Thermal cautery surgical forceps

A portable, thermal cauterizing forceps device for use in surgery. The device incorporates a pair of ceramic heater elements mounted within the tips of the tines of a forceps. The forceps is used to grasp tissue or blood vessels and apply heat to effect cauterization. In the case of the first embodiment of the invention, the forceps instrument incorporates a battery and control electronics. The thermal-forceps is of a self-contained wireless, handheld disposable design. In a second embodiment of the invention, the forceps handpiece is connected to an external power source. Both embodiments of the forceps incorporate set of rapidly heating ceramic heater elements that may be composed of silicon nitride. An LED provides the operator feedback as to the operating level of the heaters and/or battery reserve. Enhancements to the second embodiment include a rechargeable power supply, variable control of the heater temperature, as well as a, digital display of the tip temperature.

BACKGROUND OF THE INVENTION
 The present invention relates to a handheld, portable thermal-cauterizing
 forceps including an integrated thermal heating surface disposed at each
 tip.
 There are many surgical cautery devices available for the surgeon to ablate
 and vaporize tissue. Hot knives and cutting coagulators have been used to
 make skin incisions. The cautery can also be used in surgery to aid in
 hemostasis or control bleeding by coagulating blood vessels. Employing
 various cautery modalities decreases the duration of some surgical
 procedures by providing the surgeon a rapid method of coagulation without
 the need for suture ligation of blood vessels encountered during
 dissection.
 Typically, surgical cautery is accomplished by directing a heating process
 onto tissue. The heat may be generated by either a thermal or
 electro-surgical process. Most commonly, an electro-surgical process using
 a radio frequency (RF) is used. The RF units generate heat by using high
 frequency electrical current and the resistive nature of tissue to produce
 heat. This technique requires a bulky generator and heavy electrical
 components to operate. Typically, RF electrocautery units require a power
 lead cable to the electro-surgical hand instrument and a large surface
 area grounding pad. More often than not, radio frequency surgical units
 are bulky expensive units which require a cable connection. Employing RF
 cauterization in a surgical operation may add significant cost to the
 procedure because the grounding pad, cable and handpiece must all be
 either re-sterilized or replaced in the case of disposable use.
 A less common method of generating heat for coagulation of tissue is by
 thermal cautery. Thermal cautery is achieved by electrical heating of a
 resistive-wire loop or resistive electronic part by applying an electrical
 voltage. The prior art describes many handheld disposable, hot-wire loop
 cautery instruments. These devices have severe limitations as to their
 scope of use in surgery. The heat generated by the handheld battery
 powered devices is very small with a low heat capacity. The available
 patented devices are effective for cauterization of only the smallest of
 blood vessels, such as, vessels in the sclera of the eye. These battery
 powered hot-wire cautery instruments are not effective for use in
 cauterization of larger blood vessels encountered in most surgical
 procedures. A technique employing the electrical over driving of a zener
 diodes to produce heat has also been described in several patents. This
 device is primarily for limited endoscopic applications.
 SUMMARY OF THE INVENTION
 In order to overcome the limitations and disadvantages of the prior art,
 the present invention provides, in an embodiment, a new and improved
 hand-held, high energy, portable thermal cautery forceps. More
 particularly, the new and improved surgical forceps instrument includes an
 enclosure which houses a battery and electronic control. Active ceramic
 heaters are provided on the two tips of the operative end of the forceps.
 In a second embodiment, the thermal forceps may alternatively be powered
 by an external power source.
 The new thermo-cautery forceps device in accordance with an embodiment of
 the invention provides the surgeon with several significant improvements
 in the state of the art. A first benefit of the thermal-cautery forceps is
 that it is cordless and fully portable. In the first embodiment of the
 invention, no cables or external power supply is necessary. This keeps the
 operative field clear of wires and cables. The thermal cautery of this
 invention does not require any grounding pad or foot switches.
 A second benefit is the very high heating capacity of the thermal elements
 of the device. Temperatures of over 1000.degree. C. are easily obtainable.
 A preferred tip operating range is from 650.degree. to 700.degree. C. This
 heat capacity and temperature can easily cauterize medium and large blood
 vessels.
 A third benefit provided by the new and improved thermal cautery forceps of
 the invention is its ability to heat to operating temperature in a very
 short time period, for example, within about one second. The preferred
 embodiment uses silicon nitride, ceramic heater elements. These new
 ceramic heaters exhibit rapid heating and cooling characteristics. Silicon
 nitride ceramic heaters have been used successfully in other fields
 outside surgery. To the inventor's knowledge, this is believed to be the
 first use within the field of surgical thermal coagulation.
 In an alternative embodiment, less expensive alumina heaters and ceramic
 resistors or diodes may be employed in substitution for the silicon
 nitride ceramic heater elements to provide cost savings. However, such
 alternative types of heaters may be less preferred because longer times to
 obtain operating temperatures may be required.
 In an embodiment, the preferred power source is a battery rendering the
 device completely portable. Four lithium metal 3 volt batteries can be
 utilized as well as dual 9 volt batteries, one for each tine. One
 preferred battery is TADIRAN.RTM. which provide 11.5 volts and are
 rechargeable. A 12 volt direct current power supply can be utilized as
 well with a connecting cord or cable.
 A fourth advantage provided by the new and improved forceps is the
 placement of the thermal cautery heater elements at the ends of forceps
 tines. The unique position of the ceramic heater elements allows tissue
 and blood vessels to be easily grasped and directly coagulated in a
 controlled manner. The application of a closing or gripping pressure of
 the forceps against the tissue or vessel enhances the effectiveness of the
 coagulation.
 A fifth benefit of the forceps device in accordance with the invention is
 to decrease the cost and enhance the availability of surgical cautery. The
 first embodiment of the thermal forceps allows for the device to be
 packaged as a sterile disposable instrument. The instrument can be used in
 emergency or field operations. The device may be used for hemostasis
 during outpatient surgical procedures in clinics and in surgery centers,
 as well as, at emergency scenes
 Other objects and advantages provided by the present invention will become
 apparent from the following Detailed Description taken in conjunction with
 the Drawings, in which:

From the above description it is apparent that the objects of the present
 invention have been achieved. While only certain embodiments have been set
 forth, alternative embodiments and various modifications will be apparent
 from the above description to those skilled in the art. These and other
 alternatives are considered equivalents and within the spirit and scope of
 the present invention.
 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
 In accordance with a preferred embodiment of the invention, a new and
 improved thermocautery surgical forceps comprises a surgical forceps body
 including a pair of elongate tine members extending from the forceps body
 to respective free end tip portions spaced from the forceps body. The tine
 members are mounted to the forceps body in a manner providing resilient
 compressible movement of the tine members between a normally open
 position, wherein the tines are disposed in aligned, parallel,
 spaced-apart relationship, and a squeezed closed position, wherein the tip
 portions of the tine members are disposed in confronting abutting
 relationship. Each tine member includes a tissue contact surface 18', 19'
 defined on an inner facing surface of the tine member adjacent the tip
 portion. A ceramic heater element is disposed in each tine member so as to
 effectively heat the tissue contact surface to an elevated tissue
 cauterizing temperature. The ceramic heater elements are optionally
 connected to a power source. The tine members may be squeezed together to
 their squeezed closed position to grippingly, squeezably engage tissue to
 be cauterized between the tip portions. The tissue contact surfaces on the
 tines may be heated to a tissue cauterizing temperature to effectively
 thermocauterize the gripped tissue.
 Referring now to FIGS. 1-6, a preferred embodiment of the new and improved
 thermocautery surgical forceps generally designated by reference numeral
 10 is shown. Forceps 10 includes a forceps body or housing 12 for the
 battery 14 (see FIG. 5) and electrical control components 16. Specialized
 ceramic heating elements 18, 19 are disposed on the tips 20, 21 of the
 forceps tines 22, 24. FIGS. 1-6 relate to the first embodiment of the
 invention, that of a portable unit 10 with an internal battery supply 14.
 FIGS. 7-11 relate to the second embodiment of the invention, that of a
 cautery unit 26 configured as a thermal forceps 28 with an external power
 supply (not shown).
 As shown in FIG. 1, the first embodiment of the cauterizing instrument 10
 generally comprises a housing 12 and an integrated forceps tines assembly
 32. The housing 12 encloses the battery 14 (see FIG. 5), and a number of
 electrical control components 16, such as controller electronics 34, an
 LED 36 and an internal power switch 38. The forceps tines 22, 24 of the
 instrument, as shown in FIG. 1, exit from openings in the front end of the
 housing 12. The forceps assembly comprises two tines 22, 24 of equal
 length. Each tine 22, 24 is constructed of a heater-carrier 40, 41 and an
 insulator cover-piece 42, 43. The heater-carriers 40, 41 comprise a metal
 arm 44, 45 that supports an attached ceramic heater unit 46, 47. Each
 insulator cover-piece 42, 43 is a shroud 48, 49 that covers the heater 46,
 47 and its carrier arm 44, 45. Each shroud cover 48, 49 is heat resistant
 and protects the surgeon's fingers from the heat generated by the ceramic
 heaters 46, 47. Each shroud 48, 49 includes a recess 50, 51 to fit the
 operators thumb and index finger to aid in holding the instrument. Inward
 compression on the shrouds 48, 49 act to compress the heater carrier arms
 44, 45 and will cause the switch 38 (see FIG. 5) to close.
 FIG. 2 shows a top view of the instruments with the LED 36 exiting the rear
 of the housing enclosure and the forceps shroud cover with finger recess
 The enclosure is rectangular in shape having a closed end and an open end
 The open end allows the forceps assembly to exit from the enclosure. The
 enclosure is composed of a plastic formed with an injection process. The
 open end of the enclosure is shown in FIG. 3. The forceps are shown as
 well as the LED 36 on the top of the housing. The position of the LED 36
 allows the surgeon easily visualize the operation of the instrument. The
 surgeon can see the LED 36 while it is held in the hand and operated. FIG.
 4 shows the closed end of the housing.
 Shown in FIG. 5 is a cross-sectional view of the enclosure containing a
 battery 14 for power supply. The battery may be rated form 3 volts to 24
 VDC depending on the heating characteristics required. The battery 14 may
 be of an alkaline or lithium cell. In addition, two 9 volt batteries may
 be used, one for each tine 22, 24. Lithium metal batteries may also be
 utilized. One preferred battery is sold under the trademark TADIRAN.RTM..
 The battery positive and negative terminals 54, 56 are connected to the
 instrument circuitry by a terminal battery clip. Also, contained within
 the enclosure is a small circuit board 34 that is populated with an
 integrated circuit and support components. The circuit board 34 has
 connections to the power supply 14, LED 36, heater elements 118, 19 and
 switch mechanism 38. This circuit board 34 acts as a logic-controller to
 regulate the current delivered to the heating elements. The
 logic-controller circuit monitors the temperature and resistance of the
 heater elements 18, 19 and regulates the voltage supply. At the onset of
 operation the logic circuit allows high current to flow to the heaters 18,
 19 aiding in initial rapid heating. The current is then reduced to
 maintain the heaters 18, 19 at a set temperature. The controller circuit
 logic also controls the LED 36 to indicate the operative state of the
 heater elements 18, 19. The LED 36 will illuminate only if the battery
 power reserve or supply voltage attain a specified level and heaters reach
 the preset operational temperature. The logic controller also measures the
 internal resistance and temperature of the heater elements 18, 19. The LED
 36 will fail to illuminate if these values fall outside the normal
 operational limits.
 In an alternative design of the first embodiment a small piezo-electric
 speaker may be incorporated into the forceps enclosure. In the alternative
 design (not shown) the logic controller is further able to supply a
 piezo-electric speaker with supply voltage. The piezo-electric speaker
 provides the operator with auditory feedback pertaining to the operation
 of the instrument. The speaker emits a sound to give the surgeon an audio
 feedback as to the operation of the instrument. The sound indicates that
 the heating elements 18, 19 are at the normal operative temperature for
 effective cauterization.
 Also shown in FIG. 5, is the mounting arrangement of the forceps tines 22,
 24. Each tine 22, 24 is mounted on opposite sides of a rectangular
 neoprene spacer 52. The pair of tines 22, 24 and neoprene spacer 52 are
 fasted together by a binding pin 54 with end caps. The off-center
 arrangement fastening of the tines 22, 24 to the neoprene spacer 52 allows
 for a spring like tweezer effect.
 An electrical open/close single pole switch 38 is incorporated into the
 instrument. The switch 38 is positioned within the housing enclosure 12
 between the base of the forceps tines 22, 24. The switch 38 is composed of
 two contacts 58, 60 that are brought into contact when the forceps 10 are
 squeezed together. Closing the switch 38 allows current to be delivered to
 the heaters. The contacts 58, 60 meet, as soon as, closure of the tines
 22, 24 is begun and stays in a closed position as long as the tines 22, 24
 are closed. Release of the forceps tines 22, 24 will open the switch 38
 and current supply to the heaters 46, 47 will terminate.
 The typical wiring diagram and schematic is shown in FIG. 6. The schematic
 shows a DC battery 14 with positive and negative leads 54, 56 connected to
 the logic control circuit board 34. The circuit board 34 is able to
 regulate the current delivered to the heater elements 46, 47 by measuring
 the internal electrical resistance of the heaters 46, 47 and the voltage
 available from the battery 14. The controller also will vary the initial
 resistance of the heater circuit to obtain quick heat up at power on. The
 controller logic also controls the illumination of the LED 36. The LED 36
 is illuminated when a preset temperature of the heaters 46, 47 is reached.
 The ON/OFF switch 38 incorporated into the forceps 10 is also depicted.
 The switch 38 that is closed upon closure of the forceps 10 allows current
 to flow to the heaters 46, 47. Two heaters 46, 47 are shown which are
 wired in parallel. The internal resistance of the two heaters 46, 47 is
 about 5 to 10 ohms, preferably about 8 ohms, or 4 ohms per heater 46, 47.
 The typical heater 46, 47 is composed of either alumina of silicon nitride
 or similar glass or ceramic material. This material specification is used
 due to high wattage density, rapid heat increase to 1000 degrees within
 one second, high level of insulation and non-stick nature of the ceramic
 to charred tissue. The preferred tip operating temperature range is 650 to
 700.degree. F. The second embodiment 26 of the invention is shown in FIGS.
 7-12. In this embodiment an external power source is used to power and
 control a simple thermal cautery forceps. The forceps 26 in this
 embodiment is either of an inexpensive disposable or a more durable
 reusable design. FIGS. 7, 8, 10 and 11 show the externally powered cautery
 forceps 28. FIG. 7 is a side elevational view of the thermal cautery
 forceps 28 instrument of the second embodiment of the invention. A cable
 72 connects the forceps to the external power supply unit (not shown).
 Each tine 74, 76 is composed of a rigid metal carrier with ceramic heater
 78, 80 and an insulating plastic shroud 82, 84. FIG. 8 is a top plan view
 thereof; FIG. 9 is an end elevational view there of illustrating the
 forceps tine end. FIG. 10 is an end elevational view of the end opposite
 the forceps illustrating the cable connector 86. FIG. 11 is a
 cross-sectional view of the second embodiment of the present invention,
 showing the housing 88 and cable connection. A pair of wires 90, 92
 connects the cable 72 to the pair of thermal heater elements 78, 80 wired
 in parallel. Also shown in FIG. 11 is the neoprene spacer 94. The spacer
 94 is positioned between the forceps tines 74, 76. An off center-binding
 pin 96 extends through the tines 74, 76 and the spacer 94 provides a
 spring effect. The spring effect also activates the ON/OFF switch 98. The
 switch 98 is composed of two electrical metal contacts 100, 102 affixed to
 the inside of each forceps tine 74, 76.
 FIG. 12 is a front elevation of the external power supply unit 103. This
 unit 103 contains a power switch 104, audio speaker 106, digital
 temperature display 108, SET/READ switch 110, temperature control knob
 112, recharging indicator lamp 114 and ready LED lamp 116. The power
 supply unit 103 may be a 12 volt DC unit.
 As shown in FIG. 12, the cable 72 connected to the forceps 26 enters the
 power unit 103. The power switch 104 is located on the front panel 118
 that illuminates when switch 104 is on. The speaker 106 signals the
 surgeon of proper heater element temperature for cauterization. The
 speaker 106 will sound when the instrument reaches the SET temperature
 after the forceps are squeezed together to initiate heating. The output of
 the speaker 106 is vented outside the power unit through a small port
 shown in FIG. 12. The unit also contains a temperature control. The
 temperature may be varied by positioning the SET/READ switch 110 to the
 SET position and rotating the temperature adjust knob 112 to the desired
 temperature. The digital temperature display 108 reports the desired set
 temperature in degrees fahrenheit. The temperature adjust control 112 may
 either be of an analogue or digital type. This control allows the surgeon
 to select a temperature for a desired effect depending on the thickness
 and moisture content of the tissue to be cauterized. The digital
 temperature display 108 may indicate the actual temperature of the ceramic
 heater elements 78, 80 when the SET/READ switch 110 is positioned in the
 READ position. The LED indicator 114 is incorporated into the power
 supply, which is illuminated when the batteries are recharging. The Heater
 On Indicator 116 is incorparated into the power supply, which is
 illuminated when the heater elements are heated. This occurs whenever the
 power unit is connected to a 110 VAC line. A charging circuit (not shown)
 regulates the recharging process.
 FIGS. 13 and 14 illustrate a holster 130 for accommodating the forceps 10
 or 26. A cavity 132 receives the tine end of the forceps 10 or 26. A loop
 134 or slits 136, 138 may be provided for attaching the holster 130 to a
 belt 140.
 The foregoing discussion of the invention has been presented for purposes
 of illustration and description. Further, the description is not intended
 to limit the invention to the form disclosed herein. Consequently,
 variations and modification commensurate with the above teachings, and the
 skill or knowledge in the relevant art, are within the scope of the
 present invention. The embodiments described herein above are further
 intended to explain modes known of practicing the invention and to enable
 others skilled in the art to utilize the invention in such, or other
 embodiments and with various modification required by their particular
 applications or uses of the invention. It is intended that the appended
 claim be construed to include alternative embodiments to the extent
 permitted by the prior art.