fig1 a shows an embodiment of a cautery device 100 that includes an elongated housing 102 that extends longitudinally along an axis a - a from a proximal end 104 to a distal end 106 . the device 100 also includes a removable hollow cautery tip 108 that extends longitudinally from the housing coaxially with axis a - a . the cautery tip 108 defines an open channel 110 that extends axially completely through the tip 108 . the open channel 110 is preferably coaxial with the axis a - a . the housing 102 defines a handpiece 112 that is arranged so that it may be grasped in a user &# 39 ; s hand like a writing instrument to direct the cautery tip 108 during a surgical procedure while also allowing a user of the device 100 to actuate buttons 114 , 116 that extend from the housing 102 . as will be described in greater detail below , the cautery tip 108 receives electric power to operate the tip 108 so that it can be used to perform various cautery tool procedures , such as cutting and coagulation . also , the cautery device 100 is constructed to selectively permit gas to flow through the open channel 110 of the cautery tip 108 . the cautery device 100 is operated in various modes in response to selective actuation of one or more of the buttons 114 , 116 , as will be described in greater detail below . each of the buttons 114 , 116 may operate the cautery device 100 in a corresponding mode of operation , such as a coagulation mode and a cutting mode . also , one or more of the buttons 114 , 116 may be a multi - function button . for example , each respective button 114 , 116 may be arranged to both control a gas flow of a gas through the cautery tip 108 , as well as control power output to the cautery tip 108 based on the mode of operation corresponding to each button 114 , 116 . more specifically , in one embodiment , a first button 114 may correspond to the cutting mode and a second button 116 may correspond to the coagulation mode . in such an embodiment , selectively actuating the first button 114 may set a first gas flow rate through the cautery tip 108 and a power level corresponding to the cutting mode , while selectively actuating the second button 116 may set a second gas flow rate to the cautery tip 108 and a power level corresponding to the coagulation mode . thus , a user of the device 100 may select the operating mode of the device by selecting and pressing a corresponding button 114 , 116 . a power cord 118 and a gas tube 122 extend from the proximal end 104 of the cautery device 100 . the power cord 118 supplies electric power to the device 100 from an electric power supply 120 . the gas tube 122 supplies a gas to the device 100 from a source of pressurized gas 124 . the gas may be an inert gas such as carbon dioxide or nitrogen . preferably , the gas is heavier than oxygen to drive away oxygen from the area proximate to the cautery tip 108 so that the gas issuing from the cautery tip 108 can create a non - flammable zone around the tip 108 . fig1 b shows the cautery device 100 with a portion of the housing 102 removed for purpose of illustrating some housed elements of the device 100 . the device 100 includes a valve train 126 coupled to the buttons 114 , 116 . the valve train 126 has a proximal end 128 that is formed as a barbed male coupler 130 for coupling to a distal end of the tubing 122 ( fig1 a ). the valve train 126 also has a distal end 132 that may be formed as a female quick - connect tube coupler 134 for removably coupling to a proximal end 136 of the cautery tip 108 . in the embodiment shown in fig1 b , the valve train 126 includes a first valve 138 that may be actuated by the first button 114 and includes a second valve 140 that may be actuated by the second button 116 . in one embodiment the valves 138 , 140 are biased so that they are normally - closed valves such that the user must depress the respective button to open the valves 138 , 140 . when the cautery tip 108 is fluidly coupled to the valve train 126 , the valve train 126 controls the flow of pressurized gas through the tip assembly by operation of the valves 138 , 140 , which are actuated using the buttons 114 , 116 . the cautery tip 108 is removably coupled in a collet 144 that is provided at the distal end of the handpiece 112 . the cautery tip 108 extends through the collet 144 . more specifically , when the cautery tip 108 is fully coupled to the handpiece 112 , as shown in fig1 b , the cautery tip 108 is fluidly coupled to the valve train 126 and is electrically coupled to an electrical unit 146 ( shown partially concealed beneath the valve train 126 in fig1 b ) via an electrical coupler 148 , as will be described in greater detail below . in the embodiment shown in fig1 a and 1b , the cautery tip 108 has a generally cylindrical , proximal portion 150 that extends through the collet 144 and to the fluid and electrical couplers 134 , 148 . the cautery tip 108 also has a flattened distal portion 152 . the cylindrical proximal portion 150 tapers to the flattened distal portion 152 distally of the collet 144 . the cautery tip 108 is formed of a metal that is coated with a conductive polymer . a silicone cover may also be applied to a portion of the tip 108 between the flattened portion 152 and the collet 144 . the flattened distal portion 152 has a generally rectangular cross - sectional profile . it will be appreciated , however , that the cautery tip 108 may have other profiles than that shown in fig1 b . the cautery tip 108 is removably coupled to the handpiece 112 to facilitate tip replacement and interchanging different cautery tips ( e . g ., with different forms ) with the same handpiece 112 . to provide such interchangeability , the electrical and fluid couplers 148 and 134 may be constructed as removable couplers , such as a fluid quick - connect coupler and an electrical socket , respectively . the electrical unit 146 is electrically connected to the wire 118 . the electrical unit 146 controls the flow of electrical power to the tip 108 to operate the device 100 in one of its operating modes through actuation of the aforementioned buttons 114 , 116 . as shown in fig2 , in one embodiment , the electrical unit 146 may be constructed as a printed circuit board 200 having a plurality of circuits 202 , 204 from the power source to the electric coupler 148 . each of the circuits 202 , 204 may correspond to a respective one of the buttons 114 , 116 and , therefore , to a mode of operation of the device 100 . specifically , circuit 202 includes a first switch 206 that may be actuated by the first button 114 and circuit 204 includes a second switch 208 that may be actuated by the second button 116 . each circuit 202 , 204 may be constructed to regulate the power level delivered to the cautery tip 108 when the respective switches 206 , 208 are actuated . for example , a first circuit 202 may be activated by the first switch 206 to energize the tip 108 so that it can cut tissue ( e . g ., a cutting mode ), while the second circuit 204 may be activated by the second switch 208 to energize the tip 108 so that it can coagulate fluid ( e . g ., a coagulation mode ). by way of example , in one embodiment , button 114 may be used to operate the device 100 in a cutting mode and button 116 may be used to operate the device 100 in a coagulation mode . a surgeon may press button 114 to simultaneously open the first valve 138 to allow for the gas to flow at a first flow rate to the tip assembly 142 and to energize the first circuit 202 to supply electrical energy to the tip 108 sufficient for operating the device 100 in a cutting mode . similarly , a surgeon may press the second button 116 to open the second valve 140 to allow for a second gas flow rate to the tip assembly 142 and to simultaneously energize the second circuit 204 to supply electrical energy to the tip 108 sufficient for operating the device 100 in a coagulation mode . the first and second flow rates may be the same or different based on the operating mode selected by pressing the associated buttons 114 , 116 . the first and second flow rates are sufficient to supply the gas at least in a quantity to the open end of the tip 108 to create a zone about the tip which is not flammable when the device is operated in any of its operating modes , e . g ., coagulation or cutting . also , each of the first and second flow rates may be variable based on the range of motion ( distance the button is depressed ) of the switch button . in one embodiment , the flow of gas and electricity to the cautery tip 108 may be interlocked together so that a flow of gas is initiated only when the tip 108 is energized in one of its operating modes ( e . g . cutting or coagulation ). also , in another embodiment , the flow of gas may be initiated without ( independently of ) energizing the tip 108 . for example , the buttons 114 and / or 116 may have a range of motion in which an initial range of motion ( i . e ., of button depression ) of the button may only permit gas to flow and a secondary range of motion ( i . e ., further button depression ) of the button may cause both gas and electricity to flow to the tip . the flow of gas and electricity may thus occur together or without electricity ( i . e ., gas only ). the construction of the valve train and the operation of the gas and electricity flow will now be described in greater detail . fig3 shows cutaway section views of the valve train 126 shown in fig1 b . fig3 shows a section view of the device 100 along section 3 - 3 in fig1 a . as shown in fig3 , the valves 138 and 140 are arranged as gate valves . the construction of valve 138 will now be described . it will be appreciated that the construction of valve 140 may be the same , although dimensions may be different . valve 138 has a valve body 302 that is disposed in the first channel 402 ( fig4 ) of the valve train 126 . valve 138 has a valve stem 304 that is received in a vertical bore 306 of the body 302 that intersects with the first channel 402 ( fig4 ). the valve stem 304 has a teardrop shaped port 308 formed therein , which is tapered towards the bottom of the valve stem 304 and is enlarged toward the top of the valve stem 304 . the valve stem 304 is coupled to the first button 114 . a coil spring 310 is interposed between the button 114 and the body 302 to bias the valve stem 304 in an upward , closed position in which the port 308 is not in communication with the first channel 402 , as is shown in fig3 . when the valve stem 304 is positioned as shown in fig3 , the stem 304 is seated in the housing and fully blocks the port 308 to maintain the valve 138 in a closed position . the valve stem 304 is constructed to move vertically in the vertical bore 306 so as to progressively open and close the flow of gas through the port 308 and the first gas channel 402 . the electrical unit 146 is shown below the valve train 126 . the first switch 206 is aligned with the valve stem 304 . a first coil spring 312 extends upward from the first switch 206 . when the first valve 138 is in the fully closed position , the spring is spaced from the bottom of the valve stem 304 . the first switch 206 may be constructed to actuate in response to compression of the first coil spring 312 . the valve stem 304 may be moved downward from the closed position by pushing on the button 114 against the force of the spring 310 . as the valve stem 304 moves downward , the bottom of the port 308 will begin to come into fluid communication with the first gas channel 402 , creating a relatively small opening for gas to flow between the port 308 and the first channel 402 . also , as the bottom of the valve stem 304 moves downward it begins to compress the first coil spring 312 , which causes the first switch 206 to actuate ( i . e ., to close the first circuit 202 ), permitting power to flow through the first circuit 202 to the cautery tip 108 at a power level regulated by the first circuit 202 and corresponding to a first operation mode . as the valve stem 304 is moved progressively further downward , the port 308 is progressively moved further downward enlarging the opening between the port 308 and the first channel 402 until the top of the port 308 is aligned with the top of the channel 402 , in which case the valve 138 is considered to be in a fully open position . the further movement of the valve stem 304 , however , does not change the state of the first circuit 202 , which remains energized owing to the further compression of the first coil spring 312 . thus , in view of the foregoing description it will be appreciated by one of skill in the art that in at least one embodiment of the cautery device 100 a user can regulate the flow rate of gas through the valve train 126 and the cautery tip 108 by adjusting the travel distance of the button 114 . such flow regulation may be useful for a surgeon to adjust the flow rates around tissue vessels of different sizes . for example , for blowing gas around small vessels , a user may desire only a relatively small wisp of gas , while for blowing gas around larger vessels , a user may desire a relatively larger flow to displace fluid from the area . fig4 shows a detailed section view of the device 100 across section 4 - 4 in fig3 . the valve train 126 defines the first gas channel 402 in which the stem 304 of the first valve 138 is received and a second gas channel 404 in which a second valve stem 305 ( fig3 ) of the second valve 140 is received . the first and second channels 402 , 404 both extend from the proximal end 128 to the distal end 132 of the valve train 126 . the first gas channel 402 has a first opening 406 that is aligned with the first bore 306 of the first valve 138 . the first opening 406 receives the first valve stem 304 . the second gas channel 404 has a second opening 410 that is aligned with a second bore 307 ( fig3 ) of the second valve 140 . the second opening 410 receives the second valve stem 305 ( fig3 ) of the second valve 140 . the first valve stem 304 is constructed to move vertically in the opening 406 to actuate the first switch 206 of the first circuit 202 of the electrical unit 146 , which is below the valve train 126 . similarly , the second valve stem 305 is constructed to move vertically in the opening 410 to actuate the second switch 208 of the second circuit 204 of the electrical unit 146 . the first and second valves 138 , 140 may be of the same construction or may be different . in one embodiment of the device 100 , the first and second buttons 114 , 116 may be pressed independently of one another and both can be pressed partially between the open and closed valve positions . however , the cautery tip 108 may be configured to operate in only a single operating mode , such as cutting or coagulating . for example , in one embodiment the electrical unit 146 may be constructed to ignore the actuation of all pressure switches ( e . g ., 206 , 208 ) other than the switch that is actuated first in time . in another embodiment , however , the electronic unit 146 may be constructed to ignore the actuation of all pressure switches ( e . g ., 206 , 208 ) other than the switch that sets the highest power output to the cautery tip 108 . in any event , it will be appreciated based on the foregoing disclosure that the independent opening of multiple valves ( e . g ., 138 , 140 ) will increase the gas flow rate issuing from the cautery tip 108 relative to if only a single valve was opened . alternatively , in one embodiment , instead of independent operation of buttons 114 , 116 , the two buttons 114 , 116 shown in fig1 b may be covered by a cover and connected together with a rocker arm ( not shown ) so that only one button ( 114 or 116 ) may be depressed at a time . in a further aspect , the tube 122 and electrical wire 118 extending from the handpiece 112 in fig1 a may be integrally formed into a multilumen tubing 500 , as show for example in fig5 and 6 . the multi - lumen tubing 500 defines a central lumen 502 for carrying the gas , and defines circumferentially spaced lumens 504 around the central lumen 502 for carrying electrical conductors 506 . the electrical conductors 506 may be bare conductors or may be insulated inside the lumens 504 . the tubing 500 is preferably constructed of an electrically insulated material . the tubing 500 may extend from a first end 508 , at the proximal end 104 of the housing 102 of the device 100 , to a second end 510 proximal of the first end 508 . the second end 510 of the tubing 500 may have terminations to connect to the fluid and electrical power supplies 516 and 522 . in one embodiment , a push - on barbed fitting 512 is inserted into the central lumen 502 and the barbed fitting 512 is connected to a tube 514 for fluid coupling to a supply of gas 516 . also , in one embodiment , the conductors 518 extend beyond the second end 510 of the multilumen tubing 500 a certain distance and terminate in an electrical connector 520 , such as a three prong plug , for electrical coupling to a mating electrical receptacle 522 . in yet another aspect , the device 100 may include a safety switch 600 ( fig6 ) that may be electrically connected in series with the electrical unit 146 to cut off power to the cautery tip 108 when the device 100 is disposed in a designated holder 700 ( fig7 ) that is constructed to hold the device 100 when it is not in use ( i . e ., not being actively handled by a user ). in one embodiment , a magnetic reed switch 600 is coupled between the electrical unit 146 and the electrical supply 120 . the magnetic reed switch 600 may be a normally closed switch that will normally energize the electrical unit 146 when it is not in the presence of a magnetic field . the holder 700 may include an elongated , open receptacle 701 , shown in fig7 , which can receive the device 100 . also , the holder 700 may include a permanent magnet 702 mounted to the receptacle 701 so that a magnetic field may be generated by the magnet 702 inside the receptacle 701 . preferably , the permanent magnet 702 is mounted at a position inside the receptacle 701 , such that the magnetic field will open the reed switch 600 when the device 100 is disposed in the receptacle 701 . in one embodiment , the cautery device 100 is disposed vertically or at a downward angle within the receptacle 701 with the tip 108 pointed down towards a bottom of the receptacle 701 . the magnet 702 is positioned in the receptacle 701 so that the magnet 702 is at or near the location of the reed switch 600 when the device 100 is disposed in the receptacle 701 with the tip 108 pointed down . when the device 100 is placed inside the receptacle 701 , the magnetic field generated by the magnet 702 will open the reed switch 600 and prevent closure of the activating circuits . thus , when the device 100 is disposed in the holder , the cautery tip 108 cannot receive power and cannot heat up , which may prevent accidental fires . there have been described and illustrated herein several embodiments of a cautery device . while particular embodiments of the invention have been described , it is not intended that the invention be limited thereto , as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise . thus , while particular button and cautery tip arrangements have been disclosed , it will be appreciated that other button and tip arrangements may be employed as well . in addition , while a particular type of safety switch has been disclosed , it will be understood that other switches having the same or similar functionality can be used . for example , and not by way of limitation , gmr ( giant magneto resistive ), amr ( anisotropic magneto resistive ), and hall effect switches may be used . also , while a particular multi - lumen geometry has been disclosed , other geometries are possible . also , while carbon dioxide may be preferred as an inert gas , it will be recognized that other gases that are non - flammable may be used . it will therefore be appreciated by those skilled in the art that yet other modifications could be made to the provided invention without deviating from its spirit and scope as claimed .
a cautery device includes an elongated handpiece extending axially from a proximal end to a distal end and a cautery tip extending coaxially with the handpiece from the distal end of the handpiece . the tip defines a channel extending coaxially with the handpiece along an entire length of the cautery tip from a proximal open end to a distal open end . the device includes a gas supply connection extending from the proximal end of the handpiece for supplying gas to the cautery tip . the gas supply connection is fluidly coupled to the cautery tip . the device includes an electric supply connection extending from the proximal end of the handpiece for supplying electricity to the cautery tip . the electric supply connection is electrically coupled to the cautery tip . the gas supplied to the cautery tip is introduced to the channel at the proximal open end and exits the tip at the distal open end .