Current Status and Future Prospects of Electrosurgical Equipment Research

Electrosurgical devices (commonly referred to as electrosurgical units) are the most widely used and highest value-added devices in surgical procedures. Broadly defined, electrosurgical devices refer to equipment that utilizes high-frequency electrical energy to perform operations such as tissue cutting, separation, and hemostasis, including high-frequency electrosurgical units, bipolar electrosurgical units, radiofrequency knives, ion knives, argon plasma coagulators, and liposuction knives. In a narrow sense, electrosurgical equipment refers to high-frequency electrosurgical knives that directly utilize the principle of high-frequency alternating current to generate heat through tissue, thereby achieving tissue separation and vascular coagulation [1]. A typical high-frequency electrosurgical knife generally consists of a high-frequency power source and surgical electrode plates. The current flows through the human body and returns to the high-frequency power source via the electrode plates, generating heat at the point of contact between the electrosurgical knife and the tissue to achieve tissue cutting and hemostasis. With advancements in materials and manufacturing processes, after several generations of improvements, various types of electrosurgical instruments capable of adapting to different surgical scenarios are now widely used in clinical practice. To help clinicians better understand and select electrosurgical equipment suitable for surgical needs, and to fully leverage the precision and efficiency advantages of high-frequency electrosurgical instruments, this article provides an overview of the current status and future prospects of electrosurgical equipment.

1. The Birth of Electrosurgery and High-Frequency Electrosurgical Instruments

In the early days of surgery, tissue and organs were primarily separated using surgical blades, and necrotic or tumorous tissue was excised. However, the sharpness of the blades inevitably led to bleeding from ruptured nearby blood vessels. Surgeons could only achieve hemostasis through methods such as applying pressure, ligating vessels, or applying a hot iron to the wound surface. As early as 3000 BCE, the Egyptians had already used cauterization to treat tumors and achieved good hemostatic effects [2]. The basic principle of high-frequency electrosurgical knife therapy is cauterization, so electrosurgery was initially referred to as diathermy and developed as a surgical technique based on cauterization therapy. The 20th century marked a period of rapid development for electrosurgery, which was also referred to as radiofrequency surgery at the time. This technique involves introducing shortwave radiofrequency (RF) current into tissue, causing it to generate heat, thereby achieving the effects of tissue disruption, vessel coagulation, or tissue destruction. Unlike cauterization, electrosurgical procedures involve the current heating the local tissue as it passes through it, rather than the electrosurgical probe itself generating heat, thereby enhancing surgical safety and controllability. During his exploration of radium therapy for cancer, William T. Bovie accidentally discovered that high-frequency currents had effects similar to those of radium rays. This significant discovery inspired him to develop electrosurgical equipment, and he ultimately succeeded in inventing it [3]. In 1926, Dr. Bovie successfully removed an intracranial vascular tumor at Brigham Hospital in Boston, marking the widespread recognition of electrosurgical devices in the medical community. Electrosurgical equipment was subsequently rapidly commercialized and became the most widely used and valuable device in surgical procedures [4]. To this day, the clinically well-known Bovie knife is named after William T. Bovie, commemorating his inventions and contributions in the field of electrosurgery.

2. Basic Principles of Electrosurgical Equipment

Electrosurgical instruments are surgical tools that utilize the principle of high-frequency alternating current heating to evaporate tissue moisture, thereby achieving tissue separation and hemostasis functions [5]. Electrosurgical equipment consists of a high-frequency generator and two electrodes. The current is applied to the surgical site via a small active electrode (electrosurgical needle tip), passes through the patient's body, and returns to the electrosurgical unit via a negative electrode plate (large-area contact) connected to the patient's body. The fundamental principles involved include the electrolytic effect, the Faraday effect, and the thermal effect [6]. The electrolytic effect causes ion polarization within the tissue under the influence of low-frequency alternating current, leading to chemical burns in muscle tissue due to high ion concentration. Additionally, low-frequency alternating current is close to the frequency of human nerve conduction, potentially causing nerve conduction disorders, muscle stimulation, or even cardiac arrest, which can be life-threatening—this is the Faraday effect. The high-frequency alternating current used in electrosurgical devices is significantly higher than the frequency of human nerve conduction, thereby avoiding the electrolytic effect and Faraday effect, making it safe for use on the human body [7].Thermal effects include heat generation and thermal tissue damage, with heat generation occurring exclusively in high-current-density tissue regions adjacent to the electrosurgical knife tip. In this region, current flowing through the tissue converts electrical energy into thermal energy, thereby causing localized thermal tissue damage. As the distance from the electrode increases, the current density in deep tissues decreases rapidly, thereby limiting the extent of damage [8]. The electrocoagulation and electrosurgical cutting functions of high-frequency electrosurgical instruments rely on thermal tissue damage: in electrocoagulation mode, the current density is slightly lower, and electrocoagulation occurs when the tissue in the high-current density region is heated to the boiling point and undergoes thermal denaturation; in electrosurgical cutting mode, the current density is higher than in electrocoagulation mode, and the high current density causes the tissue temperature to rise sharply, leading to rapid evaporation and fragmentation of tissue moisture near the electrode, thereby achieving electrosurgical cutting. When using an electrosurgical knife to cut tissue, the high-frequency current causes tissue heating and evaporation, separating the electrode from the tissue. However, current can still be transmitted via electrical sparks [9]. Therefore, the high-frequency electrosurgical knife can continue to function without direct contact with the tissue. The higher the voltage or the larger the electrode tip area, the larger the sparks generated and the broader the diffusion range.

3. Classification of electrosurgical equipment

3.1 General high-frequency electrosurgical knife

A high-frequency electrosurgical knife is an electrosurgical instrument used to replace traditional surgical knives for tissue cutting or hemostasis, and it is the most representative device among electrosurgical equipment [10]. Conventional high-frequency electrosurgical knives can be divided into two types based on the working mode of the current circuit: monopolar electrosurgical knives and bipolar electrosurgical knives. Monopolar electrosurgical knives require a negative electrode plate, high-frequency electrosurgical knife, electrosurgical knife main unit, and the human body to form a circuit, with current flowing through the patient's entire body to perform hemostasis and cutting operations. Bipolar electrosurgical units do not require a negative electrode plate. The current circuit is formed by the high-frequency electrosurgical unit main unit and the bipolar electrosurgical unit, with current flowing directly from one end of the bipolar electrosurgical unit to the other. During operation, current only passes through the tissue requiring coagulation or cutting, significantly reducing the area of the patient's body through which current flows and minimizing its impact on other body parts. Bipolar electrosurgical units are commonly used in neurosurgery, plastic surgery, thyroid surgery, and other surgical procedures requiring precise manipulation [11]. However, conventional high-frequency electrosurgical units tend to cause localized carbonization and eschar formation when applied to tissue, and when used on tissue with high fat content, significant fat liquefaction occurs [12].

3.2 Adaptive High-Frequency Electrosurgical Unit  

The principle behind early high-frequency electrosurgical units for electrosurgical resection and coagulation involved delivering a constant current into tissue. However, since different tissues have varying resistances, this led to unstable power output from the electrosurgical unit when separating different tissues. During use, if the power was too low, cutting efficiency was poor; if too high, it could generate sparks, causing tissue damage or excessive cutting depth. To ensure smoother operation of high-frequency electrosurgical units and minimize tissue damage, German engineer Helmut Erbe developed the ICC (Intelligent Cut Coagulation) series of electrosurgical units in 1992, also known as adaptive electrosurgical units [13]. The principle of adaptive electrosurgical units is based on a feedback mechanism: when the electrosurgical unit's electrode contacts tissue, if the tissue's resistance or current changes, the electrosurgical unit's main unit receives a feedback signal and adjusts accordingly.Subsequently, through continuous development, the speed of feedback regulation has become increasingly faster, and the continuity of surgical procedures has also improved significantly [14]. This high-frequency electrosurgical knife can control power output, maintaining a constant output power during the cutting of different tissues. This ensures stable surgical outcomes when cutting different tissues while automatically reducing power after completion to minimize collateral damage [15]. Additionally, adaptive electrosurgical instruments can reduce the generation of electrical sparks during surgical procedures, thereby making electrosurgical procedures safer and more efficient. The emergence of adaptive electrosurgical instruments has not only improved surgical efficiency but also significantly reduced tissue damage during procedures, opening new opportunities for the development of electrosurgical procedures.

3.3 Argon Plasma Coagulator

The argon plasma coagulator, also known as the argon knife, is a high-frequency electrosurgical instrument that ionizes argon gas into conductive argon ions using high-voltage current, enabling the continuous transmission of high-frequency current to tissue [16]. The argon knife is an upgraded version of the traditional high-frequency metal electrosurgical knife, featuring an additional argon gas channel. During electrosurgical cutting and coagulation, argon gas flow helps conduct current to the wound surface, achieving effects such as reducing charring and stabilizing wound coagulation. In traditional electrosurgical knives, when current is conducted through an electric spark, the medium is air. The oxygen in the air causes the burned tissue to undergo oxidation reactions and continuously generate heat, leading to large areas of charring at the wound site. The argon knife tip can spray argon gas, isolating the electrode and tissue from the surrounding air to form an argon gas barrier. This reduces contact between the tissue wound and air during operation, preventing oxidative reactions that generate excess heat and large areas of charring [17]. Additionally, since the argon knife transmits current via argon ions, the electrosurgical blade does not come into direct contact with the tissue, thereby preventing charred tissue from adhering to the blade.

When using a conventional high-frequency electrosurgical knife for wound hemostasis, continuous bleeding from ruptured vessels makes it difficult for high-frequency current to be sustained at the wound site, resulting in poor coagulation efficacy and difficulty in controlling active bleeding. When the argon plasma coagulator is applied to the wound, it can disperse local blood by喷射ing an argon gas stream, ensuring that high-voltage current is continuously introduced into the wound, thereby producing local coagulation and achieving excellent hemostatic effects[18]. When tissue at the wound site undergoes coagulation, the local tissue resistance increases, causing argon ions to automatically flow toward the surrounding tissues with lower resistance, forming a relatively stable coagulated wound surface and ensuring local coagulation hemostasis. Therefore, the argon plasma coagulator can effectively coagulate and close local vessels while minimizing damage to surrounding or distal vessels, making it more suitable for tissues with abundant blood vessels. This achieves the effect of significantly reducing bleeding at the surgical wound site and shortening surgical time [19].

3.4 Bipolar Vascular Sealing Technology  

Bipolar vascular sealing technology evolved from bipolar electrosurgical knife technology and is currently a widely used electrosurgical technique. It is routinely used to seal vessels with a diameter of 5 mm and has been extensively applied in various laparoscopic and open surgeries. Unlike bipolar electrosurgical knives, bipolar vessel sealing devices require operation under tension-free conditions, with both ends mechanically contacting each other. Through mechanical compression between the device's two electrodes and the application of electrothermal energy, current is generated on the vessel wall. The localized current causes denaturation of collagen and elastic proteins in the vessel wall, and the denatured collagen and elastic proteins coagulate to seal the vessel, thereby achieving safe and reliable vessel sealing. The latest bipolar vessel sealing technology can even coagulate and seal vessels with a diameter of 7 mm, and the sealed vessels can withstand three times the normal systolic pressure, ensuring hemostasis at the surgical site. However, when clamping a large amount of tissue, protein denaturation and coagulation require a certain amount of time, and after bipolar hemostasis and coagulation, the electrodes are prone to adhering to eschar, resulting in suboptimal efficiency of the bipolar vessel sealer.

3.5 LEEP Knife

The LEEP knife, also known as the loop electrosurgical excision procedure, is a type of radiofrequency electrosurgical knife. It is a specialized minimally invasive electrosurgical instrument developed in recent years for the treatment of diseases in the cervix and other areas. Unlike high-frequency electrosurgical knives, which output high-frequency currents ranging from 0.1 to 2.9 MHz, the radiofrequency knife generator outputs high-frequency radio waves with a frequency of 3.0 to 4.0 MHz. The principle of the LEEP knife involves introducing high-frequency radio waves into the tissue, causing polar water molecules within the tissue to oscillate, generate heat, vaporize, and decompose, thereby cutting the tissue. After the severed blood vessels contract, the collagen in the vessel walls denatures, causing the vessels to coagulate and close, thereby achieving hemostasis. The electrode plate of a high-frequency electrosurgical knife must come into direct contact with the patient's skin, whereas the electrode plate of a radiofrequency knife does not need to touch the patient; it can simply be placed beneath the surgical site. Additionally, the radiofrequency knife does not heat up during operation, allowing for cutting and coagulation at low temperatures, making it widely used in dermatology, plastic surgery, and other fields. The LEEP knife does not produce charred tissue at the incision site, does not alter tissue characteristics, and is easy to operate. It is widely applied in gynecological diagnosis and treatment, particularly showing significant advantages in treating cervical intraepithelial neoplasia. It effectively reduces patient trauma, lowers the risk of disease recurrence, promotes postoperative recovery, and improves patients' quality of life [20,21].

3.6 Multifunctional Electrosurgical Instruments  

In recent years, a series of multifunctional high-frequency electrosurgical instruments have been developed to address various clinical needs, with the most representative being electrosurgical instruments and electrosurgical hooks equipped with suction devices. These multifunctional high-frequency electrosurgical instruments feature suction ports at the tip of the standard electrosurgical instrument or hook, connected via a central tube to the suction connection tube at the rear end, thereby integrating traditional electrosurgical cutting, coagulation, and negative pressure suction functions. When there is excessive bleeding in the surgical field, the surgeon can activate the suction switch on the handle of the electrosurgical hook to create negative pressure, functioning as a suction device. This allows for rapid and effective clearance of the surgical field, improved work efficiency, and reduced surgical duration. The second commonly used type of multifunctional electrosurgical knife is the suction-integrated electrosurgical knife. This multifunctional electrosurgical hook combines suction and irrigation functions, achieving unified multifunctionality and multi-channel capabilities. This reduces surgical duration and alleviates patient discomfort. There is also an extendable multifunctional electrosurgical hook, which features an outer sheath on the electrosurgical hook shaft, allowing the hook to move forward and backward within the sheath. The handle section is equipped with a grip, enabling precise control of the hook's position. This extendable hook eliminates the bouncing phenomenon associated with traditional hooks (caused by sudden reductions or loss of tissue tension, leading to surrounding tissue damage), expands the hook's application range, and enhances safety.

4. Future Prospects for Electrosurgical Devices

Electrosurgical devices have evolved from conventional high-frequency electrosurgical knives to bipolar electrosurgical knives, adaptive electrosurgical knives, vascular sealing technology, and argon plasma coagulators, establishing high-frequency electrosurgical knives as stable, safe, and routine surgical instruments [22]. Adaptive electrosurgical instruments deliver a stable voltage across various tissues, enabling smooth cutting of different tissues while ensuring cutting efficiency without causing damage to adjacent tissues due to excessive current. Vascular sealing technology uses computer algorithms to promptly interrupt the current, preventing thermal damage caused by continuous current output. Argon plasma coagulators utilize argon gas streams to achieve non-contact conductivity, isolating tissues from oxygen to reduce thermal damage caused by oxidative reactions and minimize extensive charring. In recent years, high-frequency electrosurgical units have evolved toward multifunctional applications, giving rise to smoke-extraction electrosurgical units, suction-integrated electrosurgical units, and retractable electrosurgical units. Each type of electrosurgical unit has its unique advantages, allowing clinicians to select the appropriate device based on the specific surgical procedure. With each innovation, electrosurgical units have become increasingly safe and stable, with an expanding range of applications—a trend that represents the inevitable direction of future development in this field.

In the era of highly developed intelligent technology, high-frequency electrosurgical instruments are also becoming increasingly intelligent. For example, intelligent electrosurgical devices for monopolar cutting can balance cutting resistance and thermal damage by controlling output power, thereby reducing thermal damage without compromising cutting performance and maintaining maximum cutting efficiency [23]. Intelligent eco-friendly high-frequency electrosurgical instruments are equipped with real-time feedback systems, spark suppression systems, automatic alarm systems, and smoke evacuation systems, addressing the bottleneck challenges in the industrialization of high-frequency electrosurgical instruments. In the future, high-frequency electrosurgical instruments and electrosurgery will continue to evolve toward greater intelligence [24]. High-frequency electrosurgery is a multidisciplinary field that integrates electronics technology and surgery. As long as scientific progress continues, the development of electrosurgery will not stagnate. It is believed that future electrosurgical devices will be applied to a wider range of surgical procedures, with broader application scenarios, enhanced safety, and gradual intelligence.