Anesthesia - General Anesthesia (general Anesthesia)

General anesthesia ("general anesthesia")

The word anesthesia comes from ancient Greek and is made up of “not” and “perception”. The term anesthesia also has its origins in ancient Greek and means something like “drowsiness”, “numb”, “freeze”. The two terms combine the various aspects of general anesthesia. An artificial, pain-free deep sleep is induced with medication. Some patients perceive the induction of general anesthesia as an unpleasant loss of control, most as a relaxed fall asleep.

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• Principle of general anesthesia
• How is the risk to be assessed?
• What consequences and complications can arise?

Principle of general anesthesia

General anesthesia consists of several components:

• Pain elimination: For induction of anesthesia and during the operation, the strongest painkillers are administered, often in combination with weak painkillers in order to increase the effectiveness and reduce side effects. The place of action of these substances is in the central nervous system or in the operated tissue.
• Loss of consciousness: In order to fall asleep quickly and to maintain deep sleep, highly effective medication is administered via the intravenous cannula or via the ventilation mask or ventilation tube. The place of action of these substances is in the central nervous system.
• Muscle relaxation: In order to achieve optimal operating conditions and to be able to insert the ventilation tube safely, drugs are administered that lead to relaxation of the muscles. The place of action of these substances is directly in the muscle tissue.

Artificial ventilation is an absolute necessity for general anesthesia. This ensures that the organism is supplied with fresh, oxygen-containing air and that the exhaled air is exhaled. Various breathing aids are used to ensure ventilation. This depends on the type and duration of the operation as well as the patient's individual factors. The range of breathing aids ranges from plastic tubes (tubes) to larynx masks and face masks. Inserting a tube is called intubation. The tube is connected to a ventilator via a hose. It also prevents blood, saliva, or gastric juice from reaching the lungs. The intubation only takes place during the patient's deep sleep and is therefore not noticed by the patient.

There are two ways to continue an induced general anesthetic:

• Inhalation anesthesia: The medication for deep sleep is added to the air by the ventilator in precisely controllable doses. Painkillers and muscle relaxing medication are administered through the intravenous cannula (balanced anesthesia).
• Intravenous anesthesia, "total intravenous anesthesia" (TIVA): All medications (pain relievers, sleeping pills, muscle relaxing medication) are administered via the intravenous cannula. With a special drug pump, painkillers and sleeping pills are given continuously.

As soon as the surgical procedure is finished, the drainage of general anesthesia begins. To do this, the anesthetist switches off the supply of anesthetic gases or intravenous anesthetic medication. Before doing this, it is ensured that the muscle-relaxing medication has been completely broken down, so that the patient's own breathing is sufficient and the breathing aid can be safely removed. If the muscle strength is insufficient, a drug to relieve muscle relaxation may have to be administered. Some sleeping pills can also be counteracted by antidotes. When the general anesthesia is diverted, an adequate dose of analgesics is maintained in order to ensure a painless and stress-free waking up.

After the general anesthesia, further monitoring and therapy take place depending on the procedure, the severity of the accompanying illnesses and the patient's risks in the recovery room or in the intensive care unit. Most people cannot remember waking up or preparing in the operating room in general. The reason for this are the sleeping pills administered.

How is the risk to be assessed?

Many patients are concerned about the thought of not waking up from general anesthesia. However, the risk of dying from general anesthesia is very low these days. Very old and very sick people as well as very young children have a slightly higher risk of anesthesia. Thanks to modern monitoring techniques and medication, as well as the anesthesiological safety culture, incidents hardly occur any more.

What consequences and complications can arise?

There is a long list of possible consequences and complications for general anesthesia. Even if these rarely occur, the patient must be informed about them before giving their written consent. The exception due to the patient's express waiver of information does not apply to all operations (e.g. not in cosmetic surgery).

Problems can arise during general anesthesia even if performed properly, such as:

• Drug allergies,
• Drug side effects,
• Cardiovascular and pulmonary complications,
• Injuries in the area of the nose, throat, airways, teeth, vocal cords or in the upper digestive tract,
• Awakening during general anesthesia,
• pain, nausea and / or vomiting, feeling cold and / or trembling after surgery.

In order to reduce the risk, a preliminary talk including notification of allergies, the optimization of physical resilience and preparation with adherence to fasting times are essential.

Common complications of general anesthesia:

• Nausea and vomiting: This affects around 15% of patients after general anesthesia, even with preventive administration of anti-nausea medication. The causes are varied, including a personal disposition (e.g. tendency to travel sickness), the type of operation and the anesthetic and emergency medication previously administered. Medicines for this undesirable complication can be administered into the IV cannula. Any tendency to nausea should be reported to the anesthesia team to avoid certain anesthetic procedures.
• Hoarseness and sore throat: Local irritation in the throat area can also occur with proper introduction and ventilation via the breathing aids (tube, larynx mask). The irritation usually disappears within the first 24 hours after the procedure.
• Feeling cold and trembling: This complication usually only occurs briefly after the anesthesia has been drained. It can be caused by cooling down during the operation in the operating room (despite the use of patient warming systems) or by the anesthetic medication. Active warming and pain relievers can help.
• Tooth damage: Sometimes teeth are damaged despite correct handling while using the breathing aids (tube, larynx mask). Incisors that were previously loose are particularly at risk.
• Pain: The perception of pain is subjective and individual. Despite pain medication after the operation, additional pain therapies may be necessary in individual cases. These are adapted to the respective needs. Many departments have acute pain concepts in order to achieve the goal of a “painless hospital”.

Note Very rarely, life-threatening complications can occur with general anesthesia: aspiration (inhalation of vomit or foreign bodies, blood into the lungs), malignant hyperthermia (with genetic predisposition). In very few cases, after an operation, there may be temporary problems with thinking and behavior, as well as impaired consciousness.

In addition, there are patient-dependent risk factors for complications. For example, being seriously overweight can increase the risk of intubation and ventilation problems. In addition, measures that may be carried out during anesthesia can cause undesirable side effects and consequential effects, e.g.:

• Insertion of central venous catheters or invasive blood pressure measurement: pain, cardiac arrhythmias, bleeding, infection, injuries to the lungs, heart, nerves, vessels and their treatment.
• Urinary catheter: sensation of pain, bleeding, infection, injuries to the urethra, bladder and neighboring structures.
• Insertion of a nasogastric tube and ultrasound of the heart via the esophagus: sensation of pain, tooth damage, injuries in the oropharynx, esophagus, chest and stomach, bleeding, infection.
• Administration of foreign blood products: Infections (hepatitis, HIV and other infections), and transfusion reactions.