FR2579888A1 - Method and apparatus for regulating the temperature of a coolant fluid to a predetermined temperature level, and utilisation of this method or of the apparatus for producing medical hypo/hyperthermia - Google Patents

Abstract

The invention relates to a method and an apparatus for regulating the temperature of a coolant fluid. This apparatus is characterised in that it comprises heating or cooling elements 8 consisting of thermal elements of the Peltier type 10 formed by the junction of metals of different types disposed in contact exchanging heat with the coolant fluid; a d.c. electrical current cell is connected at least temporarily to each thermal element of the Peltier type 10 via a polarity inverter; temperature detection means 16 detecting the temperature of the coolant fluid and a regulation device supplying the said thermal elements 10 with d.c. and possibly modifying the polarity of the said d.c. delivered to the said thermal elements by acting on the polarity inverter as a function of the value of the temperature detected in relation to the set-point temperature. This apparatus is preferably used for producing medical hypo/hyperthermia.

Description

TEMPERATURE CONTROL METHOD AND APPARATUS
FROM A HEAT-FLUID AT A TEMPERATURE LEVEL
PREDETERHIN, AND USE OF THE SAME OR OF
THE APPARATUS FOR PERFORMING MEDICAL HYPO-HYPERTHERMIA
The invention relates to a method and an apparatus for regulating the temperature of a heat transfer fluid at a predetermined temperature level, as well as to the use of this method or of the apparatus for carrying out medical hypo-hyperthermia.

There are currently known on the market various devices for carrying out medical hypo- and / or hyperthermia, the therapeutic indications of which are generally as follows
- the warming up of those operated on during the intervention and postoperatively
- warming of patients in shock (traumatized, drowned, intoxicated ...)
- the cooling of operated patients taking into account the fact that certain surgeries require a lowering of the patient's temperature then a warming up during or at the end of the intervention (cardiac surgery, neurosurgery)
- cooling hyperthermia resistant to appropriate chemotherapy (intensive care and emergencies)
- cryotherapy localized on painful post-operative wounds, this technique being promised for wide use
- storage of bodies at 4 OC before subsequent obituary treatment (especially in hot countries).

 There are currently small devices constituting heaters, comprising a water tank, a immersion heater intended to heat the water, or external resistors, a thermostat and a pump, so as to convey the water to a device for use, such as a blanket. The price of such small devices is relatively modest, but these devices have the major drawback of providing only a single reheating function, and they can therefore only be used to carry out patient reheating or hyperthermia. These devices cannot be used for cooling patients or hypothermia. Om also knows large devices for heating or cooling a coolant. These devices include control electronics, a water tank with immersion heater, a chiller using a compressor with an exchanger and a circulation pump. These large devices have not been used in practice because their price, weight and size are prohibitive.

 The present invention therefore relates to the new technical problem consisting in providing a solution which makes it possible to heat or cool at will a heat transfer fluid with a particularly simple infrastructure, while being particularly reliable.

 The present invention solves this new technical problem for the first time.

 According to a first aspect, the present invention provides a method of regulating the temperature of a heat-transfer fluid at a predetermined temperature level, called the set temperature, preferably for supplying one or more devices, such as blankets, the function of which is heating or cooling the central or peripheral temperature of a patient, characterized in that one or more Peltier type thermoelements are produced, formed by the junction of a metallic wire of a different nature; said thermo-elements are placed in contact with heat exchanges with said heat transfer fluid; a source of direct electric current is provided which is connected to said thermoelement by means of a polarity reverser; the temperature of the heat transfer fluid, or preferably of said patient, is detected; and the thermoelements are supplied with direct current of a polarity carrying out a thermal release if the detected temperature is lower than the set temperature or of a reverse polarity carrying out a heat absorption if the detected temperature is higher than the set temperature. Preferably, according to a method of the invention, the DC power supply to the thermo-elements is stopped if the difference, measured between the detected temperature and the set temperature, is small, that is to say advantageously does not exceed one or more degrees depending on the precision of the regulation sought. According to a particularly preferred embodiment of the method according to the invention, the aforementioned Peltier type thermoelements are included in dissipators themselves forming a reservoir for the heat transfer fluid. . According to a particularly preferred characteristic, the heat transfer fluid is a liquid, advantageously water. According to a particular embodiment, the heat transfer fluid is glycol water, preferably containing from about 10 to about 30% by weight of glycol. According to yet another characteristic of the process according to the invention, when the starting temperature of the heat transfer fluid is comparatively low relative to the set temperature, at least one immersion element is immersed in the heat transfer fluid, so as to accelerate the heating of the heat transfer fluid, advantageously to bring it to a temperature close to the temperature of The present invention also relates, according to a second aspect, to an apparatus for regulating the temperature of a heat transfer fluid at a predetermined temperature level, called the set temperature, preferably for supplying one or more devices, such as blankets, the function of which is to heat or cool the central or peripheral temperature of a patient, comprising a reservoir of heat transfer fluid, one or more heating or cooling elements of said heat transfer fluid, and preferably a member for circulating said fluid from said tank and from said device to said tank, characterized in that at least some of said heating or cooling elements are constituted by Peltier type thermoelements formed by the junction of metals of different nature arranged in contact with heat exchanges with said heat transfer fluid; a source of direct electric current is connected, at least temporarily, to each thermo-element by means of a polarity reverser; temperature detection means, detecting the temperature of said heat transfer fluid and transmitting to them a regulation device; and a regulating device comprising means for displaying said set temperature, supplying said thermo-elements with direct current, possibly modifying the polarity of said direct current supplied to thermo-elements by acting on said inverter as a function of the value of the temperature detected relative to the set temperature.

According to a particularly preferred embodiment, this device is further characterized in that the aforementioned thermo-elements, Peltier type, are included in the dissipator, themselves forming the reservoir of the heat transfer fluid. According to a particularly preferred embodiment, the device according to the invention comprises a first set of dissipating elements arranged in said reservoir and in contact with the wall of the reservoir, and a second set of dissipating elements arranged outside said reservoir; and in that the Peltier thermo-elements are arranged between said first and second sets of dissipating elements, preferably in openings formed in a heat-insulating intermediate plate. Preferably, the aforementioned first set of dissipating elements is formed by fins, arranged substantially vertically, while the second set of dissipating elements is formed by fins arranged substantially horizontally. As mentioned above, the heat transfer fluid is preferably constituted by water, preferably by water containing glycol. An alternative embodiment, currently preferred, consists in using water containing from approximately 10 to approximately 30%, better still, approximately 20% by weight of glycol.

 The present invention also relates, according to a third aspect, to a use of the method or of the apparatus, previously described, for carrying out medical hypoet / or hyperthermia. Preferably, for this use, the above-mentioned reference value is the desired hypo- or hyperthermia value, and in this case a probe for detecting the patient's temperature is provided. Thanks to the invention, this leads to a great simplification of carrying out the regulation of the temperature of a heat-transfer fluid at a predetermined temperature level, with a device of reduced dimensions, which can be easily used to carry out medical hypo-hyperthermia. . Another advantage lies in the fact that the manufacturing cost of such a device according to the invention is particularly modest. Finally, the operation is particularly simple, while the regulation is also very reliable. Other objects, characteristics and advantages of the invention will appear in the light of the explanatory description which follows, relative to a currently preferred embodiment of the invention, shown in the accompanying drawings, given simply by way of illustration, and which therefore cannot in any way limit the scope of the invention.

In the drawings
- Figure 1 shows a schematic view, partially broken away, partially exploded of the essential part of a first embodiment of an apparatus for regulating the temperature of a heat transfer fluid according to the present invention, according to arrow I in roman numeral from figure 2
- Figure 2 shows an overview of the device, showing in detail the control device
- Figure 3 shows the preferred use of the device which is the subject of Figures 1 and 2 to achieve hypo-hyperthermia of a patient, schematically representing a device, such as a blanket, whose function is to heat or cool a patient's central or peripheral temperature.

 With reference to FIGS. 1 to 3, an apparatus according to the invention for regulating the temperature of a heat transfer fluid at a predetermined temperature level, known as the set temperature, is represented by the general reference number 1. This apparatus is provided preferably to supply one or more devices, such as blankets designated by the general reference number 2 in FIG. 3, the function of which is to heat or cool the central or peripheral temperature of a patient.

 This device comprises, in a manner known per se, a reservoir 4 of heat transfer fluid 6, one or more heating elements 8 or cooling of the heat transfer fluid 6 and preferably a member 50 for circulating said fluid, said reservoir #, said device 2 and from said device 2, to said reservoir.

 This device is characterized according to the invention in that at least some of said heating or cooling elements 8 are constituted by Peltier type thermoelements 10, represented in FIG. 1 and which are formed by the junction of metals of different nature. These Peltier type thermo-elements are arranged in contact with heat exchanges with the heat transfer fluid 6, as is clearly understandable from FIG. 1 in particular.

 This device also comprises a source of direct electric current, represented by the general reference number 12 in FIG. 2, which is connected, at least temporarily, to each thermoelement 8, by means of a polarity reverser 14.

 This apparatus further comprises temperature detection means 16, detecting the temperature of said fluid, and transmitting it to a regulation device, represented by the general reference number 18 in FIG. 2. This regulation device 18 supplies direct current said Peltier type thermo-elements 10, and optionally modifies the polarity of said current delivered to said thermo-elements by acting on the polarity reverser 14 as a function of the value of the temperature detected by the detection means 16 relative to the temperature of instructions.

 According to a preferred embodiment, concerning the use of the apparatus according to the invention for carrying out medical hypo-hyperthermia, the set value is the desired value of hypothermia or hyperthermia and the apparatus further comprises a probe 20, shown schematically in FIG. 2, for detecting the patient's temperature.

 According to a currently preferred embodiment, the Peltier thermo-elements 10 are included in the dissipators 22, 24 and 26, 28, respectively, as clearly visible in FIG. 1, themselves forming the reservoir 4 of heat-transfer fluid. According to the embodiment shown, the Peltier thermo-elements 10 are arranged in openings 30 which can be through, formed in the side walls, such as 32, 34 of the reservoir 4. According to the embodiment shown, currently preferred, the apparatus according to the invention comprises a first set of dissipating elements 22, 26, arranged in the reservoir 4 and in contact with the wall of the reservoir, and a second set of dissipating elements 24, 28, arranged outside of said reservoir 4, while the Peltier thermoelements 10 are arranged between said first and second sets of dissipating elements, as is clearly visible in FIG. 1. According to this same embodiment, currently preferred, the dissipating elements 22, first set of elements, comprise a plurality of fins 23, arranged for example substantially vertically and joined together on a common sole constituting the side wall 32 of the tank. struction is identical for the dissipating elements 26, comprising fins 27, joined on a common sole 34, constituting the opposite vertical side wall of the tank. On the other side of this vertical wall 32 or 34, there is preferably a heat-insulating plate 36, 38, comprising openings such as 40, into which the Peltier thermo-elements 10 are inserted individually.

 It should be noted that the dissipating elements 24, 28, external to the reservoir 4, also consist of fins or plates joined together to a common support element 42, 44, respectively arranged here preferably laterally relative to the plates.

But a plate forming the sole can join these fins or plates. These fins are preferably arranged perpendicular to the internal fins, that is to say, here, horizontally. Additional thermo-heating elements can be provided, incorporated in all the walls of the tank which, here, have a substantially parallelepiped shape.

 According to another characteristic of the invention, the heat transfer fluid is preferably formed by a liquid, more preferably by water. In a completely preferred manner, this heat transfer fluid is water containing glycol, preferably with a glycol content of between approximately 10 and approximately 30% by weight, and better still, approximately 20% by weight. .

 According to yet another characteristic of the apparatus according to the invention, it comprises an additional heating element, called a thermal immersion heater 46, immersed in the fluid 6, for example by means of an orifice 48, disposed on the upper face of the reservoir 4, and used for rapid heating of the heat transfer fluid. This immersion heater 46 is preferably disposed substantially in the center of the tank.

 The apparatus according to the invention also comprises a pump 50 symbolized in FIG. 2 and visible in FIG. 3 of the circulation of the heat transfer fluid between the reservoir 4 and the device 2, such as a cover. There is also advantageously provided with a fan 52, preferably centrifugal at high flow rate, expressing the calories or the frigories dissipated by the thermoelement assembly 10.

 The electrical and / or electronic supply diagram is shown in detail in Figure 2.

This comprises a conductive wire 60 connected to earth and two alternating current supply wires 62, 64.

A general protection 66 and a general switch 68 have been provided on wire 62. An indicator 70 for energizing the entire apparatus is provided. An indicator 72 for energizing the pump 50 is also provided.

These wires 62, 64 supply a transformer 74, supplying a diode bridge 76, so as to obtain the direct current source 12. There is provided in parallel on this diode bridge, respectively, a very low voltage circuit protection 78 and a capacitor 80 according to the structure shown in FIG. 2. The polarity reversal device 14 is disposed between the positive and negative poles at the output of the diode bridge 76 which supply the Peltier thermo-elements 10 by conducting wires 82, 84 , on which are provided power relays 86, 88 and indicators 90, 92 respectively forming a hot indicator and a cold indicator.

The thermo-heating elements 44 are supplied with alternating current by means of a particular regulation device 96 reacting to the temperature value detected by the detection device 16. On the other hand, the electronic regulation device 18 is conventional . It has connection or contact points 102 to 106 and two connection points A, B, conductor wires of the immersion heater 46. The particular structure of the thermo-elements
Peltier 10 is of any type known per se. In general it is a succession of welds between wires end to end in two different conductive materials, more particularly in metals of two different natures.

 The operation of such an apparatus conforms to the method described above and is particularly simple.

 For example, a temperature setpoint to be reached is displayed on the electronic regulating device 18 after switching on by the general switch 68. Depending on the temperature value detected, either on the patient by the probe 20, or heat transfer fluids by the probe 16 through an orifice 8, disposed on the upper face of the tank 4, or both, we act on the polarity reverser 14 so as to deliver a direct current of polarity suitable for the thermo-element Peltier 10, so as to heat the coolant if the detected temperature is lower than the set temperature, or absorbing heat if the detected temperature is higher than the set temperature. Thus, regulation is obtained in a particularly simple manner. We can reach a cold power of at least 300 Watts which allows to reach negative temperatures necessary for example for the conservation of bodies. The temperature reduction can be 10 OC in 15 minutes from 41 OC.

 On the other hand, it is easy to heat the heat transfer fluid and to warm patients, such as operated patients. In general, hypothermia or medical hyperthermia can be carried out, which constitutes the preferred use or application of the installation according to the invention.

 Naturally, the invention can be modified at will. Thus, the invention includes all the means constituting the technical equivalents of the means described as well as their various combinations.

Claims (12)

 1. Method for regulating the temperature of a heat transfer fluid at a predetermined temperature level, called the set temperature, preferably for supplying one or more devices, such as blankets, the function of which is to heat or cool the central temperature or peripheral of a patient, characterized in that one or more thermo-elements formed by the junction of a metal wire-of different nature are produced; said thermoelements are placed in contact with heat exchanges with said heat transfer fluid; a source of direct electric current is provided which is connected to said thermo-element by means of a polarity reverser; the temperature of the fluid, or preferably of the patient, is detected and said thermo-elements are supplied with direct electric current of a polarity producing thermal release if the detected temperature is lower than the set temperature, or of a reverse polarite performing heat absorption if the detected temperature is higher than the set temperature. #  2. Method according to claim 1, characterized in that the DC power supply is stopped if the difference between the detected temperature and the set temperature is relatively small.  3. Method according to claim 1 or 2, characterized in that the aforementioned thermo-elements are included in dissipators themselves forming the reservoir of the heat transfer fluid.  4. Method according to one of claims 1 to 3, characterized in that the aforementioned heat transfer fluid is a liquid, preferably water containing glycol or even preferably at a content between about 10 and about 30% in weight.  5. Apparatus for regulating the temperature of a heat transfer fluid (6), at a predetermined temperature level, called the set temperature, preferably for supplying one or more devices (2), such as blankets, the function of which is heating or cooling the central or peripheral temperature of a patient, comprising a reservoir (4) of heat transfer fluid, one or more elements (8) for heating or cooling said heat transfer fluid and preferably a member (50) for circulation of said fluid from said reservoir to said device and from said device to said reservoir, characterized in that at least some of said heating and cooling elements (8) are constituted by Peltier type thermo-elements (10) formed by the junction of metals of nature different, arranged in heat exchange contact with said heat transfer fluid; a source of direct electric current (12) is connected at least temporarily to each thermoelement (10) by means of a polarity reverser (14); temperature detection means (16) detecting the temperature of said fluid; and a regulating device (18) supplying direct current to said thermo-elements (10) and possibly modifying the polarity of said direct current supplied to said thermo-element (10) by acting on said inverter (14) as a function of the value of the temperature detected relative to the set temperature.  6. Apparatus according to claim 5, characterized in that the aforementioned Peltier type thermo-elements (10) are included in dissipators (22,24,26,28) themselves forming the reservoir (4) of the heat transfer fluid.  7. Apparatus according to claim 6, characterized in that the Peltier thermo-elements are arranged in openings (30 or 40) formed in the side walls (32 or 34) of the coolant tank.  8. Apparatus according to claim 6 or 7, characterized in that it comprises a first set of dissipating elements (22,26) disposed in said tank and in contact with the wall (32,34) of the tank, and a second set of dissipating elements (24,28) disposed outside the tank while the aforementioned Peltier thermoelements (10) are arranged between said first and second dissipating assemblies, preferably in openings (40) formed in an intermediate plate ( 36.38) thermal insulation.  9. Apparatus according to one of claims 5 to 8, characterized in that the aforementioned heat transfer fluid is a liquid, preferably water containing a glycol and more preferably containing from about 10 to about 30% by weight of glycol.  10. Apparatus according to one of claims 5 to 9, characterized in that it comprises a heating element called immersion heater (46), immersed in said heat transfer fluid and used for rapid heating of the heat transfer fluid, preferably disposed substantially in the center of the tank.  11. Use of the device according to any one of claims 5 to 10, for carrying out medical hypohyperthermia.  12. Use according to claim 11, characterized in that the set value is the desired hypothermia or hyperthermia value and the device comprises a probe (20) for detecting the patient's temperature which is transmitted to the device regulation (18).