US 3051180 A
Description (OCR text may contain errors)
Aug. 28, 1962 J. ADAMSAY ETAL 3,051,180
BODY TEMPERING APPARATUS Filed July 31. 1959 2 Sheets-Sheet 1 /N vENm/es JACK ADAMSRAY P54 08mm PERSSON ATTY- 1962 J. ADAMS-RAY ETAL 3,051,180
I BODY TEMPERING APPARATUS Filed July 31. 1959 2 Sheets-Sheet 2 United States Patent Ofiice 7 3,051,180 Patented Aug. 28, 1952 3,051,180 BODY TEMPERING APPARATUS Jack Adams-Ray and Per-Oskar Persson, Stockholm, Sweden, assignors to Richard Magnus Kinda] Filed July 31, 1959, Ser. No. 830,775 Claims priority, application Sweden Dec. 3, 1954 4 Claims. ((11. 128-373) This application -is a continuation-in-part of our application Serial No. 549,811, filed November 29, 1955 and now abandoned.
The invention relates to an apparatus for lowering the temperature of a human body, a form of treatment which is called hypothermia and is used considerably in many fields of medicine. Surgeons and internal specialists claim encouraging results from its application to heart and cranial operations, shock treatments, attacks of poisoning, etc. Recently, encouraging results have also been reported from its use in treating sunstroke in the Middle East. The use of hypothermia hitherto has been limited by the inadequate resources at disposal.
Heretofore, in order to bring about hypothermia, ice water or cooling pads with a circulating fluid have in general been used. Both of these methods, as well as the process whereby the patients blood is cooled by an external apparatus, have certain disadvantages.
.An object of the present invention is to provide an apparatus which makes it possible to lower the temperature of a human body in its entirety by means of which an accurate and quick functioning control of temperature is possible, while inconveniences heretofore known are avoided.
Another object of the invention is to make it possible to control the body temperature at a certain level a desired length of time after it has been lowered.
The novel features that are considered characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment when read in connection with the accompanying drawings, wherein like reference characters indicate like parts through the several figures, and in which 5 FIG. 1 is a side view, partly in section, of a body temperature-controlling apparatus according to the invention provided with a support for a patient.
- FIG. 2 is an end view of the apparatus shown in FIG. 1.
FIG. 3 is a schematic circuit diagram of the apparatus shown in FIGS. 1 and 2 for controlling the temperature of ahuman body.
' As shown in the drawings, the apparatus for lowering the/temperature of a patients body comprises a lower portion and an upper portion 11. The upper portion 11 has removable wall members 12, -13 of semi-circular form as best shown in FIG. 2. Portion 11 is of a length to accommodate the entire body of a person, and is fitted with removable arch-like top members 14 made in separable sections preferably of a transparent material, such as acrylonitrile plastics, so that the patient can be constantly observed from outside. Any one of the top sections 14 can be removed so that the patient can at all times be reached for treatment. The top sections 14 can be made of double thickness to obtain better insulation. When one top section 14 is removed, for example for anoperation, a transparent adhesive plastic film is attached to the edges of the remaining adjacent top sections 14 and the top edges of the lower section 10 in order to restore the flow path for the air within the apparatus. The adhesive film is further suitably attached to the skin of the body just over and around the place where the operation is to be performed. When starting the operation, the surgeon cuts through the plastic film and the skin simultaneously. The plastic film is not removed until the operation is finished and the surface around the cut remains sterile all the time.
Directly beneath the removable top members 14 is mounted a support 15, preferably of a rustproof material such as stainless steel, on which a patient may lie while undergoing treatment. The support 15 has a longitudinally slidable upper member 16.
The space 17 for the patient in the upper portion 11 is separated from the space 18 within the lower portion 10 by a wall 19 having openings 20 and 21 so that a current of air may be circulated through the system by a circulating fan 22 driven by a motor 23 which can be regulated to provide an air flow at different speeds. The fan 22 draws in air from the space 17 and forces the same to circulate in the system. Some fresh air might, of course, be added and used. This makes possible the exposure of the entire body of the patient to the flowing air, whereby a very effective heat transfer to or from the patient is made possible.
Experience has shown that following the cooling of a human body for medical treatment or operation, it is necessary to heat the body effectively to a temperature just below that normal for the body before again allowing the regulation of the temperature to be effected by the individuals own natural system.
The body temperature-controlling apparatus is particularly suitable for this type of heating, but it has proved itself invaluable also in other respects connected with effective heat transfer. To a greater extent it is possible to regulate the patients body temperature, both higher and lower, to the desired degree, as for instance +20, +25, +30 C.
In order to control the temperature of the air circulating in space 17, the lower portion 10 is equipped with a cooling means 24 and a heating element 25 which can be of relatively high capacity so that, if found necessary, a very high rise in temperature of the patient can be brought about quickly. The cooling means 24 may comprise a coil connected to a refrigerating apparatus (not shown).
The support 15 is mounted on brackets 26 and provided with transversely tilting means 27 which form part.
of a hydraulic system (not shown). This system is preferably also used with a piston in a cylinder 31 intended for longitudinal tilting of the apparatus, which is mounted on an axle 28 on a frame 29 having supporting wheels 30.
The temperature in the space 17 is regulated by thermostats, and this regulation can be fully automatic so that the person in charge of the body temperature control has only to set the desired body temperature on a dial (not shown) at an instrument panel 32. The apparatus control means include a number of thermometers, not shown, on which can be read from outside the space 17 air temperature within the space as well as diflFerent body temperatures, that is, temperatures at different points inside and outside the body. A regular hygrorneter can be used to measure the humidity in the space 17. All temperatures may be Written down by a writing instrument on a paper strip.
Because of the perspiration of the human body, it
space 17 or into the air circulation system. On the other hand, it might occasionally be desirable to provide a lower relative humidity in the space than that attained by cooling alone. To reduce the humidity under such conditions, it is only necessary to supply electric heat simultaneously with the cooling.
During time-consuming operations or long medicinal use of the apparatus, it is necessary at times to keep constant the patients body temperature. With the apparatus of this invention, this can easily be done by resorting to the use of a contact thermometer to serve as the sensitive body of a thermostat. At rising body temperature, the air temperature in the space should be lowered; and when the body temperature of the patient becomes too low, the air temperature in the space should be raised.
Regulation of the temperature in the space 17 and more particularly within the body can be accomplished with the equipment diagrammatically indicated in FIG. 3, which is connected, for example, to a main electric circuit 33. For cooling the air, a compressor-driven cooling apparatus (not shown) is used, the motor 34 of which is connected to the circuit 33 over a switch 35 and regulated by means of a relay 36, and the air may conveniently be heated by means of electric elements 37 which are controlled by a switch 38 through a relay 39. The refrigerating means can be operated also by a manually operable switch 40 and the heaters by another manually operable switch 41. These switches 41 and 41 are suitably arranged at the instrument panel 32. By means of conductors 42, '43-, 44 and 45, 46, 47 respectively, relays 36 and 39 are joined in parallel in an electric circuit 48, 49, 50, 51 connected to the main circuit voltage or other easily available source of current, such as a battery. In each of the parallel conductors, a thermostat 92 and 93 is connected having sensitive bodies 95, 94, respectively, located in the space 17. Sensitive body 94 controls the minimum temperature, and sensitive body 95 controls the maximum temperature. In other words, the thermostat 92 with its bulb 94 controls the cooling of the air between two temperature limits, whereas the thermostat 93 with its sensitive bulb 95 controls the heating of the air between two other temperatures. The third thermostat 52 decides whether the heating circuit or the cooling circuit shall be operable at the moment.
In order to achieve an automatic regulation of the body temperature by means of the air in the space 17, the patients body temperature is used to regulate or control the operation of the apparatus. This is accomplished by using a body thermometer modified to serve as the sensitive member of a body thermostat 52, part of which can be inserted in the rectum of the patient or in the armpit, and works in such a way that the mercury column 53 moves in the same manner as in a thermometer in a glass tube 54. However, this glass tube has conductors 55, 56 embedded in it and connected to switch points 57, 58. When the temperature in the body rises to a certain level, an electric circuit is completed by means of these two conductors 55, 56, and it is this connecting and disconnecting function of the body thermostat 52 which is used to automatically regulate the temperature in the space 17. Other types of contact thermometers are known which can be inserted like a needle into some desired point within the body and serve the same purpose as the mercury thermometers mentioned.
The contact thermometer can stand only very weak currents, and for that reason an electronically controlled relay is used.
By means of the two conductors 55, 56, the body thermostat 52 is connected at 57, 58 to a three-way selector switch 59 provided with a movable arm 60. The arm 60 is connected at terminal 61 to a conductor 62 connected in turn to the grid 63 of an electronic tube 64. The movable arm 60 can be connected with contact point 57 or 58 or with a third contact point 65.
A transformer 66 is used to obtain suitable voltages for the electronic tube 64 and an electromagnet 67 depending on the tube conditions. The primary winding 71 of the transformer 66 is connected to the main circuit 33 by conductors 68, 69 and 70. The secondary Winding forms two parts '72 and 73. The winding 72 is connected in series with the tube 64 and the electromagnet 67 by conductors 74, 75. A point 76 at the secondary winding between the parts 72 and 73 is connected to ground by conductor 77.
A conventional filter circuit consisting of diode 100 and condensers 101, 102 is connected between conductors 77, 75 to provide DC. voltage to operate tube 64.
The winding 73 is connected to the heating filament 78 by conductors 79 and 80, the other end of which is connected to conductor 77 and ground. Conductor 79 is also connected to switch point 57 over a resistance 81 by conductor 82. Between conductors 82 and 62 a condenser 83 is connected. The conductor 74 is connected to the anode 84 of the tube 64. Electromagnet 67 controls a contact member 85.
The operation and function of the device are as follows:
(1) When the switch arm 60 is set to engage contact point 65, the body thermostat 52 will be disconnected. The contact member 85 will be held by gravity, or still better, by a spring (not shown) in its lower position in which the heating element 37 is connected to the main circuit 33 by means of conductors 48, 49, 45, 46, 47, 50, S1.
The air in the space 17 is heated to the temperature to which the maximum thermostat is set and is thereafter maintained at approximately that temperature and within the range of this thermostat. This range can vary approximately 2 C. without causing any harm to the patient.
(2) When the switch arm 60 is set to engage contact point 57, the body thermostat 52 is still disconnected but a circuit is completed through conductors 82 and 62. The low voltage will now pass through the tube 64 and give rise to a higher voltage passing the tube for lifting the contact member 85. The cooling circuit 48, 49, 42, 43, 44, 50', 51 is in function and dependent upon the thermostat 94. The temperature of the air in the space 17 is then lowered to a fixed limit, and the minimum thermostat 94 maintains a constant temperature within the range of the thermostat, which range may vary approximately 2 C.
(3) When the switch arm 60 is set to engage the third contact point 58, the body thermostat 52 will be connected through conductors 55, 56. If the body temperature is low, as shown in FIG. 3, the mercury '53 does not reach the contact 56 and the contact member 85 will be in its lower position to close the circuit through conductors 46 and 47, which means that the heating section is operative and is dependent upon the thermostat 95; At a higher body temperature, when the mercury in body thermostat 52 reaches contact '56, the contact member 85 will be lifted and only the cooling section will be in operation. Thus the air temperature in the space 17 is controlled by the body temperature itself.
-The method for regulating the temperature described above under (3) has been used, among other things, to maintain the patients body temperature as constant as possible, especially when keeping a patient in the treating chamber or space 17 a long time. The patient is commonly under narcosis when treatment starts.
It is simple to arrange the apparatus so that when the mercury column in the body thermostat 52 does not reach the contact point 56, that is, the temperature in the body is too low, the heating element 37 is connected to raise the temperature of the air in the space 17; and, conversely, when the mercury reaches the contact point 56', that is, the patients temperature is too high, the cooling machine 34 is energized to lower the temperature of the air in the space 17. However, the great heat capacity of the patients own body must be taken into consideration. This heat capacity is such that if the body thermostat 52 should call for a lower temperature and the cooling machine starts to work, the air temperature would be too low before any noticeable change would take place in the body thermostat 52. The result would be great changes in the air temperature and of the body surface, which is not desirable and might even be dangerous. A better result is obtained when limits are set for the lowest and the highest temperatures which the air may assume. According to the invention, this better result is obtained when the body thermostat 52 is combined with the thermostats 94 and 95, which are used as minimum and maximum thermostats, respectively.
If, for example, the body thermostat 52 calls for colder air, the cooling apparatus 34 is started but works only until the temperature set on the minimum thermostat 94 is reached. The same applies to warm air when the maximum thermostat 95 serves as a limitation thermostat. Assuming, for example, that the body thermostat 52 is set at +28 C. and that it calls for colder air, then the minimum thermostat 94 can be set at +20 C., which will signify that during the entire period which the body thermostat 52 calls for a lower air temperature, the temperature of the air will drop but not lower than to +20 C. When the body temperature has dropped below +28 C., the body thermostat 52 will call for a warmer surrounding, the heating element 37 is connected and will heat the air to the temperature set on the maximum thermostat 95, say for example, +30 C. This temperature is thereafter maintained until the body temperature has again climbed to |28 C., when a new cooling period begins.
It is not possible to achieve as quick changes in temperature of a patient by this method as by the method of submerging the patient in an ice bath (or in hot Water), but, on the other hand, quicker cooling can be effected without giving the patient a number of ice blisters. There are also advantages to being able to obtain necessary heating and cooling by the same apparatus. During a long operation on a patient, it is advantageous to be in a position to provide the patient with any specific body temperature that circumstances may dictate. This is not possible with any other known means.
The invention is not to be limited to the exact structure and operation of the parts as shown and described, since these can be changed in many ways without departing from the spirit of the invention.
Having described our invention, we claim:
1. Cabinet with an apparatus for lowering the body temperature of a human body comprising a space for the patient separated from the ambient atmosphere, said space forming part of a path of flow for air, means for circulating the air, a heating means and a cooling means for the air, means for supporting the patient arranged in said space so that the entire body area can be brought in contact with the air, means for regulating the heat transfer at the body surface by members for controlling the temperature difierence between the body and the circulating air, means for regulating the heat transfer at the body surface by members for controlling the heat transmission coefiicient by changing the air velocity, a body contacting thermostat which is responsive to the body temperature of the patient, means actuated by said thermostat for selectively energizing the heating means and the cooling means in dependence on the body temperature, a second thermostat for controlling the heating means connected in series with a first relay having contacts in a first main circuit containing the heating means, and a third thermostat for controlling the cooling means connected in series with a second relay having contacts in a second main circuit containing the cooling means.
2. A body temperature controlling apparatus comprising a cabinet having a first space for receiving the entire body of a patient and defining part of a path for the flow of air, said cabinet having a second space defining the other part of the path for the flow of air, heating means and cooling means in said second space, fan means in said second space for producing a flow of air across said heating means, said cooling means and said patient in the path including said spaces while said patient is in said first space, main circuit means including first and second circuits in parallel relationship and a low voltage control circuit, a first thermostat mounted in said first space for controlling said heating means at a first adjustable temperature of the air, said first thermostat and heating means being connected in said first circuit, a second thermostat mounted in said first space for controlling said cooling means at a second adjustable temperature of the air, said second thermostat and cooling means being connected in said second circuit, a third patient body contacting thermostat responsive to the body temperature of the patient, said third thermostat being connected in said low voltage control circuit, and an electronic tube having a grid and an electromagnet connected in said low voltage control circuit, said third thermostat being operatively connected to said grid to control operation of said electronic tube in correspondence to the fluctuations of the body temperature of said patient, said electromagnet having contacts to connect said first circuit to a supply circuit to energize said heating means when the temperature of the body of said patient is below the desired temperature and to connect said second circuit to said supply circuit to energize said cooling means when the temperature of the body of said patient has raised above the desired temperature.
3. A body temperature controlling apparatus according to claim 15 in which a three position switch is connected in said low voltage control circuit between said third thermostat and grid, one position of said switch maintain-ing said electromagnet operated to maintain said second circuit and said cooling means energized, the second position of said switch operatively connecting said third thermostat to said grid, the third position of said switch maintaining said first circuit and said heating means energized.
4. A body temperature controlling apparatus according to claim 2 in which said first space of said cabinet has transparent removable wall sections in which one of said wall sections can be replaced by a flexible plastic member adapted to be placed on the portion of the body of said patient which is to be treated.
References Cited in the file of this patent UNITED STATES PATENTS 1,466,652 Batter Aug. 28, 1923 2,002,235 Morrison May 21, 1935 2,098,316 Sittler Nov. 9, 1937 2,223,669 Forshee Dec. 3, 1940 2,243,999 Chapple June 3, 1941 2,353,536 Abbott et a1 July 11, 1944 2,817,340 Cuvier Dec. 24, 1957 FOREIGN PATENTS 1,148,463 France Dec. 10, 1957 OTHER REFERENCES 1937 Reprint, Fever Therapy Induced by Conditioned Air in American Society of Heating & Ventilating Engineers, page 4 of Reprint. (Copy in 128-373.)