprising an integrated compressive unit and
three modules;
[0021] FIG. 11 is a schematic view of an integrated compression
unit and elements of an integrated control for controlling the
operation of the modules of FIG. 10;
[0022] FIG. 12 is an elevational view of a different embodiment of
a compression device of this invention, comprising a bladder and a
mechanical device for cyclically compressing the limb of a patient
(shown in phantom), the mechanical device being shown in a
contracted condition;
[0023] FIG. 12A is a view similar to FIG. 12 showing the mechanical
device in an expanded condition;
[0024] FIG. 13 is an elevational view of another embodiment of a
compression device of this invention, comprising a bladder and a
different mechanical device for cyclically compressing the limb of
a patient (shown in phantom), the bladder being shown in a
contracted condition;
[0025] FIG. 13A is a view similar to FIG. 13 showing the bladder in
an expanded condition;
[0026] FIG. 14 is an elevational view of still another embodiment
of a compression device of this invention, comprising a bladder and
a different mechanical device for cyclically compressing the limb
of a patient (shown in phantom), the mechanical device being shown
in a contracted condition; and
[0027] FIG. 14A is a view similar to FIG. 14 showing the mechanical
device in an expanded condition.
[0028] Corresponding parts are indicated by corresponding reference
numbers throughout the several views of the drawing.
DETAILED DESCRIPTION
[0029] Referring now to FIGS. 1-3, one embodiment of a compression
device of this invention is designated in its entirety by the
reference numeral 1. As will be explained in detail hereinafter,
the device is used for cyclically compressing the limb of a patient
to improve blood flow in the limb. By way of example, the limb may
be a leg, foot or arm generically indicated at 3 in FIGS. 1 and 2.
In general, the compression device comprises a compressive section,
generally designated 5, sized and shaped for extending generally
circumferentially around a portion of the limb 3 for applying
compressive pressure to the limb portion, the limb and limb portion
both being numbered 3 in the figures. The compression device 1 also
includes a housing, generally designated 9, operatively connected
to the compressive section 5. The housing 9 includes first and
second housing members indicated at 15 and 17, respectively,
movable relative to each other between a contracted position in
which the housing has a first dimension D1 (FIG. 6) for relaxing
pressure on the limb portion, and an expanded position in which the
housing has a second dimension D2 (FIG. 7) greater than D1 for
compressing the limb portion. An actuator, generally indicated at
21 in FIG. 4, is provided in the housing 9 for cyclically moving
the first and second housing members between their contracted (FIG.
1) and expanded (FIG. 2) positions.
[0030] In one embodiment (see FIGS. 1 and 2), the compressive
section 5 comprises a generally annular band 27 which encircles the
limb 3. The band material is preferably soft and non-abrasive to
the skin and may include a slipping, non-compliant material at the
interface of the band and the patient. Desirably, the material is
breathable and may have hydrophilic properties that help to improve
patient comfort by creating a dry condition at the skin. (A dry
skin condition tends to minimize chafing and abrasion, since the
material is less likely to stick to the skin.) By way of example,
the band 27 may be of a non-woven PVC material which is
substantially non-stretchable. As shown in FIGS. 1 and 2 the band
27 comprises a band member (also designated 27) having opposite
ends releasably secured together by means of a fastening device 31
(e.g., mating hooks and loops, releasable adhesives, snaps, buttons
or other mechanisms) to provide circumferential adjustment to
enable the band to fit limbs of different sizes. The band member 27
comprises a single elongate piece of material. Alternatively, the
band member 27 can be formed in multiple pieces. For example, the
band member 27 can comprise a first piece releasably attached to
one side of the second housing member 17 and a second piece
releasably attached to an opposite side of the second housing
member 17. Also, the band member 27 can be of varying length and
width to accommodate limbs of differing sizes and shapes. During
use, one compression device 1 can have a thinner and shorter band
member 27 to fit around the calf, while a second compression device
can have a wider and longer band member 27 to fit around the
thigh.
[0031] In the illustrated embodiment (FIGS. 1 and 2), the band 27
includes an interior layer 35 of material secured to the exterior
layer of the band to form an interior pocket 39 which is sized and
shaped for removably receiving the housing 9 containing the
actuator 21. The pocket has at least one open end for insertion of
the housing into the pocket. A releasable closure such as a closure
flap (not shown) can be provided for closing the open end of the
pocket 39 to secure the housing in the pocket until such time as
access is needed or desired. The housing 9 may be releasably
secured in place in the pocket 39 by other means or combinations of
means. For example, in one embodiment, an attaching member (not
shown) is secured to an inside surface of the pocket 39. The
attaching member and housing 9 have mating detent components that
securely, but releasably hold the housing in place. In another
embodiment, mating hook and loop fasteners on the housing 9 and on
an interior surface of the pocket 39 or pocket closure (if used)
can be used to releasably secure the housing 9 in the pocket. In
yet another embodiment, the housing 9 is snuggly fitted between
semi-rigid holders secured within the pocket, creating a slip fit
or interference fit. A release latch can be used to hold the
housing 9 in place for additional sturdiness. After use of the
compression device 1, the housing 9 may be removed from the pocket
39 for re-use with a different (fresh) band. Typically, the band 27
is discarded after a single use.
[0032] A force-distributing device (generally designated 45) is
interposed between the housing 9 and the limb 3 for distributing
compressive forces applied by the device 1 more evenly across the
limb. As shown in FIGS. 1 and 2, this device 45 comprises a cushion
49 received in the pocket 39, the pocket being sized and shaped to
hold both the housing 9 and the device 45 at a location between the
housing 9 and the limb 3 of the patient. In the embodiment shown in
FIGS. 1 and 2, the cushion 49 comprises an extruded body of soft
resilient rubber-like material having open cells separated by
flexible walls 51 which absorb the compressive forces and
distribute them more uniformly over the limb 3. The cushion 49 has
an upper surface 55 which conforms to the bottom (base member 15)
of the housing 9 and which extends up on opposite sides of the
housing to cradle it, and a lower surface 57 which is adapted to
conform to the convex shape of a limb and which has rounded corner
edges to minimize any pinching or abrasion of the skin. In another
embodiment, the cushion 49 comprises a sealed bladder filled with
air or other suitable gas. (Various bladder embodiments are
described later in this specification.) In yet another embodiment
(not shown), the cushion comprises a substantially solid body
formed from a pliant gel-like material. Regardless of form, the
force-distributing device 45 may be attached (e.g., adhered or
otherwise fastened) to the housing 9, or it may be unattached to
the housing.
[0033] In some embodiments, the compression device may be used
without a force-distributing device (e.g., device 45). In these
embodiments, the pocket 39 is preferably of a smaller size.
[0034] As illustrated in FIGS. 3, 4, 6 and 7, the first housing
member 15 comprises a base member (also designated 15) having a
bottom wall 61, opposite upstanding side walls 63 and opposite
upstanding end walls 65. In the embodiment shown, the base member
15 is substantially rectangular, but other shapes can be used
without departing from the scope of this invention. The interior
space defined by the base member 15 is divided by a partition 67
into a first section or compartment 69 containing the actuator 21
and a second section or compartment 71 containing components for
controlling the operation of the compression device (more on this
later).
[0035] The second housing member 17 comprises a cover member (also
designated 17) having a substantially planar top wall 77 generally
parallel to the bottom wall 61 of the base member 15, opposite side
walls 81 curving down from the top wall, and opposite end walls 83
extending down from the top wall. The top, side and end walls of
the cover member 17 may have other shapes.
[0036] The base and cover housing members 15, 17 are fabricated
from a suitable material, such as a flexible plastic or a rigid
plastic having an outer coating of a more resilient material (e.g.,
an over-molded spongy or rubbery material). The parts may be molded
as one-piece parts having a relatively thin-wall construction to
reduce expense and weight.
[0037] The base and cover members 15, 17 of the housing are adapted
to be moved by the actuator 21 from their stated contracted
position to their stated expanded position. In a contracted
position, the cover member 17 is spaced relatively close to the
base member 15 and, in one embodiment, the bottom rim 87 of the
cover member mates with the top rim 89 of the base member. In its
contracted position (FIG. 6), the housing 9 has the aforesaid
dimension D1 which is shown as representing the overall height of
the housing in its contracted state. In expanded position (FIG. 7),
the cover member 17 of the housing is spaced farther away from the
base member 15 so that the housing has the aforesaid dimension D2
representing an increased overall height of the housing (FIG. 2).
The specific way in which the housing members 15, 17 are arranged
or fit together can vary without departing from the scope of this
invention. For example, rather then having abutting rims 87, 89,
the base and cover members 15, 17 may have side walls which
telescope relative to one another to provide the necessary
dimensional change.
[0038] Referring to FIGS. 4, 5A and 5B, it will be observed that
the base and cover members 15, 17 of the housing 9 are guided
between their contracted and expanded positions by a number of pins
95 extending down from the rim 87 of the cover member through guide
holes 99 in the rim 89 of the base member. (Alternatively, the
guide pins can extend up from the base member 15 through holes in
the rim 87 of the cover member 17.) The base and cover members 15,
17 are urged toward their contracted position by springs 103
surrounding the pins 99, each spring reacting at one end against
the underside of the rim 89 of the base member 15 and at its other
end against a stop 105 on the pin. Other guide and/or spring
arrangements can be used. In some embodiments, the springs 103 are
eliminated entirely, since the base and cover members 15, 17 of the
housing will move back toward their contracted position
automatically as the actuator 21 moves back to a position
corresponding to the contracted position of the housing.
[0039] Referring to FIG. 4, the actuator 21 is shown to be a
mechanical actuator contained entirely within the housing 9, i.e.,
within the space defined by the opposing housing members 15, 17.
The actuator 21 of this particular embodiment is a non-pneumatic
actuator, i.e., it does not include any components requiring the
use of pressurized air or gas for operation. As illustrated in FIG.
4, the actuator 21 includes a pair of cam shafts 115 having cams
121 mounted at one end thereof, a prime mover comprising a
reversible electric motor 125 (e.g., a small DC motor) having an
output shaft 127, and a gear train, generally designated 131,
connecting the output shaft of the motor to the two cam shafts. As
shown best in FIGS. 6 and 7, the gear train 131 comprises a pair of
cam gears 135 rigidly affixed to respective cams 121, a directional
gear 141 in mesh with one of the two cam gears 135, and a pinion
gear 145 on the output shaft 127 of the motor 125 in mesh with the
directional gear 141 and the other of the two cam gears 135. Two
additional cams 121 are mounted on the opposite ends of the cam
shafts 115, such that there are a total of four cams located for
engaging the cover member 17 of the housing 9 at intervals spaced
around the cover member to more evenly distribute the force applied
by the actuator 21 over a greater area of the cover member. The
number of cams 121 used can vary, four being shown for purposes of
illustration only. The gears and cams are preferably (but not
necessarily) of a suitable plastic for quiet operation.
[0040] The arrangement shown in FIG. 4 is such that rotation of the
motor output shaft 127 causes the two cam shafts 115 to rotate in
opposite directions. The two cams 121 on each cam shaft 115 are
shaped and contoured for contact with the bottom surfaces of the
curved side walls 81 of the cover member 17 (or other downwardly
facing surfaces of the cover member) such that rotation of the
motor output shaft 127 in one direction causes the cams 121 to
rotate, e.g., through a partial revolution, to increase the
separation between the two housing members 15, 17 against the
urging of the springs 103 to expand the overall dimension of the
housing 9 from D1 (FIG. 6) to the larger dimension indicated at D2
in FIG. 7. To contract the housing members 15, 17, the motor 125
rotates the output shaft 127 in the reverse (opposite) direction to
move the cams 121 back to their initial (FIG. 6) position. This
allows the two housing members to move back toward one another to
contract the overall dimension of the housing 9 from D2 to D1. The
magnitudes of the distances D1 and D2 will vary depending on a
variety of factors, such as the size and configuration of the base
and cover members 15, 17 of the housing, and the "throw" of the
cams 121 as determined by the contour of their cam surfaces and the
extent of rotary movement of the cam shafts 115. In general,
however, the system should be configured such that the housing
members 15, 17 expand a distance sufficient to apply the necessary
compression to a limb and contract a distance sufficient to relieve
such compression.
[0041] It will be understood that the actuator 21 described above
is only exemplary and that other actuators can be used for
effecting relative movement between the housing members without
departing from the scope of this invention. Preferably, the
actuator is non-pneumatic so that the compression device is
entirely self-contained, i.e., all components for effecting cyclic
compression are contained in a single garment which can be applied
and removed as a unit from the patient. It is also preferred that
the actuator be operable to rapidly expand and contract the housing
9 in an energy efficient manner.
[0042] The compression device 1 further comprises a control system,
generally designated 201 (see FIGS. 4 and 4A), for controlling the
operation of the device, including an on-off switch 205 positioned
on the base member 15 of the housing 9 for convenient access and
suitable electronics 211 located in the second compartment 71 of
the base member 15 for controlling operation of the motor 125. A
power source comprising a battery 221 is also located in the second
compartment 71 for supplying power to the motor 125 and other
electrical components. The battery 221 can be an off-the-shelf item
or custom designed, and it can be disposable or rechargeable. A
battery charge indicator 225 is provided on the base member 15 of
the housing 9 for indicating the remaining charge (useful life) of
the battery 221.
[0043] FIG. 4A illustrates the control system 201 according to an
embodiment of the invention. It will be understood that control
system 201 is merely exemplary and that other control circuitry
known to those skilled in the art can be used for controlling
operation of device 1 generally and effectuating control of motor
125 particularly. The control system 201 desirably includes one or
more devices 227 for indicating (either directly or indirectly) the
pressure exerted by the compression device 1 on the limb 3 of a
patient.
[0044] In one embodiment, this indicating device 227 senses a
characteristic indicative of the actual pressure applied to the
limb. By way of example, the device 227 may comprise a suitable
circuit for monitoring the amount of current and/or voltage to the
electric motor 125, which amount is proportional to the actual
pressure applied to the limb. Alternatively, the
pressure-indicating device may comprise one or more pressure
sensors for sensing the pressure in one or more chambers in the
cushion 49 (if a sealed bladder-like cushion is used), the sensed
pressure being proportional to the actual pressure applied to the
limb. In still another embodiment, the pressure-indicating device
227 may comprise one or more strain gauges on the band 27, the
tension in the band being indicative of the actual pressure on the
limb. Other devices for indicating the pressure applied to the limb
may be used.
[0045] Preferably, the control system 201 also includes a visual
indicator 231 for indicating the operational status of the
compression device 1. Although various types of visual indicators
are contemplated, FIG. 4 illustrates an example comprising an array
of tri-color lamps 235 (LED's). The array indicates, among other
things, the ON/OFF status of the compression device 1, the status
of any ongoing adjustment to a system setting (e.g., a pressure
setting), the readiness of the actuator 21 to begin cycling, the
status of communication with other compression devices which may be
in use (described in more detail later), and an alarm condition.
For example, one lamp on (amber) may indicate that the power is on
and that one or more setting adjustments are in progress. Two
lights on (green) may indicate that the power is on and that all
setting adjustments are complete. Three lights on (all green) may
indicate that all adjustments are complete and that the compression
device is successfully communicating with other compression devices
of the system. Three lights on (all red) may indicate an alarm
condition. This protocol may vary within the scope of this
invention.
[0046] Referring again to FIG. 4A, control system 201 further
comprises a central processing unit (CPU) 237, such as a
microprocessor or the like for executing computer-implemented
instructions in the form of software 237a and/or firmware 237b. In
one embodiment, the CPU 237 provides control signals to operate the
actuator 21 of compression device 1 and to carry out a desired
compression treatment regimen (as discussed below). The control
signals from CPU 237 may provide distinct compression regimens,
depending on the location of compression device 1 on the patient's
limb 3 (e.g., attached to the calf at position B or the thigh at
position C in FIG. 9). As shown in FIG. 4A, control system 201
communicates with its power source (e.g., battery 221) and visual
indicator 231 via interconnection electronics 239. The
interconnection electronics 239 send control signals from CPU 237
to the compression device's prime mover (e.g., motor 125) over, for
example, electrical or fiber optic lines. In addition, CPU 237
receives information from pressure-indicating devices 227 via
interconnection electronics 239 over the same or similar lines.
Advantageously, the electronics 211 of control system 201 also
communicate with sensing elements 409 (FIG. 11), one or more other
compression devices (e.g., modules 321 in FIG. 9), external
communications sources (e.g., RF or IR communications), and the
like via electronics 239.
[0047] Those skilled in the art are familiar with executing
software 237a and/or firmware 237b by CPU 237 to perform a number
of operations, including but not limited to: controlling the
operation of motor 125, including its output shaft 127;
communicating with pressure sensing devices 227; controlling charge
indicator 225 and/or visual indicator 231; communicating with
charge indicator 225; operating actuator 21; and sensing the
voltage or current to the motor 125 to indicate a relaxed state of
the device 1. As known in the art, a processor such as CPU 237 may
further execute computer-implemented instructions in the form of
software 237a and/or firmware 237b to control voltage or speed of
motor 125 to rotate its output shaft 127 for increasing the throw
of the cams 121, thereby increasing D2 to increase the pressure
during a compression therapy regimen. Once activated, CPU 237
determines the treatment regimen and begins treating, as described
above, by rotating motor 125, which in turns adjusts the throw of
the cams 121 for the correct pressure at the device based on its
position on the limb (e.g., higher pressure may be desired on the
ankle compared to the thigh).
[0048] A typical use of the compression device 1 can be described
as follows. Initially, the contracted housing 9 and
force-distributing device 45 (if used) are inserted in the pocket
39 of the band 27. The band is then applied to a portion of a limb
3 to be treated, as illustrated for example in FIG. 8. As initially
applied, the band 27 should be in a relatively relaxed state or
condition applying little if any compressive force to the limb.
After all setting adjustments have been made and the compression
device is ready for operation, as indicated by the lamp array 235,
the control system 201 operates the actuator 21 to expand and
contract the housing members 15, 17 through a series of cycles,
each cycle comprising a compress stage followed by a relax
stage.
[0049] During the compress stage, the electric motor 125 is
energized to rotate the cam shafts 115 in a first direction, which
causes the two housing members 15, 17 to move away from one
another, thereby increasing the overall dimension of the housing
from D1. As the housing 9 expands, the cover member 17 exerts a
force in a direction away from the limb 3 to tension the band 27
and the base member 15 exerts a force in the opposite direction
toward the leg. As a result of these forces (indicated at 251 in
FIG. 8), the limb is compressed. The force-distributing device 45
functions to distribute the compressive pressure more uniformly
across the limb. As the cam shafts 115 continue to rotate, the
pressure applied to the limb 3 increases. To prevent
over-pressurization, the control system 201 monitors the amount of
applied pressure, as indicated for example by the amount of current
and/or voltage supplied to the electric motor 125. When a
predetermined compressive pressure is reached, the control system
de-energizes the motor to stop further rotation of the cam shafts.
During this compression stage, the overall dimension of the housing
increases from D1 to D2.
[0050] After a predetermined compressive pressure is applied to the
limb 3 for a duration of time (compress interval), the control
system 201 operates the motor 125 to rotate the cam shafts 115 and
cams 121 thereon in the opposite direction to contract the housing
members 15, 17 and thus reduce the overall housing dimension from
D2 back to D1 to relax the pressure on the limb. The relax pressure
may range from zero to some pressure greater than zero but less
than the compression pressure, as sensed by the current and/or
voltage to the motor 125 or by some other suitable means. The relax
pressure (if any) is maintained for a period of time (relax
interval) sufficient to allow blood to return to the limb. The
length of this time period may be fixed (e.g., sixty seconds) or it
may vary depending on when a vascular refill condition is detected.
In this regard, there is typically some increase in the
circumferential size of the limb as blood returns to the compressed
portion of the limb. This increase in size can be used to trigger
the start of a new cycle. In one embodiment, the pressure sensing
device of the control system 201 is used to detect the increase in
limb size. For additional details regarding detection of a vascular
refill condition, reference may be made to U.S. Pat. No. 6,231,532,
assigned to Tyco Healthcare Group LP. This patent is incorporated
herein by reference for all purposes not inconsistent with this
disclosure.
[0051] The cycling continues as described above until the motor is
de-energized automatically by the control system 201 or manually by
actuating the power switch 205. After use, the housing 9 is removed
from the pocket 39 of the band 27 for re-use with a fresh band.
[0052] During operation of the device 1, particularly during
initial start-up, the compressive pressure applied by the device
may need to be adjusted. The control system 201 can make any
necessary adjustment by varying the "throw" of the cams 121 until
the pressure sensing device of the control system 201 indicates
that the desired compressive pressure is being applied. Thus, to
increase the pressure, the control system 201 simply operates the
motor 125 to rotate its output shaft 127 through a greater number
of degrees to increase the throw of the cams 121 and thus increase
dimension D2 of the housing 9. To decrease the compressive
pressure, the control system 201 operates the motor 125 to rotate
its output shaft 127 through a shorter segment of rotation, thereby
decreasing the throw of the cams 121 to decrease dimension D2.
[0053] As illustrated in FIG. 9, two or more compression devices
(e.g., 1A, 1B and 1C) can be used simultaneously on the limb or
limbs of a patient. By way of example, as will be understood by
those skilled in this field, a plurality of compression devices 1
can be used on the same limb to cyclically compress different
portions of the limb in a sequential manner. Alternatively, the
compression devices can be applied to different limbs for
compressing the limbs alternately or concurrently or in some other
synchronized manner. The compression devices 1A, 1B and 1C may
operate completely independent of one another, or they may be under
the control of a single integrated control system. If an integrated
control system is used, it may be similar to the control system 201
described above for a single compression device but modified to
include wireless (e.g., RF) transmitters and receivers and/or other
components enabling communication between the multiple compression
devices.
[0054] In the example of FIG. 9, a first compression device 1A is
secured around the ankle for applying a first compressive pressure
(e.g., 45 mmHg); a second compression device 1B is secured around
the calf for applying a second compressive pressure (e.g., 40
mmHg); and a third compression device 1C is secured around the
lower thigh of a patient for applying a third compressive pressure
(e.g., 30 mmHg). The devices 1A, 1B, and 1C can be physically
interconnected, color-coded, or otherwise identified to indicate
where they are to be placed and/or the different compressive
pressures they will apply. The integrated control system operates
the devices sequentially through a series of cycles, each of which
includes a compress stage followed by a relax stage.
[0055] During the compress stage of an exemplary cycle, expansion
of the ankle compression device 1A is started at time T.sub.1=0
seconds, for example, to apply the first compressive pressure;
expansion of the calf compression device 1B is started at time
T.sub.2=2.5 seconds, for example, to apply the second compressive
pressure; and expansion of the thigh compression device 1C is
started at time T.sub.3=5.5 seconds, for example, to apply the
third compressive pressure. Each compression device continues to
expand until the proper pressure is reached, as sensed by the
sensing device incorporated into the control system 201 of the
compression device. Further expansion of the compression device is
then stopped. There may be some overlap of the times during which
the compression devices expand, but in general the compression
applied by the devices should occur in a progressive manner to move
the blood in the limb in a direction toward the heart.
[0056] After the compress stage has ended (e.g., at a cycle time of
T.sub.4=11 seconds), any further expansion of the compression
devices 1A, 1B, 1C is stopped, and the devices are contracted
simultaneously to relax or release the pressure on respective
portions of the limb. The relax stage preferably continues for an
interval of time sufficient to allow blood to return to the limb,
as discussed above. A new cycle begins after the relax stage of the
previous cycle has ended (e.g., at time T.sub.5=71 seconds). The
cycles continue to repeat until the compression devices are shut
off, which may occur automatically via the control system or by
manual operation.
[0057] FIG. 10 shows another embodiment of a compression system of
this invention, generally indicated at 301. The system includes two
or more compression devices, three such devices 303, 305, 307 being
illustrated. The compression devices are similar to the compression
device 1 described above except that the compressive sections are
integrated into a single compressive unit 309 sized and shaped for
extending generally circumferentially around a limb such as a leg.
As used herein, the term "integrated" means any configuration where
the compressive sections are physically connected to one another.
By way of example, the unit 309 may comprise an elongate panel
sized to encircle the limb and to be releasably secured in place by
an appropriate number of fasteners along adjacent edges of the
panel to form a sleeve around the limb. The compressive unit 309
may have other configurations. Pockets 315 are provided on the unit
309 for removably receiving respective "modules" 321 of the
compression devices 303, 305, 307. Each such module 321 includes a
housing 9, an actuator 21 and, preferably, a force-distributing
device 45, the construction and operation of which are described
above. These modules 321 operate to apply compressive pressure to
different portions of the limb. The modules 321 may be removably
attached or otherwise removably connected to the unit 309 by means
other than pockets.
[0058] In use, the compressive unit 309 is applied to the limb and
the modules 321 are operatively connected to the unit, as by
placing the modules in respective pockets of the unit. The modules
are then operated to compress respective portions of the limb in a
sequential manner, i.e., in a direction toward the heart. This
direction is important so as not to cause injury to the patient.
After the treatment has ended, the modules 321 are removed from
respective compressive sections of the unit 309. The unit 309 is
then typically discarded. The modules can be re-used with a
different unit 309 holding multiple modules, or with one or more
bands each holding only one module. Because the modules 321 can be
positioned at different locations with respect to a limb during
re-use, it is desirable to have an integrated control system which
senses the location of the modules with respect to the limb, and
which coordinates the operation of the modules after they have been
placed in position so that proper sequential and gradient
compression of the limb is achieved. Preferably, the coordination
of these modules should not interfere with the operation of other
modules applied to a different limb of the same patient or with the
operation of other modules on a limb or limbs or a different
patient.
[0059] FIG. 11 illustrates an exemplary integrated control system,
generally designated 401, for controlling the operation of two or
more modules 321 when they are placed on the compressive unit 309.
In this embodiment, the compressive unit 309 has three compressive
sections or zones CZ1, CZ2 and CZ3 corresponding to different
locations on the limb (e.g., ankle, calf and lower thigh), but it
will be understood that the number of zones can vary. Each zone
comprises a module sensing area 405 at a location where a module
321 is to be placed on the unit 309. This location may correspond
to the location of a pocket (e.g., like pocket 39) or other means
for operatively and removably connecting the module to the unit
309. The integrated control system 401 comprises location sensing
devices on the unit 309 and on the modules 321 (FIG. 10), for
sensing the zone (e.g., CZ1, CZ2 or CZ3) in which each module is
located when the modules are positioned on the compressive unit
309. In one embodiment, these location sensing devices comprise
small sensing elements 409 in the module sensing areas 405 and
cooperating sensing elements (not shown) on the modules 321. By way
of example, these sensing elements 409 can be magnetic elements
secured to the unit 309 for actuating magnet sensing elements on
the modules to open or close circuits of the control system 401.
Alternatively, the sensing elements 409 can be optical elements on
the unit 309 (e.g., areas of different colors or optical patterns)
and optical sensing elements on the modules 321 for optically
sensing, either reflectively or absorptively, the optical elements
on the unit 309. Alternatively, the sensing elements 409 can be
electrical contacts on the unit 309 which mate with electrical
contacts on the modules 321 when the modules are placed in position
on the unit 309. Other sensing elements can be used without
departing from the scope of this invention.
[0060] The integrated control system 401 also includes means for
providing communication between the modules 321. For example, as
shown in FIG. 11, electrical or fiber-optic lines 421 may be
embedded or otherwise secured to the unit. When positioned on the
unit 309, the modules releasably connect with these lines 421 in a
suitable manner (e.g., via quick-connect connectors) to provide the
communication necessary for providing control information to and
from the modules. In FIG. 11, the first (lower) and second (middle)
sensing areas 405 are connected by a single pair of communication
lines; the second and third (upper) sensing areas 405 are connected
by two pairs of communication lines. Other line configurations are
possible. Alternatively, communication between the modules may be
by wireless RF or IR. Through the use of frequency coded
communication transmission, close proximity and/or suitable
shielding, the RF or IR communication signal is preferably directed
only to the modules 321 on the unit 309 and not to other modules on
different limbs or other patients. By means of this communication,
the control system 401 is able to coordinate the operation of the
modules 321, e.g., the pressure applied by each module to a
respective limb portion, the timing of each compression cycle, and
the detection, indication and/or correction of various parameters
or errors (e.g., pressure, timing).
[0061] It will be observed from the foregoing that the integrated
control system 401 performs two functions. First, it senses the
location of each module 321 with respect to the compression zone in
which it is placed. Second, based on this sensed location, the
system coordinates the operation of the modules 321 to achieve the
desired sequential and gradient compression of the limb.
[0062] According to aspects of the invention, the integrated
control system 401 cooperates with control system 201, such as
shown in FIG. 4A, which may be part of each of the modules 321. In
this instance, CPU 237 communicates via interconnection electronics
239 over one or more of the lines 421. The software 239a executed
by CPU 237 may be modular such that control system 201 is capable
of controlling operation of module 321 in any one of the sensing
areas 405. In this embodiment, the CPU 239 is responsive to
communications via line 421 and/or sensing elements 409 for
identifying the relative position of the associated module 321 and
providing control signals as a function of the identified position.
Each control system 201 associated with one of the modules 321
operates independently to effectuate a compression regimen in one
location on compression unit 309, but its operation is coordinated
with that of the control systems 201 associated with other modules
321. As described above, the control signals from each CPU 237 may
provide distinct compression regimens, depending on the location of
compression device 1 on the patient's limb 3 (e.g., attached to the
calf at position B or the thigh at position C in FIG. 9). For
example, when control system 201 identifies one or more compression
devices 1A, 1B or 1C attached to the patient's limb 3, as in FIG.
9, software 237a causes the control systems 201 to place their
associated modules 321 in a standby mode until the user activates
one of the modules. Once activated, CPU 237 executes software 237a
to determine the treatment regimen for the respective position of
the associated module 321 and begins treatment.
[0063] In an alternative embodiment, one control system 201
functions as a master controller for controlling operation of all
of the modules 321 connected thereto. In another alternative
embodiment, the control system 201 associated with one module 321
is responsive to the control system associated with another module
321 as a function of the relative positions of the modules on the
patient's limb 3. In yet another alternative embodiment, the
integrated control system 401 comprises the control systems 201
associated with the compression devices 1 of modules 321 operating
cooperatively.
[0064] FIG. 12 illustrates an alternate embodiment of a compression
device of this invention, generally designated 501. This device is
substantially the same as the compression device 1 of the previous
embodiment and corresponding parts are identified by the same
reference numbers. In this embodiment, the force-distributing
device comprises one or more bladders 505 (only one being shown)
filled with air or other suitable gas. The combination of the
bladder(s) 505, housing 9 and actuator 21 form a module 509
received (e.g., removably received) in the pocket 39 of the
compressive section 5. As described below, the module 509 is
adapted for cyclic expansion and contraction in opposite generally
radial directions 511 with respect to the limb portion 3 between a
contracted condition (FIG. 12) in which the module has a first
dimension 551 for relaxing pressure on the limb portion, and an
expanded condition (FIG. 12A) in which the module has a second
dimension 553 greater than the first dimension for compressing the
limb portion.
[0065] The bladder 505 provides additional pressure and size
adjustment when compressive treatment is provided to the patient.
The bladder 505 is a sensing bladder for sensing a characteristic
of compression therapy on a patient. The bladder 505 has a sensing
device 521 in communication with the contents of the bladder for
sensing, for example, the pressure of the contents of the bladder,
and for outputting a signal indicative of that characteristic to
the control system 201. Placing the sensor in-situ with the bladder
medium provides for greater accuracy and control of the compression
afforded during treatment. The bladder pressure directly impacts
blood flow, in that, a lower pressure distributes less force from
the mechanical device to the patient limbs, and likewise a higher
pressure distributes a greater amount of the force from the
mechanical device to the patient's limb. The ability to adjust the
bladder pressure with precision allows the patient to tailor
treatment to their comfort level. A patient wearing the device can
adjust the nominal pressure, independent of computer instruction
operating a therapy regime, as described below in the operation of
the device. Other sensing devices for sensing other characteristics
of the compression therapy are contemplated. For example, the
sensor may be a sensor, in a thin layer composite, between the
bladder and the leg for sensing a condition of the patient (e.g.,
temperature, pulse, blood flow, oxygen level).
[0066] The bladder has a pneumatic port 513 and a suitable valve
mechanism (not shown) for inflation of the bladder by a pump 515.
In FIG. 12, this pump 515 is integral with the compression device
501 and is mounted inside or adjacent the base member 15 of the
housing 9 for communication with the port 513. Preferably, the pump
515 is a small pneumatic pump, such as a miniature battery-operated
air compressor, which consumes a relatively small amount of power.
The power is provided by the battery 221 or a separate power source
in the housing 9. Alternatively, the pump used to inflate the
bladder can be non-integral with the compression device 501. By way
of example, the pump can be a hand pump manually operated by the
patient or caregiver. A suitable transducer 521 (e.g., pressure
sensor) is provided for sensing pressure of the air (or other gas)
in the bladder 505. The bladder 505 can be sized to minimize the
distance (e.g., D2 minus D1 in FIGS. 6 and 7) by which the housing
parts 15, 17 must expand and contract to effect the necessary
cyclic compression. As a result, the size of various components of
the actuator 21 (e.g., motor 125, cams 121, gears 135, 141, 145)
can be decreased to reduce cost.
[0067] In use, one or more of the compression devices 501 are
applied to the limb 3 to be treated, as described in the previous
embodiments. A nominal pressure is maintained in the bladder(s) 505
to provide for therapy adjustment, to provide a static baseline
pressure, and to distribute the compressive forces applied by the
compression device 501 evenly about the surface of the leg or limb
of a patient. The transducer 521 provides feedback to the
controller (e.g., CPU 237 in FIG. 4a) for application of proper
therapy to the limb. The pressure in the bladder(s) 505 is
maintained by the pump 515. If desired, a pressure relief valve or
passively activated check valve (not shown) can be installed to
maintain the pressure in the bladder(s) 505 at a pressure no
greater than a predetermined pressure.
[0068] In operation, the compression device 501 cyclically
compresses both the limb and the bladder(s) 505. This action is
monitored by the transducer 521 which provides feedback to the
controller to monitor and adjust the tension in band 27.
Preferably, the aforementioned small nominal pressure is maintained
in the bladder 505 during the relax stage of each compression
cycle. This pressure is much less than in prior art systems, such
as found in U.S. Pat. No. 4,253,449 (Arians et al.) owned by Tyco
Healthcare Group LP.
[0069] Just before the compress stage of each cycle begins, the
pneumatic port 513 of the bladder 505 is closed by a suitable valve
mechanism (not shown) or other means to capture the small nominal
pressure in the bladder. As the base and cover members 15, 17 of
the housing 9 expand, the tension in the band 27 and the pressure
in the bladder 505 increase proportionally. The pressure transducer
521 monitors this change in pressure and the peak pressure value is
fed into a feedback algorithm executed in one of the software
and/or firmware modules 237a, 237b of FIG. 4a. The algorithm
functions to compare the peak pressure value to a predetermined
(selected) peak value or set point corresponding to the desired
maximum pressure to be applied to the limb during the compress
stage of each cycle. If the sensed peak pressure is higher than the
predetermined set point, then the nominal pressure in the bladder
505 is adjusted downward by venting an appropriate amount of air
(or other gas) from the bladder. Conversely, if the sensed peak
pressure is lower than the predetermined set point, then the
nominal pressure in the bladder 505 is adjusted upward by
delivering additional air (or other gas) to the bladder(s). This
adjustment process continues for subsequent cycles until the sensed
peak pressure value substantially matches the predetermined maximum
pressure set point.
[0070] In the case of an edematous patient, the level of swelling
in a limb or limbs can change over time. An advantage of this
compression device 501 is that the pressure in the bladder(s) 505,
as sensed by the pressure transducer 521, can be adjusted to reduce
or increase the volume contained within the compressive band 27 in
a manner which is inversely proportional to the amount of edema
change. For example, if the compression device 501 is set to apply
a predetermined compressive pressure of 45 mmHg during the compress
interval, but the pressure transducer 521 senses a bladder pressure
of 50 mmHg due to increased edema, the control system 201 will
automatically reduce the pressure in the bladder(s) 505 to
compensate for the increased swelling. As a result, blood flow to
the swollen limb is not unduly restricted.
[0071] The compression device 501 using one or more bladders 505 is
also capable of measuring vascular refill time (VRT). VRT
measurement is an air plethysmographic technique that determines
when the veins of a limb have substantially completely refilled
with blood after the compression stage of a compression cycle. See,
for example, the VRT measurement described in U.S. Pat. No.
6,231,532 to Watson et al., the entire content of which is
incorporated by reference herein. This VRT technique is used to
minimize the amount of time that blood remains stagnant in the
veins.
[0072] In general, a VRT measurement is made during the relax stage
of the compression cycle in which the compressive device 501 first
reaches its compressive pressure set point. Thereafter,
measurements are taken at selected intervals (e.g., every 30
minutes). The measurement process it initiated at T=T.sub.start
when the sensed pressure in the bladder decreases to a
predetermined level (e.g., 5-7 mmHg), indicating the end of the
compress stage and the start of the relax stage of the cycle. As
blood returns to the limb 3, the limb expands and causes the
pressure in the bladder(s) 505 to increase. This pressure increase
is sensed over time by the transducer 521. In one example, the
bladder pressure is sampled at one-second intervals and the
pressure is monitored by using a moving or "rolling" 10-second
window of time in which the oldest sample value is dropped from the
window and a new sample value is added every second. When the
difference between the first and last sample values in the window
decreases to a predetermined value (e.g., about 0.3 mmHg),
indicating that the refill curve has reached its plateau and that
refill is substantially complete, the measurement process is
terminated at T=T.sub.end. The vascular refill time is then
determined (T.sub.end minus T.sub.start) and, if necessary, an
appropriate adjustment to the relax interval of the compression
cycle is then made.
[0073] For example, in one embodiment the "default" relax interval
is 60 seconds. If the measured VRT is greater than 60 seconds, then
the relax interval remains at 60 seconds. If the measured VRT is
between 20 and 60 seconds, the relax interval is re-set to the
measured VRT. If the measured VRT is less than 20 seconds, then the
relax interval is re-set to a minimum time of 20 seconds, for
example. The minimum relax interval (e.g., 20 seconds) should be
sufficient to insure that the limb has substantially refilled with
blood before initiation of the compress stage of the next cycle.
The minimum relax interval may also be established by adding a
predetermined safety factor (e.g., 5 seconds) to the measured
VRT.
[0074] Under certain circumstances, the VRT measurement may be
disregarded. For example, such circumstances might include a
situation where the standard deviation of the pressure values in
the sample window exceed a predetermined maximum standard
deviation, indicating that the VRT measurement is erroneous; or a
situation where the sensed pressure in the bladder(s) 505 falls
below a predetermined minimum value (e.g., 2 mmHg) during the
measurement process, indicating a possible leak in the system; or a
situation where the sensed pressure in the bladder(s) 505 exceeds a
predetermined value (e.g., 20 mmHg) during the measurement process.
In such situations the VRT measurement is disregarded, and the
relax interval of the prior cycle continues to be used.
[0075] As explained in regard to the first embodiment, more than
one compression device 501 can be used to sequentially compress
different portions of the same limb (e.g., one leg) or different
limbs (e.g., two legs). If more than one device 501 is used, the
VRT is determined separately for each limb portion being
compressed. Preferably, the longest of the measured vascular refill
times is then used as the new relax interval for all of the
compression devices. The VRT measurements for the compression
devices are made (i.e., started and stopped) independent of one
another. Preferably, however, any adjustment to the relax interval
of the compression devices is not made until after the VRT
measurements have been completed for all devices.
[0076] As an enhanced safety feature, the control system 201 of the
compression system 501 may provide an audible and/or visual error
alarm for one or more of the following error conditions: high
pressure error, including a sensed pressure greater than a set
maximum pressure; low pressure error, including a sensed pressure
less than a set minimum pressure (e.g., also detecting the absence
of bands or sleeves); system pressure error, including a pressure
sensed during a compress stage and/or relax stage of a compression
cycle outside of desired parameters; valve error; software error;
pump error; vent and deflation error; battery error; and
temperature error, including temperatures detected outside of
specified environmental conditions. (The compression device 501 can
be modified to include one or more temperature sensors to provide
the latter feature.) An alarm system of the type described
advantageously enhances the safety of the patient during vascular
therapy. In the event of an alarm condition, it is contemplated
that the visual indicator 231 or other means may flash error
signals, sound a continuous alarm, or otherwise indicate an alarm
situation. Further, the control system 201 may be responsive to an
alarm condition to deflate the bladder(s) 505 and cease further
operation of the compression device 501.
[0077] FIG. 13 illustrates a third embodiment of a compression
device of this invention, generally designated 601. This embodiment
is similar to the previous embodiment 501 in that it comprises a
compressive section 607 adapted to extend around a portion 609 of a
limb, at least one pneumatic bladder 615, and a non-pneumatic
mechanical device, generally designated 619. The bladder(s) 615 and
mechanical device 619 combine to form a module 621 which is
received (e.g., removably received) in a pocket 623 on the
compressive section 607. The module 621 may be operatively
connected to the compressive section 607 in other ways. As
described below, the module 621 is adapted for cyclic expansion and
contraction in opposite generally radial directions 624 with
respect to the limb portion 609 between a contracted condition
(FIG. 13) in which the module has a first dimension 651 for
relaxing pressure on the limb portion, and an expanded condition
(FIG. 13A) in which the module has a second dimension 653 greater
than the first dimension 651 for compressing the limb portion.
[0078] In one embodiment, the compressive section 607 comprises a
band member 635 having opposite ends which are releasably connected
by a suitable fastening device 637 (e.g., similar to 31 in the
first embodiment) to form an annular band around the limb. The
compressive section 607 may have other configurations.
[0079] The mechanical device 619 is non-pneumatic in the sense that
it does not include pneumatic components requiring or involving the
use of pressurized air or other gas. In the embodiment of FIG. 13,
the device 619 includes an inner platen 625 seated on the bladder
615, an opposing outer platen 627, and one or more springs 631
between the platens urging the platens away from one another. The
springs 631 of the mechanical device 619 generate a force tending
to move the outer platen 627 in a direction away from the limb to
expand the module 621 and thereby tension (tighten) the band member
635 around the limb. In this embodiment, the limb is cyclically
compressed by varying the pressure in the bladder(s) 615 to expand
and contract the bladder. The pressure may be varied by cycling the
operation of a small pneumatic pump 641, such as a miniature
battery-operated compressor mounted on or adjacent the inner platen
625. The pump 641 communicates with a pneumatic port 645 on the
bladder(s). A pressure sensor (not shown) monitors the pressure in
the bladder(s) 615. A pressure relief valve or passively activated
check valve (not shown) can be installed to maintain the pressure
in the bladder(s) 615 at a pressure no greater than a predetermined
pressure.
[0080] In operation, the pump 641 inflates the bladder(s) 615 which
causes the module 621 to expand to compress the limb portion 609 to
a predetermined pressure during a compress stage of the compression
cycle. The pump 641 deflates the bladder(s) 615 to a predetermined
pressure after an appropriate compress interval has ended. This
causes the module 621 to contract for relieving the pressure on the
limb during the relax stage of the compression cycle. As indicated
at 624 in FIG. 13, the module 621 expands and contracts in opposing
generally radial (not circumferential) directions relative to the
limb portion 609.
[0081] FIG. 14 illustrates a fourth embodiment of a compression
device of this invention, generally designated 701. This embodiment
is similar to the compression device 501 previously described in
that it comprises a compressive section 707 adapted to extend
around a portion 709 of a limb, at least one pneumatic bladder 715,
and a non-pneumatic mechanical device, generally designated 719.
The bladder(s) 715 and mechanical device 719 combine to form a
module 721 which is received (e.g., removably received) in a pocket
723 on the compressive section 707. The module 721 may be
operatively connected to the compressive section 707 in other ways.
As described below, the module 721 is adapted for cyclic expansion
and contraction in opposite generally radial directions 724 with
respect to the limb portion 709 between a contracted condition in
which the module has a first dimension 761 for relaxing pressure on
the limb portion, and an expanded condition (FIG. 14A) in which the
module has a second dimension 763 greater than the first dimension
for compressing the limb portion.
[0082] In one embodiment, the compressive section 707 comprises a
band member 735 having opposite ends which are releasably connected
by a suitable fastening device 737 (e.g., similar to 31 in the
first embodiment) to form an annular band around the limb. The
compressive section 707 may have other configurations.
[0083] The bladder(s) 715 is positioned between the limb portion
709 and the mechanical device 719. The bladder(s) has a pneumatic
port 725 for inflation and deflation of the bladder, as by a hand
pump manually operated by the patient or caregiver.
[0084] The mechanical device 719 is non-pneumatic in the sense that
it does not include pneumatic components requiring or involving the
use of pressurized air or other gas. In the embodiment of FIG. 14,
the device 719 includes a housing comprising a base housing member
727 seated on the bladder 715, an opposing cover housing member
729, and an actuator 731 inside the housing for moving the housing
members toward and away from one another, as described in regard to
compression device 501. In the illustrated embodiment, the actuator
731 comprises one or more cams 741 movable between a first position
(shown in solid lines in FIG. 14) in which the housing members 727,
729 are relatively closely spaced in a contracted position or
condition, and a second position (shown in phantom lines in FIG.
14) in which the members 727, 729 are spaced farther apart in an
expanded position or condition. The cam 741 is rotated between its
first and second positions by a prime mover (e.g., a small DC
motor, not shown) having an output 747 which is connected to the
cam 741 by a gear train 751 or other suitable means. The cam(s)
741, prime mover and gear train 751 are located inside the base
housing member 727, similar to the compression devices 1, 501
described above. The "throw" of the cam(s) 741 may be adjustable,
as described previously. Alternatively, it may be non-adjustable to
reduce cost. A pressure sensor (not shown) monitors the pressure in
the bladder(s) 715. Alternatively, to reduce cost, a pressure
relief valve or passively activated check valve (not shown) can be
installed to maintain the pressure in the bladder(s) 715 at a
pressure no greater than a predetermined pressure.
[0085] To operate the compression device 701, the bladder(s) 715 is
inflated to a suitable pressure using the pneumatic port 725. The
actuator 731 is then energized to move the base and cover members
727, 729 toward and away from one another to expand and contract
the module 721 to conduct successive compression cycles on the limb
portion 709. As indicated at 724 in FIG. 14, the module 721 expands
and contracts in opposite generally radial (not circumferential)
directions relative to the limb portion 709. During this operation,
the pressure in the bladder(s) 715 can be adjusted, if
necessary.
[0086] In at least some of the bladder embodiments described above,
the cost of the compression device can be reduced to a point where
the entire device can be discarded after a single use. A disposable
device has several benefits. First, it is more hygienic for the
patient population. Further, the cost of reprocessing the device or
components of the device is eliminated. Also, due to the reduced
size and weight of the various components, the device is more
portable. The bladder embodiments described above are, for the most
part, "self-contained", meaning that all components of the
compression apparatus and the control are located on the garment
worn by the patient.
[0087] When introducing elements of the present invention or the
preferred embodiments(s) thereof, the articles "a", "an", "the" and
"said" are intended to mean that there are one or more of the
elements. The terms "comprising", "including" and "having" are
intended to be inclusive and mean that there may be additional
elements other than the listed elements.
[0088] In view of the above, it will be seen that the several
objects of the invention are achieved and other advantageous
results attained.
[0089] As various changes could be made in the above constructions
and methods without departing from the scope of the invention, it
is intended that all matter contained in the above description and
shown in the accompanying drawings shall be interpreted as
illustrative and not in a limiting sense.
* * * * *