WO2023146539A1 - Méthode d'incision et d'ablation de tissus vivants et dispositifs laser chirurgicaux - Google Patents

Méthode d'incision et d'ablation de tissus vivants et dispositifs laser chirurgicaux Download PDF

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Publication number
WO2023146539A1
WO2023146539A1 PCT/US2022/014469 US2022014469W WO2023146539A1 WO 2023146539 A1 WO2023146539 A1 WO 2023146539A1 US 2022014469 W US2022014469 W US 2022014469W WO 2023146539 A1 WO2023146539 A1 WO 2023146539A1
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laser beam
surgical
energy
tissue
incising
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PCT/US2022/014469
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English (en)
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Max Shurgalin
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Max Shurgalin
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Priority to PCT/US2022/014469 priority Critical patent/WO2023146539A1/fr
Publication of WO2023146539A1 publication Critical patent/WO2023146539A1/fr

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B18/18—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves
    • A61B18/20—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using laser
    • A61B18/22—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using laser the beam being directed along or through a flexible conduit, e.g. an optical fibre; Couplings or hand-pieces therefor
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B18/18—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves
    • A61B18/20—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using laser
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B2018/00571—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body for achieving a particular surgical effect
    • A61B2018/00577—Ablation
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B2018/00571—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body for achieving a particular surgical effect
    • A61B2018/00601—Cutting
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B2018/00571—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body for achieving a particular surgical effect
    • A61B2018/00625—Vaporization
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B2018/00994—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body combining two or more different kinds of non-mechanical energy or combining one or more non-mechanical energies with ultrasound
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B18/18—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves
    • A61B18/20—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using laser
    • A61B2018/2035—Beam shaping or redirecting; Optical components therefor
    • A61B2018/20351—Scanning mechanisms
    • A61B2018/20359—Scanning mechanisms by movable mirrors, e.g. galvanometric

Definitions

  • the present invention generally relates to devices used in laser surgeries, and specifically to technologies that make possible executing concurrently with incising and ablating living tissues with a laser beam greater control of bleeding while reducing associated with haemostasis injury to nearby healthy tissues, and without requiring surgical instrument to be in contact with a living tissue.
  • bipolar electrosurgical energy instrument for stopping bleeding is a contact mode device and it is often used together with laser cutting and ablating device.
  • cutting and ablating device such as laser beam delivery handpiece
  • haemostasis device has to be interchanged with haemostasis device.
  • Desired is a technique of incising and ablating living tissues with laser precision and effecting appropriate surgical haemostasis while minimizing the spread of damage to healthy tissues and anatomical structures in need of preservation, and which is implemented in a single surgical device.
  • a laser-based method of cutting and coagulating tissue was disclosed in the patent US 4273127.
  • Laser radiation is utilized to coagulate tissue next to the cutting edge of an instrument similar to a surgical scalpel and that way to create haemostatic effect.
  • the extent of tissue coagulation is determined by the laser wavelength and the intensity of the laser radiation while the location of tissue coagulation automatically coincides with the incision because the laser radiation energy is transmitted into tissue from the device working edge.
  • the approach is lacking both the contact-less nature and precision of laser beam because it relies on a cutting instrument very much like a traditional scalpel.
  • United States patent US 8876810B1 describes a method for treatment of benign prostatic hyperplasia using laser energy to both coagulate and incise prostatic tissue. At least two laser sources are used to substantially simultaneously ablate excess tissue and coagulate tissue beyond ablation to provide a near blood-free treatment. As it was suggested in the already referenced earlier patent US 4273127, extent of issue coagulation depends on the wavelength or the frequency of laser radiation because light of different wavelengths is absorbed less or more and thus penetrates into tissue to different depths. Referring back to the method disclosed in the patent US 8876810B1, the second laser source at a different wavelength, penetrating deep into tissue, serves the purpose of expanding tissue coagulation in volume.
  • Laser energies at both wavelengths are substantially simultaneously delivered and large amount of tissue coagulation is induced to stop blood discharge from severed blood vessels and to contain bleeding.
  • the method is relevant to laser treatment of benign prostatic hyperplasia where the objective is to reduce excess prostate tissue by means of ablation and coagulation necrosis of tissue and to prevent severe blood loss during procedure.
  • the method is not adequate for precision laser surgeries and microsurgeries in which retaining most of healthy tissue and organ function, and therefore accurate control of extent of tissue coagulation, is most required.
  • the present invention features a method of incising and ablating living tissues using laser beam and effecting enhanced surgical haemostasis concurrently with incising and ablating.
  • the method does not entail touching tissue with an instrument and is implemented in a single device.
  • Enhanced haemostasis implies arresting bleeding from blood vessels severed by tissue removal with the laser beam to higher degree than conventionally attainable using laser beam alone without separate additional implements for surgical haemostasis, and at the same time minimizing damage to healthy tissues that need to be preserved, limiting the extent of tissue coagulation and necrosis.
  • the method enables adjustment and optimization between acceptable bleeding and extent of haemostasis-related damage to healthy tissues in a variety of tissues and surgical procedures.
  • the method does not rely on specific characteristics of tissue such as pigmentation or high concentration of hemoglobin or myoglobin and applicable to a diversity of living tissues.
  • the present invention also features surgical laser devices, which operate according to the method of incising and ablating living tissues using laser beam and effecting enhanced surgical haemostasis concurrently with incising and ablating, including an apparatus utilizing flexible fiberoptics for energy delivery and allowing usage of precise laser beam scanning and positioning devices such as laser beam scanners and surgical micromanipulators.
  • the present invention provides a method and devices for incising and ablating living tissues with precision of a laser beam and with greater concurrent control of bleeding, yet with less injury to surrounding healthy tissues than what is expected from administering surgical haemostasis separately.
  • a surgical laser beam to incise and ablate tissue is pulsed and it is highly absorbed in living tissues, as can be characterized by absorption coefficient at least 250 cm' 1 .
  • Enhanced haemostatic action is achieved using along with the surgical laser beam energy thus delivered in pulses, a separately controlled second energy effecting haemostasis, by providing a contact-less means of depositing the second energy in a given spot only into a limited volume of tissue that does not significantly exceed the size of tissue evaporation crater that a single pulse of the surgical laser beam creates.
  • the second energy is delivered, deposited and absorbed into tissue prior to creating tissue evaporation crater with the first surgical laser beam pulse in any and every spot of incising and ablating tissue, thus promoting coagulation shrinkage, constriction and sealing of blood vessels before severing them.
  • the second energy is heat conveyed to tissue by a heated gas jet from a hollow core optical fiber, which also transmits the surgical laser beam.
  • the second energy is another laser energy producing haemostatic heat when absorbed into tissue, delivered by the second laser beam at a wavelength chosen specifically according to the requirement of depositing the second energy into a limited tissue volume preemptively and minimizing haemostasis-related damage.
  • the two laser beams are co-propagated coaxially, via free-space optics, articulating arm, flexible optical fiber and via different combinations of all of those.
  • Known devices for precise laser beam steering in laser surgeries such as laser beam scanners and micromanipulators, can be utilized. All the above advantages and further details of the present invention are apparent in the following detailed description of the invention and the accompanying figures.
  • FIG. 1 illustrates the present invention with a basic timing diagram of the surgical laser beam delivery and the second energy delivery for preemptive haemostatic effect.
  • FIG. 2 demonstrates the present invention by showing schematically preemptive haemostatic action in a vascular living tissue.
  • FIG. 3 A, FIG. 3B and FIG. 3C present timing diagrams exemplifying the surgical laser beam delivery and the second energy delivery in different embodiments of the present invention.
  • FIG. 4 is an illustration to an embodiment of the present invention utilizing a hollow core fiber for delivery of the surgical laser beam and for producing a heated gas jet coaxial with the surgical laser beam for delivery of the second energy.
  • FIG. 5 is a block diagram of an embodiment of the present invention utilizing a hollow core fiber for transmitting the surgical laser beam and supplying the heated gas jet.
  • FIG. 6 is a block diagram of an exemplary optical arrangement in an embodiment of the present invention with the second laser beam for applying the second energy.
  • FIG. 7 is a block diagram of an exemplary optical arrangement in a preferred embodiment of the present invention with the second laser beam for applying the second energy, in which a flexible optical fiber and a laser beam scanning and positioning device are used.
  • tissue incising and ablating with a laser beam is produced by means of precision tissue elimination spot by spot via evaporation or photoablation process, which is further referred to simply as tissue evaporation irrespective of exact process.
  • the surgical laser beam according to the present invention is pulsed and is highly absorbed in living tissues, meaning that absorption of the surgical laser beam pulse results in instant vaporization of tissue in the beam target spot creating a tissue evaporation crater with almost no thermal damage spread to surrounding tissue.
  • Ultrafast lasers usually operating at a wavelength between 0.45 pm and 1.2 pm, deliver energy in trains or bursts of very short pulses of extreme peak power, causing tissue material optical breakdown and evaporation over minimal penetration depth. Therefore in the context of this invention, ultrafast laser beam energy is considered highly absorbed and pulses of pulsed surgical laser beam in this case are bursts or trains of ultrashort pulses.
  • Lasers which energy is considered highly absorbed in living tissues per the above criterion, also include but not limited to infrared lasers operating at wavelengths of strong water absorption, such as CO2 laser at 10.6 pm and Er:YAG laser at 2.94 pm.
  • providing a pulsed surgical laser beam and a means of applying a second energy, via spatially confined delivery of the second energy into tissue in any and every spot of incising and ablating tissue, producing localized thermally induced haemostatic effect preemptively, allows to achieve enhanced haemostatic performance with minimal extension of tissue coagulation and consequential tissue necrosis, further referred to as collateral tissue damage, beyond incision and ablation boundaries.
  • the second energy is heat or other form of energy that produces haemostatic heat when absorbed into tissue.
  • the second energy can be focused ultrasound energy or second laser energy, or heat delivered to tissue by a heated gas jet.
  • the means of applying the second energy according to the present invention deposits it only into a limited volume of tissue centered on the axis of the surgical laser beam and not substantially larger than tissue evaporation crater resulting from a single pulse of the surgical laser beam in any and every spot of incising and ablating.
  • the meaning of limited volume not substantially larger than the tissue evaporation crater is that the second energy is deposited in a focused manner, immediately affecting only tissue that is to be exposed to the surgical laser beam pulse.
  • Such limited volume is comparable to the surgical laser beam spot size laterally and is as shallow as or deeper than the evaporation crater but not significantly larger or deeper as to cause unacceptable collateral tissue damage, which also depends on the amount of the second energy deposited.
  • tissue absorption coefficient for the second laser beam is not less than 10 cm' 1 according to the customary in the art meaning of penetration depth as the reciprocal of absorption coefficient, in reference to the fundamental Beer-Lambert law.
  • the second energy is applied necessarily prior to delivery of the surgical laser beam pulses in any and every spot of incising and ablating.
  • Heat from the second energy deposited into tissue causes coagulation shrinkage, constriction and sealing of blood vessels in the way of the surgical laser beam before they are cut thus resulting in better control of bleeding yet without extending tissue coagulation much further beyond the evaporation crater being made by the surgical laser beam pulses.
  • a basic timing diagram of the surgical laser pulses and the second energy delivery, depicted in FIG. 1, helps to understand the process. Incising and ablating tissue starts with delivery of the second energy into the target tissue, then following with surgical laser pulse, and then keeping the second energy on between the surgical laser pulses and continuing in that manner until incising and ablating tissue is stopped.
  • FIG. 1 A basic timing diagram of the surgical laser pulses and the second energy delivery
  • FIG. 2 provides further explanation of the method by illustrating only schematically and not to any scale effects produced in a vascular tissue.
  • the four sketches in FIG. 2 depict snapshots of the tissue 201 with blood vessels 202, at four different times as tissue evaporation with the surgical laser beam pulses progresses in a single target spot of incising and ablating tissue.
  • the second energy 203 is conveyed and deposited into the tissue at the location coinciding with the surgical laser beam target spot.
  • the second energy is deposited into a limited volume 204, centered on the axis of the surgical laser beam and where the evaporation crater 206 is to be made or extended by the next coming surgical laser pulse 205.
  • Zones of where maximum tissue temperature is reached to cause qualitatively different level of tissue condition are approximately represented in grey tones in the sketches. Below 45° C tissues typically remain viable. With increase of tissue temperature to 60° C, coagulation commences with irreversible protein denaturation followed by some degree of carbonization, drying and shrinkage of tissue when temperature rises to 90° C - 95°
  • tissue evaporation commences and that requires considerably more additional heat supplied, in order to actually vaporize water from tissue. If the second energy supplied to tissue between the surgical laser pulses is limited, some but not significant evaporation can occur. Tissue absorption remains sufficiently high for the surgical laser beam from a laser source operating at wavelength of strong water absorption, such as Er: YAG laser or CO2 laser, and from ultrashort pulse lasers, or a laser source operating at wavelength of strong protein absorption, so the efficiency of tissue evaporation with the surgical laser beam pulses is not compromised. Due to protein denaturation and some tissue shrinkage, blood vessels begin to seal before growing tissue evaporation crater 206 severs them.
  • Consecutive laser pulses drill deeper into the tissue and at the same time tissue coagulation induced by the second energy expands also, supporting preemptive haemostatic effect but not extending far beyond tissue evaporation crater 206 because of limited supply of the second energy between the surgical laser pulses and heat conduction and dissipation into the bulk of tissue.
  • the sketches only depict tissue ablation in a single target spot to a certain depth.
  • the surgical laser beam is moved to make an incision or ablate an area to a certain depth, however, the motion of the beam is slow in comparison with the surgical laser beam pulse repetition rate and it takes at least a few surgical laser pulses to attain required depth in a single spot.
  • the second energy is deposited into the volume of tissue that remains centered on the axis of the laser beam in any and every spot of incising and ablating, the spot location of the second energy application moves together with the surgical laser beam as it will be more evident from further discussion of embodiments of the present invention, and the process works in the same manner as depicted in FIG. 2 for a single target spot. So surgical haemostasis is executed concurrently with incising and ablating tissue in a preemptive and enhanced manner.
  • the time interval between the surgical laser pulses further referred to as pulse period of the surgical laser beam
  • the amount of the second energy deposited into tissue in a unit of time which is determined by rate of delivery of the second energy into tissue
  • haemostatic heat diffuses out of the limited volume where the second energy is deposited and spreads more into tissue by heat conduction during the time between the surgical laser beam pulses
  • increasing pulse period of the surgical laser beam while keeping rate of delivery of the second energy low enough to prevent tissue evaporation expands coagulation volume. This way larger blood vessels can be sealed although at the necessary sacrifice of having more collateral tissue damage.
  • Reducing pulse period of the surgical laser beam conversely leads to less spread of heat and coagulation around intended incision and ablation void and less collateral tissue damage.
  • adjusting pulse energy of the surgical laser beam determines how much tissue evaporation crater grows with each laser pulse, which is kept consistent with progress of haemostatic action.
  • Adjusting pulse period, pulse duration and pulse energy of the surgical laser beam as operational parameters gives control of incising and ablating performance and adjusting rate of delivery of the second energy independently and in conjunction with the surgical laser beam pulse period and pulse energy gives control of haemostatic performance, allowing to balance between the extent of haemostasis needed, tissue cutting and ablation speed and collateral tissue damage as may be requested for a given surgical procedure.
  • pulse period of the surgical laser beam is adjustable in the range between 1 mS and 500 mS, and preferably in the range between 1 mS and 50 mS because shorter pulse period allows faster movement of the surgical laser beam to incise and ablate tissue and the shortest pulse period of ImS can be used if little or no haemostasis is needed.
  • Pulse duration of the surgical laser beam is always less than 1 mS and also does not exceed 20% of the pulse period of the surgical laser beam.
  • the delivery of the second energy at all times is synchronized with the surgical laser beam pulses to ensure preemptive manner of the second energy deposition into tissue in any and every spot of incising and ablating.
  • Pulse energy of the surgical laser beam depends on characteristics of a particular laser source used for providing it and on the beam spot size. Skilled in the art can readily determine required pulse energy for a particular surgical laser beam spot size and required incising and ablating performance. For example, in case of the surgical laser beam wavelength of 2.94 pm, the minimal surgical laser energy fluence about 1.4 mJ/cm 2 is necessary and therefore minimal pulse energy in the range between 1 mJ and 50 mJ is required to perform most shallow incising and ablating with the surgical laser beam having spot sizes between 0.25 mm and 2 mm. For faster incising and ablating of tissue, pulse energies of the surgical laser beam up to 150 mJ can be utilized.
  • the second energy delivery can be modulated between consecutive pulses of the surgical laser beam for more precise control of haemostasis induced with the second energy.
  • the second energy delivery can be modulated by amplitude, for example as shown in FIG. 3A, where the second energy is delivered at a higher level initially to quickly raise tissue temperature and then reduced to support haemostatic effect compensating for heat outflow into the bulk of tissue but without risk of overheating the affected tissue volume.
  • the modulation of the second energy delivery can simply be pulsing as exemplified by the timing diagram presented in FIG. 3B.
  • the surgical laser pulses or the second energy pulses or both can also be structured as trains of shorter pulses and pulse-width modulated.
  • FIG 3C shows the surgical laser beam pulses as bursts of shorter pulses and the second energy delivery is pulsed and pulse-width modulated, allowing fine control of rate of delivery of the second energy into tissue and resulting haemostatic effect.
  • modulation of the second energy delivery is according to a certain modulating waveform repeating itself between the trailing edges of the pulses of the surgical laser beam. All parameters defining the modulating waveform are operational parameters for controlling rate of delivery of the second energy.
  • controlling rate of delivery of the second energy means largely preventing tissue evaporation during period of time between the surgical laser beam pulses due to the second energy but inducing haemostatic performance in regards to collateral tissue damage extent, via either keeping rate of delivery constant or modulating as generally described above.
  • the operational parameters are however determined by specifics of a particular embodiment, depending on the means of applying the second energy, its technical limitations and characteristics of laser source used for providing the surgical laser beam.
  • the second energy delivery can be turned off.
  • two separate operating controls for example, two foot pedals as typically used for operating surgical tools, can be given to a surgeon to start and to stop surgical incising and ablating.
  • Skilled in the art should recognize also that the start of incising and ablating and the stop of incising and ablating in the context of the present invention means applying the surgical laser beam and the second energy together as described above to produce a certain surgical outcome in target tissue.
  • the time interval between the start and the stop can be only long enough to deliver a single pulse or just a few pulses of the surgical laser beam under electronic control in response to pressing the operating foot pedal.
  • Applying the surgical laser beam and the second energy together as described above can be continuous in response to pressing the operating foot pedal or can be paused and resumed multiple times.
  • pausing when beam scanner mirrors are moving and resuming when the scanner mirrors are in position maybe necessary.
  • Clearly different modes of incising and ablating tissue commonly referred to as “single pulse”, “repeat pulse” and “continuous” surgical laser modes, as well as the beam scanner mode with repeated starts and stops are well within the scope of the present invention.
  • FIG. 4 presents a sectional view of output end portion of the hollow core optical fiber in such device.
  • the hollow core optical fiber 401 normally having core diameter in the range from 200 pm to 600 pm, is used to transmit the surgical laser beam and also to flow inert gas, such as nitrogen or helium.
  • the second energy is heat imparted to tissue by the hot gas jet 402 coming out of the same hollow core optical fiber coaxially with the surgical laser beam.
  • the gas is heated by the heating element 403 over the fiber cladding, embedded into the fiber protective sheath 404 in the output end portion of the fiber.
  • the heating element is a thin film heater deposited over the fiber cladding.
  • Hollow core optical fibers such as PolymicroTM hollow waveguides for transmitting laser radiation at near-infrared and infrared wavelengths as well as technologies for making small heaters are well known to the skilled in the art.
  • the heated gas jet is comparable to the surgical laser beam spot size, not exceeding it more than twice in diameter and skilled in the art should recognize that some minimum gas flow is required for that, depending on the hollow fiber core diameter.
  • the second energy is thus delivered to tissue in this embodiment in a focused manner as required.
  • Such energy can be delivered in one second by gas at temperature of 130° C and cooling to 100° C upon contact with tissue and flowing at 0.4 L/min to 0.6 L/min, depending on the gas used.
  • Nitrogen gas carries a little more heat and lower flow rate of 0.4 L/min can be sufficient, while Helium or Argon require higher flow rates of 0.6 L/min. Because of certain inefficiencies of heat exchange, the maximum gas temperature in a practical device can be in the range of 130° C to 150° C and the heating element temperatures up to 160° C to 180° C.
  • FIG. 5 presents a block diagram illustrating the device further.
  • the surgical laser beam 501 from the laser source 502 is coupled into the hollow core optical fiber 401 by means of the coupling module 503.
  • the coupling module 503 launches the laser beam and gas, supplied by the gas supply and control module 504, into the hollow core of the fiber 401 as well as it provides electrical connection to power the heating element 403 via the electrical leads embedded in the fiber protective sheath.
  • the gas supply and control module 504 regulates the gas flow through the fiber.
  • the gas heating control module 505 powers the heating element 403 and regulates the gas temperature.
  • the surgical laser beam with the coaxial heated gas jet is directed to the surgical target tissue 506 by manipulating the fiber output end.
  • the heating element When the surgical laser beam is requested to perform incising and ablating, the heating element is turned on immediately and prior to the first pulse of the surgical laser beam and the heating element is kept turned on, producing the heated gas jet as long as incising and ablating process continues, as illustrated in FIG. 1, the case of constant rate of delivery of the second energy without modulation.
  • the operation of the gas heating control module 505 is thus synchronized with the operation of the laser source 502 so that the second energy is applied to tissue with the heated gas jet as FIG. 1 shows.
  • the heated gas jet is coaxial with the laser beam and thus heat is transferred to tissue in the same spot where tissue incising and ablating happens. Both the gas jet and the surgical laser beam are directed and moved together by the hollow core optical fiber.
  • the heat transfer to tissue from the heated gas jet happens before the tissue evaporation crater is created and fully completed and touching tissue with the optical fiber tip is not required.
  • the amount of heat deposited into tissue is limited by adequately chosen gas temperature and gas flow rate and due to heat conduction and dissipation into the bulk of tissue, the extent of haemostatic tissue coagulation is not expanding significantly beyond incision and ablation void.
  • the gas jet continuously reaches into a tissue ablation crater developing with each pulse of the surgical laser beam thus facilitating coagulation in just the tissue enveloping the tissue evaporation crater. Additional benefit of the gas jet is that it clears the target location of smoke and debris.
  • Adjusting the gas jet temperature by controlling the heating element temperature and also adjusting gas flow rate gives control of rate of delivery of the second energy into tissue in this particular embodiment.
  • the heating element temperature and the gas flow rate are operational parameters for adjusting haemostatic performance and the parameter adjustment ranges are 100° C to 180° C and 0.2 L/min to 0.8 L/min, respectively.
  • Working distance of one millimeter to a few millimeters between the fiber tip and target tissue is required and it should be noted that both the laser beam and the gas jet diverge with increase of working distance. At larger working distance the gas jet decays but the laser beam also diverges and cannot incise or ablate tissue as effectively.
  • Altering the surgical laser beam spot size and the area affected by heat transfer from the gas jet by changing the working distance is another way to modify incising and ablating as well as resulting haemostasis.
  • the second energy to effect preemptive haemostasis is another laser energy applied with the second laser beam copropagated coaxially with the surgical laser beam but of different characteristics and controlled separately.
  • the second laser beam energy is deposited in any and every spot of incising and ablating into a limited volume of tissue centered on the axis of the surgical laser beam and not substantially larger than tissue evaporation crater that a pulse of the surgical laser beam creates. That means that the maximum of the second laser beam power in the target spot is always centered on the axis of the surgical laser beam, ascertained by coaxial alignment of the laser beams.
  • the spot sizes of the second laser beam and of the surgical laser beam on a surgical target tissue are comparable so that the second energy is delivered into tissue in a focused manner.
  • the surgical laser beam spot size on the target tissue is adjustable and so is the spot size of the second laser beam but always remaining within a factor of two of the spot size of the surgical laser beam, meaning that the deposition of the second laser beam energy happens into limited volume of tissue not larger than twice the surgical laser beam spot size.
  • Skilled in the art are generally familiar with optical designs and techniques for aligning laser beams to be coaxial and for controlling and adjusting laser beam spot sizes. Then specific selection of the second laser beam wavelength is necessary.
  • the second laser beam needs to propagate enough into tissue so that no evaporation happens in a superficial layer and tissue is heated to some depth where tissue evaporation crater is to be made.
  • the second laser beam penetration into tissue cannot be greater than 1 mm in order to contain and control collateral tissue damage.
  • the wavelength of the second laser beam is such that tissue absorption of the second laser beam energy is characterized by absorption coefficient between 10 cm' 1 and 100 cm 1 .
  • the second laser beam energy is applied before tissue evaporation crater is created and then kept applied while the evaporation crater is being completed with the surgical laser pulses in any and every spot, in accordance with the timing diagrams presented in FIG. 1 and in FIG. 3A, FIG. 3B and FIG. 3C when the second laser beam energy is amplitude-modulated or pulsed or pulsed with pulse-width modulation, respectively.
  • operating the surgical laser beam and the second laser beam is coordinated in time, that is, synchronized, to ensure proper timing of the second energy delivery with respect to the pulses of the surgical laser beam.
  • this embodiment of the present invention necessarily includes a controller module for synchronized operation of both laser beams, which functions as a master driver for laser sources supplying the surgical laser beam and the second laser beam triggering laser emissions at the correct times when the surgical laser pulse period is adjustable as an operational parameter. If a laser beam scanner is utilized to position and scan the laser beams on the surgical target to incise and ablate in a predetermined geometrical pattern, synchronized operation of the laser beams with the scanner mirrors is also necessary and the controller module has a means of controlling laser beam scanner in that case. Skilled in the art should be familiar with how such controllers can be designed.
  • the volume of affected tissue may expand both laterally and in depth due to heat conduction but it remains limited by the amount of energy supplied by the second laser beam between the consecutive pulses of the surgical laser beam.
  • the average power level of the second laser beam and modulation parameters, if the second laser beam power is modulated, are set to ensure that tissue evaporation due to the second laser beam is negligible and tissue removal happens with pulses of the surgical laser beam.
  • Heating 1mm 3 volume of soft tissue from 37° C to 100° C requires approximately 0.25 J of energy and considering some heat dissipation into the bulk of tissue, 0.3 W to 0.5 W average power of the second laser beam delivered into tissue is sufficient to produce haemostatic tissue coagulation at a rate of 1 mm 3 per second.
  • FIG. 6 presents a block diagram of an exemplary optical arrangement in an embodiment of the present invention with the second laser beam for applying the second energy effecting surgical haemostasis, showing schematically delivery of the surgical laser beam and the second laser beam to a surgical target tissue.
  • the second laser beam provided by the ancillary laser source 601 which can include one or more lasers, is merged with the surgical laser beam provided by the main laser source 602, which can also include one or more lasers, in the optical alignment and beam-compounding module 603.
  • Skilled in the art are knowledgeable of techniques for aligning laser beams to co-propagate coaxially as a single compounded laser beam using regular and dichroic mirrors and possibly fiberoptic beam combiners.
  • the module 603 can also include optics for adding a low-power aiming beam to copropagate coaxially in the compounded laser beam.
  • the compounded laser beam is transmitted to a surgical site via beam delivery conduit 605, which is an articulating arm or an optical fiber.
  • a laser beam manipulation device 606 is often required to direct and focus the compounded laser beam on the surgical target tissue 607, allowing to adjust the beam spot size of the surgical laser beam and the beam spot size of the second laser beam on the target tissue 607.
  • a surgical micromanipulator or a handpiece with a focusing optics, connected to an articulating arm, are often used as the beam manipulation device 606.
  • an optical fiber is the beam delivery conduit 605
  • the compounded laser beam out of the optical fiber can be used without any optics.
  • the beam delivery conduit is operational at both the surgical laser beam and the second laser beam wavelengths, and at the aiming beam wavelength.
  • Using articulating arm presents no technical limitation on the choice of laser wavelength for either the surgical laser beam or the second laser beam because broadband metallic silver mirrors, which reflect light in a very wide range of wavelengths from 0.45 pm to 20 pm, are normally used in articulating arms.
  • the choice of the laser wavelengths may be more limited depending on the optical fiber spectral transmission.
  • Fiber types for laser beam delivery with core diameters ranging from 50 pm to 600 pm and possibly up to 1 mm for IR wavelengths have wide spectral transmission in multimode regime with low transmission loss over relatively short distance, at most a few meters needed in laser surgery applications.
  • Solid core fluoride glass fibers transmit from 0.5 pm to 4 pm to 4.5 pm, depending on exact fluoride glass composition and solid core sapphire fibers transmit from 0.4 pm to 4.5 pm.
  • Hollow core optical fibers also known as hollow waveguides are available with wide spectral transmission that can be optimized for specific wavelengths in the range from 1.2 pm to 12 pm by adjusting the fiber core diameter and reflective optical coatings on the inside of the fiber hollow core.
  • Solid core low-OH silica fibers transmit from 0.4 pm to 2.3 pm and can be used in an embodiment with ultrafast laser supplying the surgical laser beam and a diode laser supplying the second laser beam at about 1.9 pm wavelength.
  • Any optics used in the path of the compounded laser beam needs to be operational at both wavelengths with acceptable differences in regards to transmission or reflection losses and focusing characteristics.
  • Many optical elements operate in a wide range of wavelengths, for example, ZnSe optics can be used for laser beams at wavelengths in a wide range from 0.6 pm to 14 pm.
  • Antireflective coatings can be designed to work at two or more wavelengths and appropriate optical design is exercised to ensure required beam spot sizes and the beam spot size adjustment ranges.
  • Spherical and parabolic silver mirrors are advantageous because their focusing performance is independent of wavelength and in fact such mirrors are often used in surgical micromanipulators.
  • the overall transmission through the beam delivery conduit 605 and all optical elements in the optical path to the surgical target tissue 607 are optimized for the surgical laser beam wavelength while somewhat lower transmission of the second laser beam and the aiming beam is compensated for by using higher power from the laser sources.
  • FIG. 7 presents a block diagram of an optical arrangement similar to the one shown in FIG. 6, but in a preferred embodiment utilizing specifically an optical fiber as the beam delivery conduit with necessary fiber-coupling optics and additional implements for precise laser beam scanning and positioning.
  • the optical fiber 701 is from the fiber types discussed above with wide spectral transmission.
  • the laser beams, compounded in the optical alignment and beam-compounding module 603, are launched into the optical fiber 701 by means of a fiber-coupling module 702. Coming out of the optical fiber 701, the laser beams are directed to the surgical target tissue 607 with a laser beam scanning and positioning device 704.
  • the laser beam scanning and positioning device 704 includes a laser beam scanner 705 and a surgical micromanipulator 706.
  • the scanner 705 is used to produce precise surgical incision and ablation patterns while the micromanipulator 706 is used for accurate beam positioning, focusing and adjustment of beam spot size on the surgical target tissue.
  • the laser beam scanning and positioning device 704 is equipped with an optical collimator element 707 designed to work with the laser beams of different wavelengths.
  • the optical collimator element 707 can utilize silver off-axis parabolic mirror.
  • the laser beam scanning and positioning device 704 can alternatively include the laser beam scanner 705 with a handpiece with a focusing optics.
  • the present invention is generally applicable for incising and ablating a diversity of living tissues.
  • a surgical laser beam highly absorbed in water is used in a preferred embodiment, for example, CO2 laser operating at 10.6 pm wavelength or Er:YAG laser operating at or near 2.94 pm.
  • Er:YAG laser is advantageous because its wavelength coincides with the peak of water absorption and its penetration depth is the least, giving most precise surgical incising and ablating of tissue.
  • Ultrashort pulse laser also called ultrafast laser, can be used for providing the surgical laser beam. Ultrafast lasers deliver energy in very short pulses of extreme peak power causing tissue material optical breakdown and evaporation in any kind of tissue irrespective of exact tissue absorption at the laser wavelength.
  • an ultrafast laser is also preferred for supplying the surgical laser beam to incise and ablate a diversity of living tissues.
  • applying the second energy to tissue is sufficiently independent of exact tissue kind if the second energy is heat transferred to tissue by a heated gas jet.
  • applicability to a diversity of tissues can be achieved by selection of the second laser beam wavelength to rely on tissue water absorption as well, but in the near-IR, where water absorption is weaker.

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Abstract

Une méthode et des dispositifs chirurgicaux laser d'incision chirurgicale, d'ablation de tissus vivants à l'aide d'un faisceau laser et de réalisation d'une hémostase chirurgicale améliorée simultanément avec l'incision et l'ablation sont divulgués. La méthode nécessite un faisceau laser chirurgical qui est pulsé et qui est fortement absorbé dans les tissus vivants et une action hémostatique améliorée est obtenue en utilisant, en plus de l'énergie du faisceau laser chirurgical, administrée sous forme d'impulsions, une autre énergie commandée séparément effectuant une hémostase, par application de la seconde énergie à tout point donné d'incision et d'ablation d'une manière préemptive et focalisée, ce qui réduit au minimum les dommages liés à l'hémostase causés aux tissus environnants. Dans un mode de réalisation, un jet de gaz chauffé provenant d'une fibre optique à âme creuse transmettant le faisceau laser chirurgical est utilisé. Dans d'autres modes de réalisation, un rayonnement laser auxiliaire à une longueur d'onde choisie spécifiquement pour réduire au minimum les dommages liés à l'hémostase causés au tissu est utilisé pour obtenir un effet hémostatique préemptif et contrôlé.
PCT/US2022/014469 2022-01-30 2022-01-30 Méthode d'incision et d'ablation de tissus vivants et dispositifs laser chirurgicaux WO2023146539A1 (fr)

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Citations (5)

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US20080240172A1 (en) * 2001-08-24 2008-10-02 Biolase Technology, Inc. Radiation emitting apparatus with spatially controllable output energy distributions
US20120078160A1 (en) * 2009-03-04 2012-03-29 Gradiant Research, Llc Method and apparatus for cancer therapy
US20150305811A1 (en) * 2012-11-09 2015-10-29 Biolitec Pharma Marketing Ltd. Device and method for laser treatments
US20170189117A1 (en) * 2010-04-22 2017-07-06 Precise Light Surgical, Inc. Flash vaporization surgical systems
US11291504B1 (en) * 2021-04-03 2022-04-05 Max Shurgalin Method of incising and ablating living tissues and surgical laser devices

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080240172A1 (en) * 2001-08-24 2008-10-02 Biolase Technology, Inc. Radiation emitting apparatus with spatially controllable output energy distributions
US20120078160A1 (en) * 2009-03-04 2012-03-29 Gradiant Research, Llc Method and apparatus for cancer therapy
US20170189117A1 (en) * 2010-04-22 2017-07-06 Precise Light Surgical, Inc. Flash vaporization surgical systems
US20150305811A1 (en) * 2012-11-09 2015-10-29 Biolitec Pharma Marketing Ltd. Device and method for laser treatments
US11291504B1 (en) * 2021-04-03 2022-04-05 Max Shurgalin Method of incising and ablating living tissues and surgical laser devices

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