Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS FOR ALTERING THE BODY TEMPERATURE OF A PATIENT
BACKGROUND OF THE INVENTION
[0001] This invention generally relates to medical
apparatus for altering the body temperature of a patient
and more particularly to apparatus that enables efficient,
quick adjustment of the body temperature of a patient,
especially to induce hypothermia.
[0002] Sudden cardiac arrest remains a serious public
health issue. Approximately 350,000 individuals are
stricken in the United States annually, with overall
survival rates of roughly 5 percent. Even with the
immediate availability of the most advanced care currently
available, including cardiopulmonary resuscitation (CPR),
drugs, ventilation equipment, and automatic external
defibrillators, a survival rate of 25 percent may be the
probable best case scenario. Improved therapies to deal
with this condition are clearly needed.
[0003] Numerous incidences of recovery following
accidental hypothermia and cardiac arrest have been
reported. This observation has led researchers to consider
therapeutic hypothermia as a possible treatment for
reducing the adverse consequences of circulatory arrest.
Various studies have shown that mild systemic hypothermia
(approximately 3-5 C (5.4-9.0 F)) can reduce damage to
vital organs, including the brain. Hypothermia induced
both during and following cardiac arrest has demonstrated
this benefit. The use of cardiopulmonary bypass has also
been effective in rapidly achieving this goal. Direct
flushing of cooled fluids into the arterial system has also
been employed with success. Both invasive measures,
however, require large bore intravascular catheters and
rapid introduction of sterile solutions into the patient.
Such invasive approaches have obvious disadvantages in
dealing with out-of-hospital emergencies.
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[0004] Noninvasive cooling, if sufficiently effective
and portable, would be a preferable approach. Direct
cooling of the head alone has produced variable results.
However, post-resuscitative cooling of the entire body to
approximately 33 C (91.4 F) by noninvasive treatment has
been demonstrated to be surprisingly effective in recent
clinical studies. The use of cold gel and ice packs
produced cooling of approximately 0.9 C (1.6 F) per hour,
and resulted in a nearly 100 percent improvement in
neurologically intact survival (Bernard S.A. et al.,
Treatment of Comatose Survivors of Out-of-Hospital Cardiac
Arrest with Induced Hypothermia, 346 New Eng. J. Med. 557-
563 (2002)). In another study, cold air was found to be
capable of cooling patients at a rate of about 0.25 C
(0.45 F) per hour, which caused a 40 percent improvement in
the same endpoint (Sterz F. et al., Mild Therapeutic
Hypothermia to Improve the Neurologic Outcome after Cardiac
Arrest, 346 New Eng. J. Med. 549-556 (2002)). In yet
another study, a combination of water-filled cooling
blankets and ice packs applied to the skin resulted in a
cooling rate of 0.8 C (1.4 F) per hour (Felberg et al.,
Hypothermia After Cardiac Arrest - Feasibility and Safety
of an External Cooling Protocol, 104 Circulation 1799-1804
(2001)). It is believed that increasing the rate of
cooling from what is shown in these studies may produce a
higher rate of patient salvage.
SUMMARY OF THE INVENTION
[0005] In one aspect, apparatus for altering the body
temperature of a patient generally comprises an enclosure
defining an interior space for receiving at least a portion
of a patient's body therein. The enclosure is constructed
for conducting a heat transfer liquid into direct contact
with the portion of the patient's body received in the
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enclosure to promote heat transfer between the patient's
body and the heat transfer liquid. The enclosure has at
least one gusset that is resiliently deformable for
accommodating patients of various sizes.
[0006] In another aspect, apparatus for altering the
body temperature of a patient generally comprises an
enclosure defining an interior space for receiving at least
a portion of a patient's body therein. The enclosure has
at least one inlet in fluid communication with the interior
space for receiving heat transfer liquid into the interior
space for direct liquid contact with the patient's body to
promote heat transfer between the patient's body and the
heat transfer liquid. At least one outlet is in fluid
communication with the interior space of the enclosure for
exhausting the heat transfer liquid from the interior
space. A reservoir holds a supply of the heat transfer
liquid. A supply conduit fluidly connects the inlet of the
enclosure to the reservoir. A pump is for pumping heat
transfer liquid from the reservoir through the supply
conduit and into the interior space of the enclosure via
the inlet. A return conduit fluidly connects the outlet of
the enclosure to the reservoir for allowing heat transfer
liquid to flow from the enclosure back to the reservoir. A
first coupler joins the supply conduit and the return
conduit to the reservoir. A second coupler joins the
supply conduit and the return conduit to the enclosure.
[0007] In yet another aspect, apparatus for altering
the body temperature of a patient generally comprises an
enclosure defining an interior space for receiving at least
a portion of a patient's body therein. The enclosure has
at least one inlet in fluid communication with the interior
space for receiving heat transfer liquid into the interior
space for direct liquid contact with the patient's body to
promote heat transfer between the patient's body and the
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heat transfer liquid. At least one outlet is in fluid
communication with the interior space of the enclosure for
exhausting the heat transfer liquid from the interior
space. A reservoir is for holding a supply of the heat
transfer liquid. A supply conduit fluidly connects the
inlet of the enclosure to the reservoir. A pump is for
pumping heat transfer liquid from the reservoir through the
supply conduit and into the interior space of the enclosure
via the inlet. A return conduit fluidly connects the
outlet of the enclosure to the reservoir for allowing heat
transfer liquid to flow from the enclosure back to the
reservoir. A coupler has a first manifold and a second
manifold selectively engageable with the first manifold for
connecting the supply conduit and the return conduit to the
enclosure.
[0008] In still another aspect, the present invention
is directed to a reservoir generally comprising a bag and a
supply conduit fluidly connecting the bag to a pump inlet.
At least a portion of the supply conduit is integral with
the bag.
[0009] In yet another aspect, a method of performing
cardiopulmonary resuscitation on the patient while altering
the body temperature of a patient generally comprises
covering at least a thoracic region of the patient with a
cover having a plurality of liquid passages therein. A
heat transfer liquid is directed to flow through the liquid
passages in the cover for contact with the thoracic region
of the patient to promote heat transfer between the heat
transfer liquid and the body of the patient. Oxygen is
supplied to the lungs of the patient. The thoracic region
of the patient is compressed directly through the cover
while heat transfer liquid is directed through the liquid
passages in the cover.
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[0010] In another aspect, apparatus for adjusting the
body temperature of a patient generally comprises an
enclosure sized and shaped for receiving at least a torso
of the patient's body. A heat transfer liquid has a
temperature between about 0 C and about 5 C. A liquid
delivery system is adapted to connect to the enclosure for
distributing the heat transfer liquid through the
enclosure. A pump is fluidly connected to the liquid
delivery system for driving the heat transfer liquid
through the liquid delivery system and into the enclosure
for direct fluid connect with the patient's body. The pump
is sized and configured for driving the heat transfer
liquid through the enclosure at a rate greater than about 6
liters per minute.
[0011] In an aspect, apparatus for altering the body
temperature of a patient generally comprises an inflatable
mattress defining an interior space for receiving at least
a portion of a patient's body therein. The inflatable
mattress is constructed to conduct a heat transfer liquid
into direct contact with the portion of the patient's body
received in the interior space to promote heat transfer
between the patient's body and the heat transfer liquid.
The inflatable mattress includes a first zone inflatable to
a first pressure and a second zone inflatable to a second
pressure greater than the first air pressure. The
inflatable mattress in an inflated condition defines a well
for receiving the portion of the patient therein.
[0012] In another aspect, a method for adjusting the
body temperature of a patient generally comprises filling a
first zone of a compliant support with a fluid to a first
pressure, and filling a second zone of the compliant
support with a fluid to a second pressure greater than the
first pressure. The filled compliant support is adapted to
support and substantially underlie a portion of the
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patient's body. At least a portion of a patient's body is
positioned on the compliant support. A heat transfer
liquid is directed to flow over the patient's body in
direct liquid contact therewith to promote heat transfer
between the patient's body and the heat transfer liquid.
[0013] In still another aspect, apparatus for
adjusting the body temperature of a patient generally
comprises an enclosure defining an interior space for
receiving at least a portion of a patient's body therein.
The enclosure is adapted to contain a heat transfer fluid
for direct contact with the portion of the patient's body
received in the enclosure to promote heat transfer between
the patient's body and the heat transfer fluid. A head
positioner is for positioning the patient's head so that
the patient's breathing passageway remains out of contact
with the heat transfer fluid. The positioner is adapted to
flank the sides of patient's head thereby prevent the head
of the patient from rotating from side to side.
[0014] In one aspect, apparatus for altering the body
temperature of a patient generally comprises an enclosure
defining an interior space for receiving at least a portion
of a patient's body therein. The enclosure is constructed
for transferring a heat transfer liquid into direct contact
with the portion of the patient's body received in the
enclosure to promote heat transfer between the patient's
body and the heat transfer liquid. A drain drains the heat
transfer liquid from the interior space of the enclosure.
At least a portion of the drain is disposed beneath the
enclosure, and a hold-open is disposed to hold the drain
open to inhibit occlusion of the drain.
[0015] In another aspect, apparatus for adjusting the
core body temperature of a patient generally comprises an
enclosure defining an interior space for receiving at least
a portion of a patient's body therein. An inlet in the
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enclosure allows a heat transfer liquid to flow into the
enclosure for direct contact with the portion of the
patient's body received in the enclosure to promote heat
transfer between the patient's body and the heat transfer
liquid. A liquid delivery system directs the heat transfer
liquid to flow through the inlet of the enclosure into the
interior space of the enclosure. A control unit generally
comprises a power source, a control system, and a user
interface for powering and controlling the liquid delivery
system. The control system is preprogrammed with a target
temperature for the core body temperature of the patient.
[0016] In yet another aspect, apparatus for adjusting
the body temperature of a patient generally comprises an
enclosure defining an interior space for receiving at least
a portion of a patient's body therein. An inlet in the
enclosure allows a heat transfer liquid to flow into the
enclosure for direct contact with the portion of the
patient's body received in the enclosure to promote heat
transfer between the patient's body and the heat transfer
liquid. An outlet in the enclosure allows the heat
transfer liquid to be exhausted from the enclosure. A weir
in fluid communication with the outlet maintains the heat
transfer liquid at a predetermined height in the enclosure.
[0017] Other objects and features will be in part
apparent and in part pointed out hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Fig. 1 is a perspective of an apparatus of the
present invention in use for altering the body temperature
of a patient lying in the apparatus on a gurney;
[0019] Fig. 2 is a top plan of the apparatus of Fig.
1;
[0020] Fig. 3 is a side view of the apparatus with
portions of an enclosure thereof broken away;
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[0021] Fig. 4 is a top plan of a cover of the
enclosure;
[0022] Fig. 5 is an exploded perspective of the cover;
[0023] Fig. 6 is an enlarged fragmentary section on
line 6--6 of Fig. 4;
[0024] Fig. 7 is an enlargement of a fragment of the
cover as indicated in Fig. 5;
[0025] Fig. 8 is a top plan of a compliant support of
the enclosure with parts broken away to show internal
construction;
[0026] Fig. 9 is an exploded perspective of the
compliant support;
[0027] Fig. 10 is a section on line 10--10 of Fig. 8;
[0028] Fig. 11 is an enlarged fragment of the
compliant support shown in Fig. 10;
[0029] Fig. 12 is a perspective of a drain tube for
the compliant support;
[0030] Fig. 13 is a perspective of a housing for a
weir;
[0031] Fig. 14 is an exploded perspective of the
housing;
[0032] Fig. 15 is a section on line 15--15 of Fig. 13
showing the weir in a flow restricting position;
[0033] Fig. 16 is the section of Fig. 15 but showing
the weir in a non-restricting position;
[0034] Fig. 17 is a perspective of a mobile cart
housing a control system with portions of the cart broken
away to show an air pump and a controller of the control
system;
[0035] Fig. 18 is a perspective of the mobile cart
showing a hinged lid of the cart opened;
[0036] Fig. 19 is the perspective of Fig. 18 but
showing a pump housing and a reservoir partially removed
from the cart;
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[0037] Fig. 20 is a perspective showing the pump
housing and reservoir removed from the cart;
[0038] Fig. 21 is an enlarged, fragmentary section on
line 21--21 of Fig. 20;
[0039] Fig. 22 is a perspective of an umbilicus for
fluidly connecting the mobile cart to the cover and
compliant support;
[0040] Fig. 23 is an exploded perspective of the
umbilicus;
[0041] Fig. 24 is a plan view of a monitor of the
mobile cart displaying a user interface for the control
system; and
[0042] Fig. 25 is a schematic of the control system.
[0043] Corresponding reference characters indicate
corresponding parts throughout the drawings.
DETAILED DESCRIPTION OF THE INVENTION
[0044] Referring now to the drawings and particularly
to Figs. 1-3, reference number 10 generally indicates an
apparatus for adjusting the body temperature of a patient
P. The apparatus 10 generally comprises an enclosure,
indicated at 14, defining an interior space 16 for
receiving a patient's body. The enclosure 14 is adapted to
allow heat transfer liquid 18 (Fig. 17), such as water,
saline, or other suitable liquids, to flow into the
interior space 16 for direct contact with the patient's
body to promote heat transfer between the patient P and the
heat transfer liquid. In the illustrated embodiment, the
interior space 16 of the enclosure 14 is configured to
receive the entire body of the patient P, including the
torso, arms, and legs (Figs. 1-3). As a result, the amount
of surface area of the patient P available for contact by
the heat transfer liquid 18 is maximized. It is to be
understood that the enclosure 14 can be configured to
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receive less than the patient's entire body. That is, the
enclosure 14 can be configured to receive only a portion of
the patient's body.
[0045] The enclosure 14 is adapted to generally
conform to the shape of the body of the patient P received
therein to accommodate patients of various shapes and
sizes. For example, in the illustrated configuration, the
enclosure 14 is suitable for patients having a size between
about the 5th percentile and about the 95th percentile
adult male. Other enclosures adapted to receive smaller
patients (e.g., babies, children, small adults) or larger
patients are also contemplated. Although the patient P is
most commonly a human, the apparatus 10 could be configured
for and used for altering the body temperature of other
animals. More detail regarding the conforming shape of the
enclosure 14 is provided below.
[0046] As illustrated in Figs. 1-3, the enclosure 14
comprises a cover, indicated at 22, for overlying the
patient P from the neck downward, and a compliant support,
indicated at 24, for underlying the patient's entire body.
As shown in Figs. 2 and 3, the cover 22 is limp so that it
generally conforms, under its own weight, to the contours
of the upward facing surface of the patient's body it is
covering. To this end, the cover 22 includes two foot
gussets 26 located in a portion of the cover adapted to
receive the feet of the patient P. The foot gussets 26
allow the cover 22 to more readily conform to the contours
of the patient P near the feet of the patient. Each of the
foot gussets 26 comprise a pocket for receiving a
respective foot of the patient P thereby preventing the
feet of the patient from creating a tent affect in the
cover 22 (Fig. 3). In other words, each of the foot
gussets 26 are sized and shaped for receiving and
conforming to one of the feet of the patient P. It is to
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be understood that the foot gusset can be formed as a
single pocket adapted to receive both of the patient's feet
therein.
[0047] With reference to Figs. 4-7, the cover 22
comprises a generally limp sheet-like body-facing component
28 and a generally limp sheet-like outer component 30 that
are in face-to-face engagement with one another. In the
illustrated configuration, the outer component 30 is
significantly smaller than the body-facing component 28 to
conserve material. It will be understood that the outer
component 30 and body-facing component 28 can have the same
size, or the outer component can have a size greater than
the body-facing component.
[0048] The body-facing and outer components 28, 30 are
liquid impermeable and joined to one another along their
facing sides to form a plurality of passages 32
therebetween for allowing the heat transfer liquid 18 to
flow through the cover 22. Heat sealing is used to seal
the components 28, 30 together along seams 34 to form the
passages 32 because it provides adequate strength without
requiring additional raw materials (e.g., adhesive). Other
methods of forming the passages 32 or sealing the
components 28, 30 to one another, such as adhesives, are
also contemplated as being within the scope of the present
invention.
[0049] The passages 32 in the cover 22 are configured
to distribute heat transfer liquid 18 over a large portion
of the surface area of the patient's body. Specifically,
the illustrated cover 22 is configured to distribute heat
transfer liquid 18 over the patient P from the neck
downward (see, Figs. 1 and 2). As illustrated in Fig. 4,
each of the passages 32 extend generally longitudinally of
the enclosure 14 and have a width of approximately 25 mm
and a height of approximately 3 mm. It is to be understood
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that the dimensions provided for the passages 32 are
exemplary only and that the passages can be formed to have
various dimensions. It is also understood that the
passages 32 can extend in directions relative to the
enclosure 14 other than longitudinal (e.g., lateral,
oblique) and need not be parallel to one another.
[0050] Before the passages 32 are filled with heat
transfer liquid 18, the sheet-like body-facing component 28
and sheet-like outer component 30 of the passage generally
lie flat against one another. Once heat transfer liquid 18
flows inside the passage 32, however, the cross-sectional
area of the passage increases to allow heat transfer liquid
to flow between the components 28, 30 (Fig. 6). The weight
of the heat transfer liquid 18 in the passages 32 causes
the cover 22 to further conform to the contours of the
patient's body. Since the passages 32 extend throughout
much of the cover 22, the majority of the cover is weighted
against the body of the patient P by the heat transfer
liquid. It is to be understood that the passages 32 formed
in the cover 22 can have hold-opens (not shown) for
maintaining the increased cross-sectional area of the
passages even when heat transfer liquid is not flowing
through the passages. Hold-opens are described in further
detail below.
[0051] The body-facing component 28 of the cover 22
includes a plurality of openings 36 (i.e., inlets) therein
corresponding to the passages 32 for allowing the heat
transfer liquid 18 to pass from the passages to the portion
of the patient's body received in the enclosure 14 (Figs. 5
and 7). Each opening 36 is generally circular and
preferably has a diameter of about 1 millimeter (0.04
inches). The openings 36 are shown enlarged in the
accompanying Figures so that they can be seen. The small
diameter openings 36 restrict the flow of heat transfer
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liquid 18 from the passages 32 into the enclosure 14
thereby causing the entire length of the passages to fill
with heat transfer liquid. As a result, the heat transfer
liquid 18 is evenly distributed via the passages 32 to each
of the openings 36. A doghouse connector 38 is affixed to
the outer component 30 of the cover 22 for fluidly
connecting the passages 32 in the cover to a liquid
delivery system. The liquid delivery system is described
in detail below.
[0052] The number of openings 36 positioned in various
portions of the cover 22 may be varied to regulate the
distribution of heat transfer liquid 18 throughout the
enclosure 14. As illustrated in Fig. 5, the openings 36 in
the cover 22 are positioned for generally evenly
distributing the heat transfer liquid 18 over the top of
the patient's body. Heat transfer liquid 18 is directed
through the doghouse connector 38 and into the passages 32
such that the heat transfer liquid flows from a bottom
section B (i.e., the lower one-third) of the cover 22,
through a middle section M (i.e., the middle one-third) of
the cover to a top section T (i.e., the top one-third) of
the cover (Fig. 4). To even the flow distribution, the
number of openings 36 increases along the length of the
passages 32 in a direction away from the bottom section B
of the cover 22 (Fig. 5). Thus, the middle section M of
the cover 22 has a greater number of openings 36 than the
bottom section B, and the top section T has a greater
number of openings than the middle section.
[0053] In another configuration (not shown), the
diameters of the openings 36 are varied along the length of
the passages 32 in a direction away from the bottom section
B of the cover 22. Using this approach, openings 36 having
smaller diameters are positioned near the bottom sections B
of the cover 22 while openings with progressively larger
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diameters are positioned in the middle and top sections M,
T of the cover.
[0054] It is to be understood that numerous
configurations for the openings 36 are possible to
adequately distribute heat transfer liquid 18 to the body
of the patient P by varying the size, shape, and
distribution of the openings. It is also understood that
the openings 36 in the cover 22 may be positioned to
distribute heat transfer liquid 18 unevenly throughout the
interior space 16 of the enclosure 14. By having an uneven
flow distribution, a greater volume of heat transfer liquid
18 can be directed to selected portions of the patient's
body, such as those more amenable to heat transfer (e.g.,
the head, neck, torso), than other non-selected portions of
the patient's body, which are also received in the
enclosure 14.
[0055] The configuration of the passages 32 and
openings 36 illustrated in Figs. 4 and 5 is particularly
useful where CPR is to be administered to the patient P
while the patient is in a supine position in the interior
space 16 of the enclosure 14. During CPR, the chest of the
patient P is compressed through the limp cover 22 generally
along the medial line of the patient. As a result, any
passages 32 in the cover 22 corresponding approximately
with the medial line of the patient P could be repeatedly
blocked as the patient's chest is compressed thereby
reducing the flow of heat transfer liquid 18 to the
interior space 16 of the enclosure 14. Since a number of
the passages 32 and openings 36 are offset from the medial
line of the patient P, the chest compressions performed
during CPR are less disruptive of fluid flow through the
enclosure 14. In other words, chest compressions can be
performed on the patient P while the patient is received in
the interior space 16 of the enclosure 14 (i.e., directly
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through the cover 22) with minimal disruption of flow of
heat transfer liquid 18 to the patient.
[0056] In the illustrated embodiment, the cover 22 is
made of a transparent material, such as polyvinyl chloride
(PVC), polyethylene, or polyurethane, so that the body of
the patient P received within the interior space 16 of the
enclosure 14 can be viewed through the cover. It is to be
understood, however, that the cover 22 can be made of a
non-transparent material or have a portion that is
transparent and a portion that is non-transparent.
[0057] With reference now to Figs. 8-12, the compliant
support 24 is a pneumatic support, which (like the cover
22) generally conforms to the shape of the patient's body
when the body rests on the support. Moreover, the
compliant support 24 minimizes pressure concentrations
beneath the patient P which facilitates the flow of heat
transfer liquid 18 beneath the patient and minimizes the
possibility of pressure sores developing in the skin of the
patient. Generally, the compliant support 24 comprises an
inflatable base 42 (broadly, a"first zone"), which is the
portion of the compliant support upon which the patient P
rests, and two generally oblong, inflatable tubes 44A, 44B
(broadly, a"second zone") forming a periphery around the
base. In the illustrated embodiment, one of the inflatable
tubes 44A is arranged on top of the other tube 44B. It is
to be understood, however, that more or fewer (i.e., one)
inflatable tubes 44A, 44B can be used to form the periphery
of the base 42. It is also to be understood that the
inflatable tubes could be disposed side-by-side instead of
one on top of the other.
[0058] The stacked inflatable tubes 44A, 44B and base
42 cooperatively form a watertight well, generally
indicated at 46, for receiving the entire body of the
patient P therein. The well 46 is configured to generally
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conform to the body of the patient P thereby minimizing the
volume of the interior space 16 of the enclosure 16 and the
amount of heat transfer liquid 18 necessary to effectively
alter the body temperature of the patient P. More
specifically, the patient P is positioned in a supine
position on the base 42 with the base and the tubes 44A,
44B in a deflated state. The base 42 and inflatable tubes
44A, 44B are then inflated to enclose the patient's body
within the well 46 and generally conform the well to the
profile of the patient's body. As the inflatable tubes
44A, 44B are filled with air (or other suitable gas), the
tubes generally conform to the sides of the patient P. The
base 42 is typically inflated to a pressure that is less
than the inflated pressure of the inflatable tubes 44A,
44B. As a result, the base 42 easily conforms to the
contours of the patient P because of the patient's weight.
More specifically, the weight of the patient P causes the
base 42 to assume a bowl-shape that is tailored to the
patient's body (Fig. 3). The base 42 and inflatable tubes
44A, 44B can be inflated manually or with an air pump. It
is to be understood that the compliant support 24 may have
different shapes and sizes or be conformable with the
patient's body in a way different from that described
herein.
[0059] With reference to Fig. 8, the well 46 comprises
a pocket 48 sized and shaped for receiving the head and
neck of the patient P, a broader region 50 for receiving
the torso of the patient, and a tapered pocket 52 for
receiving the legs and feet of the patient. The pocket 48,
which is adapted for receiving the head and neck of the
patient P, is configured to support the head in an upward-
facing direction thereby maintaining the patient's
breathing passageways (i.e., nose and mouth) out of contact
with the heat transfer liquid 18. The pocket 48 prevents
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the head of the patient P from moving to a side-facing
direction and holds the head of the patient at a relatively
higher position than the torso of the patient. It is to be
understood that a head rest (not shown) can be used to
support the patient's head. The head rest can be formed as
one-piece with the compliant support 24 or provided
separately.
[0060] The broader region 50 of the well 46 further
includes a pair of shoulder gussets 54 for receiving the
shoulders of the patient P. The shoulder gussets 54 allow
the base 42 to expand in the shoulder region of the patient
P, which is often the broadest region of the patient, to
accommodate patients with varying shoulder widths.
[0061] As illustrated in Fig. 3, the well 46 is deeper
in the broader region 50 receiving the torso of the patient
P than in the pocket 48 receiving the head or the tapered
pocket 52 receiving the legs and feet since a large portion
of the patient's weight is contained in the torso. More
specifically, the well 46 has a depth D in the broader
region 50 adapted to receive the torso between about 2.5
centimeters (1 inch) and about 20 centimeters (8 inches),
and preferably between about 10.2 centimeters (4 inches)
and about 15 centimeters (6 inches), which correspond
generally to about one-half of the chest heights of adult
males between the 5th percentile and 95th percentile.
[0062] The variation in depths in the well 46 allows
more heat transfer liquid 18 to accumulate around the torso
of the patient P, a region of the body amenable to heat
transfer, than around the head, legs, and feet of the
patient P. The reasons for managing the depth of the heat
transfer liquid 18 in the pocket 48 adapted to receive the
head of the patient P are apparent and explained previously
herein. It is to be understood that the well 46 can have a
generally uniform depth D or have depths different from
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those indicated without departing from the scope of this
invention. For example, an enclosure designed for use with
smaller adults, children, or babies, would have depths less
than those disclosed herein.
[0063] With reference to Figs. 9 and 10, the
illustrated compliant support 24 is formed using four
flexible sheet-like components. As illustrated, a first
component 56A and a second component 56B are paired
together, and a third component 56C and a fourth component
56D are paired together. The paired components 56A, 56B
and 56C, 56D are placed in face-to-face engagement with one
another and joined at first seals 58A, 58B that extend
around the peripheries thereof and at second seals 58C, 58D
that are spaced inward from the peripheries. The portions
of the components 56A-D located between the first seals
58A, 58B and the second seal 58C, 58D cooperatively define
the inflatable tubes 44A, 44B. Particularly, the paired
first and second components 56A, 56B form the lower tube
44B, and the paired third and fourth components 56C, 56D
form the upper tube 44A. Referring again to Fig. 9, a
respective doghouse connector 60 extends into each of the
portions of the components 56A-D located between the first
seals 58A, 58B and the second seals 58C, 58D for allowing
the inflatable tubes 44A, 44B to be inflated using an
exterior air source (i.e., manually or an air pump).
[0064] The paired first and second components 56A, 56B
forming the lower tube 44B are overlaid by the paired third
and fourth components 56C, 56D forming the upper tube 44A
and sealed together. More specifically and with reference
to Fig. 10, the third component 56C is sealed to the second
component 56B along a continuous seal 57 to define a sealed
chamber 62 that is formed between the joined first and
second components 56A, 56B and the joined third and fourth
components 56C, 56D. The sealed chamber 62 is inflatable
18
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and, when inflated, underlies and provides support for the
patient P received in the well 46. A doghouse connector 64
extends into the sealed chamber 62 for allowing air to be
introduced into the sealed chamber 62 to thereby inflate
the base 42 using a suitable exterior air source.
[0065] A porous layer 66 is used to cover the well 46
so that the porous layer is disposed between the body of
the patient P and the fourth component 56D (Figs. 3 and
10). The porous layer 66, such as rich loft polyester
batting or open-cell polyurethane foam, allows heat
transfer liquid 18 to flow between the body of the patient
P and the well 46 and thereby across the skin of the
patient. The porous layer 66 prevents areas of the well 46
from being sealed off from the body of the patient P
contacting the fourth component 56D, which would inhibit
flow of heat transfer liquid 18 beneath the body of the
patient.
[0066] With reference to Figs. 8, 10, and 11, the
third and forth components 56C, 56D also cooperatively
define a plurality of supply passages 68 for allowing heat
transfer liquid 18 to be supplied beneath the body of the
patient P, and two return passages 70 for allowing heat
transfer liquid to be drained from the well 46. The
illustrated supply and return passages 68, 70 are formed
using heat sealing but it is to be understood that other
methods of forming the passages 68, 70 or sealing the
components 56C, 56D to one another, such as adhesives, can
be used. The passages 68, 70 have a length approximately
equal to the about half the length of the compliant support
24 and are generally located in the broader region 50 of
the well 46.
[0067] Since the return passages 70 rely on gravity
for fluid flow, the return passages are substantially
larger in cross-section than the supply passages 68 (Fig.
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11). The supply passages 68 can be sized smaller since a
pump is used to drive heat transfer liquid 18 into the
passages. A reinforcing layer 72 is attached to the third
component 56C beneath the passages 68, 70 to provide
additional structural integrity to the passages. It is to
be understood that the number, location, and dimensions
provided herein for the passages 68, 70 are exemplary only
and that more or fewer passages can be formed and that the
passages can be formed to have various dimensions, various
location on the compliant support.
[0068] Referring now to Figs. 10 and 11, each of the
passages 68, 70 formed in the compliant support 24 are
supported by a hold-open 74, which holds the passages open
and permits flow of the heat transfer liquid 18 through the
passage past the hold-open. The hold-opens 74 provide the
rigidity necessary to maintain the passages 68, 70 open
even when subjected to a load, such as the weight of the
body of the patient P which bears on the passages formed in
the well 46. The hold-open 74 may be a porous material,
such as open-celled foams, particulate matter (e.g.,
polystyrene beads), batting, non-woven materials, or
mechanical devices, such as coil springs. One suitable
open-celled foam is a reticulated polyurethane foam having
approximately 25 pores per inch manufactured by Foamex of
Eddystown, Pennsylvania, USA, and sold under the trade name
SIFO.
[0069] With reference again to Figs. 8 and 9, the
fourth component 56D of the compliant support 24 has a
plurality of openings 76 (i.e., inlets) therein
corresponding to the supply passages 68 for allowing the
heat transfer liquid 18 to pass from the passage into
direct fluid contact with the underside of the patient's
body received in the well 46. Each of the illustrated
openings 76 is generally circular and has a diameter of
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about 1 millimeter (0.04 inches). The openings 76 are
enlarged in the accompanying figures so that they can be
seen. The small diameter openings 76 restrict the flow of
heat transfer liquid 18 from the passage 68 into the
enclosure 14 thereby causing the entire lengths of the
passages to fill with heat transfer liquid and evenly
distributing the heat transfer liquid along the lengths of
the passages.
[0070] The forth component 56D also has a plurality of
larger sized apertures 78 (i.e., outlets) therein
corresponding to the return passages 70 for allowing heat
transfer liquid 18 to exit the well 46. The return
passages 70 and the well 46 of the compliant support 24 are
fluidly connected to at least one large diameter (e.g., 2.5
centimeters (1 inch)) outlet 80 extending through all four
of the sheet-like components 56A-D for draining heat
transfer liquid 18 from the well. It is contemplated that
the large diameter outlet 80 may be larger or smaller than
2.5 centimeters. The illustrated outlet 80 is preferably
sufficiently sized to allow heat transfer liquid 18 to be
drained from the well 46 by gravity at a rate equal to or
greater than the rate at which the heat transfer liquid is
being delivered to the interior space 16 of the enclosure
14 to prevent the enclosure from overflowing. Moreover,
the illustrated large diameter outlet 80 is located in the
broader region 50 of the well 46, which is adapted to
receive the torso of the patient P. As indicated above,
the broader region 50 is typically the deepest portion of
the well 46 or, in other words, the lowest portion of the
well. As a result, large diameter outlet 80 is located in
what is typically the lowest portion of the well 46. The
well 46 may have more than one outlet 80, the outlet may be
positioned at other sections of the enclosure, and the
outlet may have other sizes and shapes.
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[0071] Referring to Figs. 9 and 12, a drain tube 82 is
fluidly connected to the large diameter outlet 80 for
transferring heat transfer liquid 18 away from the interior
space 16 of the enclosure 14. At least a portion of the
drain tube 82 is located underneath the compliant support
24. As a result, the drain tube 82 is provided with at
least one hold-open 84 to keep the drain open during use of
the apparatus 10. In the illustrated configuration, the
hold-open 84 for the drain tube 82 are two, elongate
inflatable tubes that flank the sides of the drain. One of
the elongate inflatable tubes is located adjacent one side
of the drain tube 82 and the other inflatable tube is
located adjacent the opposite side of the drain tube. It
is to be understood that other types of hold-opens 84,
including those described above, could be used or that the
drain tube 82 could be formed from material with sufficient
rigidity as to not warrant the use of the hold-open.
[0072] With reference now to Figs. 1 and 13-16, a weir
86 (broadly, "a flow restrictor") is in fluid communication
with the drain tube 82 and the large diameter outlet 80 for
maintaining the depth D of the heat transfer liquid 18
within the well 46 at a predetermined level thereby
allowing the heat transfer liquid to accumulate in the well
adjacent and beneath the patient P. Specifically, a drain
tube outlet 83 is attached to a weir inlet 85 so that heat
transfer liquid flowing from the interior space 16 of the
enclosure 14 flows through the drain tube 82 and into the
weir 86. It is to be understood that the flow restrictor
may be a device besides the weir 86, such as an inverted U-
shaped tube or an adjustable valve, without departing from
the scope of this invention.
[0073] The weir 86 includes a dam 87 of a
predetermined height which the heat transfer liquid 18 must
flow over before it is drained from the enclosure 14 (Fig.
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13). For instance, if the heat transfer liquid 18 is
maintained at a depth of between about 7 centimeters (2.8
inches) and about 15 centimeters (6 inches) in the well 46,
the weir 86 needs to have a height H sufficient to prevent
heat transfer liquid below the selected height from flowing
out of the well. Since the weir 86 maintains heat transfer
liquid 18 at a given depth D in the well 46, the weir
creates a positive gage pressure as measured at the large
diameter outlet 80, which would between about 0.69
kiloPascals (0.1 pounds per square inch) and about 1.47
kiloPascals (0.2 pounds per square inch) for the well 46
with a depth of heat transfer liquid between 7 centimeters
(2.8 inches) and about 15 centimeters (6 inches).
[0074] The weir dam 87 is located in a weir housing 88
and cooperates with the housing 88 to selectively retard
the flow of heat transfer liquid 18. As illustrated in
Fig. 14, the weir dam 87 comprises a generally rectangular
web affixed to shaft 89. A cap 91 of the weir housing 88
is also affixed to the shaft 89 but is spaced from the weir
dam 87. The cap 91 is rotatably secured to the weir
housing using a clamp 93. The cap 91 includes a handle 90
for rotating the cap 91 and thus, the shaft 89 and weir dam
87 with respect to the housing 88.
[0075] The handle 90 can be used to selectively move
the weir 86 between a flow restricting position (Fig. 15)
wherein the weir dam 87 creates a spillway which the heat
transfer liquid 18 must flow over before it is exhausted
from the well 46, and a non-restricting position (Fig. 16)
wherein the weir dam is rotated and substantially allows
the heat transfer liquid to flow unimpeded from the well.
The non-restricting position of the weir 86 is used to
rapidly purge the interior space 16 of the enclosure 14 of
heat transfer liquid 18. A weir outlet 95 allows heat
transfer liquid 18 that has passed over the weir dam 87 to
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exit the weir housing 88. It is to be understood that the
flow restrictor could be automatically moved between the
restricting position and non-restricting position using a
controller, which is described below.
[0076] As illustrated in Fig. 1, the weir housing 88
is secured by an upper support 92A and a lower support 92B
integrally formed with the compliant support 24. The upper
and lower supports 92A, 92B are adapted to hold the weir
housing 88 and thereby the weir 86 in proper alignment with
respect the compliant support 24.
[0077] As shown in Figs. 1 and 2, the cover 22 and the
compliant support 24 are adapted for engagement with each
other. The cover 22 includes a first sealing portion 94
(Fig. 4) and the support 24 includes a second sealing
portion 96 (Fig. 8) for engaging with the first sealing
portion 94. The sealing portions 94, 96 allow the cover 22
to be completely or partially removed from compliant
support 24. In the illustrated embodiment, the sealing
portions 94, 96 comprise a hook and loop fastening system.
For example, a strip of hook material is shown adhered to
the compliant support 24, and a strip of loop material is
shown adhered to the cover 22 for engaging the hook
material located on the compliant support. It is to be
understood that the loop material can be placed on the
compliant support 24 and the hook material on the cover 22.
It is also understood that other types of fastening systems
(e.g., adhesives, slide fasteners, snaps) can be used. It
is further understood that a portion of the cover 22 can be
bonded to the compliant support 24 to thereby hingedly
attach the cover to the compliant support.
[0078] The cover 22 is slightly smaller than the
support 24 which allows the sealing portions 94, 96 of both
the cover and the compliant support to lie above and
laterally inward from the sides of the support. As a
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result, the sealing portions 94, 96 are positioned away
from the medial line of the patient P received in the
interior space 16 of the enclosure 14 thereby allowing CPR
to be administered to the patient without interference from
the sealing portions.
[0079] Furthermore, the sealing portions 94, 96 are
positioned on a portion of the enclosure 14 that is
maintained generally horizontal. As a result, the
potential for the sealing portions 94, 96 to be bent or
otherwise deformed is minimized. Bending and deformation
of the sealing portions 94, 96 may diminish the ability to
seal or to be opened or closed. Moreover, the sealing
portions 94, 96 are positioned at a location above the
depth D at which heat transfer liquid 18 accumulated in the
well 46 of the compliant support 24, which reduces the
demand on the sealing portions (i.e., the sealing portions
do not have to form water tight seals). Lastly, the
sealing portions 94, 96 are conveniently located for a user
thereby providing the user with easy access to the patient
P.
[0080] Referring now to Figs. 1, 17-19, and 25, the
apparatus 10 further comprises a control system, generally
indicated at 100, for controlling operation of the
apparatus 10. The control system 100, which is mounted on
a mobile cart 98, includes a controller 102, a monitor 104
(broadly, a"user interface"), a delivery system, and a
temperature sensor 108 for measuring the temperature of the
patient P. The monitor 104 includes a LCD touch screen
display for visually indicating particular parameters of
the control system 100 and for allowing the user of the
system to selectively control particular system functions
(Fig. 24). The monitor 104, for example, could display a
target temperature along with the actual body temperature
of the patient P, and the temperature of the heat transfer
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liquid 18, among other things. With respect to user
control of the system 100, the user can start, pause, and
stop the delivery system using the touch screen display of
the monitor 104. It is also understood that other system
100 functions could be controlled by the user using the
touch screen display of the monitor 104.
[0081] The delivery system of the control system 100
comprises the liquid delivery system and a gas delivery
system. The liquid delivery system is a generally closed,
continuous flow system in which heat transfer liquid 18 is
cycled through the interior space 16 of the enclosure 14.
The liquid delivery system comprises a fluid reservoir 112,
two liquid inlet pumps, generally indicated at 114, with
disposable gear pumpheads contained within a housing 140
driven by motorized drive gears 115, and an umbilicus 120.
The umbilicus 120 fluidly connects the reservoir 112 and
two liquid pumps 114 to the interior space 16 of the
enclosure 14. It is to be understood that the delivery
system can have fewer or more components without departing
from the scope of this invention.
[0082] The reservoir 112 holds heat transfer liquid 18
before the pumps 114 pump the heat transfer liquid into the
interior space 16 of the enclosure 14. The reservoir 112
may have insulation (not shown) to help maintain the
temperature of the heat transfer liquid 18 before it is
pumped into the enclosure 14. Although various sized
reservoirs may be used, the reservoir 112 in the
illustrated embodiment has a capacity sufficient to hold
about 30 liters (about 8 gallons) of heat transfer liquid
18. It is to be understood that reservoirs having
different capacities may be used. For example, a reservoir
for holding heat transfer liquid for the child or baby
sized enclosure may have a smaller capacity where as a
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reservoir for holding heat transfer liquid for a larger
enclosure may have a larger capacity.
[0083] A phase change material 122 (e.g., ice) is also
placed into the reservoir 112 to alter and/or maintain the
temperature of the heat transfer liquid 18 to an inlet
temperature, measured before the liquid enters the
enclosure 14 (Fig. 17). In the illustrated embodiment,
approximately 10 liters (2.6 gallons) of ice 122 are placed
into the reservoir 112 but other quantities of ice could be
used. Moreover, additional ice 122 can be added to the
reservoir 112, if necessary, during the operation of the
apparatus 10 to maintain the heat transfer liquid 18 at the
desired inlet temperature. Besides phase change materials
122, various other types of heat exchangers (e.g., Peltier
device) are contemplated as being within the scope of the
present invention.
[0084] The illustrated reservoir 112 comprises a
plastic bag removable supported in the mobile cart by a
frame 124 with handles (Fig. 19). Moreover, the mobile
cart includes a reservoir viewing window 126 for allowing
the user to visually observe the ice 122 and heat transfer
liquid 18 contained in the reservoir 112. The window 126
has a heat transfer fill line 128 to indicate the level to
which heat transfer should be placed into the reservoir,
and an ice and heat transfer fill line 130 to indicate the
level to which ice 122 should be added to the heat transfer
liquid in the reservoir. Ice 122 and heat transfer liquid
18 can be added to the reservoir 112, as necessary, during
operation of the apparatus 10. It is contemplated that the
ice 122 could be added to the reservoir 112 before heat
transfer liquid 18. It is also contemplated the ice 122
and heat transfer liquid 18 could be pre-measured before
placing them into the reservoir 112.
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[0085] As illustrated in Figs 18-21, the reservoir 112
has two integrated passages 132 formed by heat sealing a
separate sheet of material 134 to the bag. The passages
132 are used as intake passages for the pumps 114 (Fig. 19)
for allowing the pumps to draw heat transfer liquid 18 from
the reservoir 112 through the passages. The passages 132
include hold-opens 136 (as described above) to prevent the
pumps 114 from drawing closed the passages during use (Fig.
21). The passages 132 have openings 138 adjacent the
bottom of the reservoir 112, which prevents the buoyant ice
122 from being drawn into the pumps 114 while allowing the
heat transfer liquid 18 to be drawn into the pumps (Fig.
20). It is to be understood that passages 132 can be
formed separately from the reservoir 112 and could be
formed from conventional polymeric tubing.
[0086] The two inlet pumps 114 are in fluid
communication with the passages 132 formed in the reservoir
112, the umbilicus 120, and the passages 32, 68 in the
enclosure 14 so that the pumps can pump heat transfer
liquid 18 from the reservoir into the enclosure. More
specifically, one of the pumps 114 directs heat transfer
liquid 18 to the passages 32 in the cover 22 for directing
heat transfer liquid 18 over the top of the body of the
patient P, and the other inlet pump directs heat transfer
liquid to the passages 68 in the compliant support 24
thereby directing heat transfer liquid underneath the
patient's body.
[0087] Each of the pumps 114 can be operated
independently of the other. Accordingly, heat transfer
liquid 18 can be selectively directed for flow over the top
of the body of the patient P, underneath the patient's
body, or both (i.e., simultaneously over the top of the
patient's body and underneath the patient's body). In the
illustrated embodiment, one of the pumps 114 is capable of
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transferring liquid to the passages 32 in the cover 22 at a
flow rate of about 8 liters per minute (2.1 gallons per
minute). The other pump 114 is capable of directing heat
transfer liquid 18 to the passages 68 in the compliant
support 24 at a flow rate of about 6 liters per minute (1.6
gallons per minute). Thus, the two pumps 114 are capable of
pumping heat transfer liquid 18 into the interior space 16
of the enclosure 14 at a flow rate of about 14 liters per
minute (3.7 gallons per minute). It is to be understood
that the pumps can have capacities other than those
described herein and that a single pump or more pumps can
be used to pump heat transfer liquid 18 into the interior
space 14 of the enclosure 16.
[0088] The pumps 114 described above were specifically
designed gear pumps for use in this apparatus 10 (Fig. 9).
However, the pumps 114 can be conventional gear pumps, such
as the UGP-2000 series manufactured by B&D Pumps, Inc. of
Huntley, Illinois, USA, or a roller-type pumphead with a
motor drive, such as the 500 series process pump
manufactured by Watson-Marlow OEM of Paramus, New Jersey,
USA. Should higher flow rates or other parameters be
required, alternative pumps, such as higher capacity gear
or centrifugal pumps, may be used without departing from
the scope of the present invention.
[0089] Both of the pumps 114 incorporate detachable
pumpheads (not shown) that are contained in the housing 140
(Figs. 18-20). The housing 140 and thus, the pumpheads are
disposable to minimize the likelihood of cross-
contamination to subsequent patients. The pumpheads are
the only part of the pumps 114 that contact the heat
transfer liquid 18. In the illustrated embodiment, the
pumphead housing 140 is held in place using a rotatable
hold-down 142. As illustrated in Fig. 18, the hold-down
142 can be rotated to a position above the pumphead housing
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140 thereby supporting the pumphead housing in position.
As shown in Fig. 19, the hold-down 142 can be rotated so
that the hold-down is clear of the pumphead housing 140
thereby allowing the pumphead housing and thereby the
pumpheads to be removed from the pumps 114 and the mobile
cart 98. Accordingly, after use, the pumpheads can be
removed from the pumps 114, discarded properly, and a new
pumpheads (i.e., a new pumphead housing 140) installed on
the pump for use with the next patient.
[0090] The control system 100 further includes the gas
delivery system for delivering pressurized air to inflate
the various inflatable components of the compliant support
24. The gas delivery system comprises an air pump 116 and
a plurality of pressure sensors 144 (Fig. 17). As shown,
the air pump 116 and sensors 144 are located in a housing
146 of the mobile cart 98, and a portion of the housing 146
is shown broken away to expose the air pump and sensors.
The air pump 116, such as a conventional reciprocating or
scroll-type compressor, is in fluid communication with the
compliant support 24 for inflating the inflatable tubes
44A, 44B, the sealed chamber 62, and the drain hold-opens
84. For example, the pump 116 may have the capacity to
fill the inflatable tubes 44A, 44B of the compliant support
24 with air at a rate of about 500 liters per minute to a
positive gauge pressure of about 3.4 kiloPascals (0.5
pounds per square inch), the sealed chamber 62 to a
positive gauge pressure of about 0.76 kiloPascals (0.11
pounds per square inch), and the drain hold-opens 84 to a
positive gauge pressure of about 3.4 kiloPascals (0.5
pounds per square inch). It is to be understood that other
types of air pumps can be used and that the air pumps can
have different flow rates then those indicated.
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[0091] The pressure sensors 144, which are shown in
Fig. 17, are adapted to measure the air pressure within at
least the inflatable tubes 44A, 44B and the sealed chamber
62 of the compliant support 24. In the illustrated
configuration, one pressure sensor 144 is positioned within
a first air line 143 that communicates with the inflatable
tubes 44A, 44B and a second pressure sensor is positioned
within a second air line 145 that communicates with the
sealed chamber 62. But the gas delivery system could have
more or fewer pressure sensors 144 without departing from
the scope of this invention.
[0092] The pressure sensors 144 are connected to the
controller 102 so that their air pressure measurements are
conveyed to the controller so that the controller can
compare the detected pressure measurements to predetermined
pressures. The controller 102 is further connected to the
air pump 116 so that if the detected measurements differ
from the predetermined pressures, the controller can
activate the pump to bring the air pressures within the
inflatable tubes 44A, 44B and the sealed chamber 62 to
about the predetermined pressures. Accordingly, should air
leaks occur during operation of the apparatus 10, the air
pump 116 will be activated, as necessary, to maintain the
proper air pressures within the complaint support 24.
[0093] Referring to Figs. 22 and 23, the umbilicus 120
is used to simply and easily connect the heat transfer
liquid pumps 114 and the air pump 116 to the enclosure 16.
The umbilicus 120 includes two flexible air supply
conduits 148 for supplying air from the air pump 116 to the
inflatable tubes 44A, 44B, the sealed chamber 62, and the
drain tube hold-opens 84. Specifically, one of the air
supply conduits 148 feeds the inflatable tubes 44A, 44B and
the drain tube hold-opens 84 and the other air supply
conduit feeds the sealed chamber 62. The umbilicus also
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includes two flexible liquid supply conduits 150 fluidly
connect the heat transfer liquid pumps 114 to the enclosure
16. One of the liquid supply conduits 150 is used to feed
liquid to the cover 22 and the other is used to feed liquid
to the compliant support 24. The umbilicus 120 further
includes a flexible liquid return conduit 152 that fluidly
connects the drain tube 82 (via the weir housing 88) to the
reservoir 112. The two air supply conduits 148, two liquid
supply conduits 150, and liquid return conduit 152 are
secured together using spaced apart retainers 154.
[0094] Each end of the umbilicus 120 comprises a
quick-connect coupling 160 to attach the ends of the
umbilicus and thereby the conduits 148, 150, 152 to the
control system 100 and the enclosure 16 to establish a
fluid connect therebetween (Fig. 2). More specifically,
one end of the umbilicus 120 attaches to the weir housing
88 and the opposite end of the umbilicus attaches to the
pumphead housing 140. Each of the illustrated quick-
connect couplings 160 comprises a first coupling member
160A (Figs. 13 and 18) and a second coupling member 160B
(Fig. 22) selectively attachable to the first coupling
member by rotating the second coupling member with respect
to the first coupling member less than about 180 and more
preferably less than 90 .
[0095] In the illustrated configuration, the second
coupling members 160B are affixed to the ends of the
umbilicus 120 (Fig. 21) and the first coupling members 160A
are affixed to the weir housing 88 (Fig. 13) and the
pumphead housing 140 (Fig. 18). Each of the first and
second coupling members 160A, 160B comprises a manifold 156
having a connector 158 for corresponding to each of the
five conduits 148, 150, 152. As a result, all five of the
conduits 148, 150, 152 are connected or disconnected
simultaneously by simply connecting or disconnecting the
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first coupling members 160A to the second coupling members
160B. It is to be understood, however, that other types of
couplings including couplings besides quick-connect
couplings and other types of quick-connect couplings can be
used. It will also be understood that each of the conduits
148, 150, 152 can be individually connected to the control
system 100 and the enclosure 14.
[0096] The apparatus 10 shown in the attached drawings
is intended to be used a medical treatment facility (e.g.,
a hospital). The enclosure 14, for example, is sized and
shaped for placement on a stretcher, such as an ambulance
or emergency gurney G, to facilitate the transportation of
the patient P in a conventional manner while placed in the
enclosure (Figs. 1-3). Accordingly, the enclosure 14 may
have a width between about 66 centimeters (26 inches) and
about 76 centimeters (30 inches) and a length between about
203 centimeters (80 inches) and about 210 centimeters (83
inches), the approximate range of dimensions for a standard
ambulance or emergency gurney G. It is contemplated that
the enclosure 14 may have other configurations without
departing from the scope of this invention. For example,
the enclosure 14 can be configured for a conventional
hospital bed (not shown). It is also contemplated since
many victims of cardiac arrest are initially treated by
first responders (i.e., police officers, firefighters,
emergency medical technicians), that the apparatus 10 can
be made portable for use remote from a medical facility.
[0097] As mentioned above, the enclosure 14 is adapted
to allow heat transfer liquid 18 to flow into the interior
space 16 for direct contact with the patient's body to
promote heat transfer between the patient P and the heat
transfer liquid. To raise the temperature of a patient P,
the heat transfer liquid 18 is directed into the interior
space 16 of the enclosure 14 at a temperature greater than
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the temperature of the portion of the patient's body. For
example, the heat transfer liquid 18 may have a temperature
in a range of about 43 C (109 F) to about 47 C (117 F),
such as about 45 C (113 F). One application of such a
warming enclosure would be to warm a patient P suffering
from unintended hypothermia.
[0098] To lower the temperature of a patient P, the
heat transfer liquid 18 is directed into the interior space
16 of the enclosure 14 at a temperature lower than the
temperature of the body portion of the patient received in
the interior space 16 of the enclosure so that the fluid
cools the body portion of the patient. For example, the
heat transfer liquid 18 may have a temperature in a range
of about 0 C (32 F) to about 5 C (41 F). Heat transfer
liquid 18 introduced into the enclosure 14 at such a
temperature has been found to cool the body at a sufficient
rate to induce hypothermia while minimizing any adverse
effects to the skin of the patient P. It is to be
understood that temperatures other than those listed above
can be used to adjust the temperature of a patient P
received in the interior space 16 of the enclosure 14.
[0099] The volume of heat transfer liquid 18 necessary
to effectively alter the temperature of the patient P is
dependent on the size and shape of the patient. For
example, a larger patient P will require more heat transfer
liquid than will a smaller patient to achieve a similar
rate of heat transfer. The heat transfer liquid 18 within
the interior space 16 of the enclosure 14 is maintained in
a relatively thin layer and near or in contact with the
patient's body positioned the well 46. As a result, the
amount of heat transfer liquid 18 necessary to effectively
alter the temperature of the patient P can be minimized.
This becomes increasingly important in remote areas where
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volumes of heat transfer liquid 18, which can become heavy,
need to be carried by hand.
[00100] The amount of time necessary to induce
hypothermia in a patient P is dependent on numerous factors
including how much of the patient's body is positioned in
the interior space 16 of the enclosure 14, the temperature
of the heat transfer liquid 18, and the amount of time the
heat transfer liquid is in contact with the patient's body.
As a result, the enclosure 14 is adapted to enclose
substantially the entire body of the patient's thereby
providing a large portion of the patient's total surface
area for heat transfer with the heat transfer liquid 18.
In the illustrated configuration, the face of the patient
is not enclosed.
[00101] One application of cooling would be to cool a
patient P suffering from cardiac arrest. It is well
recognized that organ damage can, and typically does, occur
shortly after the victim has suffered cardiac arrest. As a
result, it is often in the victim's best interest to
quickly and effectively induce hypothermia to minimize or
prevent organ damage. It is also contemplated that the
apparatus 10 may be used to treat other medical conditions
than those listed or have application in other medical
procedures (e.g., hyperthermia, trauma, stroke,
enhancements of anti-cancer therapies, surgical support,
and general thermal management).
[00102] In operation, the enclosure 14 is placed in an
uninflated state on a generally flat surface, such the
ambulance gurney G. The compliant support 24 is fully
extended to a position such that the underside of the
compliant support is resting on the gurney G. If not
already done, the cover 22 is removed from the compliant
support 24 by disengaging the sealing portions 94, 96 to
expose the center of the compliant support 24. The patient
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P is carefully placed on the base 42 of the compliant
support 24. Using the touch screen display on the monitor
104, the user activates the controller 102. For example,
as illustrated in Fig. 24, the user could press an inflate
icon button 164 or a start button 166. In response, the
controller 102 activates the air pump 116 to inflate the
tubes 44A, 44B, the hold-open 84 for the drain tube 82, and
the sealed chamber 62 to the desired pressure. As
explained above, inflating the tubes 44A, 44B and the
sealed chamber 62 conforms the well 46 of the complaint
support 24 to the portion of the patient's body received
therein.
[00103] The air pump 116 can be activated anytime
during use of the apparatus 10 by pressing the inflate icon
button 164 to maintain the tubes 44A, 44B, the hold-open 84
for the drain tube 82, and/or the sealed chamber 62 at the
desired pressure. In one embodiment, the air pressure in
the inflatable tubes 44A, 44B and the air pressure in the
seal chamber 62 is monitored using pressure sensors 144 and
compared to desired pressures or a range of desired
pressures by the controller 102. If the pressure in the
inflatable tubes 44A, 44B or sealed chamber 62 falls below
a threshold pressure, the air pump 116 is automatically
activated by the controller 102 to re-inflate the
respective component to the desired pressure.
[00104] The cover 22 is placed on the patient P to
cover the patient's body from the neck downward. The
sealing portion 94 of the cover 22 and the sealing portion
96 of the compliant support 24 are engaged thereby
enclosing the patient P in the interior space 16 of the
enclosure 14. The temperature sensor 108 (i.e.,
thermometer) is connected to the patient P for measuring
the core body temperature of the patient. The temperature
sensor 108 is also connected to the controller 102 so that
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the measured body temperature of the patient P can be
conveyed to the controller. As shown in Fig. 24, the
patient temperature can be displayed on the monitor.
[00105] The reservoir 112 is filled with the
appropriate amount of ice 122 and heat transfer liquid 18.
That is, a sufficient amount of heat transfer liquid 18 is
added to the reservoir 112 to reach the heat transfer fill
line 128 located on the mobile cart window 126, and
sufficient amount of ice 122 is added to reach the ice and
heat transfer fill line 130 (see. Fig. 1). As shown in
Fig. 24, the reservoir temperature can also be monitored
and displayed on the monitor 104.
[00106] Using the touch screen display on the monitor
104, the delivery system 92 can be activated by pressing a
run icon button 168 on the monitor. Once activated, the
pumps 114 deliver heat transfer liquid 18 to the patient's
body to adjust the temperature of the patient P to a
selected temperature. For example, it may be desirable to
quickly lower the body temperature of a patient P suffering
from cardiac arrest from about 37 C (98.6 F) to about 33 C
(91.4 F). As illustrated in Fig. 24, the target
temperature of the patient P can be displayed on the
monitor 104. Moreover, the target temperature can be
adjusted upward or downward by the user using an up arrow
key 172 and a down arrow key 174, respectively.
[00107] In this example, approximately 30 liters (8
gallons) of the heat transfer liquid 18 (e.g., water) and
approximately 4.5 kilograms (10 pounds) of phase change
material (e.g., ice) would have been added to the reservoir
112. In some instances, it may be desirable to use pre-
cooled heat transfer liquid 18. The heat transfer liquid
18, which is lowered to a temperature between about 0 C
(32 F) and about 5 C (41 F), is drawn from the reservoir
112 by the pumps 114 and pumped through umbilicus 120 and
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into the passages 32, 68 in the cover 22 and the compliant
support 24 and thereby into the top and bottom of the
interior space 16 of the enclosure 14.
[00108] With both pumps 114 operating, the heat
transfer liquid 18 directly contacts the body of the
patient P at a flow rate of about 14 liters per minute (3.7
gallons per minute). In addition to being able to pump
heat transfer liquid 18 into both the top and bottom of the
enclosure 14 simultaneously, the pumps 114 can be
selectively operated to pump heat transfer liquid 18 only
into the top of the enclosure or only into the bottom of
the enclosure. In one configuration, one of the pumps 114,
such as the pump supplying heat transfer liquid 18 to the
passages 32 in the cover 22, can be deactivated by the user
pressing a pause button 170 on the touch screen display of
the monitor 104. Both pumps 114 can be deactivated by the
user pushing the pause button 170 a second time. Both
pumps 114 can be reactivated by the user pushing the start
button 166 and/or the run icon button 168.
[00109] During operation of the pumps 114, heat
transfer liquid 18 accumulates in the well 46 in the
compliant support 24 such that a greater volume of heat
transfer liquid accumulates in the broader region 50 of the
compliant support that receives the torso than the other
regions 52, 54 of the compliant support that receive the
head, legs, and feet. The heat transfer liquid 18
accumulates in the interior space 16 of the enclosure 14
until it reaches a depth greater than height of the dam 87
of the weir 86, which is in fluid communication with the
large diameter outlet 80. The dam 87 maintains the heat
transfer liquid 18 at the target depth D of about 11
centimeters (4.5 inches), which creates a positive gauge
pressure as measured at the outlet 80 of the enclosure 14
of about 1.1 kiloPascals (0.16 psi). Any heat transfer
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liquid 18 achieving a height greater than the spillway
created by the dam 87 is drained from the interior space 16
of the enclosure 14 at a flow rate equal to or greater than
flow rates at which the heat transfer liquid is being
driven into the interior space 16 of the enclosure 14 by
the pumps 114.
[00110] The heat transfer liquid 18 is directed back
into the reservoir 112 through the liquid return conduit
152 of the umbilicus 120 where it is re-cooled by the phase
change material 122 before being recirculated back into the
interior space 16 of the enclosure 14. Heat transfer
liquid 18 is continuously recirculated through the
enclosure 14 until the patient's temperature reaches or
approaches the selected temperature. The patient's
temperature may drop slightly after the heat transfer
liquid 18 has been stopped and, as a result, it may be
desirable to stop the flow of heat transfer liquid before
the patient's temperature drops to the selected temperature
to prevent overshoot (i.e., lowering the patient's body
temperature below the selected temperature). For example,
the controller 102 can be programmed to shut off the liquid
delivery system when the core body temperature of the
patient is within 1 C or 2 C of the target temperature to
prevent the patient's core body temperature from falling
below the target temperature. In addition, the controller
102 can be programmed to send a warning (i.e., an audio or
visual alarm) to a user if the core body temperature falls
below the target temperature.
[00111] Once the temperature of the patient P has
reached the predetermined temperature (e.g., 1 C or 2 C
above of the target temperature), the pumps 114 are
automatically shut off by the controller 102 and the heat
transfer liquid 18 is purged from the enclosure 14. The
interior space 16 of the enclosure 14 can also be purged by
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the user pressing a purge icon button 176. In yet another
way, the interior space 16 of the enclosure 14 can be
purged by deactivating the pumps 114 by pressing the pause
button 170 twice and rotating the handle 90 on the weir 86
to move the weir from the flow restricting position (Fig.
15) to the non-restricting position (Fig. 16).
[00112] In one configuration, the interior space 16 of
the enclosure 14 can be purged by allowing any heat
transfer liquid 18 present in the interior space to flow
via gravity through the large diameter outlet 80, through
the drain tube 82 and return conduit 152, and into the
reservoir 112. This is done by moving the weir dam 87 from
the flow restricting position to the non-restricting
position. In another configuration, the interior space 16
of the enclosure 14 can be purged by reversing the pumps
114. As a result, heat transfer liquid 18 is drawn using
one of the two pumps 114 through the openings 76 in the
passages 68 in the compliant support 24 and pumped back
into the reservoir 112. The other pump 114 is used to draw
any heat transfer liquid 18 remaining in the passages in
the cover 22 back into the reservoir 112. In this
configuration, the weir dam 87 can also be moved from the
flow restricting position to the non-restricting position
thereby allowing heat transfer liquid 18 to exit the
interior space 16 of the enclosure 14 via gravity as well
as via the pumps 114.
[00113] The inflatable tubes 44A, 44B, the sealed
chamber 62, and the drain hold-opens 84 of the compliant
support 24 can be deflated by activating the air release
valves 178 (Figs. 1 and 9). In the illustrated
configuration, the air release valves 178 comprise capped
plugs that can be activated by manually removing the cap
from the plug housing. It is to be understood that the
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other types of air release valves including automated
valves can be used.
[00114] If necessary, CPR can be performed on a patient
P received in the interior space 16 of the enclosure 14
directly through the cover 22 while heat transfer liquid 18
is being supplied to the patient. Thus, with the cover 22
covering the patient P, oxygen can by supplied to the lungs
of the patient and the chest of the patient can be
compressed.
[00115] It is to be understood that during operation of
the apparatus 10, the user is able to maintain visual
observation of the body of the patient P through the
transparent cover 22. If additional medical care is
needed, the cover 22 can be partially or completely removed
to expose the patient's body while the liquid delivery
system remains operating. To prevent the loss of heat
transfer liquid 18, the pump 114 directing heat transfer
liquid to the passages 32 in the cover 22 can be shut off
before the cover is pulled back. Moreover, all of the
apparatus' operations can occur in the ambulance on route
to the medical facility thereby not delaying any subsequent
medical care.
[00116] It is to be understood that the controller 102
can be programmed so that when the user presses the start
button 166 on the touch screen display of the monitor 104,
the apparatus 10 automatically proceeds sequentially
through the inflate, run, and purge stages of operation
without further input from the user. The user, however,
can interrupt operation of the apparatus 10 during any
stage by pressing the pause button 170, or can completely
stop the operation of the apparatus by pressing a stop
button 180. The apparatus 10 can be reactivated from the
paused or stopped position by the user pressing the start
button 166.
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[00117] The following commonly owned U.S. patents and
U.S. Patent Applications are related to the present
application and are incorporated herein by reference in
their entirety: U.S. Patent No. 6,969,399 entitled
"APPARATUS FOR ALTERING THE BODY TEMPERATURE OF A PATIENT";
U.S. Patent Application No. 10/896,506, filed on July 22,
2004 entitled "APPARATUS FOR ALTERING THE BODY TEMPERATURE
OF A PATIENT"; U.S. Patent Application No. 10/950,152,
filed on September 24, 2004 entitled "APPARATUS FOR
ALTERING THE BODY TEMPERATURE OF A PATIENT"; and U.S.
Patent Application No. 10/948,918, filed on September 24,
2004 entitled "APPARATUS FOR ALTERING THE BODY TEMPERATURE
OF A PATIENT".
[00118] In view of the above, it will be seen that the
several objects of the invention are achieved and other
advantageous results attained.
[00119] When introducing elements of the present
invention or the preferred embodiment(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.
[00120] As various changes could be made in the above
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.
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