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Description  |
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BACKGROUND OF THE INVENTION
This invention relates to the application of cold or heat to affect heat
transfer to or from the human or mammalian body. The necessity for such an
application may arise in a wide range of circumstances. Most common are
injuries, bruises, sprains, or other trauma to bone, muscle, ligaments,
tendons, skin and other forms of mammalian tissue. The application of cold
or cooling to reduce swelling, reduce pain and promote healing at the
traumatized area of the human or mammalian body is often recommended.
Similarly, the application of heat or heating to the human or mammalian
body is used to warm up or "loosen-up" joint tissue such as ligaments or
tendons prior to use to facilitate an increased range of motion prior to
normal or strenuous physical activities.
Other circumstances in which the need for application of cold or heat
therapy to the human or mammalian body may arise include post-surgical
therapy to reduce pain and swelling and promote healing, as well as in
orthopedic therapy, sports medicine therapy and rehabilitation programs
and applications. Of particular importance are the areas of athletic
injury and subsequent therapy, healing and rehabilitation in humans, and
injury and subsequent therapy, healing and rehabilitation in thoroughbred
race horses.
The most common method of achieving the desired cooling effect has been
application of an ice bag to the desired therapy site. This method has
several limitations. Ice bags can be cumbersome to apply, and in the case
of animals, for example thoroughbred race horses, may be difficult to
maintain on the therapy site. Ice bags can apply uneven cooling to the
therapy site, are often difficult to contour to the area of the mammalian
body to be treated, and the intensity of cooling is difficult to control.
Often the application is either too cold, or not cold enough. A common ice
bag has further limitations as well. As the ice melts, an ice bag may
leak, causing inconvenience or more serious consequences. Finally, the
static application of cold or cooling can become uncomfortable and
unpleasant, usually resulting in the subject prematurely terminating the
application before the full beneficial affect can be achieved.
A number of variations have been proposed to improve upon the ice bag or
pack, but none fully addressed all of its shortcomings. For example, some
have been known to use a bag of frozen peas (or other vegetables) as a
substitute for an ice bag. The frozen peas allow more uniform cooling of
the site, generally contour to the site better than a bag of ice cubes,
and apply less severe cooling. Of course, this alternative has a number of
drawbacks as well. A bag of frozen peas has limited available cooling
capacity, and as with any bag, contouring to a part of the mammalian body
such as the human knee can be difficult or impossible, resulting in uneven
cold application.
Other variations on the basic ice bag or ice pack include a wrap or
strap-on device which holds the source of cooling on the therapy site.
These devices generally are designed for use on specific locations on the
human body, and generally contour better to the therapy site and are held
in place by means of belts or straps. These devices also have several
shortcomings, however. Certain types have built-in reservoirs to provide a
source of cooling, such as containers of frozen water. These devices must
be kept frozen until ready to use, and once their cooling capacity is
expired, they must be re-frozen before they can be used again. The
intensity of cooling with these wrap or strap-on devices is also difficult
to control, and they are capable of applying only static cooling to the
site. There are also generally cumbersome, as the source of thermal
cooling must be located entirely within the device and held at or on the
therapy site.
Also available are chemical cold-packs comprised of two or more chemical
substances stored separately in a flexible packet. When needed, the packet
is manipulated, causing an internal seal to break and the chemical
substances to mix. The substances, when mixed, have an endothermic
reaction which causes the packet to cool. While these devices are useful
in remote sites and in certain emergency situations, they afford little
advantage over the ordinary ice bag. Furthermore, they can generally be
used only one time, are of limited cooling capacity or duration, operate
at one non adjustable temperature, and are prohibitively expensive for use
in a regular cold therapy program.
More recently, a commercially available apparatus for accomplishing the
desired cooling of the human knee has been developed which incorporates a
cold reservoir consisting of a large cooler. The water within the cooler
is circulated by means of a pump which circulates the cooled water from
the cooler through a tube to a bladder and back trough a tube to the
cooler. The bladder is applied to the therapy site and held in place by
means of a wrap or strap device. This apparatus has many advantages over
an ice pack or ice wrap. The cooler and source of cooling, generally ice,
is held in a container separate from the therapy site. In this type of
device, the rate of cooling is adjusted by increasing or decreasing the
flow resistance by using a manually operated flow restriction valve or
electrically setting the pump speed to a predetermined fixed value.
This apparatus also has several shortcomings. The device is incapable of
supplying a measured and controlled cooling temperature to the therapy
site, and is incapable of providing tactile stimulation to the therapy
site. The device is also cumbersome in that the pump used to circulate the
cooling fluid must be manually submerged in the cooler, and there is an
ever-present danger of electrical shock due to the proximity of the
electrical power cord and the circulating water.
The most common method for achieving the desired heating effect has been
through the application of a hot water bottle or steamed towels to an
injury site. As with similar cold therapy modalities, this form of heat
therapy suffers from the same shortcomings in terms of ease of application
and temperature regulation due to a lack of any temperature control
mechanism at the injury site.
DESCRIPTION OF THE PRIOR ART
Heretofore, a number of devices and systems have been employed to impose
cold with or without pressure on parts of the human or mammalian body.
Miller (U.S. Pat. No. 2,531,074 of Nov. 21, 1950) discloses an appliance
for a dry massage of a therapy site by water of controlled temperature in
a sequence at alternatively high and low pressures applied to a multitude
of adjacent chambers of flexible wall material and suggests that the water
can be either heated or cooled.
Chessey (U.S. Pat. No. 2,726,658 of Dec. 13, 1955) discloses a system,
including a coolant control and supply unit, and a liquid-impervious
appliance receiving the coolant and applied as a pad to a body portion of
an animal, including a mechanical refrigeration system thermostatically
controlled by the temperature of the coolant which is pumped through the
appliance.
Grossan (U.S. Pat. No. 3,993,053 of Aug. 5, 1975) discloses a massaging
system including a flexible pad having fixed to one face a set of elastic
tubing coils forming part of a recirculating hydraulic system, including a
pump for creating pulsating fluid flow, and suggests that the pressure and
temperature of the circulating liquid may be controlled by the operator.
Copeland, et al. (U.S. Pat. No. 4,149,529 of Sep. 16, 1977) discloses a
portable apparatus for controllably cooling and variably applying pressure
to a portion of a mammalian body including a liquid supply, control unit,
means to circulate the liquid and heat exchanger in the fluid reservoir
mounted in a supply unit of sufficient size to support the weight of a
human and receive a human limb such that the reservoir may be employed as
a whirlpool bath.
Although all the devices described above may be functional and presumably
operable, there is a need for an improved apparatus for applying cold or
heat to a human or mammalian body which is small enough to be easily
transported and used in a wide variety of locations, adaptable to many
different mammalian body forms and potential therapy sites, capable of
providing controlled temperature therapy at a preset temperature or by a
preprogrammed temperature profile, capable of monitoring the therapy
temperature directly at the therapy site, and capable of providing tactile
stimulation to the therapy site to alleviate the problems of static
cooling and enhance the beneficial effects of the cooling therapy. The
present invention fulfills these needs, and further provides related
advantages.
SUMMARY OF THE INVENTION
The present invention provides an easily transportable apparatus for
applying closed-loop temperature controlled cold or heat to a portion of
the human or mammalian body. The apparatus comprises an insulated water
reservoir within a sturdy housing, covered by a splash-proof lid, and is
small enough is be easily situated in any convenient location for
cold/heat therapy by the user. Within the reservoir housing but external
to the reservoir is contained a self-priming fluid pump with a means of
exchanging a measured portion of the re-circulation water with water from
the reservoir to maintain the circulation water at a desired temperature.
The pump is powered by a small mechanically integrated electric motor.
Also contain in this area are the microprocessor-based temperature and
pump/heat exchanger control electronics, and internal fluid tubing
connections between the pump and the water reservoir, and between the pump
and supply line connectors mounted on the housing. User controls and a
temperature read-out display are also located on the reservoir housing.
The reservoir in the reservoir housing can accommodate crushed ice, ice
cubes or a pre-formed freezable cold source, such as commonly used in
portable coolers, and contains enough cooling capacity for generally all
therapy applications. The reservoir may be easily recharged with
additional ice if needed while therapy is continuing, and without the need
for the subject to remove the bladder from the therapy site. For heat
therapy, hot water can be introduced into the reservoir or the reservoir
fluid can be actively heated by an immersible heater to maintain a
constant temperature for controlled heating applications.
The apparatus monitors the therapy temperature and produces an audible
signal when the cold or heat source is exhausted and the apparatus is no
longer able to maintain the desired therapy temperature within certain
preset tolerances.
The fluid supply lines from the pumps are connected to self-sealing, "quick
disconnect" connectors, allowing the user to quickly and conveniently
attach and detach various bladder types for various therapy applications.
The apparatus can also be adapted to support simultaneous use of multiple
bladders fluidly connected in series for therapy at multiple sites, as in
bilateral surgery applications. Connecting the bladder to the reservoir
housing is a pair of fluid supply lines which are terminated at one end by
the mating half of the "quick disconnect" connectors mounted in the
reservoir housing.
The supply line pair is held together and encapsulated by a layer of
insulating material, such as closed-cell polyurethane foam, making the
entire tubing assembly water-tight, durable, flexible, and fully insulated
to reduce the ambient heat load on the unit and enhance the comfort and
ease of use of the therapy apparatus. The supply line assembly may be of
various lengths to suit the particular therapy subject and application.
The supply line assembly may be permanently affixed to the bladder or
attached by means of "quick-disconnect" connectors at its terminal end.
Affixed within the supply line assembly is a pair of thermistors or other
suitable temperature-sensing devices, one located in each of the pair of
fluid supply lines at or near the quick disconnect mounted in the
reservoir housing, the output of which is monitored by the control
electronics to implement the closed-loop temperature control of the cold
or heat therapy.
Various shapes and sizes of bladder are contemplated to accommodate the
various therapy subjects, whether human or animal, and the various therapy
sites of the mammalian body. All bladders will generally consist of two
layers of flexible plastic or other material, completely sealed or welded
at the edge or seam, and constructed to allow generous expansion and
contraction in response to the varying pressure imposed by the pumps when
applying tactile stimulation, and to ensure even distribution of
circulation water or other fluid and the subsequent cooling/heating effect
on the therapy site.
The bladder is generally held within a mating strap or wrap, depending upon
the therapy subject and site. The strap or wrap may be a fabric or rubber
type material, such as neoprene rubber, which is secured to the therapy
site by means of belts, straps, "Velcro" fasteners. The strap or wrap,
when fastened properly, holds the bladder firmly and evenly against the
therapy site, while allowing expansion and contraction in response to the
pressure fluctuations created by the pump when applying tactile
stimulation.
The apparatus maintains temperature control at the therapy site by a
controlled dynamic mixing of cold/hot water from the reservoir with the
re-circulation water returning from the bladder within the heat exchanger.
By using the real-time temperature information generated by the
temperature sensing devices, the microprocessor controls the rate of
reservoir/recirculation fluid mixing within the heat exchanger. This
maintains the circulation water temperature, and thus the injury site
bladder temperature. To ensure even temperature distribution at the
therapy site or sites, particularly when multiple bladders are used in
series, maximum flow rates and delivery pressure is maintained to minimize
the difference between outgoing and returning water temperatures
regardless of the heat load. To achieve tactile stimulation at the desired
therapy temperature, the pump is periodically turned off for a brief
interval to allow the pressure within the bladder to return to zero before
turning the pump back on. This action causes the bladder to undergo a
deflation/inflation cycle which in turn causes a tactile stimulation in
the tissue directly in contact with the bladder. The microprocessor-based
control electronics and associated operating program operate the pump
accordingly to provide maximum flow of circulation fluid and impose
periodic pressure variations on the bladder such that the desired
temperature control and tactile stimulation are provided at the therapy
site.
The present invention provides an important advance in cold/heat therapy of
human and other mammalian subjects that improves ease of use and enhances
therapy effectiveness. Other features and advantages of the present
invention will be apparent from the following more detailed description of
the preferred embodiment, taken in conjunction with the accompanying
drawings, which illustrates, by way of example, the principles of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of the apparatus as typically used by a human
subject when applying cold therapy to the knee joint.
FIG. 2 is a perspective view of the reservoir housing with portions removed
or broken away to reveal internal structure.
FIG. 3 is a schematic view of the insulated supply lines and bladder
showing the internal structure of the bladder.
FIG. 4 is a cross-sectional view of a bladder.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring initially to FIG. 2, there is shown the reservoir housing 4 which
includes a protective outer case 2, and inner ice reservoir 19 which is
formed within the outer case 2 and open at the top, but otherwise
leak-proof. The walls of the reservoir 19 are spaced within and apart from
the walls of the outer case 2, the internal space thus formed around the
inner reservoir 19 is filled with a thermal insulation 18. The bottom wall
3 of the reservoir 19 is also covered with thermal insulation 18, thus
insulating the reservoir 19. The reservoir 19 is covered during operation
of the apparatus using a lid 5 which is also thermally insulated and
incorporates a seal which fits snugly in the opening of the reservoir 19
to prevent leakage caused by splashing during movement of the apparatus.
The device has pump/heat exchanger 13 that includes an electric-powered
fluid pump and a heat exchanger. The fluid pump is connected to
micro-processor-based control electronics and an associated operating
program. The fluid pump has its fluid input connected to the heat
exchanger containing controlled temperature fluid and its fluid output
connected by a fluid supply tube to a bladder device. The pump has the
capability of pumping fluid from the heat exchanger to the bladder device
when operated.
Within the space adjacent to the reservoir 19 and within the outer case 2
are mounted the pump/heat exchanger 13, electric motor 9,
microprocessor-based control electronics 7. Pressurized water from the
pump/heat exchanger 13 is supplied to the outlet quick disconnect 11 with
the return water routed to the air/water separator 15 via the return quick
disconnect 12 through return tube 1. To maintain a closed system, air from
the priming valve 14 is vented back to the reservoir 19 via vent tube 17,
with air vented from the air/water separator 15 via vent tube 16. Closed
loop control is affected by two thermistors 20 placed in the supply tube
to the outlet quick disconnect 11.
The fluid pump/heat exchanger has its fluid input connected to the
reservoir containing cooled/heated fluid and the returning circulation
water. The mixing of the reservoir and returning water is controlled by
the control electronics to provide output water at a constant selected
temperature to the bladder device via the supply tubes.
Electrical power is supplied from a conventional AC wall outlet through
power connector 10 and power leads connecting to the switching power
supply electronics 8.
Mounted on the reservoir housing 4 are user-operated display/control
electronics 6 with push-button controls for user input and a digital
display for setting and monitoring therapy temperature and time.
Referring to FIG. 3, the bladder supply line assembly 40 is attached to the
reservoir housing 4 by the mating halves of the "quick-disconnect" supply
line connectors 21 and 22, connecting a pair of flexible supply tubes 41
and 42 to the internal fluid supply tubes via quick disconnects 11 and 12.
The flexible supply tubes 41 and 42 are encased in thermal insulation 43
which reduces ambient heat loads and provides a comfortable means of
managing the supply line assembly 40 on the therapy subject. Various
lengths for the supply line assembly 40 are contemplated depending upon
the particular therapy subject and application.
The supply line assembly 40 may be permanently affixed to the bladder 60 or
attached by means of additional "quick-disconnect" supply line connectors
48 and 49.
Referring to FIG. 3, the bladder 60 may be permanently affixed to the
supply line assembly 40 or attached by means of the mating halves of
additional "quick-disconnect" supply line connectors 38 and 39. Various
bladder shapes and sizes are contemplated for application on specific
therapy sites, such as the human knee, ankle, or elbow, to sufficiently
surround the therapy site to achieve optimal cold therapy results. The
general structure of the bladder 60 is preferably two layers of flexible,
weldable polymer or other suitable material 61, which are heat-welded or
otherwise sealed completely around the outer seam of the bladder 62.
Bladder supply tubes 63 and 64 are attached to the bladder 60 by means of
a leak-proof seal 65. The bladder 60 may incorporate one or more internal
seams 66 or internal walls (not shown), the function of which is to direct
the flow of cooling fluid from the bladder supply tubes 63 and 64
uniformly through the bladder 60, and provide control over expansion of
the bladder 60 in response to the higher periodic pressure imposed during
tactile stimulation of the therapy site as illustrated in FIG. 4.
Referring to FIG. 1, the bladder 60 is held on the therapy site preferably
by means of a wrap 70 made of neoprene rubber or other suitable
insulating, flexible material, which is shaped to hold the bladder 60
snugly on the therapy site but allow flexibility for expansion and
contraction of the bladder 60 during tactile stimulation of the therapy
site. The wrap is held in place preferably by means of "Velcro" fasteners
which are attached or sewn onto the wrap 70 such that the wrap 70 can be
adjusted by the particular user to fit snugly and comfortably.
The apparatus maintains therapy temperature control at the therapy site by
pumping circulation water at a precisely determined temperature from the
pump/heat exchanger 13 through the bladder 60 to achieve the desired
preset therapy temperature or preprogrammed therapy temperature-time
profile, as monitored by the thermistors 20. The reservoir 19, pump/heat
exchanger 13, supply tubes 41 and 42, and bladder 60 form a fluid circuit
in which fluid may flow in either direction. Net flow through the bladder
60 is achieved by creating a pressurized output flow via the pump/heat
exchanger 13 with the spent water returning from the bladder 60 to the
air/water separator and ultimately to the inlet side of the pump/heat
exchanger 13. The pump/heat exchanger 13, under microprocessor control,
continuously displaces a precise amount of re-circulation water with water
from the constant temperature reservoir to precisely maintain the
temperature of the circulation water exiting the pump/heat exchanger 13.
The displaced re-circulation water is returned to the reservoir via the
air/water separator 15 to maintain a constant volume in the circulation
system. To ensure a uniform temperature distribution at the therapy site
or sites, particularly when multiple bladders are used in series in
post-bilateral surgery therapy, maximum flow rate and pressure through the
circulation system is maintained.
To achieve tactile stimulation when this mode of operation is selected by
the user, while maintaining the preset or preprogrammed therapy
temperature, the pump/heat exchanger 13 is periodically turned off for
preprogrammed intervals to periodically allow the pressure in the bladder
60 to be cycled between zero and maximum. This imposed periodic pressure
variation on the bladder 60 will provide tactile stimulation at the
therapy site while maintaining the desired therapy temperature through the
resulting deflation/inflation cycles in response to the pressure
variations.
The control electronics 7 incorporate sufficient non-volatile electronic
memory to allow storage, recall and implementation of a plurality of
preprogrammed or user-programmed therapy temperature-time profiles, in
addition to the operating program of the apparatus. In addition to the
plurality of p | | |
