Patent Application
20080147058
This invention relates to an electrocautery system that is provided with user-directed, lightweight, compact, optionally self-powered, safe lighting of an operational site at which an electrocautery operation is to be performed. More particularly, this invention relates to a self-contained, lightweight, compact, manually-handled electrocautery system provided with internally-cooled lighting directable by a user at an operational site, that is self-powered for both electrocautery and lighting needs.
Safe, well-directed, adequate lighting of an operational site is essential during surgical procedures, both while a surgical tool is being applied to tissue and to enable the user to otherwise view and manipulate the tissue at and around the operational site. The carefully controlled application of a relatively high temperature to selected tissue, to effect an incision or local fusion cautery of the same, is the primary purpose of a cauterization procedure.
In a monopolar electrocautery system, this involves the application of a particularly shaped electrically conductive element at the end of a hand-piece, sometimes referred to as a “pencil”, to the tissue of a patient who is made a part of a shared electrical circuit. Alternatively, for incisions only, the hand-piece at a distal end may have an electrically heated thin wire stretched out tautly between two adjacent electrodes. In yet another alternative, in a bipolar system, tissue may be pressed between two cooperating electrodes movable relative to each other. In all of these alternatives, the user typically operates either a foot switch or a manual switch located on the pencil to cause a controlled flow of electrical current through the electrode(s). The electrode(s) will typically have a small thermal capacitance, and will therefore cool quite rapidly when the electrical current flow ceases.
The lighting portion of the system also heats up due to the release of waste heat while the user is cauterizing tissue and, often for relatively longer periods, while the user is manipulating tissue at and around the operational site. Local temperatures at or close to the light-generating element could consequently reach values high enough to cause damage to nearby tissue. Preferably, this heat must be removed on a more or less continual basis to limit the resulting temperature rise to eliminate the risk of inadvertent damage to adjacent tissue.
For prolonged surgical operations, particularly in confined regions, e.g., during gynecological or laryngeal surgery, it is very important for the user that both the physical size and the weight of the hand-held electrocautery element be limited to the extent possible. This means that there are serious physical limits on any means employed to effect heat transfer from the light-generating portion of the electrocautery system during its use, particularly when the light-generating element is mounted to the hand-held electrocautery element. Fans to cause forced convection of cooling airflow, or liquid cooling flows, therefore are generally impractical and intrusive when the user is operating within a confined body cavity of a patient.
Electrical power for cauterization and for lighting may be obtained from an electrical mains supply, via appropriately designed circuitry. Various circuits are commercially available, and electrical engineers of ordinary skill in the art may choose to design their own alternatives, to adapt any available electrical power supply to suit the needs of a chosen cautery element or lighting-element. Power for both needs simultaneously, or solely for lighting, may also be provided by self-contained power storage elements such as batteries, rechargeable cells or supercapacitors contained within or mounted to the body of the pencil.
The prior art provides numerous solutions, of varying effectiveness, both for the lighting needs and for cooling of the light-generating element. Examples of prior art relating to means for providing light during surgery include U.S. Pat. No. 2,029,487, of Kleine, titled “Illuminated Cautery Electrode” and U.S. Pat. No. 6,428,180, of Karram et al., titled “Surgical Illumination Device and Method of Use”. Examples of prior art relating to removal of heat from lighting elements include U.S. Pat. No. 6,709,128, of Gordon, titled “Curing System”, that employs a forced convection motor-driven fan; and U.S. Pat. No. 6,834,977, of Surhiro et al., titled “Light Emitting Device”, wherein conduction of heat along electrical conductors is suggested.
It is a principal object of this invention to provide a lightweight, compact, cautery device in which a hand-held cauterization element is provided with a lighting element that can be readily employed by a user to clearly light an operation site within a confined region in a patient's body both during actual cauterization and while otherwise viewing and manipulating tissue.
Another object is to provide a surgeon with a lightweight, compact, self-powered, cautery device that is entirely self-contained and can provide clear lighting of an operation site within a confined region both during an actual procedure and while otherwise viewing and manipulating tissue at and about an operation site.
A related object is to provide, in an electrocautery system, a hand-held cauterization element that can operate on a single outside source of electrical mains power to operate both a cauterization electrode in a monopolar cauterization system and to provide the user safe and clear lighting of the operation site for prolonged periods both during actual cauterization procedures and otherwise.
An even further object of this invention is to provide, in a cautery system that utilizes laser light energy to effect incision and cauterization with a hand-held cauterization element, means for providing safe, clear lighting of an operational site within a confined region in a patient's body—both during an incision or cauterization procedure and also while the user is viewing, manipulating or otherwise operating on tissue.
These and other related objects of the invention are realized by providing a lightweight, compact, cautery device having a hand-held body, for selectively incising or cauterizing tissue at a lighted operational site that may lie within a confined region or cavity of a patient's body. The device comprises:
In another aspect of the invention, there is provided a method for enabling a user to safely direct clear lighting to an operational site from a hand-held cauterization tool both during an actual incision/cauterization procedure and while otherwise viewing, manipulating or operating within a confined region of a patient's body.
These and related objects are realized by providing a method for enabling safe, convenient, well-lit cautery, by application of a power-heated cautery blade mounted to a distal end of a hand-held body to tissue in a surgical operation, comprising the steps of:
As best understood with reference to
The circuit inside control unit 110 is connected by a cable 124 to foot-operated switch unit 126 controlled by the application of foot pressure by the user. As illustrated in
Cutting/incision typically requires a higher power flow, to generate a higher tissue-contact temperature than does cautery/coagulation for most tissues. The required heating of the monopolar cautery blade 122 to apply this heat is obtained by resistance heat released at the tissue contact point when blade 122 is contacted to the patient's tissue at a selected operational site to complete an electrical circuit through the patient's body. Cautery blade is typically shaped to effect cutting at an elongate edge that is not mechanically sharp like a knife but generates a relatively high current density by tissue contact at a small contact surface area. Heat-induced disintegration of the contacted tissue cells is probably a major factor that causes the cutting of tissue. The actual “cutting” mechanism no doubt also involves some local arcing between the blade and tissue because of the electrical potential differences—which would result in physical weakening and disintegration of tissue cell walls.
Cauterization of tissue usually requires a lower local temperature, obtained by reduced voltage and/or frequency of the current flow and by applying the heat and some mechanical pressure over a larger contact area. This is generally effected by applying the side of blade 122 to tissue to be fused by local heating at a temperature not sufficient to cause the level of cell disruption involved in cutting. Both cautery, e.g., of a severed artery, and coagulation of body fluids may be effected in this manner.
It is a combination of controlled power flows and user skill that provides the best results. Naturally, the user must be able to see the operational site clearly, i.e., clear, consistent and dependable lighting is very important. Logic dictates the lighting unit be optimally located on the handpiece, that the elements to provide it be small and light in weight, and that the light be bright and directable at the user's discretion both during an actual surgical procedure and otherwise while the user is viewing and/or manipulating tissue at and about the operational site. Since the power needs of such a lighting system generally are different from those of the blade 122, and yet another control is involved to operate it, the circuit becomes more complicated. Note that plug 170 is shown in
Details of how the present invention addresses these needs follow below.
First embodiment 400, per
The second embodiment, per
Note that stalks 416 or 452, power unit 414, light-emitting element 418, and even cable 408 can be made in known manner to be detachably fitted to the body and/or to each other as needed. This allows for the benefits of modularization, i.e., a manufacturer could produce such elements in various lengths, light-emitting capabilities, etc., and a user could easily fit together the assembly optimum for his or her intended use. Large surgical facilities might find this highly economical. It would also facilitate reuse of some or all or these components after cleaning, sterilization and reassembly—perhaps at reduced costs by workers abroad.
The preferred light-emitting element is an LED that provides a white light, and has a forward bias voltage of 3.4V and requires a constant current of about 350 mA, i.e., a power requirement of about 1.2 W. While this is only a small fraction of the power required by the cautery blade (about two orders of magnitude larger) over a period of minutes it is possible for the light-emitting element to reach tissue-contactable surface temperatures high enough to cause serious tissue damage by inadvertent contact. There is also the danger that even the user might contact such a hot surface during the surgical operation and, despite wearing surgical gloves, might suffer pain and/or serious distraction. There is also concern about flammable items, e.g., small surgical drapes, alcohol soaked items and the like, becoming too hot unexpectedly, and about the presence of oxygen that is often required for patients and must be kept in the vicinity of the surgical zone. For all these reasons it is desirable to remove heat away from the light-emitting element as efficiently as possible. This must be done, to the extent possible, without adding to the size or weight of the handpiece and without increasing power requirements.
The most satisfactory solution to the above-referenced cooling problem is to utilize the already present elements wisely by making them do double duty whenever possible, e.g., make electrical conductors also serve as thermal conduits to transfer heat away from hot regions. This logic is applied beneficially in this invention as follows: the base that supports the light-emitting element (an LED, for example) has a certain mass and 6B make this feature very clear in perspective views. Note that his feature is present in both the cable-powered and the self-contained embodiments, e.g., those per
The preferred light-emitting element is an LED that provides a white light, and has a forward bias voltage of 3.4V and requires a constant current of about 350 mA, i.e., a power requirement of about 1.2 W. While this is only a small fraction of the power required by the cautery blade (about two orders of magnitude larger) over a period of minutes it is possible for the light-emitting element to reach tissue-contactable surface temperatures high enough to cause serious tissue damage by inadvertent contact. There is also the danger that even the user might contact such a hot surface during the surgical operation and, despite wearing surgical gloves, might suffer pain and/or serious distraction. There is also concern about flammable items, e.g., small surgical drapes, alcohol soaked items and the like, becoming too hot unexpectedly, and about the presence of oxygen that is often required for patients and must be kept in the vicinity of the surgical zone. For all these reasons it is desirable to remove heat away from the light-emitting element as efficiently as possible. This must be done, to the extent possible, without adding to the size or weight of the handpiece and without increasing power requirements.
The most satisfactory solution to the above-referenced cooling problem is to utilize the already present elements wisely by making them do double duty whenever possible, e.g., make electrical conductors also serve as thermal conduits to transfer heat away from hot regions. This logic is applied beneficially in this invention as follows: the base that supports the light-emitting element (an LED, for example) has a certain mass that can serve as a thermal mass, heat capacitance or heat sink, i.e., it will absorb some of the heat from the LED to cool it temporarily. It will be especially effective in this if it can shed some of the collected heat, e.g., by conducting it to electrical conductors touching it. This is to some extent inherent in the structure, but designing the base and the conductors with this in mind, and selecting materials that are particularly good thermal and electrical conductors significantly enhances this benefit. The electrical conductor so employed to do double duty will also serve as a second sink for limited periods—clearly beneficial to the cooling effort. Even further, the far end of electrical conductor so employed will be able to transfer some of the conducted heat to the power unit, e.g., to the mass of the power cell if there is one. Eventually, the user's own hand will absorb some of the transferred heat away from the handpiece. Accordingly, the conductors contacting the light-emitting element base, and the base itself, are preferably contain at least one of aluminum, copper, gold, brass, beryllium-copper alloy, platinum and titanium. These materials are considered good electrical and thermal conductors, and there may be others that would qualify equally well.
Note that a number of cautery systems utilize laser light energy to effect cutting by direct application of laser light to the tissue to cause intense local heating thereof. A variation of this is to absorb the laser light internally at the surface in a thin external coating on the cautery blade to heat the coated surface and apply it for cautery or coagulation. Even such systems can be improved for use in confined regions by supplementing them with the cooled lighting system taught herein. The electrical conductors that convey power, e.g., from a self-contained power source such as a single-use or rechargeable cell in or on the handpiece, can also be adapted to help in removing heat from the light-emitting element as taught herein.
The nominal voltage of the signals delivered from the electrocautery power supply to the electrodes is greater than that required or directly usable for LED power. A step down transformer 710 is therefore used to modify the voltage. The scavenged signal from the transformer 710 is then rectified and filtered in rectifier 720, and the rectified output is converted to the appropriate lower voltage in regulator 730 and then provided to LED 740. As will be understood by persons of ordinary skill in the electrical arts, this will allow the user to operate both the cautery and the lighting elements via the switches on the handpiece. The former could be a two-position type that would allow selection of the correct power for cutting or coagulating as needed.
It may be highly useful to provide a supplementary power source in the handpiece, e.g., a battery, to power just the lighting function for lighting when the power otherwise scavenged from the cautery power flow is not available. Circuit 800, per
Yet another option is to add to the cautery signal a supplemental power flow and then strip it away for use in the lighting function. Such a supplemental power flow could be in the nature of a direct current addition to the primary alternating current flow. This will require the addition of two more conductors to provide the necessary electrical pathways in the circuit. Circuit 900, per
The power conversion portion 1020 performs a voltage boost function, necessary because most suitable white light LEDs have a forward bias voltage higher than the 3.2V nominal voltage of a lithium cell. It must provide a constant voltage to ensure steady, clear and consistent lighting regardless of any decline in the output voltage from the power cell(s) as the energy stored therein is depleted to exhaustion. The power conversion portion 1020 preferably is based on a commercially available device marketed as a ZETEX ZXSC310. This is an integrated circuit which, when combined with a high performance external transistor, enables the production of a high efficiency boost converter for LED driving operations from a battery cell power source. Details of the ZETEX device, and certain variations thereof, may be found in ZETEX Semiconductors Bulletin, Issues 2 and 3, for March 2004. Some of the exemplary circuits are identified as “Prior Art” in
As noted earlier, employment of electrical conductors and heat sink masses constitutes efficient use of the mass and volume of the lighting system itself to ensure against unacceptably high temperature damage to inadvertently contacted tissues. Referring to
Various structural options are available in selecting the electrical conductors, some of which are indicated in
Other similar flexible and malleable choices include:
per
per
per
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Persons of ordinary skill in the relevant arts will no doubt consider and employ other obvious variations of the structures disclosed and suggested herein. All such modifications and variations are intended to be comprehended within this invention which is limited only by the appended claims.
| Number | Date | Country | |
|---|---|---|---|
| 60690384 | Jun 2005 | US |
