Note: Descriptions are shown in the official language in which they were submitted.
CA 02375764 2002-O1-11
Method and device for preserving animal and human preparations as well
as microorganisms and for prolonging the viability of orl~ans and body
parts to be transplanted
The invention concerns a method and a device to preserve anirnal and human
preparations as well as microorganisms or similar material to be treated, in
particular for medical research andlor training and to prolong the viability
of
organs and body parts to be transplanted which serve as material to be
treated,
whereby carbon dioxide is expelled from the cells of the materiel to be
treated.
In medical training and research humans and experimental animals or individual
body parts or organs are required. At the same time the problem is that these
preparations should be available as fresh as possible, without iinjuries, in
large
numbers and independently from the tune, i.e. care demand. At filhe same time
the
dead tissue should be as similar to the living tissGe as possible: to obtain
results
as close as possible to the practical. On this occasion the con.~istency of
the
tissue, its elasticity, colour and shape are paramount.
In techniques used so far the preparations have to be placed into formalin or
something similar. However, in this case it is a disadvantage that the colour
and
consistency change considerably. In addition, formalin is a toxi~~c material
that
chemically modifies the tissue. This will change the functional !behaviour of
the
cell tissue fragments, resulting in considerable disadvantages as far as the
purpose of the research is concerned. In addition, due to the toxicity a reuse
is
not possible, so that transplants of such preparations, treated with formalin,
is out
of the question. There is the further possibility to deep freeze the
preparations.
However, during the thawing out the natural decomposition is ;activated and
accelerated, so that the preparations have to be used within hours.
A further possibility is to use fresh preparations. For this purpose the
animal is
slaughtered shortly before. This, however, necessitates a well organised and
expensive effort, since the regulations regarding protection of animals
specifies,
for example, quarantine regulations, special disposals, permission by the
ethical
commission.
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In the case of body part or organ transplants there is, inter alia, the
problem of
transport. Organs have to be transported sometimes over thousands of
kilometres from the donor to the recipient. The danger in this case is that
the
natural decomposition could set in. To retard this, the organ is cooled and
sometimes it is placed into a nutritive solution. Despite this the organ has
to be
used within hours before the cells are permanently damaged.
The use of oxygen for the purpose of reduction of the natural decomposing
process is already known.
Research publications are also known, wherein hyperbaric oxygen is used under
pressure to improve the healing of a wound.
Furthermore the transplanting of a rat's ear is known, whereby the hyperbaric
oxygen was used under a pressure of 2 bar with the aim to improve the adhesion
of the transplanted organ.
When a rat's liver was transplanted, it was treated with hyperbaric, 100%
oxygen
at 2.5 bar pressure over the atmospheric one before its removal so that to
reduce
ischemic damages (anaemia) during the renewed blood circulation of the organ.
Furthermore, the transplant of a rabbit's lung using EuroCollins solution
(nutritive
solution) and a 95% oxygenl5% C02 atmosphere at a pressure of 2 bar is known.
It is known from experiments, that in the case of rat cells, subjected to
hyperbaric
oxygen under a pressure of 2.8 bar for a longer period, damages have occurred.
Therefore the state-of the-art in the medicine is the use of high-percentage
(95%
or higher) oxygen as well as pressurising.
For the oxygen supply either oxygen bottles or an oxygen concentrator is used.
To purchase and practically operate either of them, not-inconsiderable
expenses
are required. When oxygen bottles are used, they have to be continuously
exchanged, thus rendering the operation of the device elaborate. In addition,
the
3
prescribed safety regulations have to be observed when handling and storing
oxygen bottles.
Therefore it is a particular task to produce a method to preserve and treat
preparations, with the aid of which preparations can be preserved even over a
relatively long period of time, so that surgical exercises could be carried
out on
these within the prolonged preservation period under lifelike conditions. In
addition, a prolonged viability should be provided for the organ or body part
transplant.
The solution for this method according to the invention is in particular that
the
preparation or the similar material to be treated is subjected inside a vessel
to
atmospheric air that is increased periodically up to at least app~rox. 10 bar
and
subsequently, after a specifiable period of time that is adjusted to suit the
material
to be treated, is reduced, that after the decrease of the pressure air is
supplied
from the outside and the pressure is increased up to at least approx. 10 bar
and
that at least two pressure phases are provided for a treatment.
The use of atmospheric air, in conjunction with the periodic pressurising,
considerably simplifies the treatment method since an elaborai:e supply of
oxygen
from oxygen bottles or the use of an oxygen concentrator becomes redundant. In
addition, the treatment can be concluded after a considerably ~;horter time.
This is
the result of being charged by relatively high pressures which, according to
an
embodiment of the invention, can be 10 bar up to approx. 100 bar. This
charging
of the material to be treated by high pressure affects a faster diffusion of
the
oxygen of the air.
Experiments have shown that already two pressure phases with reliefs between
them will sufficiently prolong the durability.
The treatment, using the method according to the invention, allows the post-
decrease preservation of humans, animals and microorganisms or their parts.
The decay commences usually within a few hours. The method according to the
invention can delay this up to several weeks. At the same time the colour of
the
CA 02375764 2002-O1-11
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tissue as well as its consistency, especially with regard to strength and
elasticity,
are retained, so that it can be used as a fresh preparation. Accordingly,
preparations are available that are very lifelike and can be removed, for
example,
for surgical courses, from the preserving device. At the same time the
consistency of the tissue is almost that of fresh tissue. This is demonstrated
by
physically testing the elasticity of the tissue.
Apart from the scientific advantages, the method also facilitates the
organisation
itself. Several preparations can be preserved and used when r~:quired and
experiments can be carried out independently from the supply/.5laughter of
experimental animals. This results in a financial saving, at least when
compared
with experiments using fresh preparations.
The method can save in animal experimentations, since a multiiple use and
storage of individual preparations is possible.
The longer durability of pre-treated preparations can be also attributed to
the fact
that the development of certain groups of germs can be hinder~:d by the oxygen
gas. The oxygen contained in the atmospheric air, supplied uncler pressure,
has a
growth-hindering effect on the germ and possibly even a bactericidal effect.
This
bactericidal effect acts effectively against the accelerated decay processes.
Moreover, oxidative changes are also prevented or at least reduced over a
longer
period of time, what can be noticed by a near-realistic colour of the flesh of
the
animal preparation.
In the case of animal and human preparations one could deal Moth with part
preparations and complete body preparations.
By virtue of the method according to the invention in the case of body part or
organ transplants now a prolonged period of time is available, within which
after
its removal the organ is brought to the place of transplant and used there,
because the viability of the organs and body parts can be retained longer.
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In a useful manner the material to be treated is pressurised with high
pressure on
the one hand and on the other hand with a pressure reduced relative to the
high
one for different time spans, while the pressurising with high pressure lasts
at
least for approx. 1 to 10 minutes per period and in particular laats longer
than the
pressurising with low pressure. The duration of the pressurisinl~, the maximum
pressure used for this and the number of pressure periods can be adjusted to
suit
the respective preparation by varying one or several of these parameters.
The periodic pressurising of the material to be treated can be carried out
over
time spans of a few seconds, preferably of 3 minutes, up to 20 hours.
This extremely broad time span for a periodic compressed air treatment is the
result of the broad field of application of the method according to the
invention for
very different preparations.
Accordingly, the time span of the periodic pressurising is chosen depending
from
the allocated maximum pressure andlor the material to be treated.
It is useful to supply filtered andlor cooled atmospheric air to the treatment
vessel.
By supplying cooled air, the vessel for the preparations or the like can be
practically placed anywhere, i.e. also outside of a cooling chamber. The
supply of
filtered air also contributes to this, since due to this the vessel c;an be
placed
practically anywhere.
By means of the preserving method according to the invention, the preparations
(complete bodies or part preparations) treated with it are available for a
relatively
long period of time with a consistence corresponding almost to that of fresh
preparations. To produce conditions as close as possible to real life during
experimentations, the animal or human preparations, in addition to the
consistency of fresh preparations achieved by preservation, an additional near-
realistic measure could provide that after being preserved, when carrying out
experiments, especially simulating surgical operations, the blood vessel
system
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6
of a preparation, formed by a part preparation or a complete body preparation,
is
connected to a through-flushing by fluid, in particular to an artilicial blood
circulation and that for this purpose the preparation or the similar material
to be
treated with at least one large blood vessel is connected to a preferably
pulsating
fluid supply, in particular with at least one large artery andlor at least one
vein.
When simulating surgical operations on the preparations, this fluid supply to
the
blood vessels has the effect that in a realistic manner during the incision of
the
preparation it trickles from the smaller blood vessels whereas the fluid
squirts
from the large blood vessels. Thus a near-realistic blood and fluid flow is
produced in the blood stream of the preparation.
The preservation method according to the invention can be particularly well
used
in combination with the method of artificial blood circulation, because in the
case
of this preservation method particularly the colour and consistency of the
walls of
the vessels of the large and especially of the small arteries and veins are
retained
even after longer preservation. Thus when a surgical operation is being
simulated, unexpected bleedings may occur, for example by an erroneous
incision, just like this is the case in actual operations. Thus the surgeon
sees
directly a realistic result of his activity.
This case can be simulated particularly life-like, so that the entire
operation will
have a life-like effect. Thus the surgeon can be presented with difficult
situations
also, so that he could securely master it also in practice.
It is useful if the blood vessel system of a preparation formed ~~y a part
preparation or a complete body or an organ or body part is fluslhed through
before
andlor during andlor after preservation with a particularly anti-clotting
fluid or a
blood substitute or the like.
This flushing through of the blood stream of the preparation or of the organ
or of
the body part can be carried out immediately after the slaughtering of the
animal
or after the removal of the organ or the like, so that to remove residual
blood and
CA 02375764 2002-O1-11
7
to prevent an adhesion of the vessels. By virtue of this the blood stream
system
remains passable for the subsequently supplied fluid, should it be necessary.
An organ or body part to be transplanted can be connected before andlor during
andlor after the preservation to a through-flushing by fluid, prevferably to a
blood
circulation.
It is advantageous if a blood substitute, having a colloid-osmotic pressure
that is
comparable with that of blood, is used. As a result of this the blood or
similar fluid
flowing in the blood stream of the preparation during its preparation can flow
out
under as realistic as possible conditions when the preparation is incised.
A preferred embodiment of the invention provides that the blood substitute or
similar fluid is filled into the blood stream of the preparation by means of a
pressure pump connected to at least one blood vessel.
With the aid of the above described treatment method according to the
invention
a preparation can also be prepared over a relatively long period of time under
near-realistic conditions. Since the preparation can be kept fresh over a
longer
period of time, larger quantities of these preparations can be stored and made
available practically any time.
The method according to the invention is particularly suited for research and
training in the intervention radiology. It can be particularly well used for
catheterisation, injections and microsurgical interventions using computer
tomography control or magnetic resonance tomography control, since the life-
like
preservation of tissue structures and the possibility of an artificial blood
circulation
provides small vessels, realistic and life-like exposures (computer tomography
images or magnetic resonance images).
There is also the possibility to intermediately store compressed atmospheric
air at
a pressure of between approx. 10 bar and approx. 1000 bar arid then supply it
to
the vessel, preferably filtered andlor cooled.
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By means of the intermediate storage the air, heated by the compression, can
be
intermediately stored and it can cool off during this time before being
conveyed to
the treatment vessel. By virtue of this the cooling effort is reduced because,
inter
alia, more time is available for this.
In a useful manner the vessel for the material to be treated is cooled
preferably
by a cooled ambient atmosphere, while the time spans with a periodic pressure
increase and a subsequent pressure decrease in the vessel are so determined,
that at the end of each time span a specifiable temperature will prevail in
the
vessel. By the incremental increase of the pressure and the partial decrease
of
the pressure, following each increase, in a desired manner the pressure level
is
brought closer to the intended end pressure on the one hand and due to the
decrease of the pressure a reduction of the temperature, incre<~sed during the
period of pressure increase, is achieved on the other. The decrease of the
pressure takes place following the increase of the pressure before a
perceivable
temperature increase occurs in the treatment vessel. Each decrease of pressure
can be, for example, approx. ~~s of the previous pressure increase.
Experiments
have shown that at the same time the temperature in the treatment vessel can
decrease even below the temperature of the cooling atmosphere surrounding the
treatment vessel. The subsequent pressure increase preferably takes place
again
when an approximate temperature equalisation has been achieved, for example
after 20 seconds.
The device provided for the carrying out of the method according to the
invention
has a vessel that can be closed in an airtight manner to accommodate the
material to be treated, with a gas supply line and a gas discharge line
connected
to said vessel.
The device is characterised in that a compressor is connected to the gas
supply
line to supply ambient air to the vessel, that a discharge valve is provided
in the
gas discharge line, that a pressure sensor is provided to measure the internal
pressure of the vessel and that the compressor, the discharge ~ralve as well
as
the pressure sensor are connected to a control device for the purpose of a
periodic supply and discharge of the air.
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The device according to the invention has an altogether simplE: construction
and
is constructed from cost-effective, commercially available single components.
The
treatment of preparations, organs, body parts and the like can be carried out
with
this device by placing them into the pressure vessel and subsequently
periodically charging them with air while the vessel is enclosedl. The
compressor,
connected to the vessel to produce the compressed air, in conjunction with the
discharge valve as well as with the pressure sensor can operable according to
a
operating program that can be set by the control device, so that a practically
fully
automated operation is possible.
The control device can comprise a program memory, in which the various
treatment programs can be stored, whereby each material to be treated andlor
the treatment time available are taken into consideration.
In a preferred manner in the air supply line, in particular after the
compressor, a
filter andlor a cooling equipment is provided. By including a filter and a
cooling
equipment the device represents a complete operating unit that can be
installed
practically anywhere.
A variation of the embodiment of the device according to the im~ention
provides
that as the source of the compressed air at least one high-pressure reservoir
is
provided for an operating pressure of approx. 10 bar up to 100() bar.
The use of a high-pressure reservoir makes it possible to operate the device
according to the invention from one or several of such reservoirs, while this
can
be carried out also removed from a filling station with a compressor.
However, on the other hand it is possible to connect the high-pressure
reservoir
to the compressor or make it connectable and to connect its delivery end, via
the
air pressure valve, to the treatment vessel. In this case the high-pressure
reservoir (or several of them) acts as an intermediate vessel. Accordingly,
the
compressor needs to be operated only for the filling operation wind, unlike
the
case for a compressor directly connected to the treatment vessel, needs not be
continuously operated over the entire duration of the treatment.
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CA 02375764 2002-O1-11
In a useful manner the treatment vessel is connected with a cooling equipment
and arranged preferably in a cooled ambient atmosphere, in particular in a
cooling chamber. Accordingly, the material to be treated, situated in the
treatment
vessel, can be cooled to the respective desired temperature and kept at this
5 temperature, e.g. at approx. 4°C. In addition, the increase in
temperature, caused
by a pressure increase, is compensated for by the cooling.
The invention is explained with its essential details in the follovring based
on the
drawings. They show in:
Fig.1 - a schematic illustration of a device for the treatment of animal and
human
preparations, organs and body parts,
Fig.2 - a schematic illustration of a device according to the invention with
high-
pressure reservoirs as intermediate vessels,
Fig.3 - an illustration approximately corresponding to that of Fic,~.2, but
with a
cooling equipment between the high-pressure reservoirs. and the vessel for
the material to be treated,
Fig.4 - a schematic illustration of a device according to the invention,
wherein a
compressor is connected to a filling station for high-pressure reservoirs
and wherein several treatment units, each with a vessel for the material to
be treated, are positioned spatially separated from one another, and
Figs.S-7 - diagrams showing the progress of pressure and temperature inside a
treatment vessel during the filling process, the treatment process and
the ventilation process.
Fig.1 shows the essential functional groups of the device 1 according to the
invention. It has a vessel 2 that can be closed in an airtight manner, into
which
the material 3 to be treated, indicated by dotted line, can be fill~:d. In the
case of
material to be treated one deals in particular with animal and human
preparations, organs or body parts.
11
The vessel 2, which can have any external shape, has a door ~~, through which
the interior of the vessel 2 can be accessed and by means of ~nihich the
vessel
can be closed in an airtight manner even after charging it with the material 3
to be
treated.
An air supply line 5 is connected to the vessel 2, said line beirng connected
to at
least one compressor 6. Preferably a cooling unit 7 is positioned in the air
supply
line 5, the cooling unit provided particularly between the compressor 6 and
the
vessel 2. The air drawn in by the compressor 6 via a suction line 8 is
preferably
first conveyed through an air filter 9.
In the air supply line 5 there is an air pressure valve 10, in particular
immediately
before the vessel 2.
Furthermore, an air discharge line 11 is connected to the vessel 2 in which
line a
discharge valve 12 is provided.
A pressure sensor 13 serves the purpose of measuring the air pressure
prevailing
in the vessel 2 and the temperature in the vessel can be measured with a
temperature sensor 16.
The valves 10 and 12, the pressure sensor 13 and the temperature sensor 16 as
well as the compressor 6 and the cooling unit 7 are connected to a control
device
14, by means of which the treatment process according to the invention is
automatically controlled. A particular operating program for the progress can
be
specified particularly via an operating field 15. By virtue of this it is
possible to suit
the various materials to be treated and other specifications.
After charging the vessel 2 with the material 3 to be treated and after
closing the
door 4 and the air discharge line 11 with the aid of the discharge valve 12 in
an
airtight manner, the compressor 6 is switched on via the control device 14, so
that
in the case illustrated air, cooled with the aid of the cooling unit 7, is
conveyed via
the air supply line 5 into the interior of the vessel. On this occa;>ion the
internal
pressure of the vessel is built up to at least 10 bar.
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12
When the pre-set pressure is reached, it is sensed by the pres:>ure sensor 13
and
the compressor 6 is switched off via the control device 14. In this high-
pressure
phase the air supply line 5 is closed with the aid of the air pressure valve
10.
After a period of time, that can also be set, the discharge valve 12 is opened
by
the control device 14, until the air pressure in the interior of they vessel 2
is
reduced to a specifiable value that can be detected by the pre:~sure sensor
13.
This pressure, reduced in comparison with the prior prevailing high pressure,
may
be between atmospheric pressure and the prior prevailing high pressure,
however, its reduction up to atmospheric pressure is preferred. The discharge
valve 12 is subsequently closed again, the air pressure valve 10 is opened and
compressed air is conveyed again by the compressor 6, until a specified
pressure
is reached in the vessel 2, that is again at least 10 bar. The nuimber of
periodic
pressurising with reliefs of the pressure in between, can be varied depending
on
the material to be treated.
With the aid of the temperature sensor 16 the cooled compres~~ed air, conveyed
via the cooling unit 7, can be kept in a specified temperature range.
The temperature is preferably kept in a region around 0°C, because
at this
temperature a particularly good exchange of carbon dioxide and oxygen takes
place inside of the material to be treated. In addition, the bacterial
decomposition
is minimised at this temperature.
Fig.2 shows a constructive variation of the device 1a according to the
invention,
wherein high-pressure reservoirs 17 are provided between the compressor 6 and
the treatment vessel 2. In the embodiment two of these high-prEasure
reservoirs
17 are illustrated, while the number of the reservoirs may vary depending on
the
requirements and site conditions. Instead of several small reservoirs a
corresponding larger one could be employed.
With the aid of the compressor the high-pressure reservoirs 17 are filled with
compressed air, while the filling pressure may be in the range o~f, for
example,
CA 02375764 2002-O1-11
13
50-1000 bar. The filling pressure is usually approx. 300 bar, bE:cause
commercially available reservoirs can be used for these pressures.
The high-pressure reservoirs) 17 is (are) connected to the ve;~sel 2 via a
compressed air supply line 18 and the air pressure valve 10 located on the
inlet
side of the treatment vessel 2.
In the case of reservoirs 17 acting as intermediate vessels for i:he
compressed air
a pressure-reducing valve (not illustrated) may be provided, so~ that
compressed
air at a constant pressure that is independent, to a great extent, from the
internal
pressure of the reservoir can be supplied to the vessel 2via the: compressed
air
supply line 18.
In the embodiment shown in Fig.2 the treatment container 2 is :situated inside
of a
cooling chamber 19 to enable to keep the internal temperature of the vessel 2,
for
example, at approx. 4°C.
The use of high-pressure reservoirs 17 has, inter alia, that adv,~ntage that
the
compressor has to be operated only to fill the reservoir 17 and iit does not
operate
while the pressure in these reservoirs is adequate.
When device 1a is started up, atmospheric pressure prevails first in the
treatment
vessel 2 and the material 3 to be treated is placed in these vessels 2. At
this time
the temperature of the ambient atmosphere within the vessel 2 is 4°C or
less.
When the discharge valve 12 is closed, the filling process commences, whereby
the inside pressure of the vessel 2 is increased periodically with increase
and
decrease phases up to a specified end pressure, e.g. 20 bar.
Fig.S is a diagram, showing the progression of the pressure inside of the
vessel 2
during the filling process on the one hand, and on the other, in dotted line,
the
progress of the temperature of the internal atmosphere of the vessel. In this
embodiment the pressure increases from the atmospheric one up to 15 bar and
the temperature moves between approx. 5°C and 0°C.
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14
Beginning with the atmospheric pressure in the vessel 2, first of all the
pressure is
increased in a first period, whereby the pressure increase can be 10 bar. This
pressure increase also brings about an increase of the tE:mperature in the
interior
of the vessel, which, however, is compensated by a subsequent decrease of the
pressure by approx. ~~3 to ~r1 of the previous pressure increase, together
with the
cooling of the vessel 2. If the level of temperature after the decrease of the
pressure and a following time span is within a permissible range, the next
pressure increase takes place with a subsequent partial decrease of the
pressure, in each case while observing the temperature of the vessel.
Experiments have shown that despite the increased overall pressure by
decreasing the pressure short-term temperatures may occur below the
temperature specified for the cooling.
The periods with pressure increase and pressure decrease are repeated until
the
required pressure level of, for example, 15 bar, is reached. In practice this
could
occur after 5-10 minutes.
This operational state remains over the treatment period of the material 3 to
be
treated. From the diagram according to Fig.6 it can be seen that the pressure
is
varied periodically, whereas the temperature is kept constant at approx.
0°C.
During the treatment period a partial air exchange can be carried out, whereby
some air is discharged and subsequently compressed air is supplied. This
limited .
air exchange can be carried out at short time intervals, while at somewhat
longer
time intervals, for example on every hour, the air exchange can be to a
greater
extent. At the same time a partial, or perhaps even a complete air exchange is
possible in the treatment vessel.
After the treatment period, after the removal of the maternal 3 to be treated
from
the vessel 2, the pressure is reduced, while this may last, for example, half
an
hour. A relatively slow reduction of the pressure takes place, so that a too
quick a
temperature reduction will be avoided by virtue of the pre;>sure reduction.
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15
Fig.7 shows the ventilation process, wherein the pressure is reduced over a
period of approximately half an hour from approx. 15 bar to atmospheric
pressure.
Fig.3 shows a further version of the device 1 b according to the invention,
wherein
the treatment vessel 2 is not situated in a cooling unit, as is the case in
Fig.2. For
this reason a cooling equipment 7a is connected downstream to the reservoirs
17, so that cooled air could be supplied to the vessel 2 to achieve the
desired
temperature in the vessel.
In the case of the embodiment according to Fig.4 a compressor 6 with a filling
station 20 is allocated to several treatment units 21, each having a vessel 2,
an
air pressure valve 10, a discharge valve 12 as well as a control device 14.
The
treatment units 21 can be arranged spatially separated from the compressor 6.
To each treatment unit 21 at least one mobile high-pressure reservoir 17 can
be
connected. This high-pressure reservoir can be filled at tlhe central filling
station
20, to which the compressor 6 is connected, and then connected to the
respective treatment unit. Thus only one single filling station with
compressor is
required, via which several treatment units 21 can be supplied.
CA 02375764 2002-O1-11
