Local anesthesia is mainly used when it is only a small-area anesthesia of the skin (for example, a visit to the dentist) should be. A basic distinction is made between surface anesthesia and infiltration anesthesia and several other subtypes. The goal is always to eliminate pain in a specific part of the body for a certain period of time, while maintaining consciousness and motor function, in contrast to general anesthesia.
What is local anesthesia?
Local anesthesia is used primarily when only a small area of the skin is to be anesthetized (for example, during a visit to the dentist). Local anesthesia (also called local anesthesia) is an anesthetic in which the sensation of pain is temporarily switched off in a precisely defined area of the skin. The agents used in this process are called local anesthetics. These have their effect on the branches of the nerve endings directly in the subcutis and prevent the transmission of pain impulses to the brain. These nerve inhibitions are reversible and subside after some time. As a result, medical procedures can be performed without pain, while the ability to move and consciousness are not eliminated.
Function, effect, and goals
Local anesthesia is a branch of regional anesthesia, with two basic forms: infiltration anesthesia and surface anesthesia. In surface anesthesia, the appropriate agents are injected directly into the skin of the area where the surgery is to be performed. Typical examples are dental treatment or the removal of a birthmark. In infiltration anesthesia, sprays or drops may be applied with cotton swabs to the cornea, mucous membranes or conjunctiva. Typical of these procedures are gastroscopies, awake intubations (the insertion of a breathing tube into the mouth and throat) and eye examinations. Furthermore, a distinction is also made between conduction anesthesia, which involves entire regions of the body supplied by specific nerves. There is also intravenous regional anesthesia, in which a cuff is used to tourniquet an extremity and the anesthetic is then injected into a vein. There are also central line anesthesias (spinal anesthesia and peridural anesthesia), which work in such a way that spinal nerves close to the spinal cord are blocked, thus rendering several parts of the body painless for a certain period of time. There are shorter or longer acting local anesthetics. It is possible to add adrenaline to the anesthetic to extend the duration of action. This is because the adrenaline constricts the vessels, thereby restricting the blood flow to the tissue, so that the local anesthetics are effective for longer. It should be borne in mind that adrenaline must not be used on toes or fingers, for example, because otherwise the tissue may die. By using local anesthetics, treatments can be performed without pain, which would otherwise be accompanied by very unpleasant side effects for the patient. The advantage is that consciousness and motor function are preserved, so the patient “fully participates” in everything. For this reason, local anesthetics are also less risky than anesthetics that eliminate consciousness and motor function. In contrast to general anesthesia, local anesthetics hardly affect brain and lung function, acid-base balance, and metabolism. This allows treatment with local anesthetics even when the patient is in poor general condition and general anesthesia is too risky. Therefore, when possible, local anesthetics are predominantly used, while general anesthesia is used only when it is not possible to perform the treatment otherwise.
Risks and dangers
However, various allergic reactions can occur as a side effect of local anesthetics. These also represent the most common adverse side effects of these anesthetic procedures. Theoretically, poisoning (intoxication) can also occur in tissues with a good blood supply, where the local anesthetic is rapidly removed. This is accompanied by nervousness, dizziness and seizures. A drop in blood pressure and cardiac arrhythmia can also be the result. The latter side effects are very rare, however, as usually only very small areas of the skin are anesthetized.This means that the quantities of local anesthetics that could trigger poisoning are not required. In general, however, it can be said that local anesthetics are far less risky than general anesthesia, so when in doubt, these procedures are more likely to be used.
