WO1999012608A1

WO1999012608A1 - Apparatus and method for the generation of heat

Info

Publication number: WO1999012608A1
Application number: PCT/SE1998/001616
Authority: WO
Inventors: Daniel Larsson; Thomas Lundeberg
Original assignee: Cefar Medical Ab
Priority date: 1997-09-11
Filing date: 1998-09-11
Publication date: 1999-03-18
Also published as: SE9703285L; AU9193798A; SE511201C2; SE9703285D0

Abstract

The invention relates to an apparatus and a method for pulsed heat stimulation of an arbitrary part (9) of the body, whereby the heat stimulation being applied to said body part (9) at an arbitrary heat stimulation temperature has a frequency varying between 0.1 Hz and 20 Hz. Due to this heat stimulation frequency, a very efficient pulsed heat stimulation is accomplished in order to achieve as high a signal generation in the nervous system as possible.

Description

APPARATUS AND METHOD FOR THE GENERATION OF HEAT

FIELD OF THE INVENTION

The present invention relates to an apparatus as well as a method for pulsed heat stimulation of an arbitrary part of the body.

STATE OF THE ART

The use of heat for stimulating and anaesthetising a part of the body is previously known. By transferring heat to the part of the body to be treated, various pain- relieving and anaesthetising substances are released in said part of the body. The heat transfer furthermore causes a softening and massaging effect in the part of the body to be treated.

Consequently, there is a great interest among doctors, specialists in acupuncture, masseurs, etc. in using this stimulation effect from heat when treating patients. During a preliminary investigation performed in order to determine what is known within the above heat stimulation technique, the following documents were found.

CN 1079672 This document describes acupuncture with a "photon needle". The complete patent publication is only available in

Chinese. US 3 938 526 The document describes an electrical heater for acupuncture needles. SU 1553-126 The document describes how a laser is used as an energy source and how needles are used in acupuncture. US 5 250 068 The document shows acupuncture with a needle connected to optical fibres. The needle conveys light or heat to that part of the body where it is introduced.

In the above documents, the heat is applied continuously to the part of the body to be treated.

In the paper "Clinical Efficacy of Electrical Heat Acupuncture", American Journal of Acupuncture, Vol. 21, No 1, 1993, a method is described where electrical, intermittent heat acupuncture is used to efficiently reduce tension in the spinal stretching muscle. This method uses intermittent heat stimulation at 47°C with a periodic interval of 30 seconds. The heat is thus transferred to the part of the body to be treated during 15 seconds, whereupon the heat is switched off and the body part is allowed to rest for 15 seconds, etc. This intermittent heat stimulation produces an improved sensorial stimulation effect than does continuous heat stimulation. However, it has been empirically proved, that the treated part of the body is quickly adapting to this prolonged intermittent time interval of 15 seconds of heat stimulation and 15 seconds of rest, respectively, which entails a deteriorated senso- rial stimulation of said body part. This low frequency of heat supply tends to be perceived by the part of the body under treatment as being continuous, which leads to a fading away of the therapeutical effect of the sensorial stimulation.

Accordingly, an object of the present invention is to solve this problem and to provide a very efficient, pulsed heat stimulation in order to achieve as large a signal generation in the sensorial nervous system as possible.

SUMMARY OF THE INVENTION

The above object is accomplished by the provision of an apparatus and a method for pulsed heat stimulation of an arbitrary part of the body where the heat stimulation being applied to said body part at an arbitrary heat stimulation tempera- ture, has a frequency varying between 0.1 Hz and 20 Hz (cycles/second).

In order to further enhance the effect of the sensorial stimulation, the pulsed heat stimulation may, at an arbitrary predetermined frequency, be given intermittently to an arbitrary part of the body during an arbitrary period of time.

Further characteristics of the present invention are given in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of embodiments of the invention will be given below, with reference to the accompanying drawings. Fig. 1 shows an apparatus for active heating and passive cooling, respectively, of an arbitrary part of the body; Fig. 2 shows an apparatus for active heating and active cooling, respectively, of an arbitrary part of the body; Fig. 3 shows another apparatus for active heating and active cooling, respectively, of an arbitrary part of the body; and Fig. 4 shows a different embodiment of the apparatus of Fig. 3.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Accordingly, the invention relates to an apparatus and a method for pulsed heat stimulation of an arbitrary part of the body. We have found empirically, that a supply of heat to the part of the body to be treated, which has a frequency within the range of 0.1 Hz to 20 Hz, will not allow the body part to get used to the sensorial stimulation, entailing an enhancement of the therapeutical effect. Heat receptors in the body have a maximum firing speed of about 10 Hz. In order to achieve maximum pulsed heat stimulation (maximum signal generation in the nervous system) a heat stimulation frequency of about 10 Hz must be regarded as optimal and especially preferable. However, we have found empirically, that frequencies as low as 0.1 Hz can be used. As the frequency increases from 0.1 Hz, the sensorial stimulation also increases, and thereby the therapeutical effect. Thus, it has been empirically shown that the limit for adaptation to the sensorial stimulation lies at 0.1 Hz.

Heat generated by a thermode (heat electrode), apart from its muscle-relaxing effect, also has an anxiolytic (calming) effect. This effect is most pronounced and clean (i.e. without any dominant influence on the fibres conveying heat) at a local temperature of about 38-41°C. In a comparison between continuous and pulsed heat, it has been found that the effect is more pronounced for pulsed heat, and that the reason for this is that local adaptation is thereby avoided. The maximum activation frequency for the individual heat receptor is about 6 Hz; thus higher pulse frequencies do not achieve any improved effect (at constant temperature stimulation).

When receptors conveying higher temperature heat ("painful heat") are activated, a pain-relieving, circulation-increasing and anti-inflammatory effect is observed. The latter two effects can be achieved without a sensation of pain, pro- vided the stimulation is pulsed and held at a temperature of 42-43 °C. For the latter stimulation, frequencies corresponding to 2 Hz or lower would be preferable. The effect of activation of heat receptors can be attributed to a release of transmitter substances like e. g. Calcitonine Gene-Related Peptide (CGRP) from heat receptors in the peripheral tissue. The effect is not only obtained locally, in the stimulated tissue, but also in deeper lying structures due to axon reflexes, dorsal root reflexes and somato-visceral reflexes.

In the different embodiments shown in Figs. 1-4, control electronics 1 is used to control the heat pulsing frequency in the various electrodes 2, 3, 10, 13. These electrodes 2, 3, 10, 13 are applied to the skin area/body part 9 to be treated and are heated by means of control electronics 1 at a frequency preferably varying between 0.1 Hz and 20 Hz. Consequently, the body part 9 is supplied with pulsed heat with a frequency varying within said frequency interval.

In order to further increase the therapeutical effect of the heat stimulation, the pulsed heat may be supplied intermittently to the body part 9. As an example, pulsed heat is supplied with a frequency of 10 Hz to the skin area/body part 9 during a period of time of 10 seconds. The pulsed heat is then removed from said skin area/body part 9 during a period of time of 10 seconds, etc. In this case, the intermittent stimulation period and the pause period of time, respectively, are both 10 seconds. It is of course to be understood that these intermittent stimulation intervals can be varied arbitrarily. Neither must the intermittent stimulation period be of the same length as the intermittent pause period. The pulsed heat supplied to the skin area/body part 9 may e.g. be applied to a surface similar to TENS electrodes (Trans- cutaneous Electrical Nerve Stimulation), which have an area of about 3x5 cm and 5x 10 cm².

Fig. 1 shows an apparatus comprising control electronics 1, an electrode 2 and the skin area/body part 9 to be stimulated. This device utilises active heating of a heating element in the electrode 2 and passive cooling of said element. Passive cooling means that the element is cooled by its environment when the current heat- ing the element is switched off or reduced. For example, the electrode 2 may use a Kapton element. The Kapton element in the electrode 2 comprises a resistive loop being heated by a pulsed voltage from the control electronics. A voltage pulsing of about 10 Hz means that the Kapton element is actively heated 10 times per second, and that the element in the electrode 2, between the pulses, i.e. 10 times per second, is cooled by its environment. The pulsation frequency of the voltage is preferably varied between 0.1 Hz and 20 Hz. It is of course to be understood that also lower and higher frequencies may be used by the Kapton element of Fig. 1. It has been empirically found, with the different embodiments according to Figs. 1-4, that the selected voltage difference between a voltage maximum and a voltage minimum in the element is sufficient for generating a corresponding temperature difference, which by the treated patient is perceived as pulsed heat. The heating element used in the electrode 2 should have as little mass as possible. A low mass of the element ascertains that it will not be "sluggish" in regard to quick temperature changes. Compare for example an aluminium foil that is scalding hot in the oven but will be at room temperature "instantly" outside the oven.

Fig. 2 shows an apparatus comprising control electronics 1, an electrode 3 with an element that is actively heated and actively cooled. The electrode 3 is applied to the skin area 9 and is heated and cooled actively by the control electronics 1. The electrode/element 3 thus lies in close contact with the skin area 9 when the electrode 3 is actively heated and cooled, whereby the electrode actively heats and cools, respectively, the part of the body closest to the skin area 9. An example of such an element heating and cooling the electrode 3 is a Peltier element.

Generally, it can be stated that when connecting a Peltier element to a DC source, it will act like a heat pump and may be used for heating and cooling. The element uses the Peltier effect. The hot side can be cooled by a heat exchanger. Common applications are cooling/heating of laser components, fibre optics, floppy disks and hard disks, food and beverages. Correct mounting is important and the most common one is a mechanical mounting between a heat exchanger and the cooled object. Thermal grease may be applied to both sides of the element. By the invention, it is preferred to use wiring between the control equipment (not shown) and the element/electrode 3, and control electronics 1 for reversing the voltage polarity to achieve switching between hot and cold.

Figs. 3 and 4 depict an apparatus using an electrode 10, 13 comprising two elements 7, 8, 1 1, 12, of which one element 8, 12 is hot and the other element 7, 11 is cold. Both elements 7, 8, 1 1, 12 move e.g. up and down in cylinder arrangements 5,6 in the electrode 10, 13, as may be understood from the two-way arrows. The elements 7, 8, 11, 12 are alternately in contact with the skin area 9 and will thus actively cause cold and heat, respectively, in the part of the body closest to the skin area 9. The elements 7, 8, 11, 12 may be e.g. mechanically moved close to the skin area 9 or away from the skin area 9, by means of a motor. This will furthermore cause a certain mechanical stimulation in the part of the body closest to the skin area 9.

Fig. 3 shows the elements 7, 8 brought into contact with different locations of the skin area 9. Fig. 4 shows the elements 1 1, 12 brought into contact with the same location of the skin area 9.

The above could be compared to having an ice cube in one hand and a heated ball in the other hand, and then alternately touching the skin with the ice cube and the heated ball at the same spot. The embodiments according to Figs. 3 and 4 can easily achieve a heat stimulation frequency of 20 Hz.

What has been described above is only to be taken as preferable embodiments of the invention, and the protective scope of the invention is solely defined by what is stated in the accompanying claims.

Claims

1. Apparatus for heat stimulation of an arbitrary part of the body, comprising organs (2, 3, 10, 13) for application onto the body part (9) in order to produce the heat stimulation, characterised by said heat stimulation being pulsed, in order to accomplish pulsed heating of said body part (9), at a frequency varying between 0.1 Hz and 20 Hz.

2. Apparatus according to claim 1, characterised by said pulsed heat stimula- tion being mtermittent, with an arbitrary cycle time, e.g. 10 seconds of pulsed heat stimulation followed by 10 seconds of heat interruption.

3. Apparatus according to claim 1 or 2, characterised by comprising control electronics (1) and an electrode (2) with a heating element, said electrode (2) being applied onto said body part (9) to be stimulated, and said electrode (2) being actively heated by said control electronics (1) and passively cooled by the environment, at a frequency varying between 0.1 Hz and 20 Hz.

4. Apparatus according to claim 3, characterised by said heating element com- prising a resistive loop being heated by means of a pulsed voltage, whereby said element is cooled by the environment between voltage pulses.

5. Apparatus according to claim 1 or 2, characterised by comprising control electronics (1), and an electrode (3) with a heating element, said electrode (3) being applied onto said body part (9) to be stimulated, and said electrode (3) being actively heated and cooled, respectively, by said control electronics (1) at a frequency varying between 0.1 Hz and 20 Hz.

6. Apparatus according to claim 5, characterised by the control electronics (1) being effective to reverse the voltage polarity in order to achieve switching between hot and cold in the electrode (3).

7. Apparatus according to claim 1 or 2, characterised by comprising control electronics (1) and┬╗an electrode (10, 13) containing two heating elements (7, 8, 11, 12), one heating element (8, 12) being hot and the other heating element (7, 11) being cold, said heating elements (7, 8, 11, 12) being free to move inside the electrodes (10, 13) and being alternately brought into contact with said body part (9) to accomplish switching between hot and cold in said body part (9).

8. Apparatus according to claim 7, characterised by said heating elements (7, 8) being arranged spaced apart; so as to be brought into contact with said body part (9) at different locations.

9. Apparatus according to claim 7, characterised by said heating elements (11, 12) being arranged to be brought into contact with said body part (9) at the same location.

10. Apparatus according to any one of claims 7 to 9, characterised by a motor (4) for moving said elements (7, 8, 11, 12) mechanically, in a direction towards said body part (9) as well as in a direction away from said body part.

11. Apparatus according to any one of the preceding claims, characterised by said pulsed heat stimulation having a frequency of about 10 Hz.

12. Method for heat stimulation of an arbitrary part of the body, characterised by said heat stimulation being pulsed in order to accomplish pulsed heating of said body part (9) at a frequency varying between 0.1 Hz and 20 Hz.

13. Method according to claim 12, characterised by said pulsed heat stimulation being intermittent, with an arbitrary cycle time, e.g. 10 seconds of pulsed heat stimulation followed by 10 seconds of heat interruption.

14. Method according to claim 12 or 13, characterised by an electrode (3) with a heating element, said electrode (3) being applied onto said body part (9) to be stimulated, and being actively heated and cooled, respectively, at a frequency varying between 0.1 Hz and 20 Hz.

15. Method according to claim 14, characterised by the voltage polarity over the heating element being reversed in order to achieve switching between hot and cold in the electrode (3).

16. Method according to claim 12 or 13, characterised by an electrode (10, 13) containing two heating elements (7, 8, 11, 12), one heating element (8, 12) being hot and the other heating element (7, 11) being cold, wliich are being alternately brought into contact with said body part (9) to accomplish switching between hot and cold in said body part (9).

17. Method according to claim 16, characterised by said hot and cold heating elements (7, 8) being brought into contact with said body part (9) at different locations.

18. Method according to claim 16, characterised by said hot and cold heating elements (11, 12) being brought into contact with said body part (9) at the same location.

19. Method according to any one of claims 12 - 18, characterised by said pulsed heat stimulation having a frequency of about 10 Hz.

20. Method according to any one of claims 12 - 18, characterised by said pulsed heat stimulation having a frequency of about 6 Hz and causing heating to about 38- 41┬░C.

21. Method according to any one of claims 12 - 18, characterised by said pulsed heat stimulation having a frequency of about 2 Hz and causing heating to about 42- 43┬░C.