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BACKGROUND OF THE INVENTION
This invention relates to diathermy apparatus, and more particularly to a
diathermy hand piece in which at least the radio frequency generating
portion of the power supply is carried within the hand piece so as to be
in close proximity to the electrode working tips or electrode.
More generally, diathermy is a medical treatment in which heat is produced
internally within the tissue of the patient by exposing the tissue to a
high frequency oscillatory electrical current via a pair of energized
electrodes or the like. The principles of diathermy medical treatment are
typically utilized for electrocoagulation in which a mono- or bi-polar
coagulator or forceps is used for hemostasis. By utilizing bi-polar
coagulators, pinpoint hemostasis of tiny bleeders in the operating field
is possible with minimal effects on surrounding tissue. Since thermal heat
is not used for diathermy cauterization purposes, diathermy coagulation is
usable in a wet operating field, whether used in conjunction with a saline
irrigation agent or whether the operating field is bloody. The advent of
such bi-polar diathermy coagulator apparatus has led to many medical
advances in neurological and microsurgical techniques because it is now
possible to effectively restrict the area of tissue damage. It will be
understood that the general principle of diathermy coagulation is that by
heating the tissue, the tissue proteins are coagulated thus stopping
bleeding. By using carefully controlled diathermy coagulator apparatus,
charring and other excessive heating of the tissue surrounding the
bleeders is minimized.
Several years ago, upon the introduction of diathermy techniques, radio
frequency generators were used to energized the coagulators. Typically,
these radio frequency generators were quite large in size and were located
remotely from the mono-polar or bi-polar forceps or hand piece. The radio
frequency energy generated by the radio frequency generator was carried to
the hand piece by elongate electrical leads or the like. In many early
diathermy instruments, a quenched spark gap transmitter was utilized as
the radio frequency generator. The wave forms generated by such quenched
spark gap power supplies were of fairly high voltage which resulted in
relatively deep tissue penetration and were intermittent such that little
heat was generated and such that each cycle produced only a small degree
of coagulation. Thus, as compared to heated wire cauterization apparatus,
a uniform heat at a predetermined tissue depth produced less heat with
more coagulation, provided more control for the surgeon, and resulted in
less charring and other damage to the surrounding tissue.
As mentioned, the radio frequency generators of prior art diathermy
apparatus were located remotely from the electrodes utilized by the
surgeon and the electrodes were connected to the radio frequency generator
by relatively long electrical lead wires. Because of the large size of the
radio frequency generator, it was often difficult to find space for the
radio frequency generator in a crowded operating room. Also, because of
the large size of the radio frequency generator and the type of equipment
(i.e., an oscillatory radio frequency source), it was difficult to
sterilize the radio frequency generator without causing damage to the
generator or without applying harmful chemicals. Also, by energizing the
electrodes with high frequency radio frequency energy via long lead lines,
various capacitive loads were impressed on the radio frequency output
which in turn required the radio frequency generator to emit more power
than was necessary for diathermy treatment of the patient. This
inefficiency in radio frequency generators has resulted in increased
danger to the patient and in increased radio frequency interference with
other electronical equipment now commonly utilized in the modern operating
room. Further, many prior art diathermy coagulators, referred to as
mono-polar coagulators, required that the patient be grounded by a
suitable grounding pad. Also, as was conventional, prior art diathermy
coagulators were typically activated by means of a foot switch actuated by
the surgeon. It was found that in various microsurgery applications, the
requirement of a foot switch was awkward and often required the surgeon to
change his body position from a desired position while performing
neurological or microsurgery.
SUMMARY OF THE INVENTION
Among the several objects and features of the present invention may be
noted the provision of a diathermy apparatus in which the requirement of
bulky, remotely located radio frequency power supply is omitted;
The provision of such a diathermy apparatus, as for use for
electrocoagulation and surgical cutting, which is energized at a frequency
so as to minimize capacitive load losses between the radio frequency
generator and the electrodes;
The provision of such a diathermy apparatus which reduces radio frequency
emissions in the operating room which may have a deleterious effect on
other operating room electronic equipment;
The provision of such diathermy apparatus which can readily accommodate a
wide variation in impedance and capacitance levels in living tissues, and
may be readily, selectively adjusted by the surgeon without movement from
his operating position relative to the patient;
The provision of such diathermy apparatus which may be readily sterilized
and maintained in a sterile condition (as by sealing it in a plastic bag
or the like) until needed by the surgeon;
The provision of such diathermy apparatus which lessens the likelihood of
forming standing waves in the leads between the radio frequency power
source and the electrodes which could result in undesired side effects for
the patient, which readily allows variations in wave forms so as to best
suit the conditions of the tissue being treated, and which eliminates or
significantly lessens the danger of electrocution both to the patient and
to the surgeon; and
The provision of such diathermy apparatus in which at least the radio
frequency generator and preferably the power supply are self-contained in
the hand piece thus making the diathermy apparatus of the present
invention compact, making the instrument easily maneuverable by the
surgeon, eliminating the requirement of elongate electrical leads or
cords, making the instrument light in weight, and providing an instrument
which is highly and accurately movable by the surgeon in the operating
field, and in which all controls for energization and de-energization and
varying the intensity and frequency of the radio frequency energy applied
to the tissue may be readily controlled by controls carried by the hand
piece.
Other objects and features of this invention will be in part apparent and
in part pointed out hereinafter.
Briefly stated, a hand-held medical diathermy treatment apparatus of the
present invention comprises a housing, a power supply, and at least one
electrode carried by the housing. Further, means is supplied with
electrical power from the power supply for generating a radio frequency
oscillatory current ranging between about 1 kilohertz to about 20
megahertz to the above-mentioned electrode. At least a portion of the
radio frequency generator means is located within the handle and a
manually operable switch is carried by the housing for selective
energization of the radio frequency generator means whereby, upon
energization, the apparatus is capable of cycling a plurality of times
outputting up to about 20 watts of power on each cycle for a time
sufficient to perform desired treatment (e.g., up to 20 seconds or more).
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an isometric view of a hand-held or portable diathermy treatment
hand piece of the present invention;
FIG. 2 is a side elevational view of a coaxial bi-polar electrode probe
adapted to be plugged into the hand piece shown in FIG. 1;
FIG. 3 is an end view of the electrode assembly shown in FIG. 2, taken
along 3--3 of FIG. 2, with the scale of FIG. 3 being somewhat enlarged for
purposes of clarity;
FIG. 4 is a top plan view of an alternative arrangement of a pair of
bi-polar electrodes utilizing tweezer-type or forceps-type electrode tips;
FIG. 5 is a side elevational view of the electrode assembly shown in FIG.
4;
FIG. 6 is a block diagram view of the major components of the hand held
diathermy apparatus of the present invention, including a battery pack
power supply, an on/off switch, a radio frequency generator, a control for
varying the power output of the radio frequency generator, and output
receptacles into which the electrode probes shown in FIGS. 2-5 may be
inserted;
FIG. 7 is a schematic diagram of a self-oscillating flyback converter for
energizing the electrodes; and
FIG. 8 is a schematic view of another radio frequency generator circuit for
energizing the electrodes.
Corresponding reference characters indicate corresponding parts throughout
the several views of the drawings.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring now to the drawings, and particularly to FIGS. 1-5, a diathermy
treatment apparatus or hand piece of the present invention is indicated in
its entirety by reference character 1. The hand piece includes a housing 3
which may be readily gripped by a surgeon and which may be readily
maneuvered and operated in the operating field for carrying out a variety
of diathermy treatments with all of the controls (as will be hereinafter
explained in detail) carried directly on the hand piece so as to
facilitate operation of the hand piece by the surgeon without unnecessary
detractions, such as the requirement of a foot switch for actuation of the
hand piece and the like. More specifically, housing 3 is provided with a
removable panel 5 providing access to one or more batteries 7 located
within the housing, the batteries constituting a direct current (DC) power
source for a radio frequency (RF) generator located entirely within the
housing (as shown in FIG. 6) for supplying a radio frequency oscillatory
current to one or more output electrodes (as will be hereinafter described
in detail) for diathermy treatment. While batteries 7 are herein disclosed
to be located within the hand piece housing 3, it will be understood that
within the broader aspects of this invention, the direct current power
supply (e.g., the batteries or an inverter) may be located remotely from
the hand piece and electrically connected thereto by suitable leads. It
will further be appreciated that within the broader aspects of this
invention, the radio frequency generator is desirably located within the
hand piece so as to minimize capacitance changes, standing wave problems,
RF energy interference, and the like between a remotely located radio
frequency generator interconnected to the electrodes by long leads, as was
heretofore conventional. In other words, it is an object of this invention
to reduce, as much as possible, the distance between the radio frequency
generator and the electrodes.
Further, in accordance with this invention, hand piece 1 includes a trigger
operated switch 9 readily disposed for operation by the index finger of
the surgeon for energization and de-energization of the diathermy
apparatus 1. A rotary switch or potentiometer 11 is provided on the hand
piece which may be utilized by the surgeon for varying the power output of
the radio frequency generator means in a manner as will be more
particularly described in regard to the schematics shown in FIGS. 7 and 8.
Also, a light indicating diode warning light, as indicated at 12, is
provided for indicating the status of batteries 7. Thus, all necessary
controls for the diathermy hand piece of the present invention are carried
by the hand piece, and the necessity of a foot actuated switch and long
power leads and switch leads are eliminated.
Referring now to FIGS. 2 and 3, a removable bi-polar electrode probe
assembly, as indicated in its entirety at 13a, is provided for being
plugged into the end of housing 3 for electrical connection with the radio
frequency generator. More specifically, electrode probe 13a is a so-called
coaxial electrode probe having a first or central coaxial electrode 15 and
a second or outer electrode 17 surrounding the inner electrode 15.
Intermediate electrical insulation 19 is provided between the electrodes
15 and 17. An outer layer of insulation 20 surrounds the outer electrode,
and the outer insulation 20 is covered by a stainless steel sheath 21. The
electrode probe assembly 13a has a body portion 23. Male electrode
terminals 25a and 25b are, respectively, electrically connected to
electrodes 15 and 17. Thus, the electrode assembly 13a may be readily
plugged into a socket (not shown) in the left-hand end (as viewed in FIG.
1) of housing 3 so as to electrically connect the electrodes 15 and 17 to
the radio frequency generator of the hand piece 1 of the present invention
in a manner as will hereinafter appear. Also, in this manner, electrode
probes may be readily changed by the surgeon during surgery without the
necessity of complicated disassembly of the apparatus. Further, the
electrode probes may be readily sterilized in any conventional manner and
sealed in a sterile plastic bag or the like until ready for use.
Referring to FIGS. 4 and 5, an alternative embodiment of the electrode
assembly is indicated in its entirety by reference character 13b. More
specifically, electrode assembly 13b has a pair of spaced bi-polar
tweezer-type electrode forcep tips 27a, 27b extending outwardly and
downwardly from the end of the insulative electrode body with a gap G
between the electrode tips. This type of electrode assembly is
particularly well suited for bi-polar coagulation techniques.
While not shown, those skilled in the art will appreciate that a mono-polar
electrode probe used in conjunction with a patient grounding mat may be
used with the handpiece 1 of the present invention for mono-polar
diathermy techniques, including mono-polar coagulation and surgical
cutting.
Referring now to FIG. 6, the basic components of the diathermy hand piece 1
of the present invention are shown in schematic or block diagram form.
More particularly, it can be seen that batteries 7 are connected in series
via the on/off switch 9 to a radio frequency generator, as indicated in
its entirety by reference character 29. The output (i.e., the power) of
radio frequency generator 29 is selectively controlled by means of a
rotary potentiometer 11. Further, the output of radio frequency generator
29 is supplied to a pair of female electrical receptacles, as indicated at
31a, 31b, for receiving the electrical terminals 25a, 25b of either
electrode assembly 13a or 13b such that the electrode probes may be
readily plugged into or removed from receptacles 31a, 31b.
Referring now to FIG. 7, a first detailed embodiment of the radio frequency
generator 29 is illustrated in its entirety by reference character 29A.
More particularly, radio frequency generator 29A is so-called
self-oscillating flyback converter suitable for driving a higher voltage
which utilizes the core characteristics of a transformer 30 to determine
the frequency output of the generator. More specifically, a diode D1, such
as an IN4148 diode, prevents negative spikes from occurring at the VMOS
gate of a power transistor Q1. Resistor R1 may be, for example, a 100 ohm
resistor and is used as a parisitic suppressor. Capacitor C1 may, for
example, have a capacitive value of about 0.1 microfarads. With the
transformer shown, such as is commercially available from Indiana General
of Valparaiso, Indiana, under the trade designation F626-12-Qz, the
operating frequency of the frequency generator 29A is about 250 kilohertz.
As indicated, the voltage source supplied to one of the terminals may vary
between about 3 and 15 volts. Accordingly, batteries 7 of the present
invention may range from a plurality of AA size conventional alkaline
batteries to one or more conventional D size alkaline batteries, depending
on the desired power output of the device and the number of repeated
operations desired before it is necessary to change the batteries.
In FIG. 8, still another embodiment of another radio frequency generator is
indicated in its entirety by reference character 29B. Generally, batteries
7 are connected in series by means of the selectively operable, on/off
switch 9 to an oscillator circuit, as generally indicated at 33, which
generates a square wave at, for example, a frequency of about 500
kilohertz. The outputs of oscillator 33 are driven in opposite polarities
and are supplied to output transistors Q2, such as IRF532 transistors,
commercially available from International Rectifiers, El Segundo,
California, via NAND gates 35 and a MOS driver 37 with a speed-up RC
circuit 39 interposed between the NAND gates 35 and the MOS driver 37. A
toroid transformer 41 having a toroidal core 43 is driven in a push-pull
manner by transistors Q2. More specifically, the toroid transformer 41 has
a double primary 45, with each primary 45 consisting of 7 windings, and a
secondary winding 47 having 35 windings. The toriod may, for example, be a
type 204T250-3C8, commercially available from Ferroxcube of Saugerties,
New York. The secondary winding 47 of transformer 41 is directly connected
to the output terminals 31a and 31b of the hand piece. The power output is
controlled by sequentially gating the two NAND gates 35 "on" and "off" at
a variable duty cycle by means of a variable duty cycle oscillator 49 at a
frequency far below the frequency of oscillator 33. Variable duty cycle
oscillator 49 comprises two NAND gates 51 interconnected to the power
output adjustment switch 11.
In actual operation, a hand-held diathermy apparatus 1 of the present
invention utilizing the frequency generator power supply, as generally
indicated at 8, was successfully used in opthalmalic operations as a
bi-polar coagulator for small blood vessels. This device produced up to 4
watts of power for several short periods up to about 10 seconds each from
two standard "C" size alkaline batteries 7. In other tests, the apparatus
delivered about 4 watts of power into a 500 ohm load (not shown) which was
found to be sufficient for coagulation of small blood vessels.
Batteries 7 with higher power densities and yet of reasonable physical size
and weight are available. For example, two "C" size battery cells, such as
model CSC933B30, commercially available from Electrochem Industries, Inc.,
of Clarence, New York, deliver about 16 watts of power for several short
periods of about 10 seconds each. It has been found that this power can
fulfill several applications for surgical diathermy.
It will be appreciated that if still higher power outputs are required for
the radio frequency generator, the battery or DC power supply may be
separated from the hand piece and connected to it by lead wires. Since
only DC current is flowing through the above-mentioned lead wires, the
capacitive changes and standing wave phenomena, heretofore disclosed as a
problem in regard to prior diathermy apparatus in which the radio
frequency generator was located remotely from the hand piece, is
eliminated.
Also, those skilled in the diathermy art will recognize that it will be
possible to utilize the hand piece 1 of the present invention as a
uni-polar coagulator in which case one of the two output terminals 31a,
31b is attached to a ground plate electrode (not shown) in electrical
contact with the patient's body, and the other electrode is connected to
the coagulating hand piece. Also, by utilizing higher radio frequency
energy, for example, about 13 megahertz, a single electrode usable for
cutting procedures is feasible.
It will also be understood that electrodes 13a or 13b may be readily
sterilized in any conventional manner and sealed in a plastic bag or the
like ready for use. Also, hand piece 1 is preferably made of sanitary
construction such that after surgery it may be readily cleaned and
sterilized, such as with suitable gas, and sealed in a bag for use.
Generally, the term "diathermy" is herein used in a broad and not in a
limiting sense. For example, it will be appreciated that this apparatus
and method may be utilized for conventional diathermy bi-polar and
uni-polar coagulation procedures, and for other applications. In
particular, the apparatus of this invention, having a radio frequency
output ranging between about 1 kilohertz to microwave frequencies, may be
utilized for the treatment of living tissues by integrating at least the
output stage of the radio frequency generator 29 into the hand piece. It
will be further appreciated that when such higher frequency radio
frequency energy is utilized (i.e., radio frequencies having a wavelength
shorter than about 1 meter or less), many of the standing wave problems
typically associated with prior art diathermy apparatus in which the radio
frequency generator is located remote from the hand piece and connected
thereto by elongate lead wires is eliminated because the distance from the
radio frequency generator 29 of the present invention and the electrodes
15 and 17 is considerably less than the wavelength of the radio frequency
energy.
In view of the above, it will be seen that the other objects of this
invention are achieved and other advantageous results obtained.
As various changes could be made in the above constructions without
departing from the scope of the invention, it is intended that all matter
contained in the above description or shown in the accompanying drawing
shall be interpreted as illustrative and not in a limiting sense.
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