Types of electrosurgery

A distinction is made between monopolar and bipolar electrosurgery. In monopolar electrosurgery, the patient's entire body is a conductor. Electric current passes through it from the surgeon's electrode to the patient's electrode. Previously, they were called active and passive (return) electrodes, respectively. However, we are dealing with alternating current, where there is no constant movement of charged particles from one pole to another, but their rapid oscillations occur. The surgeon's and patient's electrodes differ in size, area of contact with tissue, and relative conductivity. In addition, the very term "passive electrode" causes insufficient attention from doctors to this plate, which can become a source of serious complications.

Monopolar electrosurgery is the most common system for delivering radiofrequency current in both open and laparoscopic procedures. It is fairly simple and convenient. The use of monopolar electrosurgery for 70 years has proven its safety and effectiveness in surgical practice. It is used for both dissection (cutting) and coagulation of tissue.

In bipolar electrosurgery, the generator is connected to two active electrodes mounted in one instrument. The current passes only through a small portion of tissue clamped between the jaws of the bipolar instrument. Bipolar electrosurgery is less versatile, requires more complex electrodes, but is safer, as it affects tissue locally. They work only in the coagulation mode. The patient plate is not used. The use of bipolar electrosurgery is limited by the lack of a cutting mode, surface burning, and the accumulation of carbon on the working part of the instrument.

Electrical circuit

A prerequisite for high-frequency electrosurgery is the creation of an electrical circuit through which current flows, producing cutting or coagulation. The components of the circuit are different when using monopolar and bipolar electrosurgery.

In the first case, the complete circuit consists of the ECG, the surgeon's voltage-supplying electrode, the patient's electrode, and the cables connecting them to the generator. In the second case, both electrodes are active and are connected to the ECG. When the active electrode touches the tissue, the circuit is closed. In this case, it is referred to as the electrode under load.

Current always follows the path of least resistance from one electrode to another.

When tissue resistance is equal, the current always chooses the shortest path.

An open but live circuit can cause complications.

In hysteroscopy, only monopolar systems are currently used.

Hysteroscopic electrosurgical equipment consists of a high-frequency voltage generator, connecting wires, and electrodes. Hysteroscopic electrodes are usually placed in a resectoscope.

Sufficient dilation of the uterine cavity and good visibility are essential for the use of electrosurgery.

The main requirement for the expanding medium in electrosurgery is the absence of electrical conductivity. High- and low-molecular liquid media are used for this purpose. The advantages and disadvantages of these media are discussed above.

The vast majority of surgeons use low-molecular liquid media: 1.5% glycine, 3 and 5% glucose, rheopolyglucin, polyglucin.

Basic principles of working with a resectoscope

1. High quality image.
2. Activation of the electrode only when it is in the visible zone.
3. Activation of the electrode only when it is moved towards the resectoscope body (passive mechanism).
4. Continuous monitoring of the volume of fluid introduced and excreted.
5. Termination of surgery if fluid deficit is 1500 ml or more.

Principles of laser surgery

The surgical laser was first described by Fox in 1969. In gynecology, the CO2 laser was first _used by Bruchat et al. in 1979 during laparoscopy. Subsequently, with the improvement of laser technologies, their use in surgical gynecology expanded. In 1981, Goldrath et al. first performed photovaporization of the endometrium with an Nd-YAG laser.

A laser is a device that generates coherent light waves. The phenomenon is based on the emission of electromagnetic energy in the form of photons. This occurs as excited electrons return from an excited state (E2) to a calm state (E1).

Each type of laser has its own wavelength, amplitude and frequency.

Laser light is monochromatic, has one wavelength, i.e. is not divided into components, like ordinary light. Since laser light is very slightly scattered, it can be focused strictly locally, and the area of the surface illuminated by the laser will be practically independent of the distance between the surface and the laser.

In addition to the laser power, there are other important factors affecting the photon: tissue - the degree of absorption, refraction and reflection of laser light by the tissue. Since each tissue contains water, any tissue boils and evaporates when exposed to laser radiation.

The light of argon and neodymium lasers is completely absorbed by pigmented tissue containing hemoglobin, but is not absorbed by water and transparent tissue. Therefore, when using these lasers, tissue evaporation occurs less effectively, but they are successfully used for coagulation of bleeding vessels and ablation of pigmented tissues (endometrium, vascular tumors).

In hysteroscopic surgery, the Nd-YAG laser (neodymium laser) is most often used, producing light with a wavelength of 1064 nm (invisible, infrared part of the spectrum). The neodymium laser has the following properties:

1. The energy of this laser is easily transferred through a light guide from the laser generator to the required point in the surgical field.
2. The energy of the Nd-YAG laser is not absorbed when passing through water and transparent liquids, and does not create directed movement of charged particles in electrolytes.
3. The Nd-YAG laser provides a clinical effect due to the coagulation of tissue proteins and penetrates to a depth of 5-6 mm, i.e. deeper than the CO2 _laser or argon laser.

When using the Nd-YAG laser, energy is transmitted through the emitting end of the light guide. The minimum power of the current suitable for treatment is 60 W, but since there is a small loss of energy at the emitting end of the light guide, it is better to use a power of 80-100 W. The light guide usually has a diameter of 600 μm, but light guides with a larger diameter can also be used - 800, 1000, 1200 μm. An optical fiber with a larger diameter destroys a larger surface area of tissue per unit of time. But since the effect of energy must also spread deeper, the fiber must move slowly to achieve the desired effect. Therefore, most surgeons using the laser technique use a standard light guide with a diameter of 600 μm, passed through the surgical channel of the hysteroscope.

Only a certain part of the laser energy power is absorbed by tissues, 30-40% of it is reflected and scattered. Scattering of laser energy from tissues is dangerous for the surgeon's eyes, so it is necessary to use special protective lenses or glasses if the operation is performed without a video monitor.

The liquid used to expand the uterine cavity (physiological solution, Hartmann's solution) is fed into the uterine cavity under constant pressure and simultaneously sucked out to ensure good visibility. It is better to use an endomat for this, but a simple pump can also be used. It is advisable to perform the operation under the control of a video monitor.

There are two methods of laser surgery - contact and non-contact, described in detail in the section on surgical interventions.

In laser surgery, the following rules must be observed:

1. Activate the laser only when the emitting end of the light guide is visible.
2. Do not activate the laser for a long period of time when it is in an inactive state.
3. Activate the laser only when moving towards the surgeon and never when returning to the fundus of the uterus.

Following these rules helps to avoid perforation of the uterus.