WO2007012834A1

WO2007012834A1 - Improved ultrasonic scalpel

Info

Publication number: WO2007012834A1
Application number: PCT/GB2006/002764
Authority: WO
Inventors: Maurice Howieson
Original assignee: Cytyc Caymen Limited
Priority date: 2005-07-27
Filing date: 2006-07-27
Publication date: 2007-02-01
Also published as: GB0515376D0

Abstract

An improved ultrasonic scalpel (1) for use in surgical procedures is described. Traditional ultrasonic scalpels known in the art generate surgical smoke when deployed during operations. This surgical smoke is potentially dangerous to both the operating room personnel and patients alike. The described ultrasonic scalpel (1) incorporates apparatus for striking an ionised plasma flame (2) at the distal end of the scalpel (13) where the blade (15) is located. The presence of the ionised plasma flame (2) thus provides for improved cauterisation levels at the incision site, as well as burning off the surgical smoke produced so reducing the risk of infection experienced by the operating room staff and the patient.

Description

Improved Ultrasonic Scalpel

The present invention relates to medical apparatus and in particular to an improved ultrasonic scalpel for performing surgery.

Ultrasonic scalpels are commonly employed by those skilled in the art to produce incisions during surgery since these devices assist in avoiding trauma, extensive scaring, and other limitations normally associated with the thermal cutting of electro surgery and laser surgery. An example of such a device is described in US Patent No. US 6,514,267, in the name of IEP Pharmaceutical Devices Inc., entitled "Ultrasonic Scalpel".

In practice an ultrasonic scalpel takes advantage of dissection technology that results from the oscillating motion of a scalpel blade. Ultrasonic energy is transmitted through a connection or mount between an ultrasonic energy source and a hand held coupler within which is mounted the surgical tool, for example a surgical blade mounted at the tip of the coupler. This connection facilitates transmission of energy from the ultrasonic energy source, through the coupler, to the scalpel blade in order to impart on it a reciprocating vibrating motion.

The vibration of the scalpel blade also generates low levels of heat at the location of incision. Proteins are caused to denature as hydrogen bonds break due to the vibrational energy and heat transferred to the tissue by the vibrating scalpel blade. The denatured proteins form a coagulum that act to seal the bleeding vessels. Because the ultrasonic energy coagulates and cuts at low temperatures (i.e. levels below 80°C) the risk of thermal injury to a patient is minimised with the result that tissue damage and post operative adhesion effects are reduced and therefore the recovery time of the patient is also reduced.

It is known that post operative adhesion is closely connected with the temperature at the incision site. Increases in temperature cause lateral or deep tissue injury which have been shown to be linearly related to the time of activation of the ultrasonic transducer within the device. Since ultrasonic scalpels do not produce excessive heat they do not result in boiling or charring of tissue, but simply blanching and coagulation. These factors make ultrasonic scalpels particularly suitable for a range of medical processes.

However, ultrasonic scalpel tissue dissection creates gases and by-products, referred to as "smoke" that can be easily observed and which exhibit a distinctive odour. Typically, the mean aerodynamics size of particles generated through ultrasonic scalpels is in the region of 0.35-6.5μm. Furthermore, large quantities of cellular debris have also been found in the plume generated by an ultrasonic scalpel.

Studies concerning the composition of these plumes indicate that they are composed of human tissue blood and blood by-products. These studies have lead to recent concerns that surgical smoke is potentially dangerous to both operating room personnel and patients . The potential risks to the operating room personnel include pulmonary irritation and inflammation, transmission of infection and genotoxicity . The potential dangers to patients occur primarily during laparoscopic procedures where surgical smoke is concentrated in the peritoneal cavity. These potential dangers include carbon monoxide toxicity, port-site metastases from cancer spread through aerosolised cells and toxicity to the peritoneal compartments and its contents. Significantly, intra- peritoneal smoke also impairs visualisation of the surgical field.

Surgical masks provide inadequate protection in filtering such smoke, although they are more efficient at capturing larger sized particles. In practice the poor fit of such masks can seriously compromise their filter performance. As a result there is a direct requirement for protection for surgeons and operation room personnel to minimise their exposure to these harmful plumes.

It is therefore an object of the present invention to provide an ultrasonic scalpel capable of removing, or at least minimising, the volume of surgical smoke produced during an operation. Summary of Invention

According to a first aspect of the present invention there is provided an ultrasonic scalpel of a type comprising a blade located at a distal end, the ultrasonic scalpel further comprising an electrical supply, a gas supply and a gas supply conduit arranged so as to provide means for striking an ionised plasma flame at the distal end of the scalpel.

The ability to strike an ionised plasma flame at the distal end where the blade is located has the advantage that an ionised plasma flame can be employed to further cauterise an incision made by the blade and to burn off a smoke plume generated by an ultrasonic scalpel so as reduce the risk of infection experienced by a surgeon, operating room staff or the patient on which the device is being used.

Most preferably the ionised plasma flame provides a means for increasing the temperature of a smoke plume produced by the ultrasonic scalpel to a temperature above 80 'C.

Preferably the blade provides for an insulation free tip employed for the striking of the ionised plasma flame. Alternatively, the electrical supply comprises an insulated wire connected to an insulation free tip and arranged so that the insulation free tip is located at the distal end.

Preferably the electrical supply comprises a resonant electrical circuit that imparts an operating power of less than 33W to the ionised plasma flame. Most preferably the operating power is less than 16W.

Preferably the ultrasonic scalpel further comprises an ultrasonic transducer and an armature suitable for converting ultrasonic energy produced by the transducer to a mechanical vibration of the blade.

Most preferably the ultrasonic transducer and the armature are housed within a length of the gas supply conduit.

Preferably the ultrasonic scalpel further comprises a transducer switch that allows for manual activation of mechanical vibration of the blade.

Preferably the ultrasonic scalpel further comprises a plasma switch that allows for manual activation of the striking of the ionised plasma flame.

Optionally the transducer switch is located on the gas supply conduit. Alternatively, the transducer switch comprises a foot activation switch. Optionally the plasma switch is located on the gas supply conduit. Alternatively, the plasma switch comprises a foot activation switch. Optionally the transducer switch and the plasma switch comprise a single activation switch.

Preferably the gas supply comprises helium gas. Alternatively the gas supply comprises a gas selected from the group comprising hydrogen, argon, neon, nitrogen or a combination of these gases. Optionally the gas supply further comprises an oxygen gas component. Specific Description

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 presents a side, cut away view of an ultrasonic scalpel, in accordance with an aspect of the present invention: (a) in the absence of an ionised plasma flame; and (b) in the presence of an ionised plasma flame.

Figure 2 presents a block diagram of an electrical and gas supply employed by the ultrasonic scalpel of Figure 1 ; and

Figure 3 presents a block diagram of some of the electrical components of the electrical and gas supply.

For consistency and clarity purpose the various features of the described ultrasonic scalpel are referred to by the same reference numerals throughout the specification.

Figure 1 presents a side cut-away view of an ultrasonic scalpel 1 in accordance with an aspect of the present invention. In particular, Figures l(a) and (b) presents the ultrasonic scalpel in the absence and presence, respectively, of an ionised plasma flame 2 generated at the distal end of the device. The ultrasonic scalpel 1 can be seen to comprise a hand piece 3 that is connected to an electrical and gas supply 4 by means of a gas supply conduit 5, an insulated electrical wire 6 and a switch wire 7.

The hand piece 3 comprises a hollow housing 8 the external surface of which is ergonomically shaped so as to be easily grasped by a surgeon so allowing them to grip and manipulate the hand piece 3 during surgery.

Located coaxially within the hollow housing 8 are those elements required for the operation of an ultrasonic scalpel 9, namely an ultrasonic transducer 10 for energising an armature 11 that then moves a keyed cylinder 12 in a reciprocating motion, as indicated by the arrows in Figure 1. Located at the distal end 13 of the hollow housing is an aperture 14 that provides for the keyed cylinder 12 to exit the hollow housing 8 such that it may be connected with a blade 15. In practice the blade 15 can be one of several special purpose blades pre-fitted for the ultrasonic scalpel to be employed within different types of surgery. It may be made of metal, ceramic, a combination of both or any other material suitable for the purpose. An aperture 16 is provided in the blade 15 for receiving an extrusion 17 of the keyed cylinder 12 so as to provide the required connection of these elements.

On the external surface of the hollow housing 8 are located an ultrasonic transducer switch 18 and a plasma activating switch 19 that provide a means for activating power and a gas flow to the hollow housing, as appropriate, and as described in detail below. Figure 2 presents a block diagram of the electrical and gas supply 4 employed by the ultrasonic scalpel of Figure 1. The electrical and gas supply 4 is designed to produce a low powered plasma and is of a type similar to that described by the present authors within US Patent No. US 6,225,593, entitled "Medical Apparatus for Generating an Ionised Gas Plasma Flame" . In addition the electrical and gas supply 4 is employed to provide the electrical energy required to drive the ultrasonic transducer 10.

In particular, an electrical power source in the form of a sinusoidal generator 20 is provided which is capable of providing at its output 21 an alternating (sine wave) voltage at a fixed frequency (fl) in the low kilohertz region and with a magnitude less than 100 V with respect to earth, typically 5 V for low power (5W) operation. In the described embodiment, the fixed frequency (fl) is selected to be 50 kHz.

The sinusoidal generator output 21 is connected to a circuit network 22 (the function of which will be explained) having an output 23 connected to a step-up transformer 24 with a turns ratio of 30 to 1. The transformer 24 increases the voltage from the circuit network output 23 to provide sufficient working voltage for the hand piece 3, when employed to generate an ionised gas plasma flame. Insulated wire 6 is effectively coupled to earth capacitively due to parasitic effects and this is represented by a reactive element 25. The reactive element 25 also represents capacitive coupling to earth of the transformer windings. A detector 26 is connected to a transformer output signal 27 and the function of the detector 26 is described in more detail below.

Conduit 5 surrounds a portion of the length of the wire 6, i.e. the wire 6 is completely surrounded by conduit 5 for some of its length. The conduit 5 is electrically non-conducting and defines a gas-flow channel exteriorly of the wire 6 and the standard ultrasonic scalpel elements 9. A gas source 28 is used to supply the conduit 5 at its end adjacent the transformer 24 with a substantially inert gas, which in the presently described embodiment is helium. The gas pressure used is typically 1.5 psi. This low pressure (1.5 psi) has the advantage of reducing the amount of gas that is injected into the bloodstream of a patient 29 when an ionised plasma flame 2 is struck around the blade 15 of the ultrasonic scalpel 1. As can be seen the other end of the conduit 5 forms the hollow housing 8 of the hand piece 3.

To regulate and control the ultrasonic scalpel 1 a controller 30 is provided, the outputs of which control the sinusoidal generator 21, the gas source 34 and the ultrasonic transducer 10. The controller 30 is responsive to the manually-controlled switches 18 and 19 thus allowing for easy operator adjustment of the gas flow and the electrical power.

The ultrasonic scalpel 1 operates in the following manner. The activation of the transducer switch 18 causes an electrical supply to be provided to the ultrasonic transducer and so the blade commences its reciprocating motion. A surgeon can then commence with making an incision on the patient 29 at the desired location. The hollow housing 8 enables helium gas from the gas source 28 which flows through the conduit 5 to issue from the distal end 13. Within the hollow housing 8, the blade 15, when electrically energised, causes the issue of helium to become a self-ignited ionised plasma flame 2 (i.e. "strikes" the plasma) .

As can be seen from Figure 2 the detector 26 is connected in a feedback circuit which is used to control the amplitude of the voltage of the sinusoidal generator output 21. The detector 26 continuously monitors the voltage of the transformer output 27. If the voltage at the transformer output 27 exceeds a predetermined value (for example 1200V) then the detector 26 automatically reduces the amplitude of the voltage of the sinusoidal generator output 21 so as to reduce the voltage at the transformer output 27 to the predetermined value.

Figure 3 shows a block diagram of electrical components that are contained within the circuit network 22. The circuit network 22 comprises a limiting element 31 and a resonating reactive element 32 in the form of an inductor, the value of which is selected in relation to that of the reactive element 25 to achieve resonance at the chosen fixed frequency fl of the generator 20. The voltage magnification that results from resonance, although limited by element 31, means that a relatively low sinusoidal generator output voltage will be sufficient (once magnified by the circuit 22 and stepped- up by transformer 24) to initiate a plasma flame 2 at the distal end of the hand piece 3. In this embodiment the sinusoidal generator 20 generates an alternating voltage with a frequency of 50 kHz. The reactive element 25 typically has a (measured) capacitance value of approximately 100 pF, while the value of resonating reactive element 32 is selected as 100 μH to ensure that the circuit network 22 is approximately at resonance for the frequency of 50 kHz.

The limiting element 31 (sometimes known as a Q-spoiling resistor) determines the quality factor of the resonant circuit. The limiting element 31 is added to reduce the sharpness of the resonant peak; that is, to limit the voltage magnification produced by the resonant circuit comprising reactive element 25, and resonating reactive element 32. The limiting element 31 is used because the detector 26 may not be able to respond quickly enough to transient changes in the plasma or when the sinusoidal generator 20 is energised. The detector 26 is used in addition to the limiting element 31 so that the value of the limiting element 31 is not critical. The value of the limiting element 31 is selected to ensure that there is sufficient magnification of the generator output signal 21 to initiate a discharge, but not so much magnification that breakdown problems occur.

Employing the described the electrical and gas supply 4 provides for the total power delivered to the ionised plasma flame 2 to be very low (typically ~5W) . The function of the plasma flame 2 is therefore two-fold. In the first instance, due to the close proximity to the patient 29, the inherent temperature (typically 800 'C) of the plasma flame 2 acts to cauterise the site of the incision. This cauterising action is in addition to that performed by the vibrating blade 15 alone. In practice the combined level of cauterisation is greater than those achieved though the independent employment of an ultrasonic scalpel and the cauterising apparatus described previously in US Patent No. 6,225,593. It is believed that this is a direct result of a channelling effect experience by the helium gas within the incision created by the vibrating blade 15. Thus the vibrating blade 15 can be considered to focus the plasma flame 2 to the site where cauterisation is required to be preformed. Irrespective of the precise mechanism involved the increased level of cauterisation has the advantage of increasing the field of vision for the surgeon carrying out the operation on the patient 29.

More significant is the fact that the presence of the ionised plasma flame 2 also acts to rapidly heat, to a temperature above 80 "C, the by-products produced by the vibrating blade 15. Critically it is found that above this temperature the by-products contained within the plume of smoke are burned off and so the plasma flame 2 acts to effectively sterilise the plume without increasing the risk of further tissue damage to the patient 29. As a result the risk of infection to the surgeon, operating room staff and the patient 29 themselves is significantly reduced through the employment of the described ultrasonic scalpel 1.

It will be appreciated that various modifications may be made to the above embodiment within the scope of the present invention. For example, the described embodiment employs the elements of a traditional ultrasonic scalpel 9 as the distal end of the insulated electrical wire 6, which are then employed within the ignition process for the ionised plasma flame 2. However in an alternative embodiment the insulated wire β may extend directly so as to terminate near to the end of the blade 15 in an insulation-free tip.

The ultrasonic transducer switch 18 and the plasma activating switch 19, within the above described embodiments, are located on the external surface of the hollow housing 8. However, in an alternative embodiment, one or both of these switches may comprise foot operating switches so that one or both of these switches can be located remotely from the hollow housing. The function of the switches is to provide a means for activating power and a gas flow to the hollow housing, as appropriate.

It should also be noted that the vibrating blade 15 and the plasma flame 2 can be used independently of each other through the presence of the independent activating elements, namely transducer switch 18 and plasma switch 19. Thus in addition to the described combined effects a surgeon may choose to employ the device as a traditional ultrasonic scalpel or as an ionised plasma flame for cauterisation.

In other embodiments of the present invention the gas used is a gas with a low breakdown potential such as hydrogen (H₂) , argon (Ar) , neon (Ne) , nitrogen (N₂) or a combination of these.

Although the electrical supply and the gas supply have been described as a single combined element it will be appreciated by those skilled in the art that these elements may be provided as two independent elements. In addition, the electronic components may be arranged as integral components of the hand piece.

The transducer switch and the plasma switch that allow for manual activation of mechanical vibration of the blade and for the striking of the ionised plasma have been described as separate switching means. In an alternative embodiment these switch may be combined so as to provide for simultaneous activation.

The foregoing description of the invention has been presented for the purpose of illustration and description, and is not intended to be exhaustive or to limit the invention to the precise form disclosed. The described embodiments were chosen and described in order to best explain the principals of the invention and its practical applications, to thereby enable others skilled in the art to best utilise the invention in various embodiments and with various modifications as are suited to the particular use upon completion. Therefore, further modifications and improvements may be incorporated without departing from the scope of the invention herein intended.

Claims

1) An ultrasonic scalpel (1) of a type comprising a blade (15) located at a distal end (13), the ultrasonic scalpel (1) further comprising an electrical supply (4, 6, 7), a gas supply (28) and a gas supply conduit (5) arranged so as to provide means for striking an ionised plasma flame (2) at the distal end (13) of the scalpel.

2) An ultrasonic scalpel (1) as claimed in claim 1 wherein the ionised plasma flame (2) provides a means for increasing the temperature of a smoke plume produced by the ultrasonic scalpel (1) to a temperature above 80 "C.

3) An ultrasonic scalpel (1) as claimed in claim 1 or claim 2 wherein the blade (15) provides for an insulation free tip employed for the striking of the ionised plasma flame (2) .

4) An ultrasonic scalpel (1) as claimed in claim 1 or claim 2 wherein the electrical supply (4, 6, 7) comprises an insulated wire (6) connected to an insulation free tip and arranged so that the insulation free tip is located at the distal end.

5) An ultrasonic scalpel (1) as claimed in any of the preceding claims wherein the electrical supply (4, 6, 7) comprises a resonant electrical circuit (20, 22, 24) that imparts an operating power of less than 33W to the ionised plasma flame (2) . 6) An ultrasonic scalpel (1) as claimed in claim 5 wherein the operating power is less than 16W.

7) An ultrasonic scalpel (1) as claimed in any of the preceding claims wherein the ultrasonic scalpel (1) further comprises an ultrasonic transducer (10) and an armature (11) suitable for converting ultrasonic energy produced by the transducer (10) to a mechanical vibration of the blade (15) .

8) An ultrasonic scalpel (1) as claimed in claim 7 wherein the ultrasonic transducer (10) and the armature (11) are housed within a length of the gas supply conduit (5) .

9) An ultrasonic scalpel (1) as claimed in any of the preceding claims wherein the ultrasonic scalpel (1) further comprises a transducer switch (18) that allows for manual activation of mechanical vibration of the blade (15) .

10) An ultrasonic scalpel (1) as claimed in any of the preceding claims wherein the ultrasonic scalpel (1) further comprises a plasma switch (19) that allows for manual activation of the striking of the ionised plasma flame (2) .

11) An ultrasonic scalpel (1) as claimed in claim 9 or claim 10 wherein the transducer switch (18) is located on the gas supply conduit (5) . 12) An ultrasonic scalpel (1) as claimed in claim 9 or claim 10 wherein the transducer switch (18) comprises a foot activation switch.

13) An ultrasonic scalpel (1) as claimed in any of claims 10 to 12 wherein the plasma switch (19) is located on the gas supply conduit (5) .

14) An ultrasonic scalpel (1) as claimed in any of claims 10 to 12 wherein the plasma switch (19) comprises a foot activation switch.

15) An ultrasonic scalpel (1) as claimed in any of claims 9 to 14 wherein the transducer switch (18) and the plasma switch (19) comprise a single activation switch.

16) An ultrasonic scalpel (1) as claimed in any of the preceding claims wherein the gas supply (28) comprises a gas selected from the group comprising helium, hydrogen, argon, neon, nitrogen or a combination of these gases.

17) An ultrasonic scalpel (1) as claimed in claim 16 wherein the gas supply (28) further comprises an oxygen gas component.