GB2286660A - Peltier effect cooling apparatus for treating diseased or injured tissue - Google Patents

Abstract

Apparatus for cooling a limb including a thermoelectric module (2) which operates by the Peltier effect. A heat sink (6) is in contact with the "hot" surface of the module (2) to dissipate heat therefrom. A reservoir (19, figure 4) contains cooling fluid for cooling the heat sink (6), a pump circulates the cooling fluid, and a refrigeration unit cools the cooling fluid. The apparatus provides control of the temperature of the "cold" surface of the thermoelectric module (2), to obtain cooling of an injured animal limb to a temperature between 13 and 18 DEG C, or to sub-zero temperatures to treat skin cancer. <IMAGE>

Description

ANIMAL TREATMENT APPARATUSThis invention concerns apparatus for treating diseased or injured animal tissue, for example inflamed limbs. The term 'animal" is used herein includes man.

Apparatus for treating damaged animal limbs has been proposed hitherto in GB2202447-A, the apparatus effecting the treatment by cooling the damaged limb using a thermoelectric module having opposed surfaces across which a temperature differential is created using the Peltier effect. In use, the thermoelectric module has a shot" surface and a "cold" surface, the latter being used to effect cooling of the damaged animal limb. Heat from the "hot" surface is dissipated through a heat sink, the heat sink being force cooled using a liquid which is circulated from a reservoir by a pump.

Although the apparatus described in GB2202447-A does effect cooling of limbs to which it is attached, it is difficult to control the temperature to which the limb is cooled by the apparatus. This is a disadvantage in the light of more recent indications that healing of an injury can be enhanced if the injury is held at a temperature between 13 and 18"C.

Furthermore, it has been proposed that skin cancer can be treated using sub-zero temperatures, and such temperatures are difficult if not impossible to achieve using the apparatus described in GB2202447-A.

According to the present invention there is provided apparatus for cooling a limb of an animal, the apparatus comprising;(a) a thermoelectric module having opposed surfaces across which a temperature differential can be created using thePeltier effect, one of said surfaces in use being the "cold" surface, and the other of said surfaces in use being the "hot" surface;(b) a heat sink in contact with the "hot" surface of the module for dissipating heat from the "hot" surface;(c) a reservoir of cooling liquid for cooling the heat sink;(d) a pump for circulating cooling liquid from the reservoir to the heat sink: and(e) a refrigeration unit for cooling the cooling liquid.

The use of the refrigeration unit enables the cooling effect of apparatus in accordance with the present invention to be controlled so that limbs treated thereby can be cooled to desired temperatures, for example the 13 to 18"C range described above or to sub-zero temperatures. Indeed, the so-called "cold" surface can, if desired, be turned into a "hot" surface by turning off the refrigeration unit and reversing the electrical supply to the thermoelectric unit.

An embodiment of apparatus in accordance with the present invention will now be described, by way of example, with reference to the accompanying diagrammatic drawing in which:Figure 1 is side view of a cooling unit of the embodiment;Figure 2 is an underneath view of the cooling unit ofFigure 1; Figure 3 is a perspective view of the control unit of the embodiment;Figure 4 is a part cut away perspective view of the secondary cooling unit of the control unit; andFigure 5 is a side view of a modification of the cooling unit of Figure 1.

Referring to Figure 1, the illustrated apparatus includes a cooling unit 1 having a thermoelectric module 2 mounted beneath a metal face plate 3, for example of aluminium, the upper surface 4 of the plate 3 in use being placed on the limb to be treated (not shown). The lower surface 5 of the thermoelectric module 2 is in thermal contact with a heat sink 6 through which in use cooling liquid can be passed to effect cooling of the thermoelectric module 2 via inlet and outlet connections 7 and 8. Electrical connection to the thermoelectric module 2 is made via connecting wires 9. The flow of cooling fluid through the heat sink 6 can be seen from Figure 2.

The cooling unit 1 is connected to a control unit 10 shown inFigure 3. The control unit 10 includes a controllable direct current power source 11 for activating the thermoelectric module 2, the direct current power source 11 being supplied from the mains electricity supply via cables 12.

The control unit 10 also supplies a supply of coolant from a secondary cooling unit 13 to the heat sink 6 via connecting tubes (not shown), the coolant being pumped by a pump 14 which is controlled by the control unit 10 and powered from the mains electricity supply via cables 12. A fan 15 is provided to give forced ventilation of the equipment within the control unit 10.

Control of the functioning of the apparatus is effected using control switches shown generally at 16 on the top of the control unit 10. The control unit 10 can, for example, include a microprocessor to effect control of the temperature of the face place, such control, for example, carrying out a predetermined temperature cycling of the face plate 3 and thereby the limb to which it is applied. The control unit 10 can also be used to control more than one cooling unit 1, for example two or more such units applied to the same animal.

The secondary cooling unit 13 is shown in more detail in Figure 4, with various parts of its case cut away. The unit 13, which includes a conventional refrigeration unit, has a compressor 17 connected in known manner to a condenser 18. The condenser 18 is located within a coolant reservoir 19, and operation of the compressor 17 results in the coolant within the reservoir 19 being cooled.

Coolant input and output connections 20 and 21 are connected by flexible pipes (not shown) to the outlet and inlet connections 8 and 7 respectively of the cooling unit 1 via the pump 14 which circulates cooled coolant from the reservoir 19 to the heat sink 6. The coolant which is used preferably includes antifreeze in order to prevent freezing of the coolant within the circulating system.

The temperature of the coolant in the reservoir 19 can be controlled by a pre-set thermostat 23 in the secondary cooling unit 10. However, as illustrated in Figure 4, it is generally preferred to use a temperature sensor 24, for example a thermistor, which in use is placed on the skin of the animal being treated. The temperature of the coolant circulated by the pump 14 from the reservoir 19 can thus be controlled according to the surface skin temperature detected by the sensor 24. When a temperature sensor 24 is used, it is generally preferred to interpose a sealed bag 25 containing antifreeze, or some other thermal buffer, between the thermoelectric module 2 and the temperature sensor 24. The bag 25 serves to provide a thermal buffer between the skin of the animal being treated and the "cold" surface of the thermoelectric module 2.

When sub-zero temperatures are to be used, it is generally preferred that cold from the face plate 3 be applied only to those localised areas of the animal where the potentially destructive effects of such temperatures are required, for example in the treatment of skin cancer. This can be effected by the use of a metal face plate 3 having a profiled upper surface with insulation on those areas of the plate which it is desired should not contact the animal, thereby providing a plate 3 with relatively high heat capacity but only a relatively low area of contact of metal portions of the plate with the skin of the animal.

Using the present invention it is possible to produce a temperature differential between the face plate'3 and the coolant in excess of 100C even at sub-zero temperatures. The ability to maintain such temperature differentials can enable limbs to be cooled to desired temperatures, for example the 13 to 18"C range for healing, or to sub-zero temperatures, for example for treatment of skin cancer.

By reversing the polarity of the potential applied to the thermoelectric module 2 and shutting off the pump 14 it is possible to heat the face plate 3. Thus as a result of cooling the coolant using the secondary cooling unit 13 and controlling the voltage applied to the thermoelectric module 2 it is possible to regulate the temperature of the face plate 3 over a very wide range.

Claims (4)

Claims

1. Apparatus for cooling a limb of an animal, the apparatus comprising;(a) a thermoelectric module having opposed surfaces across which a temperature differential can be created using thePeltier effect, one of said surfaces in use being the "cold" surface, and the other of said surfaces in use being the "hot" surface;(b) a heat sink in contact with the "hot" surface of the module for dissipating heat from the "hot" surface;(c) a reservoir of cooling liquid for cooling the heat sink;(d) a pump for circulating cooling liquid from the reservoir to the heat sink; and (e) a refrigeration unit for cooling the cooling liquid.

2. Apparatus according to claim 1, including a thermal buffer for location between the thermoelectric unit and the limb to be treated.

3. Apparatus according to claim 2, including a temperature sensor for sensing the surface temperature of the limb.

4. Apparatus for cooling a limb of an animal, the apparatus being substantially as herein described with reference to the accompanying drawings.