Acupuncture apparatus

Abstract

Pulses of current are supplied to an acupuncture needle by a pulse generator whose pulse-width, frequency and amplitude are adjustably controlled, the pulse source having such high impedance as to cause essentially the desired or adjusted current to flow irrespective of the electrical impedance of the body between the acupuncture needle and another electrode applied to the body, i.e., an adjustable nominally infinte-impedance pulse source. A common pulse generator of adjustable frequency, pulse-width and intensity is used for providing drive for separate output circuits to energize plural acupuncture needles, respectively.

Description

The present invention relates to apparatus for use in acupuncture therapy and anaesthesiology.

BACKGROUND OF THE INVENTION

Acupuncture represents a time-honored technique for treating various ailments, both for curing certain ailments and for easing or erasing pain. More recently acupuncture has been found highly effective in anaesthesiology. In the practice of acupuncture, the acupuncturist inserts one or more fine needles into the patient at locations found by experience to be effective for treating each condition. These locations are called acupuncture points. The needle is fine, perhaps 0.005 inch or less in thickness, having a round, triangular or other cross-section, and ranging in length from about one-half inch to 6 inches. During and after insertion, the acupuncturist vibrates the needle according to the empirically established technique.

Electrical impulses have also been used in acupuncture, as an alternative to manual vibration. Voltage spikes of various frequencies and amplitude have been used, but with limited success.

SUMMARY OF THE INVENTION

Pursuant to the present invention, acupuncture apparatus includes what may be called constant-current or infinite-impedance means for electrically energizing the acupuncture needle(s). The body impedance may vary over a wide range, but the pulse source for the needle, or for each needle, has such a high impedance that the resulting current of each pulse is affected only secondarily by variations in electrical impedance of the patient's body. Essentially, it is the adjustment of the apparatus that determines the current flow. A further feature is in controlling the duration of the pulses, square-wave pulses in the illustrative apparatus, in contrast to the simple spikes used heretofore.

The nature of the invention including the foregoing and other features will be better appreciated from the following detailed description of an illustrative embodiment shown in the accompanying drawings. In the drawings:

FIG. 1 is a block diagram of illustrative acupuncture apparatus incorporating features of the invention; and

FIG. 2 is a detailed circuit diagram of the apparatus of FIG. 1, modified to energize plural acupuncture needles.

GENERAL

An acupuncture needle may be energized by applying electrical pulses between the needle and another electrode attached to the body, either an area contact or another needle. Since the human body acts as a volume conductor, current flows from one needle to a reference electrode (a needle or other electrode) via a rather broad front. The body impedance is quite complex, but may be approximated by a resistance R.sub.1 in series with a capacitance C.sub.1, the two shunted by another resistance R.sub.2. At the frequency range here involved, the series-equivalent resistance R.sub.1 and the reactance of capacitance C.sub.1 are approximately equal and they vary inversely with the frequency. Resistance R.sub.2 accounts for the finite d-c resistance related to the electrolytic process that takes place at the electrodeelectrolyte interface. This is a non-linear resistance which is a function of the nature of the tissue in contact with the needle electrode. For example, perspiration greatly affects the resistance of skin.

There is one of these electrode-body interface impedances R.sub.1, C.sub.1, R.sub.2 for each needle. In addition, the stimulating current may be altered by an equivalent bioelectric voltage and an associated bioelectric equivalent impedance, which represents the body tissue itself between two electrodes.

By making the source of pulses between the electrodes in the form of a source of current pulses, the current level and the corresponding degree of stimulation can be accurately controlled and will not be affected by or dependent on the particular level of body impedance among different patients or at various acupuncture points of a patient. As an absolute concept, a current-pulse source should have infinite impedance. A practical value of impedance of a current-pulse source herein is only required to be so high in relation to maximum body impedance that various body impedances that may be encountered will not notably affect the resulting current.

As extreme values, body impedance may be anything in the range of 1,000 to 100,000 ohms between an acupuncture needle and another electrode, which may be another needle or an area contact to the skin that is prepared for good conduction. Thus, a 1.0 megohm source impedance would produce prescribed levels of current stimulation within 10% regardless of body impedance. The 10% figure and the impedance variations of 1,000 to 100,000 ohms are extreme figures, so that a 1.0-megohm source impedance is perhaps higher than is absolutely required, but it represents the order of magnitude of the source impedance required.

In the illustrative apparatus in the drawing, the collector of a base-driven transistor is used to provide this impedance. Typically, the collector impedance is greater than 1.0 megohm. With an appropriate emitter resistor it may be at least 1.0 megohm at the maximum-current part of the operating characteristic and with an emitter resistor of about 1,000 ohms. Where a low current level of stimulation is desired, a 100,000-ohm emitter resistor may be used. The resulting output impedance at low- and high-current settings is:

Z.sub.o = Z.sub.c + .beta. .sup.. R.sub.e

where

Z.sub.c is the collector resistance, 1.0 to 2.0 meg;

.beta. is the current gain of the transistor, typically 50 to 100; and

R.sub.e is the emitter resistor, being 1,000 ohms to 100,000 ohms in an illustrative example.

Accordingly:

Z.sub.o = 2 meg. + 50 .sup.. 100,000 = 7 meg -- for a low-current setting, and

Z.sub.o = 1 meg. + 100 .sup.. 1,000 = 1.1 meg -- for a high-current setting.

In all settings, the impedance remains greater than the 1.0 megohm level above.

DETAILED DESCRIPTION

Referring now to the drawings, FIG. 1 shows acupuncture apparatus including a constant-current source of pulses 10 for oppositely energizing a metal acupuncture needle 12 inserted into a patient's body and another electrode 14 shown as an area contact to the patient's skin (using a conductive gel, if desired) but which may be another needle. Source 10 is nominally a constant-current source, in that its impedance is not infinite in practice but is merely a high order of impedance compared to the maximum body resistance between electrodes 12 and 14. The pulses here are unipolar squarewaves and they are of adjustable frequency, duration (pulsewidth) and intensity.

An adjustable-frequency pulse generator 16, e.g., an astable multi-vibrator with a manual frequency control 16a drives pulse generator 18 having a manually adjustable pulse-width control 18a, e.g. a one-shot multi-vibrator. The output is fed to an intensity adjuster 20, e.g., a potentiometer 20a having a manual control 20b. Intensity indicator 23 measures the pulse intensity. This is converted into current pulses by current-pulse generator 22. This advantageously takes the form of a base-driven transistor 22a having an emitter resistor and a direct connection 22c from the collector to needle 12. Direct-current supply 24 is connected between resistor 22b and electrode 14. This supply also energizes parts 16, 18 and 20 of pulse source 10.

D-C supply 24 is ideally battery-operated so as to enable the apparatus to be free of connection to a power circuit which could expose the patient to shock hazard. Moreover, because usual economical sizes of batteries have inadequate voltage for the presently desired maximum pulse intensity, d-c supply 24 advantageously includes an interrupter or inverter, a step-up transformer and a rectifier and smoothing filter, this being a conventional d-c to d-c step-up converter.

Portions of the pulse source 10 of FIG. 1 are shown in greater detail in FIG. 2, adapted to energize plural acupuncture needles separately. Potentiometer 20a is connected to the base of output transistor 22a and to the base of transistor 26 which forms part of intensity indicator 23, shown as a peak-reading detector. The pulses appearing across emitter-follower resistor 28 are rectified by diode 30 and stored in capacitor 32, and measured by a voltmeter circuit.

The emitter of transistor 22a is selectively connected by selector switch 36 to one of three current-range selecting resistors 22b-1, 22b-2 or 22b-3 which may for example be 1,000 ohms, 10,000 ohms and 100,000 ohms, respectively. These values typically impart an internal impedance of from 1.1 megohms to 7 megohms as shown above.

Collector connection 22c is provided for one needle, to be connected to terminal 1. A second transistor 22a' also has a base-drive connection to potentiometer 20a, and a separate collector connection 22c' to terminal 2 for a separate needle; and it has a corresponding cluster of emitter resistors 22b'. Additional terminals 3 to N have respective current-pulse generators. Electrode 14 is to be connected to line 38 which is connected to the negative terminal of D-C supply 24, the rest of the circuit being energized by the positive terminal of the D-C supply.

The circuit described is advantageously energized by a 60-volt D-C supply, being a relatively safe voltage even in case of component failure. The pulses may be 0.5 to 100 milliseconds long, with a repetition rate that may be adjusted as desired, from zero to 100 pulses per second and another range from 100 to 2,000 pulses per second.

The reading of indicator 34 provides a direct measurement of the output of potentiometer 22a. However, this is proportional to the resulting current levels of needles connected to terminals 1, 2, etc., where the corresponding emitter resistors 22b are selected in the related output circuits.

The foregoing represents an exemplary embodiment for achieving the purposes of the invention. However, it is readily susceptible of variation in details and proportions within the skill of the art, and consequently the invention should be construed in accordance with its full spirit and scope.

Claims

What is claimed is:

1. Acupuncture apparatus including multiple metal electrodes at least one of which is a needle of about five thousandths of an inch thick and about one-half inch to 6 inches in length for insertion into a patient's body at an acupuncture point and electrical energizing means for oppositely energizing said needle and another of said electrodes, said electrical energizing means including means for providing pulses to the needle in the frequency range between a value approaching zero and 2,000 pulses per second, and said energizing means having impedance means for regulating the current supplied to said needle having a minimum impedance of about 1 megohm at the pulse frequency, whereby the needle is supplied with essentially constant current which is affected only secondarily by varied body-impedances of patients.

2. Acupuncture apparatus in accordance with claim 1, wherein said pulses are unipolar.

3. Acupuncture apparatus in accordance with claim 1, including plural needles and wherein separate impedance means is included in said energizing means for regulating the current pulses as aforesaid to each of said plural needles.

4. Acupuncture apparatus in accordance with claim 1, further including means for adjusting the impedance means selectively to values ranging from a minimum of about one megohm as aforesaid to many megohms, whereby the needle current is subject to deliberate variation by the user of the apparatus with no more than secondary modification of the current due to varied body-impedances of patients.