Compression device for the limb

Disclosed is a compression device and method for applying compressive pressure against a patient's limb in periodic compression cycles, wherein an elongated sleeve having a plurality of inflatable chambers is placed over the foot and a portion of the leg, the chambers being sequentially inflated starting with the foot and then form a distal portion of the leg toward a proximal portion of the leg relative to the heart until all of the chambers are inflated.

BACKGROUND OF THE INVENTION 
Prior to the present invention, various compression devices have been known 
in the art for applying compressive pressure to a patient's limbs in order 
to increase blood flow velocity. Particularly useful are the SCD 
(trademark of The Kendall Company, assignee of the present invention) 
sequential compression devices providing intermittent pulses of compressed 
air which sequentially inflate multiple chambers in a sleeve, beginning at 
the ankle and moving up the leg. This results in a wave-like milking 
action which empties the veins and results in greatly increased peak blood 
flow velocity, thus providing a non-invasive method of prophylaxis to 
reduce the incidence of deep vein thrombosis (DVT). These compression 
devices find particular use during surgery on patients with high risk 
conditions such as obesity, advanced age, malignancy, or prior 
thromboembolism. When a DVT occurs, the valves that are located within the 
veins of the leg can be damaged, which in turn can cause stasis and high 
pressure in the veins of the lower leg. Patients who have this condition 
often have swelling (edema) and tissue breakdown (venous stasis ulcer) in 
the lower leg. It has also been shown that pneumatic compression can be 
highly effective in the treatment of such edema and venous ulcers. This 
treatment is usually performed at home on a daily basis. 
Devices of the foregoing description are disclosed in various patents of 
which the following are illustrative: U.S. Pat. Nos. 4,013,069 and 
4,030,488 issued to James H. Hasty; 4,320,746 issued to Edward J. Arkans 
and Frank K. Villari; and 4,938,208 issued to John F. Dye, the 
last-mentioned patent to John F. Dye being particularly directed to units 
for home treatment. 
In general, the compression devices of the prior art comprise a sleeve 
having a plurality of separate fluid pressure chambers progressively 
arranged longitudinally along the sleeve from a lower portion of the limb 
to an upper portion. Means are provided for intermittently forming a 
pressure pulse within these chambers from a source of pressurized fluid 
during periodic compression cycles. Preferably, the sleeve provides a 
compressive pressure gradient against the patient's limb during these 
compression cycles which progressively decreases from the lower portion of 
the limb, e.g. from the ankle to the thigh. 
Sequential pneumatic compression devices of the foregoing description 
applying compression to the lower limb have achieved considerable 
notoriety and wide acceptance as an effective non-invasive means for 
preventing deep vein thrombosis and for treating venous stasis ulcers. 
They function by applying pneumatic compression sequentially and in 
gradient levels from ankle to thigh for a predetermined time, e.g. 15 
seconds, followed by a period of time, e.g. 45 seconds, when no pressure 
is applied. The particular time period selected is chosen to be optimum 
for pushing venous blood out of the leg (during the compression cycle) and 
to allow arterial blood to refill the leg (during the decompression 
interval). 
It has recently been discovered that it may also be advantageous to apply 
pneumatic compression to the foot to provide significant venous blood 
movement therefrom. For example, U.S. Pat. Nos. 4,702,232 and a division 
thereof, 4,841,956, of Arthur M. N. Gardner and Roger H. Fox relate to a 
device for inducing venous-return flow, which device is intended for use 
on an impaired human leg. In accordance with the teachings of these 
patents, the cyclical succession of venous pump action which would occur 
in normal walking is achieved by involuntarily or artificially activating 
a foot pump followed by artificially induced separate transient operation 
of a proximal calf pump and then an artificially induced separate 
operation of a distal calf pump. As disclosed, the pump actions are 
achieved by providing inflatable bags or cuffs around the foot and upper 
and lower calf regions, the inflatable cuffs being separately connected by 
tubes to a fluid pressure supply means. Each cuff is inflated and then 
deflated before the next cuff is inflated. Moreover, the cuffs are not 
inflated sequentially from distal to proximal, e.g. the sequence disclosed 
in the patent of foot pump, proximal calf pump and then distal calf pump 
which procedure does not encourage an effective pumping of blood from the 
leg. 
In contrast thereto, the task of the present invention, stated simply, is 
to provide an improved compression device which provides more complete 
venous emptying by applying compression to the plantar venous plexus in 
the foot as well as sequentially to the leg, thereby more effectively 
obviating the trapping of blood which can occur in the foot veins, 
particularly during initial compression, as may be the case with the 
current sequential compression devices applying no sequential compression 
to the foot region. 
BRIEF DESCRIPTION OF THE INVENTION 
In accordance with the present invention, this task is satisfied in an 
elegant means by providing a sequential compression device comprising an 
elongated sleeve having a plurality of inflatable chambers for placement 
over the foot and a portion of leg, a means for sequentially inflating 
said chambers in an order with the foot chamber being inflated first and 
the remaining chambers of the leg subsequently in an arrangement from a 
distal portion of the leg towards a proximal portion of the leg relative 
to the heart. 
A feature of the present invention is that the chambers of the leg are 
inflated while the foot chamber remains inflated. 
Another feature of the invention is that the foot chamber propels blood 
from the foot towards the leg for compression by the inflated leg 
chambers, thereby enhancing the movement of blood. 
Yet another feature of the invention is that the chambers may be 
intermittently deflated. 
A further feature of the invention is that the inflating means can maintain 
a baseline pressure in the chambers at all times over which periodic 
compression cycles occur. 
Yet another feature of the invention is that the inflating means controls 
the maximum pressure in the chambers such that at least some of said 
pressure is decreased toward the proximal portion of the leg. 
A further feature of the invention is that in the preferred embodiment, the 
portion of the sleeve defining the foot chamber is a one-piece 
construction with a portion defining the chambers of the leg. 
The feature of the invention is that the sleeve is a simplified 
construction and used for compression of the foot and leg of the limb. 
Yet another feature of the invention is that the device inflates the sleeve 
such that the trapping of blood in the limb is minimized. 
Yet another feature of the invention is that the device inflates the sleeve 
such that the improvement of blood flow through the limb is maximized 
while trapping of fluid is minimized. 
A further feature of the invention is that dynamic control may be 
maintained over the chambers during inflation to maintain the chambers 
inflated in desired pattern. 
Further features will become more fully apparent in the following detailed 
description of the invention in conjunction with the illustrative drawing 
and the appended claims.

DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring now to FIG. 1, there is shown a device generally designated 20 
for compressing a patient's limb, such as the leg, as shown. The 
compression device 20 has a controller generally designated 22 and a pair 
of elongated sleeves 26 for covering the patient's limbs. The controller 
22, which per se comprises no part of this invention, may be of the type 
disclosed, for example, in U.S. Pat. Nos. 4,013,069 and 4,030,488, 
incorporated herein by reference, and the controller 22 sequentially 
passes fluid through a pair of conduits 34 and 35 to the sleeves 26 in 
order to inflate chambers in the sleeves, as will be discussed below, from 
a source of fluid through a conduit 28 communicating with the controller 
22, and the controller 22 may intermittently connect the inflated chambers 
of the sleeves 26 to an exhaust or conduit 30. 
With reference to FIGS. 2-4, the sleeves 26 have a leg portion 40 for 
covering the leg from the region of the ankle to the thigh, and a foot 
portion 42 for covering the foot of a patient. The sleeves 26 have a pair 
of inner fluid impervious sheets 44 and 46 which are joined together along 
lines 48 by suitable means, such as by heat sealing in order to form 
chambers in the sleeves 26. Thus, the foot portion 42 has a laterally 
extending chamber 50 at a location for covering the plantar arch 
intermediate the ball and the heel of the foot at a location underneath 
the foot, although the foot chamber 50 may extend partially or entirely 
around the upper portion of the foot after placement of the sleeve 26, if 
desired. As shown, the leg portion 40 of the sleeve 26 has a plurality of 
progressively located chambers 52a, 52b, 52c, 52d, 52e, and 52f extending 
laterally in the sleeve 26 such that they are raised to cover the ankle, 
calf and thigh of the leg at a location extending from the ankle to the 
thigh region of the leg. In a preferred form, the leg chamber 52a-f extend 
completely around the limb after placement of the sleeve 26. As shown, in 
a preferred form, the foot portion 42 is of 1-piece construction with a 
leg portion 40 and sleeve 26 to provide sleeve 26 of simplified 
construction and reduce cost. The conduits 34 and respective foot chambers 
50 and the leg chambers 52a-f in a suitable manner (not shown), such as by 
the connectors disclosed in U.S. Pat. No. 4,320,746, incorporated herein 
by reference. 
If desired, the sleeves 26 may have an inner sheet of suitable flexible 
material (not shown) covering an inner surface of the sheets 44 and 46 to 
provide comfort to the limb during the use of the device 20 after 
placement of the sleeve 26, and may have an outer sheet 58 of a loop 
material, such as a knit fabric covering an outer surface of the sheets 44 
and 46. The sleeves 26 may have elongated strips 62 of a hook material 
extending along a side of the foot portion 42 and leg portion 40 of the 
sleeve 26 for a purpose which will be described below. The conduits 34 and 
35 may be covered with a suitable tube 64 for the leg portion 40 of the 
sleeve 26 and the tube 66 of fabric for the foot portion 42 in a manner as 
disclosed in U.S. Pat. No. 4,320,746, incorporated herein by reference. 
While not necessary to the practice of this invention, as in prior 
compression devices of the general description, sleeve 26 may have an 
elongated opening 32 extending through a knee region 36 of the sleeve, 
defined by peripheral edges 38 around the opening 32. In addition, as 
shown, the sleeve 26 may have an elongated opening or cut-out 54 in the 
knee region 36 extending from one side edge toward a lateral central 
portion of the sleeve, with the cut-out 54 being defined by peripheral 
edges 60. As is described with more particularity in U.S. Pat. No. 
4,207,875 issued to Edward J. Arkans, the purpose of these openings is to 
enhance the flexibility of the sleeve in the knee region. 
Preparatory to use, the sleeves 26 are placed over the limbs of the 
patient, with the foot portion 42 located over the patient's foot, and the 
leg portion 40 over the patient's leg. The sleeves 26 are wrapped about 
the foot and leg, such that the foot portion 42 of the sleeve 26 
encompasses the foot, and the leg portion 40 of the sleeve 26 encompasses 
the leg. In this configuration, the strips 62 of the sleeve 26 may be 
placed in contact with the outer loop sheet 58 in order to engage the hook 
strip 62 at an adjustable position on the sheet 58 of loop material in 
order to secure both the foot portion 42 and leg portion 40 of the sleeve 
in place in a comfortable and snug position about the patient's limbs. 
In use, the controller 22 is operated in order to sequentially inflate the 
foot chamber 50 and leg chambers 52a-f, in an order with the foot chamber 
being inflated first and the remaining chambers of the leg subsequently in 
an arrangement from a distal portion of the leg towards a proximal portion 
of the leg relative to the heart while the foot chamber remains inflated. 
Thus, the foot chamber 50 is inflated first in order to enhance 
circulation of blood from the foot into the leg, after which the leg 
portion 40 of the sleeve is operated in order to sequentially inflate the 
leg chambers in order with the ankle being inflated first, the calf 
portion being inflated after the ankle portion, and then the thigh portion 
being inflated after the calf portion. In this manner, the leg portion 40 
of the sleeve 26 enhances the movement or circulation of blood through the 
legs after the blood from the foot has been circulated into the legs, 
thereby preventing trapping of blood in the foot, and enhancing blood 
circulation through the legs in a direction toward the heart. During the 
sequential inflation of the leg chambers 52a-f of the sleeves 26, the foot 
chamber 42 remains inflated, and, in a preferred form, each of the more 
distal chambers of the leg portion 40 also remains inflated during 
subsequent inflation of more proximal chambers of the leg portion 40 of 
the sleeves 26, such that each of the chambers of the sleeves 26 remain 
inflated during compression cycles of device 20. In this manner, the 
device maintains pressures in the respective chambers during periodic 
compression cycles, after which cycles the chambers are then deflated. 
Further, a preferred form the controller 22 controls the maximum pressure 
in each chamber such that at least some of the pressure is decreased 
toward the proximal portion of the leg. 
Thus, according to the present invention, the foot chamber 50 of the foot 
portion 42 is initially inflated during a compression cycle in order to 
enhance movement of the blood into the leg of the patient after which the 
leg chambers 52a-f are sequentially inflated in order to propel the blood 
from the limbs toward the patient's heart. In this manner, the device 20 
prevents trapping of fluid in the patient's limb while materially 
increasing the rate of blood flow through the limb during operation of the 
device 20. Stated another way, device 20 of the present invention 
maximizes the movement of fluid while minimizing the trapping of fluid in 
the limb in an improved manner. 
According to the present invention, in a preferred form, the controller 
sequentially inflates the chambers of the sleeves 26 and retains dynamic 
control during inflation in order to maintain the chambers inflated in a 
desired pattern during operation of the device. In this manner, control 
may be maintained over the inflation pressures in each of the chambers 
individually during inflation. 
It will be appreciated that various changes and additions may be made in 
the device shown in the illustrative drawing without departing from the 
scope of the invention herein contemplated. 
For example, while the device has been illustrated to be a unitary sleeve 
26 having a leg portion 40 and a foot portion 42, it will be apparent that 
the leg and foot portions may instead be separate sleeves encompassing the 
respective limb portions where compression is to be applied. 
Further, while the preferred compression devices, i.e. the "SCD" device 
manufactured and sold by The Kendall Company, assignee of the present 
invention, provide a pressure gradient, it is within the scope of this 
invention to provide compression patterns which do not. It is also within 
the scope of this invention to maintain a minimum or base pressure in each 
of the compression chambers throughout the entire inflation and deflation 
cycles. 
This base pressure may be the same in each of the chambers in the sleeve, 
e.g. on the order of about 10 mm of mercury or, alternatively, it may be 
the greatest in the foot chamber and then become progressively lower in 
each successive chamber. For example, the foot chamber may be on the order 
of 10 mm; the ankle chamber on the order of 8 mm; the calf on the order of 
6 mm; and thigh 4 mm. 
As heretofore alluded to, the patent literature is replete with references 
to sequential compression devices. In general, any of the modifications 
described and claimed in these prior patents may be incorporated into the 
novel device of this invention. 
For instance, a ventilation chamber may be included, as disclosed in U.S. 
Pat. Nos. 4,091,804 of James H. Hasty or 4,481,937 of Edward J. Arkans. 
Other modifications which may be made included, but are not limited to the 
following: providing concurrent rather than sequential inflation 
(compression) from a single pulse to apply a gradient from ankle to thigh, 
as described in U.S. Pat. No. 4,030,488 of James H. Hasty; providing means 
for monitoring the pressure in the sleeves, as disclosed in U.S. Pat. No. 
4,331,133 of Edward J. Arkans; sensing the pressure in the chambers and 
then venting to prevent over-pressurizing, as taught in U.S. Pat. No. 
4,396,010 of Arkans; and including an arterial thrombosis detection 
system, as disclosed in U.S. Pat. No. 4,574,812 of Arkans. Other changes 
and additions will be readily suggested to those skilled in the art in the 
light of the foregoing description. 
While the present invention is primarily directed to preventing deep vein 
thrombosis which can occur while a patient is bedridden, e.g. following 
surgery, it also may find utility in inhibiting edema, particularly 
lymphedema, a chronic unilateral or bilateral edema of the legs due to 
accumulation of interstitial fluid as a result of stasis of lymph, which 
is secondary to obstruction of lymph vessels or disorders of the lymph 
nodes. 
It may also be used for the treatment of chronic venous disease, one 
consequence of which is venous stasis ulceration of the leg. 
By way of recapitulation, it will be seen that the present invention 
provides an improved compression device for the limb in that it permits a 
more complete venous return or emptying of the leg since it includes 
compression to the plantar venous plexus. 
For this reason, trapping of venous blood in the foot veins during 
compression is obviated. This advantage distinguishes the present 
invention over the foot pumps of the prior art such as those described in 
the aforementioned U.S. Pat. Nos. 4,702,232 and 4,841,956 of Gardner and 
Fox in that the present invention provides a more complete emptying of the 
limb veins, particularly at the valve cusp, a locus particularly 
susceptible to stasis. 
The foregoing detailed description is given for clearness of understanding 
only and no unnecessary limitations should be understood therefrom, as 
modifications will be obvious to those skilled in the art.