Anesthesia

It is difficult to imagine а modern surgical intervention without anesthesia. At the same time, modern methods of pain relief provide not only the elimination of pain, but also the management of the main functions of the body during a surgical operation and in the immediate postoperative period.

An applied science such as anesthesiology has methods for controlling body functions using hypothermia, artificial hibernation, controlled hypo- or hypertension, and so on. Currently, the basis of anesthesiology is combined anesthesia, the main principle is the customised approach to each patient with a specific condition. Machine-controlled anesthesia with relaxants is the most common and one of the best methods of modern anesthesia.

According to the localization of the impact on the nervous system, the following types of anesthesia are distinguished:

1. Local anesthesia.
2. Conduction anesthesia.
3. Neuraxial.
4. General anesthesia.

1. Local anesthesia:

• this is a type of complete local anesthesia, aimed at the blockade of peripheral nerve receptors, fibers and ascending pathways of pain sensitivity in the central nervous system.

There are following options for the local anesthesia:

1. application (terminal, surface);
2. infiltration.

Thus, local anesthesia includes:

1. Superficial or application anesthesia. Anesthesia of the terminal sections of the peripheral nerves, as well as their receptors, can be achieved by lubrication or irrigation of the mucous membranes. The easiest way to perform local tissue anesthesia is applying local anesthesia (from the Latin applicatio), which is successfully used in dentistry, ophthalmology, otorhinolaryngology, etc. The feature of the surface anesthesia is that the local anaesthetic is applied on the surface of the mucous membrane or skin at the point of the intervention - most often the mucous membrane of the oral cavity or the skin. Due to the high concentration, application anesthetics quickly penetrate the oral mucosa or skin to a depth of 2–3 mm and block receptors and peripheral nerve fibers. It should be borne in mind that local anesthetics penetrate faster through а damaged mucous membrane (skin). The use of surface anesthesia is indicated for various low-traumatic interventions, which include the removal of temporary or permanent mobile teeth, the opening of submucosal abscesses, and painful manipulations on the gums. However, along with the advantages, the method also has significant disadvantages. The main disadvantage is the pronounced toxic effect. As a result, when applying superficial anesthesia, both local and systemic toxic effects are sometimes possible;
2. Infiltration anesthesia. It is a blockade of sensory nerves in the area of distribution of anesthesia in the submucosal layer. In general surgery, tissue infiltration is performed from the superficial layers to the deeper layers. First, a “lemon peel” is created intradermally with a thin needle throughout the projection of the skin incision. More deeply located tissues are infiltrated by moving the needle through the anesthetized skin. The infiltration method of anesthesia is widespread, which is explained by its simplicity, accessibility and effectiveness.

A variation of infiltration anesthesia is anesthesia of the cross-section of the limb, which is successfully used for limb amputation in severed patients.

Another type of infiltration anesthesia is local anesthesia according to A.V. Vishnevsky. The introduction of an anesthetic solution into tissues under significant pressure ensures direct contact of the anesthetic with receptors and nerve trunks. This is done by using a large amount of Novocaine solution, introduced by the method of tight layer-by-layer creeping infiltrate, spreading through the fascial and aponeurotic cases. The surgeon works alternately with a syringe and a scalpel. The advantage of this method is the possibility of using hydraulic tissue preparation. It is carried out with the help of a tight creeping infiltrate, which, pushing and separating the tissues, facilitates the isolation of the affected organs from the surrounding formations and adhesions. This method of anesthesia allows you to operate on almost all parts of the human body. The usage of 0.25% solution of Novocaine per operation can reach 1.5–3.0 liters. Due to the leakage of part of the anesthetic solution during tissue incision, intoxication is usually not observed.

2. Conduction anesthesia.

A type of local anesthesia with the injection of an anesthetic into the perineural tissue (perineurally) or directly into the large nerve itself (endoneurally).

The method of conduction, or regional, anesthesia is based on blocking the conduction of the nervous impulse throughout the sensory nerves. The anesthetic solution is injected directly into the perineural tissue. The proximity of the location of large blood vessels makes this anesthesia dangerous due to the possibility of damaging them. To avoid complications, the needle is brought to the location of the nerve trunk, first without a syringe: when the needle reaches the nerve trunk, the patient feels acute pain (paresthesia technique). To reduce the likelihood of complications and to verify the of nerve structures, neurostimulation (Stimuplex©) and ultrasound are used.