Local anesthesia

Introduction

Local anesthesia is the local anesthesia by eliminating pain from nerves and pathways without affecting consciousness. The local anaesthesia is always reversible and can be used for surgical procedures and painful examinations as well as for pain therapy.

Duration of stunning

The duration of local anesthesia can vary widely. The decisive factors here are the quantity, the substance and the concentration of the drug used for anaesthesia. For fingers and toes, the amount of the anesthetic is limited to 4 ml, as otherwise the blood circulation of the fingers could be disturbed.

The effect ends on average between 2 and 16 hours by breaking down and transporting the anaesthetic in the blood and distributing it to the surrounding tissue. The effect slowly diminishes and sensations such as pain and temperature gradually return. For such operations under local anesthesia it is important to be prepared for the return of pain after an operation, despite the initial freedom from pain, and to have sufficient painkillers at hand or to have them prescribed by a doctor.

How long a local anaesthetic is effective depends on which drug is used. In addition, the substances also differ in their onset of action. For example, lidocaine, a very common local anesthetic, is painless in the area of application within a few minutes. Afterwards it works for about one to two hours. Bupivacaine, another local anesthetic, is effective for two to five hours, but takes a little longer to take effect after the injection.

Side effects of local anesthesia

Important side effects of local anesthetics are allergic reactions and disorders of the central nervous system and the cardiovascular system. Within the scope of allergic reactions, symptoms can occur on the skin (e.g. urticaria, so-called hives) or on the whole body, in the sense of asthma attacks, bronchospasm and drop in blood pressure. In the worst case, an anaphylactic shock with circulatory arrest may occur.

However, this side effect occurs mainly with local anesthetics of the ester type, which are rarely used today. The influence on nerve cells can cause a typical metallic taste, also sensory disturbances in the area of the mouth and tongue are possible. Further side effects are restlessness and muscle twitching, up to and including seizures, as well as changes in the sense of speech, sight and hearing.

Higher doses can lead to paralysis of breathing and circulatory arrest. With regard to the cardiovascular system, a slowed heart rhythm and disturbances of the excitation conduction at the heart can occur. These can be reasons for a drop in blood pressure and circulatory arrest.