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Surgical Energy: Devices, Applications, and Safety

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Energy sources in surgery are critical tools used to cut, coagulate, and desiccate tissue with minimal bleeding, facilitating both open and minimally invasive procedures, including laparoscopic and robotic surgery. The appropriate and safe utilisation of these devices requires a thorough understanding of their principles, tissue effects, advantages, disadvantages, and potential complications.

Here’s a detailed discussion of the energy sources in surgery:

General Principles and Importance

Laparoscopic surgery necessitates instruments capable of effective cutting, dissection, and hemostasis. The ideal device provides these functions without significant thermal energy spread beyond the targeted area. Different energy types commonly used include mechanical, electrical, plasma, laser, and ferromagnetic heat. Energy in wattage (power) is the product of current and voltage, indicating the rate of work performed. For current to flow, a continuous circuit is necessary, typically involving the patient, electrosurgical generator, active electrode, and return electrodes. Electrical energy converts to heat in tissue as the tissue resists current flow.

Types of Surgical Energy Devices
1. Electrical Energy (Electrosurgery)

Electrosurgery uses alternating current at radiofrequency levels to heat tissue and produce cutting, desiccation, or coagulation effects. It has evolved significantly since its early development, with modern electrosurgical units (ESUs) producing various waveforms for different tissue effects. Tissue effects are influenced by current density, application time, electrode size, tissue conductivity, and current waveform. All energy sources generate tissue temperatures above 45°C, where irreversible cell damage begins.

  • Monopolar Electrosurgery

    • Principles: In monopolar electrosurgery, the active electrode is in the surgeon’s hand, and the patient return electrode is a dispersive pad on the patient’s body. The electrical current flows through the patient to complete the circuit and return to ground.
    • Tissue Effects: It offers the broadest range of tissue effects:
      • Vaporisation (Cutting): Achieved with a non-modulated high-frequency, low-voltage continuous current, causing quick temperature rise above 100°C and explosive cell vaporisation. This produces low-voltage sparks and moderate smoke.
      • Fulguration (Spray): A non-contact coagulation mode using high voltages with an intermittent frequency. It allows coagulation of diffuse bleeding and results in heating and necrosis with greater thermal spread, high-voltage sparks, significant smoke, and charring.
      • Desiccation (Deep): Direct contact coagulation, using continuous or interrupted waveforms, leading to cell wall rupture, cytoplasm boiling, protein denaturation, and tissue shrinkage (70-85°C). It has pronounced lateral thermal spread.
      • Coaptation: Vessel sealing by denaturation and renaturation of proteins, often combined with compression, similar to bipolar electrosurgery, and used for small to medium vessels (<2mm).
    • Advantages: Relatively inexpensive, readily available, versatile, and offers the widest range of tissue effects.
    • Disadvantages: The main disadvantage is the unavoidable risk of stray current injury (SCI), which can occur outside the surgeon’s field of vision and are often not noticed during surgery. Smoke production can also be problematic, especially during fulguration.
    • Safety Measures: Proper placement of the patient return electrode over a well-vascularised muscle mass, avoiding bony prominences and areas of vascular insufficiency. Use of dual-function patient return electrode pads and active electrode monitoring (AEM) systems can reduce the risk of burns and detect insulation failures. Lower power settings, brief activation times, and using “cut” rather than “coagulation” waveforms also help mitigate risks.

  • Bipolar Electrosurgery

    • Principles: The active and return electrodes are integrated into the instrument jaws, confining the current path to the tissue grasped between them. This eliminates the risk of current flowing through the patient.
    • Tissue Effects: Primarily desiccation and coaptation. Conventional bipolar typically uses low-voltage current waveforms.
    • Advantages: Eliminates the risk of SCI. Can seal vessels up to ~5mm in diameter, offering effective hemostasis with less collateral damage and thermal spread compared to monopolar.
    • Disadvantages: Lateral thermal spread continues until activation ceases. Lack of an audio signal to indicate completion of desiccation/coaptation increases the risk of thermal injury, charring, and tissue adherence. Requires a separate instrument for cutting.

  • Advanced Bipolar Electrosurgery

    • Principles: These devices feature computer-controlled tissue feedback systems that monitor tissue impedance to adjust voltage and current, maintaining the lowest possible power setting. Examples include LigaSure, EnSeal, and Gyrus PK.
    • Tissue Effects: Desiccation, coaptation, and often incorporate a cutting blade for tissue transection. They achieve vessel fusion by denaturing collagen and elastin in the vessel wall with temperatures between 60-90°C.
    • Advantages: Approved to seal vessels up to 7mm in diameter. Minimises lateral thermal spread, charring, and tissue adherence due to precise energy delivery and an audio signal indicating endpoint. LigaSure has shown faster sealing times and lower temperature increases compared to Harmonic Scalpel. EnSeal uses Positive Temperature Control (PTC) to regulate tip temperature to a maximum of 100°C, reducing overheating.
    • Disadvantages: Relatively expensive. Some devices have bulky jaws that are inferior for dissection. They may produce smoke, vapor, and particulates affecting visibility. While they aim to minimise LTS, some studies still report significant thermal effects away from the application zone.
2. Ultrasonic Energy
  • Principles: Converts electrical energy into rapid mechanical vibrations (ultrasonic frequency, at least 20kHz), which generate heat at the active site. This causes tissue fragmentation, emulsification, and removal. Devices employ a handpiece with a metal tip oscillating at high frequencies (e.g., 20kHz, or 22.5kHz to 55.5kHz). The high-speed mobilisation and cavitation (creation and explosion of air cavities) principles contribute to cell destruction and cutting.
  • Tissue Effects: Desiccation, coaptation, and mechanical tissue transection. Cutting is achieved by increasing blade surface temperature, protein denaturation, and friction. Hemostasis occurs via denatured protein coagulum and coaptation, without vessel contraction or proximal thrombus formation.
  • Examples: Harmonic Scalpel (Ultracision), Sonicision, SonoSurg. The Harmonic ACE+7 can seal vessels up to 7mm.
  • Advantages: Can cut and coagulate simultaneously, leading to less surgical time. Offers minimal lateral thermal spread (LTS), less smoke production (a ‘mist’ rather than smoke), great precision, few tissue charring/sticking, and better wound healing. Does not pass electric current through the patient.
  • Disadvantages: Can form aerosolised fatty droplets that interfere with laparoscopic visualisation. Slower coagulation compared to electrical energy. Instrument tips can reach higher temperatures and remain hot after de-activation, risking injury. Requires training and experience for cutting mode. Relatively expensive.

3. Laser Energy
  • Principles: Lasers utilise concentrated light energy to incise, coagulate, or vaporise tissue through a thermal effect, converting light to heat. The effect depends on wavelength, delivery system, and laser parameters.
  • Types and Applications:
    • CO2 Laser (10600nm): Intensely absorbed by cellular water, resulting in “superficial” injury. Minimal potential for deeper injury. Most efficient for ablation or vaporisation of large tissue volumes (e.g., tumours, endometriomas). Used with hollow tubes, waveguides, and mirrors as conventional fiberoptics are not available.
    • Argon Laser (488-514nm): Produces blue-green light, intensely absorbed by hemoglobin and melanin. Can be used in aqueous environments. Penetrates and scatters in tissues, with damage up to 6mm. Largely replaced by other technologies today. Requires eye and camera safety filters which can distort image colour.
    • Nd:YAG Laser (1060nm): Near-infrared light, carried via conventional fiberoptics. Intensely absorbed by tissue protein, highly scattered in tissue, resulting in deep penetration and greater damage below the surface than apparent. Poor cutting instrument in non-contact mode. Sapphire tips and sculpted fibers were developed to improve cutting, but their main interaction is thermal cautery.
    • KTP Laser (532nm): A frequency-doubled YAG laser producing lime green light. Intensely absorbed by hemoglobin and melanin, efficient for incision, coagulation, and vaporisation. Can coagulate vessels up to 2mm. Less cumbersome than argon lasers. High-power KTP (e.g., Niagara Laser) and KDP (Greenlight laser) are used for prostate ablation.
    • Holmium Laser (2100nm): Infrared light intensely absorbed by water. Can be carried via conventional fiberoptics. Efficient for cutting and ablation of bone and cartilage. Can be used in aqueous environments due to “Moses effect” (cavitation bubble). Incisional and ablative speed can be slower at lower fluences, but compensated by ease of use and fiberoptic durability.
    • Diode Laser (805nm): High-powered systems (e.g., Diomed laser) produce near-infrared light, carried by conventional fiberoptics. Compact size, easy portability, potential for lower costs. Wound histology and incisional speed similar to Nd:YAG laser.
    • Lithotripsy Devices: Laser-based devices (pulsed dye, alexandrite, holmium) generate photoacoustic shock waves to fragment calculi in the common duct or ureter without damaging surrounding tissues.
  • Advantages: High degree of precision and control over tissue effect. Improved hemostasis. Adaptability to fiberoptic and minimally invasive systems.
  • Disadvantages: High acquisition expense for machinery and accessories. Can potentially increase operative time during the learning curve. Requires specific training and understanding of laser-tissue interaction for safe use. Safety filters (for eye and camera) can distort vision. Risk of deep tissue damage with certain wavelengths (e.g., Nd:YAG) if not used properly. Specific cooling requirements for fibers (saline cooling is safe, gas cooling is dangerous for some applications).

4. Plasma Energy
  • Principles: The fourth state of matter, created by adding energy to gas, resulting in a high-energy, low-density state. Transmits energy through a stream of ionised inner gas with minimal electricity flow to the surgical site.
  • Examples: Argon Beam Coagulator, Plasma Jet, Helica Thermal Coagulator, J-Plasma Device, Gyrus PK.
  • Tissue Effects: Allows cutting, coagulation, and fulguration in the same instrument.
  • Disadvantages: Possibly has the highest thermal spread among all energy sources.

5. Ferromagnetic Heat Energy
  • Principles: Achieved by conducting radio-frequency current through a loop coated with thin ferromagnetic materials, generating pure thermal heat through magnetic hysteresis losses and ohmic heating. This leads to a sudden and precise rise and fall of temperature.
  • Examples: FM wand.
  • Tissue Effects: Desiccation, coaptation, and tissue transection.
  • Advantages: Generates pure thermal heat, offers similar safety patterns to US and advanced bipolar systems. No grounded pad is needed as current does not pass through the patient. Can safely seal vessels up to 7mm.
  • Disadvantages: A newer technology, potentially less widely studied compared to established modalities.

6. Hybrid Devices
  • Principles: Combine multiple energy source technologies into a single instrument.
  • Examples: Thunderbeat (combines ultrasonic and bipolar energy), LigaSure Advance (combines monopolar and bipolar electrosurgery).
  • Advantages: Reduces instrument traffic, potentially lowers overall cost, offers wide versatility (hemostasis, cutting, desiccation, histologic sealing, tissue manipulation), faster surgery, higher versatility score, better field visibility, and potentially less postoperative pain. Thunderbeat can seal vessels up to 7mm.
  • Disadvantages: Good-quality studies on their efficacy and safety may be lacking. Individual functionalities might be compromised in the hybrid setup.

Safety Measures and Risks in Surgical Energy Use

Patient safety is paramount, requiring thorough knowledge of electrosurgical fundamentals by the entire operative team. Injuries can be categorised into:

  • Surgical Misadventure: Occurs within the surgeon’s field of vision, including iatrogenic injuries (surgeon error) and lateral thermal spread (LTS) injuries. LTS is a risk with all energy sources that cause desiccation and coaptation, as they generate tissue temperatures around 100°C.
  • Stray Current Injuries (SCIs): Occur outside the surgeon’s field of vision and are not due to surgeon error, primarily associated with monopolar electrosurgery. SCIs can result from:
    • Direct Coupling: Accidental activation of the active electrode when it is in close proximity or direct contact with another metal instrument (e.g., laparoscope, grasper forceps), causing current to flow through the unintended instrument and potentially damage adjacent structures. Visualising the electrode and avoiding contact with other conductive instruments can prevent this.
    • Capacitive Coupling: Electrical current is transferred from the active electrode through intact insulation into nearby conductive materials (e.g., bowel) without direct contact. This risk is higher with plastic laparoscopic ports. Using an AEM system and limiting high-voltage settings can mitigate this.
    • Insulation Failure: A break or defect in the instrument’s insulation, allowing current to leak and potentially damage nearby structures. This is a major cause of laparoscopic electrosurgical injuries, often occurring at micro-fractures invisible to the naked eye. Reusable instruments are more prone to this due to wear and tear and repeated sterilisation. AEM systems are designed to detect and shield against these failures.


Other identified risks include:

  • Infection: From inadequately sterilised devices or reusable components.
  • Adverse Tissue Reaction: Due to non-biocompatible materials or fragments left in the body from mechanical failure.
  • Bleeding/Hemorrhaging/Blood Loss: From unintended damage to blood vessels or device malfunction.
  • Thermal Injury: From excessive energy/heat (burns). This can also be caused by fibreoptic light sources which can reach high temperatures.
  • Mechanical Injury: From the device’s power during fragmentation, emulsification, and aspiration.
  • Electrical Shock: From malfunction or failure of electrical components.
  • Neurological Deterioration: A specific risk for neurosurgical indications.
  • Interference with other devices: Due to electromagnetic (EM) emissions or susceptibility to EM interference.
  • Surgical Smoke: Contains toxic gases, vapours, and cellular material, posing risks to patients and personnel. Smoke evacuation systems are recommended.


Surgeons should be alerted to postoperative warning signs as many injuries may not be recognised intraoperatively and can present days later. Continued education and practice are crucial for improving outcomes and preventing injuries.

Market Trends and Future Prospects

The market for surgical energy devices is substantial, valued at $10.2 billion in 2023 and projected to reach $20.2 billion by 2033, with a CAGR of 7.1%. This growth is driven by the rising prevalence of chronic diseases and increasing demand for minimally invasive procedures. Radiofrequency (RF) generators with monopolar and bipolar devices currently dominate, but advanced energy devices are seeing high adoption rates due to advantages like reduced bleeding, shorter procedure times, and improved precision. Future advancements are expected to make these devices even more sophisticated and versatile. Key innovations focus on improving ergonomics, enhancing cutting and coagulation, and addressing energy-related smoke. However, challenges remain, including high costs, surgeon training, regulatory requirements, and the availability of alternative treatments.

overview of electrosurgery

1. Definition and Basic Principles of Electrosurgery

Electrosurgery differs from electrocautery in that electrocautery uses electricity to heat an object, which then burns the tissue without current entering the patient’s body. In contrast, electrosurgery involves electrical current passing directly through the patient’s tissue to produce the desired thermal effects.

The fundamental principles of electrosurgery involve:

  • Current (I): The flow of electrons, measured in amperes (A).
  • Voltage (V): The electrical potential difference, or “push,” behind current flow, measured in volts (V).
  • Resistance (R) / Impedance: Determines how much current flows; tissues have varying resistance (e.g., adipose and bone have high resistance, muscle and skin have low resistance). Heat is produced when electrons encounter resistance.
  • Power (W): The rate of work performed (W = V × I). Electrosurgical devices allow surgeons to set the power, influencing the current density and heat.

Electrosurgical units (ESUs) produce different current waveforms to achieve specific tissue effects:

  • Cutting Waveform (“Pure Cut”): Uses non-modulated, high-frequency, low-voltage continuous current. This generates a rapid temperature rise above 100°C, leading to explosive vaporisation of cells and a cutting effect with low thermal spread.
  • Coagulation Waveform (“Coag Mode”): Uses modulated, low-frequency, high-voltage intermittent current. This results in a slower temperature rise (70-85°C), causing protein denaturation, desiccation, and cell constriction, often with more lateral thermal spread. Higher voltages in coagulation mode can increase the risk of “stray electric currents”.
  • Blend Waveform: A combination of cut and coagulation waveforms, allowing for both cutting and hemostasis. It is intermittent with varying “on:off” ratios (e.g., Blend 1 is 80% cut, 20% coagulation).

Other factors influencing tissue effects include the ESU settings, total activation time, electrode size and shape, and whether the device tip contacts the tissue.

2. Types of Electrosurgery

Electrosurgery is broadly categorised into monopolar, bipolar, and advanced bipolar modalities.

2.1. Monopolar Electrosurgery

  • Mechanism: The current flows from an active electrode in the surgeon’s hand, through the patient’s body, and exits via a dispersive patient return electrode (grounding pad) to complete the circuit.
  • Tissue Effects: Offers the widest range of tissue effects:
    • Vaporisation (Cutting): Tissue destruction by explosive cell vaporisation (e.g., with non-contact pure cut waveform). Temperatures reach 100-200°C.
    • Fulguration (Spray Coagulation): Non-contact coagulation using high-voltage sparks for diffuse bleeding and small vessel hemostasis (<1mm). Temperatures can exceed 200°C.
    • Desiccation (Deep Coagulation): Direct contact coagulation leading to cell wall rupture and cytoplasm boiling for small vessel hemostasis (<1mm). Tissue temperatures are around 100°C.
    • Coaptation: Sealing of small to medium vessels (<2mm) by denaturing and renaturing proteins with contact and compression.
  • Advantages: It is a relatively inexpensive, readily available, and versatile energy source due to its wide range of tissue effects and dissection capabilities.
  • Disadvantages/Risks:
    • Stray Current Injuries (SCIs): A significant risk, often unrecognised during surgery, as they occur outside the surgeon’s field of vision. These are not due to surgeon error but to the physics of current flow. SCIs are estimated to occur in 0.1–0.5% of laparoscopic procedures, with half of bowel injuries attributed to electrosurgery.
    • Mechanisms of SCI:
      • Direct Coupling: Accidental activation of the active electrode near another conductive metal instrument (e.g., laparoscope, grasper) within the surgical field, transferring current and potentially damaging adjacent structures.
      • Capacitive Coupling: Current is transferred from the active electrode across intact insulation to nearby conductive materials (e.g., tissue, plastic port) without direct contact. This is a concern with plastic laparoscopic ports, which prevent safe current dispersal.
      • Insulation Failure: A break or defect in the instrument’s insulation, allowing current to leak and burn adjacent tissues. Reusable instruments can have insulation failures (19-39%), and even disposable ones can have defects (3%). The “Zone 2” area, distal to the protective cannula but outside the surgeon’s view, carries the highest risk for undetected injuries.
    • Patient Return Electrode Burns: Can occur if the dispersive pad has poor contact or insufficient surface area, leading to high current density at the exit point. Modern pads with impedance monitoring systems largely mitigate this risk.
    • Lateral Thermal Spread (LTS): Risk of unintended damage to adjacent structures, especially in contact mode.
    • Smoke Production: Can be problematic, especially during fulguration. Smoke plumes contain toxic gases, vapours, and cellular material, posing risks to operating room personnel.
  • Prevention of SCI: Measures include using the lowest power settings, brief activation times, ‘cut’ rather than ‘coagulation’ waveform, avoiding instrument shaft contact, avoiding contact with other instruments, and using metal laparoscopic ports. Active Electrode Monitoring (AEM) systems continuously monitor and shield against stray currents and are highly recommended as they have prevented SCIs where used.

2.2. Bipolar Electrosurgery

  • Mechanism: Both the active and return electrodes are located at the site of surgery, typically in the jaws of the instrument, confining the current flow to the tissue grasped between them. This eliminates the risk of stray current injury (SCI) through the patient’s body.
  • Tissue Effects: Primarily causes desiccation and coaptation. Tissue temperatures are around 100°C.
  • Advantages: Safer due to no SCI risk, capable of sealing vessels up to ~5mm in diameter (compared to <2mm for monopolar contact). Generally available and relatively inexpensive. Good dissection capability, especially with Maryland configuration.
  • Disadvantages: Lateral thermal spread continues until activation ceases. No audio signal indicating completion, increasing the risk of injury, charring, and tissue adherence. Requires a separate instrument for tissue cutting.

2.3. Advanced Bipolar Electrosurgery

  • Mechanism: Incorporates computer-controlled tissue feedback systems (e.g., by monitoring tissue impedance) to continuously adjust voltage and current, maintaining the lowest possible power for the desired tissue effect. An audio signal typically indicates when the endpoint is reached.
  • Devices: Examples include LigaSure™ (Covidien), EnSeal™ (Ethicon), and PlasmaKinetic System (PKS) such as Gyrus PK™ (Gyrus ACMI).
  • Vessel Sealing: Approved by the FDA to seal vessels up to 7mm in diameter, achieved by denaturing collagen and elastin in the vessel wall through combined electrical current and mechanical pressure. LigaSure™ can withstand significantly higher bursting pressures than other devices.
  • Lateral Thermal Spread (LTS): Minimised by precise energy delivery, with reported LTS values between 1mm and 4mm.
  • Advantages: Reduced LTS, minimised tissue charring and adherence, and an audio signal for endpoint indication. Some devices integrate a cutting blade, reducing the need for additional instruments.
  • Disadvantages: Relatively expensive and bulky jaws can be inferior for dissection. May still produce smoke, vapour, and particulates.

3. Comparison with Other Energy Sources in Surgery

Electrosurgery is one of several energy sources used in modern surgery:

  • Ultrasonic Devices (e.g., Harmonic Scalpel™): Convert electrical energy into rapid mechanical vibrations (20 kHz to 55.5 kHz). They cut and coagulate simultaneously using high-speed mobilisation and cavitation, generating heat from friction.
    • Advantages: Minimal LTS, less smoke (produces a “mist” instead), great precision, less tissue charring/sticking, can seal vessels up to 7mm. They offer precise dissection and reliable hemostasis.
    • Disadvantages: Can form aerosolised fatty droplets that obscure vision, slower coagulation than electrical energy, instrument tips can reach high temperatures and remain hot after de-activation, generally expensive, and require specific training.
  • Laser Energy: Utilises concentrated light to create thermal effects (cutting, coagulation, vaporisation). Various wavelengths exist (e.g., CO2, Argon, Nd:YAG, KTP, Holmium, Diode), each with characteristic tissue absorption properties and specific delivery systems.
    • Advantages: High degree of precision and controllable tissue effects.
    • Disadvantages: High acquisition and maintenance costs, requires extensive training and safety considerations (e.g., eye and camera safety filters), and general surgeons often preferred electrosurgical devices due to familiarity and ease of use.
  • Plasma Devices: Generate a stream of ionised gas with minimal electricity flow to achieve cutting, coagulation, and fulguration. Examples include Argon Beam Coagulator and J-Plasma®. They are noted for potentially higher thermal spread.
  • Ferromagnetic Heat Energy (e.g., FM wand®): Produces pure thermal heat via radio-frequency current in a ferromagnetic-coated material. No grounded pad is needed, eliminating spark, arcing, or current stray as energy returns through the generator. Can seal vessels up to 7mm with low LTS.
  • Hybrid Devices: Combine multiple energy sources into one instrument, such as the Thunderbeat™ (ultrasonic and bipolar energy).
    • Advantages: Offers versatility, faster surgery, reduced instrument traffic, better field visibility, and potentially lower overall cost, along with reliable 7mm vessel sealing.
    • Disadvantages: Good-quality studies on their efficacy and safety are still developing.

4. Overall Considerations

  • Surgeon Expertise and Training: Regardless of the energy source, a surgeon’s thorough knowledge, skill, and judgment are crucial for safe and effective use. Postgraduate training and continuous skill development are emphasised.
  • Tissue Temperature Effects: All energy sources generate tissue temperatures above 45°C, where irreversible cell damage begins. Temperatures can range from 41°C for protein denaturation to over 200°C for “black coagulation”. Surgeons must be mindful of potential thermal injury to vital structures, especially since tissue damage can be underestimated visually.
  • No Single “Ideal” Device: There is no consensus on which energy device is universally ideal for every purpose or situation. The choice often depends on the specific surgical procedure, pathology, cost, availability, and the surgeon’s personal preference and experience.
  • Complication Rates: Electrosurgical complications are reported in 1 to 5 per 1,000 cases, and are the second most common laparoscopic complication after trocar or Veress needle misplacement. Bowel injuries from electrosurgery often go unrecognised during surgery and may present days later, necessitating a high index of suspicion for delayed symptoms.

Core Principles and Mechanism of Action

Ultrasonic energy represents a significant advancement in surgical instrumentation, offering distinct mechanisms and benefits compared to other energy sources used in open, laparoscopic, and robotic surgeries.

Core Principles and Mechanism of Action

Ultrasonic surgical devices are hand-held tools that convert electrical energy into mechanical vibrations in the ultrasonic frequency range, typically at least 20 kHz, up to 55.5 kHz. This process is often facilitated by a piezoelectric part in the handpiece that transforms electrical energy into mechanical movement, transmitted to the instrument’s tip.

The tissue effects are achieved through a combination of thermal and mechanical energy. The high-speed vibration of a metal tip (an active blade) or non-articulating jaw generates heat through frictional force and induces the formation and explosion of air cavities within the tissue, a phenomenon known as cavitation. This process leads to:

  • Cell destruction through the implosion of cavitational bubbles.
  • Protein denaturation and breaking of hydrogen bonds, resulting in a 30% shrink in cell length and vessel sealing (coaptation).
  • Cutting due to increasing temperature at the blade surface and friction.

Unlike electrosurgery, ultrasonic devices achieve their effects without the passage of electric current through the patient or the tissue grasped by the device. Tissue temperatures typically reach around 100°C for desiccation and coaptation, but cutting temperatures can be higher (e.g., Sonicision™ up to 227.1°C).

Applications and Indications

Ultrasonic surgical devices are used in a wide variety of open and minimally invasive surgical specialties, including:

  • Neurosurgery (e.g., intracranial and intraspinal tumor resection).
  • Gastrointestinal and affiliated organ surgery.
  • General Surgery, Gynecological Surgery, Laparoscopic Surgery.
  • Orthopedic Surgery, Plastic and Reconstructive Surgery.
  • Thoracic Surgery, Thoracoscopic Surgery, Urological Surgery, Wound Care.

They are indicated for the fragmentation, emulsification, and aspiration of both soft and hard tissue, and can also be used for bleeding control or ligation of vessels. Specific applications include tissue division and hemostasis, which can help shorten operative times.

Key Devices and Evolution

The development of ultrasonic surgical devices has progressed through generations:

  • First Generation: Ultracision Ultrasonic Scalpel® (1989).
  • Second Generation: Harmonic ACE® (1998) and SonoSurg™ (2004), with SonoSurg™ using slower US frequencies (47 kHz vs 55.5 kHz) for better hemostatic control.
  • Third Generation: Sonicision™ (2011), notable for being the first cordless laparoscopic instrument. Later models like Harmonic ACE+® (2012) and Harmonic HD1000i® (2017) incorporated advanced tissue response capabilities.
  • Harmonic Scalpel (Ethicon) is a prominent example, capable of cutting and cauterizing tissue simultaneously, sealing vessels up to 5mm in diameter, with newer models like Harmonic ACE+7 rated for 7mm vessels. It has distinct probes like shears (up to 5mm vessels), hook, and blade (up to 2mm vessels).
  • Hybrid Devices: Thunderbeat™ (Olympus) combines ultrasonic cutting efficiency with the coagulation advantages of bipolar energy. This device allows for faster surgery, higher versatility, better field visibility, and is capable of sealing vessels up to 7mm.

Advantages
  • Combined Functionality: Simultaneous cutting and coagulation, reducing the need for instrument exchanges and potentially shortening surgical time.
  • Reduced Thermal Spread: Generally associated with minimal lateral thermal spread (LTS) compared to many electrosurgical devices, although some studies show variable results. LTS for Harmonic Scalpel can be as low as 90.4 um and 127.4 um in human peritoneum.
  • Less Smoke Production: Produce a “mist” of tissue debris and moisture rather than dense smoke, improving laparoscopic visualization.
  • Precision: Offers great precision, especially near vital structures.
  • Hemostasis: Reliable hemostasis without creating a proximal thrombus within the vessel, unlike bipolar energy.
  • Reduced Patient Pain: Some reports suggest less postoperative pain with Harmonic Scalpel use.
  • No Stray Current Injury: Since no electrical current passes through the patient, risks associated with stray current injury (SCI) such as capacitive coupling or insulation failure, common with monopolar electrosurgery, are avoided.
  • Improved Wound Healing: Reported to contribute to better wound healing.

Disadvantages and Risks

Despite the advantages, ultrasonic devices have some drawbacks:

  • Aerosolized Fatty Droplets: Can produce a mist of fatty droplets that may harm visualization through the laparoscope.
  • Slower Coagulation: May be slower for coagulation compared to electrical energy.
  • Tip Heating: The instrument tip can reach high temperatures (up to 54-58°C) after de-activation and remain hot for a variable length of time (e.g., SonoSurg™ cooling time 27.4 sec, Harmonic ACE® 35.7 sec, Sonicision™ 38.7 sec), posing a risk of damage to adjacent tissues upon accidental contact. Maximum coagulation temperatures can range from 187-193°C.
  • Training and Experience: The cutting mode, in particular, requires specific training and experience for optimal and safe use.
  • Cost: Ultrasonic devices are generally more expensive than conventional electrosurgery, which can be a factor for hospitals and surgeons.
  • Device Malfunction: Medical Device Reports (MDRs) for ultrasonic surgical instruments (LFL product code) have noted malfunctions such as unknown device problems, breakage, overheating, and leaks. Recalls have been related to device design, component integrity, and packaging/sterile barrier integrity.
  • Patient Injuries: MDRs also include reports of serious injuries like bleeding, thermal burns, and foreign bodies left in patients. For neurosurgical ultrasonic instruments (LBK product code), injuries noted include delayed/prolonged procedures, device fragments, tissue damage (dural tears, burns, swelling), CSF leaks, wound healing issues, and pseudomeningocele.
  • General Risks Identified by FDA: The FDA identifies several risks for ultrasonic surgical devices, including infection (if devices are not adequately sterilized), adverse tissue reactions (if materials are not biocompatible or fragments are left), bleeding/hemorrhaging from unintended damage, and tissue injury (thermal, mechanical, electrical leading to neurological deterioration, prolonged procedure, or even death). Interference with other devices due to electromagnetic (EM) emissions is also a risk.

Safety Measures and Regulatory Classification

To mitigate identified risks, the FDA proposes classifying ultrasonic surgical devices (under product codes LFL, NLQ, and LBK) as Class II with special controls. These special controls include:

  • Non-clinical performance testing: To characterize ultrasonic and power parameters (sonication frequency, displacement, irrigation rate, suction pressure) and demonstrate material strength, durability over shelf/use life, and integrity after reprocessing.
  • Software verification, validation, and hazard analysis.
  • Electrical, thermal, mechanical safety, and electromagnetic compatibility (EMC) testing.
  • Performance data for sterility of tissue-contacting components and pyrogenicity evaluation (for neurosurgical devices).
  • Shelf-life and use-life data to ensure continued sterility, package integrity, and functionality.
  • Biocompatibility demonstration for tissue-contacting components.
  • Animal performance data: To confirm the device performs as intended without unintended tissue injury.
  • Comprehensive labeling: Including user qualifications, technical parameters, device/procedure-related complications, operating instructions, shelf-life, use-life for reusable components, validated reprocessing methods, electrical safety, EMC information, and reprocessor identification for single-use reprocessed instruments.


These comprehensive measures are deemed necessary because general controls alone are insufficient to ensure the safety and effectiveness of these devices.

Comparison with Other Energy Sources in Surgery

In the broader context of surgical energy sources, ultrasonic devices offer unique properties:

  • Electrosurgery (Monopolar and Bipolar): While monopolar electrosurgery provides a broad range of tissue effects (vaporization, fulguration, desiccation, coaptation) and is inexpensive and widely available, it carries the unavoidable risk of stray current injury and significant smoke production. Conventional bipolar electrosurgery eliminates the patient from the circuit, thereby removing the SCI risk and allowing sealing of larger vessels (up to ~5mm), but lacks a cutting function and can lead to tissue charring/sticking. Advanced bipolar devices (e.g., LigaSure, EnSeal, Gyrus PK) incorporate tissue feedback systems to minimize lateral thermal spread and tissue adherence, and can seal vessels up to 7mm, with some models integrating a cutting blade. However, they still have lateral thermal spread and generate smoke.
  • Laser Energy: Lasers offer high precision and controllable tissue effects. Different wavelengths (e.g., CO2, Argon, Nd:YAG, KTP, Holmium, Diode) are used for various applications like incision, coagulation, or vaporization. However, lasers are associated with high acquisition costs, can increase operative time during the learning curve, and require specific training and safety considerations (e.g., eye safety filters, optical backstops).
  • Ferromagnetic Heat Energy: Newer devices like the FM wand® generate pure thermal heat by conducting radio-frequency through ferromagnetic coated materials. These can safely seal vessels up to 7mm with low lateral thermal spread and do not require a grounded pad. They appear to have safety patterns similar to ultrasonic and advanced bipolar systems.
  • Plasma Devices: Use ionized inner gas with minimal electricity flow for cutting, coagulation, and fulguration. They can have a higher thermal spread among all energies.


Overall, no single energy device is deemed universally superior; the ideal choice depends on the specific surgical needs, the surgeon’s expertise, device availability, and cost. Ultrasonic devices, particularly hybrid ones like Thunderbeat™, are highly valued for their efficiency, versatility, and ability to reduce instrument traffic and smoke while providing reliable vessel sealing and tissue transection.

Principles and Mechanism of Action

Laser energy is a versatile and precise energy source used in various surgical procedures, particularly in minimally invasive surgery. It converts light into heat, resulting in specific thermal effects on tissue.

Principles and Mechanism of Action

Laser technology generates a thermal effect by converting light to heat, followed by transfer of heat and tissue reaction. This process allows for precise and controllable effects on tissues. The interaction between the laser and tissue results in:

  • Vaporization (ablation): Where tissue is removed by intense heat.
  • Coagulation: Achieved by protein denaturation.
  • Desiccation: Occurs as water evaporates from the tissue.
  • Hyperthermia: An elevated temperature state in tissue.

The specific tissue effect depends on factors such as the laser wavelength, delivery system, and selected laser parameters. Key characteristics determining the tissue interaction include Irradiance (Power Density), which is the concentration of power (Watts per cm²), and Fluence, which is the length of exposure (Joules per cm²). Surgeons typically aim for the highest power density that can be safely controlled to minimise exposure duration and prevent unwanted conductive heating.

Types of Lasers and Their Characteristics

The sources identify several types of lasers used in surgery:

  • CO2 Laser: Produces far-infrared light at 10,600nm wavelength. This wavelength is intensely absorbed by cellular water, leading to superficial injury and minimal inadvertent damage to deeper structures. It is highly efficient for ablation or vaporization of large tissue volumes, such as tumour nodules or endometriomas. CO2 laser energy is carried via hollow tubes, waveguides, and mirrors, as conventional fiberoptics are not available for this wavelength. Its effect is independent of tissue colour. It is described as most closely resembling a scalpel incision.
  • Argon Laser: Generates visible blue-green light (488–514nm wavelengths), which is intensely absorbed by hemoglobin and melanin. This allows its use in aqueous environments like the bladder, during hysteroscopy, and arthroscopy, enabling photocoagulation of bleeding areas while irrigating. Argon laser light penetrates and scatters in tissues, potentially causing damage up to 6mm. It is colour-dependent, making it less efficient on white or lightly coloured tissue unless a chromophore like India ink or blood is applied.
  • Nd:YAG Laser: Produces near-infrared light at 1060nm. This wavelength is transmitted through conventional fiberoptics and water. It is intensely absorbed by tissue protein and chromophores, and highly scattered in tissue, leading to deep penetration and greater subsurface damage than visible light lasers. It is considered a poor cutting instrument in noncontact mode. Sapphire tips and sculpted fibers were developed to facilitate contact use, operating through a combined thermal and optical interaction.
  • KTP Laser: A frequency-doubled YAG laser, producing pure lime green light at 532nm. This wavelength is intensely absorbed by hemoglobin and melanin, making its absorption by hemoglobin very efficient. It is easily transmitted through water and conventional fiberoptics. The KTP laser is capable of incision, coagulation, and vaporization, and is noted for being more efficient than the argon laser and surpassing the YAG laser for cutting and vaporization.
  • Holmium Laser: Produces infrared light at 2100nm, which is intensely absorbed by water. Unlike CO2, it can be carried via conventional fiberoptics. Its efficient water absorption allows for cutting and ablation of bone and cartilage, and it can be used in aqueous environments due to a cavitation bubble phenomenon (“Moses effect”). High fluences can cause tissue splattering, potentially obscuring the view. It is efficient for meniscectomy and percutaneous laser disc decompression (PLDD).
  • Diode Laser Technology: High-powered diode laser systems are becoming available, promising compact size, portability, and lower capital/maintenance costs. They produce near-infrared light (e.g., 805nm for Diomed laser) and are typically applied with sculpted fiber technology.

Applications and Indications

Laser energy devices are indicated for fragmentation, emulsification, and aspiration of both soft and hard tissue, and for bleeding control or ligation of vessels. They are used in a variety of open and minimally invasive surgical specialties, including:

  • General Surgery: Initially popular for laparoscopic cholecystectomy.
  • Gynaecology: Early adopters for adhesions, fertility issues, endometriosis, and myomas.
  • Urology: For lithotripsy (kidney, ureters, bladder calculi), transurethral laser prostatectomy (TULIP), bladder neck contractures, and transurethral resection of bladder tumours (TURBT).
  • Neurosurgery: For intracranial and intraspinal tumour resection, and lumbar disc disease.
  • Orthopaedic Surgery: For lumbar disc disease and meniscectomy (though arthroscopic application is rare currently).
  • Plastic and Reconstructive Surgery.
  • Thoracic Surgery.
  • Wound Care.

Laser-based lithotripsy devices are used for stone extraction in the common duct or ureter, fragmenting calculi into small particles using photoacoustic shock waves. Future applications include laser-induced fluorescence imaging for augmented reality surgery.

Advantages
  • Precision and Control: Lasers offer a high degree of precision and the ability to control tissue effects at the desired target.
  • Hemostasis: Provide improved hemostasis.
  • Adaptability: Easily adaptable to fiberoptic and minimally invasive delivery systems.
  • Combined Effects: Can perform incision, coagulation, or vaporization.
  • Potential for Cost Reduction: While acquisition cost is high, the overall cost of illness may be lowered due to factors like shorter hospitalisation and quicker return to productivity.

Disadvantages and Risks

Despite their advantages, laser devices have several drawbacks and risks:

  • Acquisition Cost: Laser machinery and accessories are expensive.
  • Learning Curve and Training: Increased operative time can be expected during the learning curve. Surgeons require a complete working understanding of lasers, their delivery systems, and tissue effects, often necessitating specific hands-on training programmes.
  • Smoke/Plume Production: Similar to electrosurgery, lasers create a vaporised tissue plume (smoke) which is considered hazardous for operating room personnel and requires evacuation/filtration.
  • Tissue Damage:
    • Unintended Injury: Risk of damage to nearby structures due to deep penetration (Nd:YAG) or reflection of energy off instruments.
    • Overheating: Instruments (e.g., ebonized instruments used with visible light lasers, sapphire tips) can become hot, posing a risk of secondary burns upon inadvertent contact with adjacent structures.
    • Underestimated Damage: With Nd:YAG laser, the degree of subsurface damage can be grossly underestimated by surface visualisation alone.
  • Operational Challenges:
    • Delivery System Limitations: CO2 lasers lack conventional fiberoptics, requiring hollow tubes, waveguides, and mirrors, which complicate manoeuvrability and require a direct line of sight or angled mirrors.
    • Specific Cooling Requirements: Nd:YAG fibers in vascular/aqueous conditions must never be cooled with air or gas due to fatal embolism risk; only saline or irrigating fluids are safe.
    • Colour Dependency: Some lasers (e.g., Argon, KTP) are colour-dependent, performing poorly on lightly coloured tissue unless dyed.
    • Visual Interference: Camera/eye safety filters used with visible light lasers (e.g., Argon) can distort colour balance and necessitate a high-powered light source.
  • Device Fragility: Sapphire tips can be fragile, expensive, and may disconnect or be lost during operation. Sculpted fibers can be stiffer and more fragile than conventional fibers.
  • Accidental Activation: Inadvertent activation of the laser foot pedal can cause injuries; prevention involves placing only a single pedal within reach and placing the laser in stand-by mode when not in use.
  • Unrecognised Injuries: Bowel and bladder should always be checked for perforation or burns, as injuries may not be immediately apparent. Symptoms of bowel perforation can be delayed (4-10 days for electrothermal injury) and subtle.

Comparison with Other Energy Sources in Surgery

In the larger context of surgical energy sources, laser energy stands alongside electrosurgery, ultrasonic technology, plasma devices, and ferromagnetic heat energy.

  • Electrosurgery (Monopolar and Bipolar):
    • Advantages of Electrosurgery: More familiar, ubiquitous, less expensive in terms of capital equipment, and generally faster for surgeons already conversant with the technology. Monopolar electrosurgery offers the broadest range of tissue effects (vaporisation, fulguration, desiccation, coaptation).
    • Disadvantages of Electrosurgery: Main disadvantage of monopolar is the unavoidable risk of stray current injury (SCI), which often occurs outside the surgeon’s field of vision and is not due to surgeon error. It also leads to significant smoke production, charring, and tissue adherence. While bipolar electrosurgery eliminates the SCI risk and can seal larger vessels (up to ~5mm), it lacks a cutting function in conventional forms and can cause tissue charring/sticking. Advanced bipolar devices (e.g., LigaSure, EnSeal) incorporate feedback systems and often a cutting blade, sealing vessels up to 7mm with reduced lateral thermal spread and tissue adherence compared to conventional bipolar.
    • Laser vs. Electrosurgery: The surgical literature contains many comparisons. General surgeons often abandoned lasers for electrosurgery due to the latter’s familiarity and the steep learning curve for lasers.
  • Ultrasonic Technology:
    • Mechanism: Converts electrical energy to mechanical vibrations in the ultrasonic frequency range (e.g., 20 kHz to 55.5 kHz), producing heat from friction and mechanical tissue destruction through cavitation.
    • Advantages: Simultaneous cutting and coagulation, generally less lateral thermal spread (though comparison results vary), and less smoke production (producing a ‘mist’ instead). Unlike electrosurgery, it does not pass electric current through the patient. Can seal vessels up to 5mm, with newer models up to 7mm.
    • Disadvantages: Can produce aerosolized fatty droplets. May be slower for coagulation than electrical energy. Instrument tips can remain hot after de-activation, posing a risk to adjacent tissues. Ultrasonic devices are generally more expensive.
  • Hybrid Devices: Devices like Thunderbeat combine ultrasonic cutting efficiency with bipolar coagulation advantages. These aim to offer combined functionalities to reduce instrument traffic and potentially overall cost. Thunderbeat specifically is noted for faster surgery, higher versatility, better field visibility, and reliable 7mm vessel sealing.
  • Ferromagnetic Heat Energy: Newer instruments (e.g., FM wand®) generate pure thermal heat by conducting radio-frequency through ferromagnetic coated materials. They can safely seal vessels up to 7mm with low lateral thermal spread and do not require a grounded pad. They appear to have similar safety patterns to ultrasonic and advanced bipolar systems.
  • Plasma Devices: Use ionized inert gas with minimal electricity flow for cutting, coagulation, and fulguration. They may have a higher thermal spread among all energies.


Ultimately, the choice of energy source depends on the specific surgical needs, surgeon’s expertise and preference, device availability, and cost. No single energy device is universally superior, and surgeons are encouraged to acquire comprehensive knowledge of all available modalities.

Safety Measures and Regulatory Context

Ultrasonic surgical devices (under product codes LFL, NLQ, LBK) are proposed to be classified as Class II with special controls by the FDA. While the FDA documents provided focus specifically on ultrasonic devices, the principles of safety, such as performance testing, software validation, electrical/thermal/mechanical safety, biocompatibility, and comprehensive labelling, highlight the general regulatory considerations for high-risk surgical energy devices. These controls aim to mitigate risks such as infection, adverse tissue reaction, bleeding, and tissue injury (thermal, mechanical, electrical). In the context of lasers, specific safety procedures are recommended by standards like ANSI Standard Z136.3, 2005, to prevent injury to patients and personnel.

Plasma energy devices function

Plasma energy represents one of the significant energy sources employed in laparoscopic surgery. It is defined as the fourth state of matter, created by adding energy to gas, resulting in a high-energy, low-density state. In surgical applications, plasma devices utilise a stream of ionized inert gas with minimal electricity flow to transmit energy to the surgical site.

Basic Principles and Devices: Plasma energy devices function by directing an electrically charged stream of ionized gas towards the target tissue. Some specific devices mentioned in the sources include:

  • Plasmajet™.
  • Argon beam plasma coagulator.
  • Helica thermal coagulator.
  • J-Plasma®.
  • Gyrus PK™ (Plasma Kinetic technology).

Tissue Effects and Characteristics: Plasma devices are versatile, allowing for cutting, coagulation, and fulguration in a single instrument. The effects are achieved by the stream of ionized gas carrying electric current.

  • Argon Beam Coagulator operates as a rigid, non-contact application device, delivering high-frequency, low-voltage current through ionized argon gas at rates between 0.5 to 7 litres per minute. The lateral thermal spread (LTS) reported for this device ranges between 4 to 10 mm, varying with current density, gas flow rate, activation time, and distance from the tip to the target tissue.
  • Plasma Jet™ also uses a neutral argon plasma stream in a non-contact application with bipolar electrodes for coagulation and fulguration. It uses lower electrical energy (30-60 W) and a lower argon plasma stream rate (less than 0.4 litres per minute), resulting in an LTS range of 0.5 to 2 mm.
  • The Helica Thermal Coagulator uses electrically charged helium plasma at lower power levels (2-35 W) and can reach temperatures of up to 800 ºC.
  • The J-Plasma Device® is an FDA-approved multimodal electrosurgical instrument that uses a cold helium plasma stream for cutting, coagulation, fulguration, and dissection. Studies have shown its depth thermal spread (DTS) to be less than 2mm, regardless of power settings and gas flow.
  • The Gyrus PK™ is a bipolar device that employs plasma kinetic technology, delivering low-voltage electrical current to seal vessels up to 7 mm by forming an intra-luminal coagulum through protein denaturation. The maximum temperature reached is under 100 ºC. While it theoretically aims to decrease LTS due to its pulsed application, recent studies have not consistently confirmed this, with reported LTS ranging between 2.7 to 4.7 mm for sealing vessels up to 6 mm.


Comparison and Safety Context: In the broader context of energy sources in surgery, plasma devices, while highly versatile, are noted in the sources for potentially having the highest thermal spread among all energy modalities. All newer energy devices, including plasma devices, will cause variable degrees of collateral undesired effects such as LTS and a temperature rise over 45ºC. This means surgeons must use such devices carefully near vital structures, as temperatures can rise above 40 degrees Celsius just 2 mm away from the activation zone.

The market for surgical energy devices, including plasma technology, is expanding due to increasing chronic diseases and demand for minimally invasive procedures. While newer instruments are accompanied by significant marketing, surgeons bear the responsibility to understand the biophysics, tissue effects, advantages, and risks of each device. Despite their complexities, energy sources like plasma devices play a crucial role in overcoming the limitations of traditional methods in minimal access surgery, offering benefits such as cutting, coagulation, and fulguration.

Ferromagnetic heat energy

Ferromagnetic heat energy represents one of the newest energy modalities employed in laparoscopic surgery, offering distinct principles and characteristics within the broader spectrum of surgical energy sources.

Basic Principles and Mechanism: Ferromagnetic heat energy is generated through the conduction of radio-frequency current in a loop coated with thin, micron-thick ferromagnetic materials. As the radio-frequency current traverses this loop, pure thermal heat is produced via magnetic hysteresis losses and ohmic heating, which is related to the skin effect. This process leads to a sudden and precise rise and fall of temperature at the surgical site. Unlike some other energy sources, no grounded pad is needed, and there is no spark, arcing, or current stray, as the energy returns to the generator and does not pass through the patient.

Specific Device and Modes of Operation: The FM wand® is a notable instrument that utilises ferromagnetic heat energy. Its design incorporates a tip with an active blade and a thermally inner surface, ensuring that heat is conducted perpendicularly to the tissue grasped by its jaws. The FM wand® can be operated in three distinct modes:

  • FM Mode: For high-power sealing and dividing vessels less than 2mm in diameter.
  • FM2 Mode: For sealing and dividing vessels larger than 2mm.
  • FM1 Mode: For sealing only.

Tissue Effects and Characteristics: The primary tissue effects achievable with ferromagnetic heat devices include desiccation, coaptation, and tissue transection. Key performance characteristics of the FM wand® have been highlighted:

  • Vessel Sealing: It can effectively seal vessels up to 7 mm. Studies have shown that it achieves burst pressures consistent with bipolar sealers, with a mean burst pressure of 1098 mmHg.
  • Lateral Thermal Spread (LTS): The FM wand® demonstrates less than 2 mm of lateral thermal spread, with reported values as low as 1.68 mm, which is less than that of the Harmonic Scalpel (US devices).
  • Speed: It offers significant efficiency, with transection speeds 8 seconds faster than the Harmonic Scalpel (HS) and 18 seconds faster than LigaSure (LS).

Comparison within Energy Sources in Surgery: In the broader context of energy sources in surgery, ferromagnetic heat energy devices, particularly the FM wand®, are positioned as newer instruments that can safely seal vessels up to 7mm. This places them alongside advanced bipolar systems like LigaSure and ultrasonic devices like Harmonic Scalpel in terms of vessel sealing capabilities.

While all newer energy devices can cause variable degrees of collateral undesired effects such as lateral thermal spread and temperature rises above 45ºC, the FM wand® is noted for its similar safety patterns when compared to ultrasonic (US) and advanced bipolar systems. Its ability to operate without a grounded pad and without current stray differentiates it from monopolar electrosurgery, which carries risks of stray current injury.

The market for surgical energy devices is expanding due to factors like the increasing prevalence of chronic diseases and the demand for minimally invasive procedures. While newer instruments come with significant marketing, surgeons are responsible for understanding the biophysics, tissue effects, advantages, and risks of each device. Ferromagnetic heat energy, as exemplified by the FM wand®, presents a promising addition to the surgical armamentarium, offering efficient vessel sealing, precise tissue effects, and a favourable safety profile compared to other established modalities.

Hybrid devices

Hybrid devices represent a relatively new and evolving class of energy sources in laparoscopic surgery, designed to overcome the limitations of single-modality instruments by combining different energy technologies within a single instrument. This approach aims to reduce instrument traffic and potentially lower overall costs.

Two prominent examples of hybrid devices mentioned in the sources are:

  • Thunderbeat™.
  • LigaSure Advance.

Basic Principles and Mechanisms:

  • Thunderbeat™ is an innovative instrument that combines the cutting efficiency of ultrasound energy with the coagulation advantages of bipolar energy. It delivers both electrical bipolar and ultrasonic frictional heat energy. The device functions with a generator offering three levels, from a “cut and seal mode” (level 1) to a “seal mode” (level 3). Its design integrates a conventional ultrasonic scissor with a bipolar vessel clamp.
  • LigaSure Advance incorporates both monopolar and bipolar electrosurgery capabilities.

Tissue Effects and Characteristics: Hybrid devices are designed for high versatility, allowing for a range of tissue effects including hemostasis, cutting, desiccation, and histologic sealing, as well as tissue manipulation.

  • Vessel Sealing: The Thunderbeat™ can reliably seal vessels up to 7 mm in diameter.
  • Speed and Efficiency: Thunderbeat™ is noted for its “fastest in class cutting speed,” contributing to reduced operation time. Studies have shown it achieves a shorter dissection time and a faster average cutting time of 10.7 seconds compared to other devices.
  • Thermal Spread: While hybrid devices, like all newer energy devices, can cause variable lateral thermal spread (LTS) and temperature rises, Thunderbeat™ aims for minimal thermal spread. Comparative studies found no significant differences in LTS or burst pressure when Thunderbeat™ was compared to devices like Harmonic ACE® (ACE), LigaSure (LS), and EnSeal (ES).
  • Smoke and Visibility: Thunderbeat™ produces an even lower rate of smoke generation compared to other devices. The reduced mist generation also helps to maintain better field visibility during surgery.
  • Safety: Thunderbeat is listed as not causing stray current, due to its ultrasonic and bipolar combination.

Advantages in the Larger Context of Energy Sources in Surgery: Hybrid devices bring several advantages to the surgical field:

  • Reduced Instrument Traffic: By integrating multiple functionalities into a single tool, they decrease the need for frequent instrument exchanges during a procedure.
  • Enhanced Versatility: They offer a broad range of capabilities in one device, increasing the surgeon’s operational options without switching instruments.
  • Potentially Lower Costs: Incorporating multiple functions into one device may lead to reduced overall costs, though this is a secondary consideration to functionality.
  • Patient Outcomes: Thunderbeat™ specifically has been associated with shorter operative times and less postoperative pain. It also offers a higher bursting pressure compared to other devices.

Challenges and Considerations: Despite their promising benefits, hybrid devices face certain challenges and areas requiring further investigation:

  • Lack of Extensive Studies: There is a recognized lack of “good-quality studies” or “good-quality trials” on the overall efficacy and safety of hybrid devices. This means their benefits and safety profile in real-world clinical settings still need more robust evidence.
  • Compromised Functionality: A concern exists that combining multiple functionalities into a single device might compromise the effectiveness of the individual modalities.
  • Cost: Like other new-generation energy sources, hybrid devices can be relatively expensive.
  • Reusability: The Thunderbeat is specifically noted as not being reusable.

In the broader context of energy sources in surgery, hybrid devices are part of a rapidly expanding market driven by increasing chronic diseases and the demand for minimally invasive procedures. While newer instruments come with significant marketing, surgeons are urged to understand the biophysics, tissue effects, advantages, and risks of each device, rather than being solely influenced by commercial promotion. Although hybrid devices, especially the Thunderbeat™, show considerable promise in efficiency and versatility, the sources indicate that there is currently “no accord as to which device is ideal for a given purpose” or “no clear winner has yet been decided” among the advanced vessel sealers. The ultimate choice of energy source often depends on the surgeon’s preference, experience, the specific surgical procedure, and the pathology encountered.

General surgical considerations

In the larger context of Energy Sources in Surgery, the sources highlight several general surgical considerations that are paramount for safe and effective practice, transcending the specifics of any single energy modality. These considerations revolve around the surgeon’s knowledge and responsibility, device selection, adherence to safety protocols, and post-operative vigilance.

Surgeon’s Knowledge and Responsibility

A primary general consideration is the surgeon’s obligation to acquire comprehensive knowledge about all available energy sources. This knowledge should encompass the range of tissue effects each device can produce, how these effects are imparted, and the associated benefits and risks. Crucially, surgeons must engage in unbiased learning, not being solely influenced by marketing efforts from manufacturers.

Formal and continuous training is strongly emphasised. The American College of Surgeons has, for instance, introduced a compulsory module on laparoscopic energy sources for trainees. Surgeons are advised to attend specific hands-on training programmes, especially if such education was not part of their residency or if they are unfamiliar with a particular device or delivery system. Furthermore, the development of new skills should be a gradual process, starting with simpler procedures and progressively moving to more complex tasks, allowing the surgeon to build comfort and understand the limits and advantages of each device in their own hands. Practising with the devices, potentially in a pelvic trainer, is also recommended to gain a thorough understanding of tissue effects, assembly, and troubleshooting.

Device Selection

The sources make it clear that there is no single “ideal” energy device or a “clear winner” in the “battle of the vessel sealers”. The performance of an energy device is inherently dependent on the specific tissue effect or surgical purpose required. Consequently, the choice of energy source is a multi-factorial decision, influenced by:

  • Cost and availability of the devices and their proprietary electrosurgical units (ESUs).
  • The surgeon’s personal preference and experience. Preference is shaped by skill, judgment, experience, and whether a tool “feels right” or “works well” for a specific task.
  • The specific surgical procedure being performed and the presence or absence of significant pathology in the surgical field.

Despite the introduction of newer technologies, older modalities like monopolar electrosurgery and conventional bipolar electrosurgery continue to play a visible and important role due to their versatility and cost-effectiveness. This suggests that surgeons will likely rely on a combination of different energy sources or hybrid instruments.

Safety Protocols

A critical general consideration is the paramount importance of safety protocols due to the inherent risks associated with all energy devices.

  • Thermal Spread: All newer energy devices produce variable degrees of collateral undesired effects, including lateral thermal spread (LTS) and temperature rises above 45°C. It is crucial that these devices are used carefully near vital structures, as temperatures can reach over 40°C even 2mm away from the activation zone.
  • Power Settings and Activation: Surgeons should use the lowest possible power settings and limit the duration of activation to minimise the risk of tissue damage. Prolonged activation can lead to wider and deeper tissue harm.
  • Stray Current Injuries (SCI): Injuries from inadvertent energy transfer, particularly SCIs, are a well-documented risk with electrosurgery, often occurring outside the surgeon’s field of vision and not due to surgeon error but rather the physics of the energy. Mechanisms include capacitive coupling, insulation failure, and direct coupling.
    • Mitigation strategies include inspecting instrument insulation carefully, avoiding activation in open circuits or close proximity to other instruments, using all-metal cannula systems, and importantly, utilising Active Electrode Monitoring (AEM) systems. AEM can prevent SCIs by channelling capacitive current back to the ESU and by detecting insulation failures, triggering an instant shutdown.
  • Smoke and Aerosol Management: All energy devices generate smoke, vapour, and particulates, which can compromise visibility and pose potential acute and chronic health risks to operating room personnel. Smoke evacuation systems are recommended to mitigate these risks.
  • Equipment Checks: Regular checks of equipment before and during each use are essential, including ensuring proper placement of cords to avoid tangling or being tripped.
  • Basic Laparoscopy Rules: Adherence to the fundamental rules of laparoscopy at all times is necessary to ensure patient safety.

Post-Operative Vigilance

Finally, regardless of the energy source used, post-operative vigilance is a critical general consideration. The bowel and bladder, in particular, should always be thoroughly checked for perforation injuries or potential burns, especially after extensive dissections. Unrecognised injuries, particularly bowel injuries, may not present with overt symptoms immediately, often surfacing 4 to 10 days post-procedure with subtle signs such as low-grade fever, moderate abdominal discomfort, or a failure to recover at the expected rate. A high index of suspicion is therefore necessary, with prompt investigation and intervention if an iatrogenic injury is suspected, as delayed diagnosis significantly increases morbidity and mortality.

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